Mach 1 Acoustics M-2600 Service manual

M2600

Page 3 is interactive

Go To Bulletins

FR Series Power Amplifier

SERVICE MANUAL

1998, 1999 MACKIE DESIGNS, INC.

820-180-00

SERVICE ON THIS EQUIPMENT IS TO BE PERFORMED BY

EXPERIENCED REPAIR TECHNICIANS ONLY

2

CONTENTS

Click on any item to open that page

ALL BOARDS

INTRODUCTION .................................................................................3

Technical Support ........................................................................ 3

Disclaimer.......................................................................................3

BLOCK DIAGRAM ............................................................................. 4

SPECIFICATIONS ................................................................................ 5

TROUBLESHOOTING TIPS ............................................................... 6-7

RELIABILITY VERIFICATION ........................................................... 8-9

CIRCUIT THEORY ........................................................................ 10-13

ASSEMBLY DRAWINGS .............................................................. 14-19

PARTS LIST ................................................................................... 20-30

FOLD-OUT SECTIONS: schematics and pcb layouts

Channel 1 .............................................................................. 129-1

Channel 2 .............................................................................. 130-1

Input board........................................................................... 131-1

Display board........................................................................ 132-1

Power Distribution and in-rush limit..................................... 133-1

Voltage Amp and protection............................................ 170-1

Power Supply ........................................................................ 171-1

Output board ....................................................................... 172-1

15 V supply/Fan drive board ............................................. 186-1

INTRODUCTION

SERVICE ON THIS EQUIPMENT IS TO BE PERFORMED BY

EXPERIENCED REPAIR TECHNICIANS ONLY

This manual contains basic service information. It is essential that you have a
copy of the user’s manual as this contains the complete operating instructions.

SERVICE TECHNICAL ASSISTANCE

Mackie Designs, Service Technical Assistance, is available 8AM - 5PM PST, Monday through
Friday for Authorized Mackie Service Centers, at 1-800-258-6883. Feel free to call with any
questions and speak with a carefully-calibrated technician. If one is not available, leave
a detailed message and a qualified Mackoid will return your call asap.

DISCLAIMER

The information contained in this manual is proprietary to Mackie Designs, Inc. The entire
manual is protected under copyright and may not be reproduced by any means without
express written permission from Mackie Designs, Inc.

3

Block diagram

–3

OL

SIG

CH 1

+115VDC

–9

–6

DRIVE

METER

FUSE

+100VDC

SIG

–20

+15VDC

CH.1 GAIN

RELAY

OUTPUT

CHANNEL 1

CH. 1

SPEAKER

+

POWER

AMPLIFIER

LIMITER

OUT

CH. 1

-

SPEAKON

1-

1+

BRIDGED

1+

MONO

SPEAKON

1-

CH. 2

SPEAKON

1+

OUT

CH. 2

SPEAKER

-

+

1-

C MUTE

C MUTE

C UN-MUTE

C UN-MUTE

0

0

0

0

80

52

52

80

FAN

CH.1 MUTE

HOT LED

COLD LED

CH.2 MUTE

DETECTOR

OVER TEMPERA TURE

TRANSFORMER

THERMAL SWITCH

CH 1

TEMP

VARIABLE SPEED FAN CONTROLLER

SENSOR

0

0

C SPEED CONTROL CH.1

0

C – 65

0

45

CH 2

C SPEED CONTROL CH.2

C – 65
45

TEMP

FAN IDLE/V ARIABLE CH.1 PO WER DETECTOR

CH.1 DISSIPATION

SENSOR

FAN IDLE/V ARIABLE CH.2 PO WER DETECTOR

CH.2 DISSIPATION

-30VDC

+30VDC

MUTE

FUSE

+15VDC

–100VDC

INVERTER

OPERATION)

(FOR BRIDGED MONO

PROTECTION CIRCUITRY

–115VDC

PROTECT

MUTE

PROTECT

DC OFFSET

SHORT

SHORT

OUTPUT STAGE CURRENT

RELAY

OUTPUT

–3

–9

OL

–6

SIG

–20

PROTECT

PROTECTION CIRCUITRY

–115VDC

MUTE

DC OFFSET

PROTECT

SHORT

SHORT

SHORT 2

TRANSIENT SOA FLT

OUTPUT STAGE CURRENT

OUTPUT STAGE VOLTAGE

CH.2 DISSIPATION

IN-RUSH CONTROL

OUTPUT DISSIPATION

STEADY ST ATE SOA FLT

LOW VOL T AGE DETECT

22VAC

–

+

CH.1 DISSIPATION

SHORT 1

IN-RUSH CONTROL

TRANSIENT SOA FLT

OUTPUT DISSIPATION

STEADY ST ATE SOA FL T

OUTPUT STAGE VOL TAGE

LOW VOL T AGE DETECT

22VAC

SIG

CH 2

+115VDC

DRIVE

METER

FUSE

+100VDC

+15VDC

POWER

AMPLIFIER

CHANNEL 2

MUTE

FUSE

+15VDC

–100VDC

LIMITER

CH.2 115 VDC

–

+

CH.1 115 VDC

CH.2 GAIN

SHORT 2

SHORT 1

(THE SHORT LEDS ARE

JOINED IN BRIDGED MODE)

STEREO-MONO-BRIDGED

LIMIT–OFF-LOW OUT

60-90-120Hz

SIG

CH 1

FREQ

–

+

CH.2 100 VDC

STEREO-MONO-BRIDGED

Σ

STEREO-MONO-BRIDGED

–

+

22 VAC

+

–

30 VDC

+15 VDC

-15 VDC

CH.1 100 VDC

LIMITER

CROSSOVER

LOW CUT

CONTROL

CH–1

CH–2

LIMIT–OFF-LOW OUT

IN-RUSH CONTROL

TRANSFORMER

TOROIDAL PO WER

LIMIT

IN-RUSH

SWITCH

FUSE

LAMP

POWER

THRU–LOW–HIGH

FILTER

THERMAL

TRANSFORMER

(THE CHANNELS ARE

SUMMED IN MONO

OR BRIDGED MODE)

LIMIT–OFF-LOW OUT

LOW

HIGH

CROSSOVER

SIG

CH 2

60-90-120Hz

LOW

HIGH

THRU–LOW–HIGH

FILTER

LOW CUT

FREQ

MACKIE DESIGNS

M•2600

BLOCK DIAGRAM

(1/4" TRS)

LINE INPUT

LINE INPUT

(XLR-FEMALE)

(XLR-MALE)

THRU OUTPUT

(1/4" TRS)

LINE INPUT

LINE INPUT

(XLR-FEMALE)

(XLR-MALE)

THRU OUTPUT

9/21/1998

4

Specifications

Maximum Power at 1% THD, midband:

500 watts per channel into 8Ω
850watts per channel into 4Ω
1300 watts per channel into 2Ω
1700 watts into 8Ω bridged
2600 watts into 4Ω bridged

Continuous Sine Wave A verage Output Power,
both channels driven:

425 watts per channel into 8Ω from 20Hz to 20kHz,
with no more than 0.025% THD
700 watts per channel into 4Ω from 20Hz to 20kHz,
with no more than 0.05% THD
1000 watts per channel into 2Ω from 20Hz to 20kHz,
with no more than 0.1% THD

Bridged mono operation:

1,400 watts into 8Ω from 20Hz to 20kHz, with no more
than 0.05% THD
2000 watts into 4Ω from 20Hz to 20kHz, with no more
than 0.1% THD

Note: Power ratings are specified at 120VAC line voltages.
The M2600 power amplifier draws large amounts of

current from the AC line with continuous sine wave test­ing. Accurate measurement of power requires a steady
and stable AC supply. This means the line impedance
must be very low to insure that the peak AC line voltage
does not sag to less than 97% of its value.

If driving highly reactive loads, we recommend that the
limiter circuit be engaged.

Power Bandwidth:

20Hz to 70kHz (+0, -3 dB) @ 700W into 4 Ω

Frequency Response:

20Hz to 40kHz (+0, -1 dB)
10Hz to 70kHz (+0, -3 dB)

Distortion:

SMPTE IMD, TIM < 0.025% @ 8Ω

< 0.050% @ 4Ω
< 0.150% @ 2Ω

Signal-to-Noise Ratio:

> 107 dB below rated power into 4Ω

Channel Separation:

> 80 dB @ 1kHz

Damping Factor:

> 350 @ 400Hz

Input Impedance:

24kΩ balanced

Input Sensitivity:

1.23 volts (+4 dBu) for rated power into 4 ohms

Gain:

32.7 dB (43V/V)

Maximum Input Level:

9.75 volts (+22 dBu)

Rise Time:

< 5µs

Slew Rate:

Voltage Slew Rate > 60V/µs
Current Slew Rate> 30A/µs at 2Ω

CMRR:

> 40 dB, 20Hz to 20kHz

Load Angle:

8(±jx) time independent at 8Ω
4(±jx) time dependent, T > 6 min. at 4Ω
2(1±jx) time dependent, T > 2 min. at 2Ω

Transient Recovery:

< 1µs for 20 dB overdrive @ 1kHz

High Frequency Overload and Latching:

No latch up at any frequency or level.

High Frequency Stability:

Unconditionally stable, driving any reactive or
capacitive load.

Turn On Delay:

3-5 seconds

Variable Low-Cut Filter:

10Hz (Off) to 170Hz, 2nd-Order Bessel

Internal Crossover:

Switched: 60Hz/90Hz/120Hz, 4th-Order Linkwitz-Riley
Lowpass outputs switchable to internal Subwoofer
mode.
Lowpass and Highpass outputs switchable to Thru
output jacks.

Limiter Section:

Complementary Positive and Negative Peak Detecting

Indicators:

6 meter LEDs per channel

SIG (Signal Present), -20, -9, -6, -3, OL (Overload)

CH 1 & 2

PROTECT LEDs
SHORT LEDs

TEMP STATUS

COLD/HOT LEDs

Physical:

(three rack spaces high, standard rack width)
Height 5.20 inches (132mm)
Front panel Width 19.00 inches (483mm)
Chassis Width 17.24 inches (438mm)
Depth 15.65 inches (398mm)
Overall Depth 16.67 inches (423mm)
Handle Depth 1.64 inches (42mm)
Weight 55 pounds (25 kg)

5

Troubleshooting Tips-output failures

After a catastrophic failure, it is likely that some of the supply fuses will be blown. Check and
replace any fuses on the 129, 130, 133, and 171 boards. Short across the Left most lead of R1 to
the right most lead of R2 on the 133 board to short out the two 15W inrush resistors (see the
diagram on the next page). Very slowly bring up the Variac while monitoring line consumption.
It is likely that substantial line current will be pulled due to shorted output parts. If excessive
current is not pulled, but a channel still stays in “protect” mode, the unit will still need repair.

Remove the main heatsink sub-assembly from the unit and check for shorted output
transistors. Once it has been determined which channel failed, remove it’s respective V-amp/
Protection board (055-170-00) to make access to the channel board easier. If one bad output is
found, replace all 16 in the channel. When an output device shorts it can place high current
stresses on the other output parts. These output parts can fail over time. Since long term
reliability is paramount, please replace all the outputs.

All 16 of the 3W 0.33Ω emitter resistors must be verified for proper value. Any off-tolerance, or
open parts, need to be replaced. An off tolerance (higher resistance) emitter resistor will prevent
it’s related output transistor from “doing it’s share” and will place more stress on it’s mates in the
output section. Also verify the 16 base drive resistors (2.2Ω, 1/4W, fusible) are all OK. Verify that all
eight drivers and that the pre-drivers are not shorted. If one driver is shorted replace it’s mates.
Do the same with the pre-drivers. Also check all the resistors surrounding the drivers and pre­drivers. Measure the resistance between the “+I-sense” and “-I-sense” lines. The resistance should
be 82.5Ω +/-5%. If this resistance is higher, check for open 33Ω fusible resistors on these lines. Take
your time here looking to find all damaged parts: If one part is missed it still takes the same huge
amount of time to disassemble the main heatsink assembly. After replacing the outputs, drivers,
and pre-driver verify that the silicon transistor insulator wasn’t damaged (No shorts between
collector legs and the heatsink).

On the 170 board, check the VI limiters and detectors. It is not uncommon to damage these
parts when the amplifier fails in a spectacular way! Look for shorts on Q24, Q25 or open R151 or
R146. It is critical that these sections are working correctly. Shorted transistors can cause some
odd asymmetrical clipping problems. Open parts will not allow the current limiting to operate
effectively. If problems exist in these sections the amplifier might fail into a short, or might clip
prematurely when loaded to 2 Ω.

All of the above trouble shooting (not including part replacement) takes perhaps 30 to 45
minutes to do. If you take the time, and do all that is indicated above, it will allow 99% of the
amplifiers to come up the first time! Trying to hurry, and skipping what is suggested, can lead to
a frustrating and time consuming repair.

Reassemble the main heatsink sub-assembly and plug the two power supply cables back
into the 171 board (This can be done without installing the assembly back into the unit). Slowly
bring up the supply and verify that line consumption isn’t excessive and that the output is
centered (no DC offset). This can be measured on the “AMP-OUT” testpoint on the 170 board. It
might be desirable to defeat the amplifier muting temporarily (Short “MUTE-VA” to “-15V-AMP”
testpoints on the 170 board) so the channel is active even when the supplies are still very low. If
the amp stays centered, power down the assembly and discharge the two main +/-100V
supplies on both channels. Remove any temporary jumpers and reinstall the assembly into the
chassis. Power the unit and verify that the repaired channel will pass a nice clean rail to rail sine
wave. Next proceed to the “Reliability Verification” section on page 8.

WARNING: FUSIBLE RESISTORS MUST ONLY BE REPLACED BY THE EXACT REPLACEMENT PARTS.

ALWAYS CHECK THE PARTS LISTS TO VERIFY WHICH RESISTORS ARE THE FUSIBLE TYPE
BEFORE REPLACING ANY RESISTORS IN THIS AMPLIFIER.

6

Various test points

Q24

R146

MUTE-VA

J18

SOA

POWER

ADD A TEMPORARY SHORT

(SEE TROUBLEHOOTING TIPS)

-15V-AMP

J19
SOA
TRANSIENT

BIAS
TEST

170 board (Bias and check points)

Q25
R151

AMP

BIAS

OUT

ADJUST

133 board (inrush bypassing)

186 board (fan speed adjustment)

J1

J2

J3

R1

129 channel board

BR= BASE RESISTOR (2.2 OHM, 1/4W FUSIBLE)
ER= EMITTER RESISTOR (0.33 OHM, 3W)

ER ER ER ER ER ER ER ER ER ER ER ER ER ER ER

BR BRBRBRBRBRBR

ER

+I SENSE

BRBRBR

-I SENSE
J6

+I SENSE

BRBRBRBRBR

7

Reliability Verification Procedure

After the unit has been repaired, the following should be done to assure long term reliable
operation. If a distortion analyzer is present, distortion specifications should be verified. See the
previous page for the 170 and 186 boards with some test points noted.

1. Adjust the bias control (R163 on 170 Board) in both channels for 12mV +/- 1mV measured
at the bias test points (J23 along 170 board back edge) after unit has idled for a few
minutes. This is with no signal and no load. The Pot and test points are clearly marked on
both the top and bottom sides of the 170 board.

With Full AC line voltage applied to unit, it will pull around 130W from the line (1.6A at
120V). Measure for DC offset on both output connectors, it should be less than +/- 50mV.

2. Verify and adjust the fan speed if needed. On the 186 board, short pin 1 to pin 2 on J3.
Adjust R1 for 28V (+0V -1V) across J1 and J2. Remove the shorting jumper on J3. All the
test points and pots are clearly labeled on the back side of the PCB and are easily
accessed with the main heatsink sub-assembly installed.

3. Apply a 1KHz sine wave to the inputs and verify that the unloaded outputs have a
waveform that is symmetrical and undistorted. Drive the outputs into clipping and
carefully verify symmetrical “flat-topping” on the waveform.

4. Reduce the output levels, install a 0.1µF capacitor jumper from the output to ground
connections, and verify that clipping behavior is proper. Verify that no high frequency
oscillation occurs near and at clipping (parasitic oscillation).

5. Remove capacitive loading and minimize sine output. Verify and re-adjust the bias if
required. Note that the bias will not drift appreciably in a unit that is functioning properly.

6. Connect the amplifier directly to the AC line and connect an 8Ω dummy load to both
channels. Each 8Ω dummy load should have a minimum power rating of 500W. Bring the
sine wave level up on both channels and verify symmetrical clipping. The output will clip
somewhere between 150V - 180V pk/pk depending on how stiff the line is. Clipping
should be as described above. Add the 0.1µF capacitive loading and verify clipping is still
well behaved.

7. Individually load Channel 1 and Channel 2 with 2Ω . Each 2Ω dummy load should have
minimum power rating of 1500W. Clipping should be symmetrical, well behaved , and
occur somewhere around 120V - 140V pk/pk. Verify that clipping is well behaved after
adding the 0.1µF capacitive loading. Reduce the output level to zero and remove the
loading.

8. Next verify the two different short detectors. Perform these tests first on channel-1 and
then repeat for channel-2. On the 170 board, short J18 pins 1 and 2 (this defeats the
average power SOA detector and allows the transient SOA detector to be tested).
Adjust the output level to 60V pk/pk and short the channel-1 output line. Channel-1’s
front panel “short” and “protect” LEDs should turn on and the respective channel will
mute for about 5 seconds. On the 170 board, remove the short on J18 and install a short
on J19 pins 1 and 2 (this defeats the transient SOA detector and allows the average
power SOA detector to be tested). Adjust the output level to 60V pk/pk and short the
channel output line. Channel-1’s front panel “short” and “protect” LEDs should turn on
and the respective channel will mute for about 5 seconds. Remove the shorting jumpers
on channel-1 and repeat above testing on channel-2.

8

9. Place the amplifier in bridge mode and connect 4Ω loading to the bridge outputs
(across both “+” output binding posts). The 4Ω dummy load should have a minimum
power rating of 2000W. Slip some card stock between the heatsink-outlets and chassis
sides to temporarily restrict the airflow. Monitor one of the outputs and adjust for a 60V
pk/pk signal. Short across both outputs and verify that all four ‘Short” and “Protect” LEDs
light and the amplifier mutes for 5 seconds.

10. Remove the short, monitor one of the outputs, and adjust for a 90V pk/pk sine output
(1000W of output power bridged). After a few minutes the fan will begin running faster
and faster (heatsink between 45°C and 65°C) and a short time later the amplifier will
mute (heatsink at 80°C). The “Hot” and “protect” LEDs will come on. Remove the card
stock and after a few minutes the amplifier will come out of mute mode and the “cold”
LED will return.

11. Disconnect the loading and remove the input signals. Reconnect the amplifier to a
Variac and confirm that the idle consumption is roughly 130W or 1.6A, as before.
Connect the amplifier to speakers and verify that it sounds OK with music.

12. Perform the following leakage test before returning the amplifier to your customer:

1. Connect the amplifier under test to an AC power source using a ground-lift
adaptor, leaving the amplifier’s safety ground floating. Turn the amplifier on.

2. Make a small loading RC circuit as shown in the diagram below, and connect
the AC volt meter between the AC power source ground and any exposed metal
on the unit under test.

3. The meter reading should be less than 750mV AC (note: this is equivalent to

0.5mA of leakage current).

4. Flip the plug over in the receptical so the hot and neutral are swapped.
Verify that the reading is still less then 750 mV AC.

9

Circuit Theory

Much of the circuitry in the M•2600 we hope is self explanatory from the schematics. This
section will explain the unique circuits and architecture. Examples in this section will refer to
Channel 1 for circuitry that is identical on both channels.

INPUT CIRCUITRY

The signal path begins with the INPUT BOARD (055-131-00). Following Channel 1’s input, signal
is fed to a unity gain differential op-amp, U1A. The signal is next sent to U1B which serves as a
12dB/Oct. highpass filter. If not in SUBWOOFER mode, and if running in STEREO mode, the
summing amp (U3B) and 24dB/Oct. Likwitz-Riley Crossover (U3A, U2, U4) are bypassed. The signal
is sent via J11 to the gain control on the DISPLAY BOARD (055-132-00). After the gain control, the
signal is buffered by U1A, returned to the INPUT BOARD and routed to the Channel-1 amplifier
board via J6.

Channel 2’s input signal path is electrically identical to Channel 1’s in STEREO mode.

In PARALLEL MONO mode, Channel-1’s and Channel 2’s input signal is summed via U3B and is
sent to both channel’s front panel level controls via SW3A and SW3B.

For BRIDGE MONO operation, these summed inputs are sent to the channel-1 front panel
level control which in turn feeds the channel-1 amplifier and also the inverter U10A. The output of
U10A is routed to the channel-2 amplifier via SW3C. Also in BRIDGE mode, SW3D connects both
channel-1’s and channel-2’s protection circuits together. The result being that when one
amplifier detects a short circuit condition it will mute and immediately tell channel-2 to mute.
Muting lasts around 5 seconds and the amplifier un-mutes until the next shorted condition is
detected.

The limiters (U6, U5, U7 and their associated components) are always in the signal path. When
the limiter is switched off (via SW4) the LDR (Light Dependant Resistor) is in parallel with the
source resistor (R39) and will not reduce signal amplitude. When the limiter is switched on, the
LDR (U5B) is switched as a shunting element to ground. The Baker clamp in the power amplifier
detects clipping and the LDR shunts away driving voltage until clipping almost disappears. This
type of limiter is know as a feedback style (As opposed to feedforward style) of limiter.

U6 is also used for the amplifier input slew clamps, comprised of local +/-5V supplies (D7, D8
and associated) and clamping diodes (D13 and D14). These diodes clamp the voltage feeding
the power amp to around 10V pk/pk or about 6dB above the amplifier’s clipping point. This
ultimately limits the risetime of the signal presented to the power amplifier, controlling common­mode conduction in the power amplifier output stage.

Output from each crossover can be routed to the rear panel THRU jacks via SW2 and SW6. In
the THRU position the THRU jack is hardwired to the input jacks. In LOW and HIGH output modes,
the lowpass and highpass outputs of the crossover respectively are fed to the THRU jack. In these
modes the output is impedance balanced via R28, R29 and R23.

POWER AMPLIFIER CIRCUITRY

The M•2600 use a class AB triple darlington output stage with complementary output
devices. The output stage and the bias trackers are on the channel boards (129 and 130 boards)
while the voltage amplifier and amplifier protection circuits are housed on two identical v-amp
/ protection (055-170-00) boards. Each channel has local main +/- 100V power supplies, and a +/

- 115V stacked supply for the front end circuitry. Each amplifier also has floating +/-16V supplies

10

that float along with the amplifier output line (D3 & D4 and associated parts on the 129 board).
Common +/-15V supplies are shared throughout the product.

Referring now to the 170 schematic: The amplifier is muted for 3 seconds on power up as C29
charges via R56. When this voltage has charged above 11.6V, U3C goes low turning on Q7,
providing current for the differential pairs. The output of U3C, labeled “MUTE-VA”, when low turns
on the Voltage Amplifier. Two seconds after MUTE-VA goes low, mute “MUTE-OP” goes low (Q27)
closing the OutPut relay passing signal along to the output terminals. (Wait a minute! Differential
Pairs? Read on…)

An immediately obvious departure from standard designs is the Differentials and Symmetrical
Voltage Amps. The reasoning behind this front end architecture is actually quite simple.
Transistor transfer characteristics are not entirely linear, so even the best conventional front end
design will introduce some distortion. Most amplifiers use negative feedback to reduce this
problem (creating a few more in the process). Mackie FR Series amplifiers take a different
approach. By using two complementary “mirror image” front end circuits, any distortion caused
by non-linear transistor curves is effectively canceled out in the bias string, without feedback!

Another design feature unique to Mackie FR Series Amplifiers is the Baker Clamp. The Baker
Clamp has two functions; 1) Prevent output transistors saturating, 2) Drive the LIMITER LDR.
Referring to the again to the 170 schematic: Q20 is a common base amplifier, it will turn on if
Q2’s collector rises more than three diode drops above the +100V supply, preventing Q2’s
collector from rising further. There are three diode drops between Q2’s collector and the base of
pre-driver transistor (Q26 on 129 board). Once the output from the collector of Q2 makes it to
the emitter of the output devices, there will be a total of six diode drops in series. Three “drops”
up and six down: As a result, the output transistor emitters will never see a voltage greater than
three diode drop below the +100V supply (even if the +100V supply fluctuates) and will never
saturate. This will consequently remove saturation of the output stage, as a source common
mode conduction. When the amplifier clips, Q20 and Q15 also send out “clipping pulses” at
their collectors that is coincident with baker clamp conduction. These clipping pulses are cross­coupled to Q21 and Q22 and are stored in C47 and C51. These stored pulses allow for quick
attack and slow release required by a peak limiter. Output from Q21 and Q22 is coupled to the
LDR LED section via R110 and R152.

PROTECTION CIRCUITS

The M•2600 has several protection circuits in addition to main rail fuses on each channel.
Circuits mute the amp if the output devices are loaded beyond their safe operating area (SOA).
If there is DC on the output line, output relays open, disconnecting the load. The amplifier will
also mute if the power transformer or main heatsink get too hot, if the input AC line voltage is
low, or if either of the +/-15V supplies fails.

Turn-On Inrush Current Limiter

For the first second of operation there are two 15W power resistors (located on the 133
board) in series with the power transformer which eliminates what would otherwise be an
extremely high turn-on current. After 1 second these resistors are shunted with a relay. This relay is
turned on when the collector of Q26 (170 board) goes high. Note that either or both Q26’s on
the two 170 boards can turn on this relay.

11

SOA protection

There are two SOA detectors in the M-2600: One that monitors steady state output stage
dissipation and one that monitors transient high current events. Both detectors need to monitor
the output stage current.

A voltage, representing output stage current, is derived by first sampling the voltage drop
across the output transistor emitter resistors. These voltages are rectified via U9A R87, R88, R59
and R89. The rectified voltage is converted to a current via U9B, Q23, and associated. This current
is referenced to the output line and must first be re-referenced to the +115V supply via Q14, D47
and associated. The current available at the connector of Q14 is converted to a voltage that is
ground referenced via R138 and R162. This is buffered via U8A and adjusted via R162 such that
1 amp of output stage current is equal to 100mV of detected output.

This current is compared to what represents a safe operating current at U4A (part of the
transient SOA-Fault detector). If the current is greater than allowed for more than 10mS (Timing
determined by R77 and C36), U4B sends out a fault indication which mutes the amplifier via U3C
and associated, and fires the short led for 5.5 seconds (U3B and associated).

While the output stage is quite tolerant of very high current demands for a very short time, it
would destroy itself if it had to provide these currents on a long-term basis. The second detector
actually looks at long-term dissipation in the output stage, and if excessive, will mute the
amplifier. We already have a signal that is proportional to output stage current as described
above. This signal is fed to one input of analog multiplier U7 via R80 and R84.

U6A and U6B and their associated components look at the -100V supply and the amplifier
output line. These voltages are converted to currents via R101, R129 and R130 and are rectified
and summed such that for every volt between the output line and the supply rail, 100mV is
presented as output. This second signal is presented to the other input of multiplier U7 via R133
and R82. Output from U7 is in the form of a current and is converted to a voltage via R136 and
U8B. The gain of this multiplier is such that for 200 watts of output stage dissipation, 1 volt of
output is obtained. The output of U8B is instantaneous power and is long-term averaged via
R135 and C40. The cutoff of the filter is quite low in frequency, such that even a 20Hz signal on
the amplifier output results in very little ripple voltage at C40. If the voltage on C40 is greater
than 5V (equivalent to 1000W of output stage dissipation), U4C will toggle, muting the amplifier
and firing the SHORT LED as above. Approximately 200mS of dissipation above 1000W is required
to cause a fault.

DC Fault Detection

The amplifier output drives the subsonic lowpass filter of the DC fault detector (R154, C65
and C64). If the amplifier were to fail and short to the +100V rail, C64/C65 will charge to more
that 5V in a few hundred milliseconds. Local +/-5.1V references on U2C and U2D set the threshold
where: when the amplifier output voltage is “stuck” to greater than +/-5.1V, either comparator
output will go low. This will open Q27, and in turn open the speaker relay on the respective
channel board. When the amplifier is initialized, “MUTE-VA” is high and this biases C64/C65
above 5.1V via D14 and R36. This offset results in a delay of about 2 seconds from when the
amplifier turns on (“MUTE-VA” low) and when the speaker relay closes.

Low Voltage Detector

D15, D2, and R7 supply a local 5V reference and are supplied current from the unregulated
+30V supply via R32. 22VAC from the +/-30V windings is half-wave rectified via D26 and stored
by C18. R53 limits the absolute peak current to protect D26. The voltage on C18 is divided down

12

via R33 and R8 and compared against the 5V reference at U3A. If the AC line voltage falls to
around 60% of nominal (around 70VAC), the output of U3A goes low, resetting the mute and
short monostables via D5 and D12. If the +15V supply fails, D3 and D4 bias the U3A inputs such
that the amplifier is also muted. In the event of the -15V supply failing, R7 is no longer able to
pull the anode of D15 low, and this also causes U3A to go low and mute the amplifier.

THERMAL MANAGEMENT

The T-Design Heatsink/Fan cools the output devices evenly and does not collect dust on the
circuitry. The fan operates at variable speeds, controlled by output stage dissipation and
temperature data supplied from both LM35DZ’s mounted on the heatsink.

Fan Control Circuit

Referring to the 186 board: The fan voltage comes from a feedback regulator circuit formed
by U3B, Q2, Q1 and associated components. The fan supply is actually referenced to the -30V
supply, so U3A and Q3 act to shift the ground-referenced control voltage “FAST-FAN” to a -30V
supply reference. The output voltage of this regulator is adjusted via R1. D7 and C9 give the fan
an initial full fan voltage “kick” (28V) to insure the fan starts spinning. The “FAST-FAN” control line
varies from -1.6V (Slow) to -15V (Fast). Short J3 temporarily and adjust R1 for a voltage across the
fan equal to 28V.

Referring to the 170 board: The fan is never allowed to go faster than idle speed (Slow) unless
the output stage dissipation is greater than 136 watts and the heatsink temperature is above
45°C. When the output stage dissipation is greater than 136W, U4D goes low. This eliminates D1
from supplying current to U2A. This decreases the reference voltage on U2A pin7, allowing it to
work as a linear amplifier. With D1 conducting, U2A is effectively biased such that it’s output is
high and the resulting fan speed is low.

With 136W of output stage dissipation, U2A is allowed to linearly amplify the temperature
sensor voltage on U1 via R2 and R5. C5, C15, C16, and C17 provide high frequency stability to
this stage. The amplifier will linearly decrease the “FAST-FAN” voltage (increasing fan speed)
between 45°C and 65°C. Above 65°C, U2A is saturated with the fan speed maximized. D11
isolates the Channel-1 and Channel-2 U2A circuits from each other. The connection of the U2A
controllers is such that whichever channel is being used the hardest will determine the ultimate
fan speed.

Thermal Shutdown

Heatsink temperature is sensed by U1 mounted to the main heatsink (one for each channel).
The output of the sensor (10mV / °C) is compared to a 800mV reference at U2B. When the sensor
is over 800mV (80°C) the output of U2B goes low, muting the amplifier via D27 and associated,
and running the fan fast via D24. Hysteresis is built into the comparator via R3, such that the
sensor voltage must reduce to 520mV (52°C) before the comparator goes back high and the
amplifier un-mutes.

A thermostat is built into the power transformer. If the power transformer temperature
exceeds 130°C the thermostat closes and brings the “THERM” line to ground via Q1 and it’s
associated parts on the 171 board. This shorts out the 800mV reference, and the U2B output goes
low, muting the amplifier. Note that overheating of the power transformer is very unlikely but if it
does occur, the amplifier will stay muted for over an hour before the transformer cools and the
amplifier un-mutes itself.

13

Final Assembly

14

The circled item numbers are shown in the parts list on page 20

The circled item numbers are shown in the parts list on page 20

15

The circled item numbers are shown in the parts list on page 20

Final Assembly

16

The circled item numbers are shown in the parts list on page 21

Amplifier/Heatsink Assembly

17

The circled item numbers are shown in the parts list on page 21

Amplifier/Heatsink Assembly

18

The circled item numbers are shown in the parts list on page 21

Amplifier/Heatsink Assembly

19

Master Parts List 090-078-00 M2600 Assembly, 120v

Item# Part # Description Rev Qty

1 040-257-00 CBL ASSY 24GA 3P .098 6IN B 1

2 040-272-00 DIS 14G 1010 BRN 7.5 QDX2 B 1

3 040-273-00 DIS 14G 1010 BLU 6.5 QDX2 A 1

5 040-301-00 CBL ASSY SW PWR 23IN A 1

6 055-131-00-01 PCB ASSY INPUT - 2600 A 1

7 055-132-00-01 PCB ASSY DISPLAY M2600 A2 1

8 055-133-00-01 PCB ASSY PWR DIST 120V A1 1

9 055-171-00-01 PCB ASSY PWR SPLY M2600 A 1

10 055-172-00-01 PCB ASSY SPKR OUTPUT 2600 A 1

11 080-076-00 SA AMP M2600 A6 1

12 080-087-10 SA HANDLE RIGHT M2600 A 1

13 080-087-20 SA HANDLE LEFT M2600 A 1

080-115-00 ASSY WIRE RCPT GND A 1

23 080-117-00 SA XFMR M2600 120V A 1

400-331-00 INSERT JACK BAN M-MAN RED A AR
400-332-00 INSERT JACK BAN M-MAN BLK A AR

15 500-022-00 SW RCKR ILLUMINATED A 1

510-044-00 FUSE SB 30A 3AB A 1
16 550-245-00 SCRN CHASSIS M2600 B 1
17 550-246-00 PNT SIDE RAIL RT- M2600 A 1
18 550-370-00 BRKT BRIDGE RECT HEATSINK A 1
19 550-371-00 BRKT XFMR MOUNT M2600 A 1 (transformer bracket)
20 550-376-00 PNT COVER TOP M2600 A 1
21 550-378-00 PNT SIDE RAIL LT - M2600 A 1
46 550-419-00 FAB BRKT CBLE SHLD M2600 A 1
22 551-029-40 EXTR SCRN DSPLY BZL-M2600 C 1
49 640-009-00 LC IEC SJT 20A/125V 12AWG A 1
31 700-005-00 SEMS 8-32X1/2 PHP BLKZC A 2
24 700-011-00 MCH 4-40X1/4 BTNSKT BLKOX A 8
25 700-027-00 SEMS 8-32X3/8 PHP BLKZC A 2 4
26 700-028-00 SEMS 6-32X1/4 PHP BLKZC B 13
27 700-041-04 MCH 6-32X3/8 FL 100DG BLK A 7
30 700-085-03 SCR PHP M3X6 STL BLK ZC A 4
32 700-091-00 SEMS 8-32X3/4 PHP BLKZC A 6
34 700-094-04 MCH 4-40X3/8 82DEG FL BLK A 2
35 700-096-00 BOLT HEX 5/16X3-3/4 GR5 Z A 1 (transformer bolt)
33 700-097-00 MCH 8-32X1/4 FL 82DG UCUT A 4
29 701-016-00 5-20X5/16 PHPII TYP B BLK A 14
36 705-001-00 KEPNUT 6-32 A 4
37 705-003-00 NUT HEX-SPLD W/400-214-00 A AR
38 705-008-00 NUT LOCK 8-32 A 2
39 705-019-00 NUT STOVER LOCK 5/16X18 A 1 (transformer nut)
40 710-002-00 WASHER-SPLD W/400-214-00 A AR
41 710-024-00 WASH FLAT 5/16 HARD (USS) A 1 (transformer bottom washer)
47 710-034-00 WASH STL .063X.344X.688 A 1 (transformer top washer)
48 730-001-00 THERMAL JOINT COMPOUND A AR
49 740-003-00 TYRAP 8IN BLK A 4
42 710-032-00 WASH SHLD FIBRE .317X.750 A 1 (transformer shoulder washer)
53 720-007-00 TAPE DS 30MIL X 1.0W URTH A AR

730-016-00 LOCTITE 242 A AR

750-001-00 BUMPON ROUND BLK .63X.31 A 4
43 760-048-01 KNOB 9MM LT GRY B 2
44 760-061-00 KNOB VOLUME AMPS A 2
45 780-111-00 WASH RUB (W/TRANSFORMER) A 2 (transformer insulator washers)

790-002-00 BAG POLY 12 X 18 2MIL A 1

NOTE:The Item numbers in
the first column of this page
refer to the Final Assemby
Drawings on pages 14-16

20

Item# Part # Description Re v Q ty

790-022-00 POLY-SHEET 52CF X 26 4MIL A 1

800-087-00 BOX - M2600 A 1

800-107-00 BOX SLEEVE M2600 A 1

810-076-00 INSERT - M2600 A 2

810-082-00 FOAM CORNER M2600 A 4

820-078-00 OWN MANUAL M2600 ENG/DOM A 1

080-076-00 Amplifier/Heatsink subassembly

Item Part# Description Rev Qty

080-076-00 SA AMP M2600 A6 1
1 040-263-00 DIS 16GA 10C .165X2 19.5 A 2
2 055-129-00-01 PCB ASSY CHANNEL 1 - 2600 A3 1
3 055-130-00-01 PCB ASSY CHANNEL 2 - 2600 A2 1

055-170-00-02 PCB ASSY V-AMP PROT M2600 A3 2
5 055-186-00-01 PCB ASSY PREDRV/FAN M2600 A2 1

080-116-00 FAN ASSY M2600 A1 1
34 410-013-00 SILPAD CUT M2600 NEW A 1
33 410-014-00 SILPAD CUT M2600 NEW A 1
7 550-368-00 COWLING HEATSINK M2600 A 1
8 550-372-00 BRKT FAN SHROUD M2600 A 1
9 550-373-00 BRKT SUPPORT PCB 28DEG A 2
10 550-377-00 BRKT TO-92 MOUNTING A 2
11 550-393-00 BRKT WIRE HARNESS M2600 A 1
12 550-403-00 FAB SEC HEATSINK M2600 A 2
13 550-420-00 FAB BRKT WIRE SHLD M2600 A 1
14 550-421-00 FAB BRKT VAMP SHLD M2600 A 1
15 551-045-00 FAB HEATSINK M2600 B 1

700-005-00 SEMS 8-32X1/2 PHP BLKZC A 4
16 700-010-04 TF 6-32X3/8 PHP BLKZC A 14
17 700-028-00 SEMS 6-32X1/4 PHP BLKZC B 5
18 700-034-00 SEMS 4-40X1/4 PHP BLKZC A 5
19 700-087-00 TF 4-40X5/8 TORX 1/4 WASH A 23
20 700-088-00 TF 4-40X5/8 TORX 3/8 WASH A 33

700-110-00 MCH 3-48X1/2 SKTCP SS A 22
22 705-008-00 NUT LOCK 8-32 A 4

710-020-00 WASH NO.4 COMPRESSION A 44
23 710-036-00 WASH FLT STL NO.4 .030THK A 22
24 710-044-00 WASH SHLDR TO-220 DELRIN A 22
25 730-001-00 THERMAL JOINT COMPOUND A AR
33 730-025-00 LOCTITE 222 A AR
26 740-003-00 TYRAP 8IN BLK A 3
27 740-011-00 HEATSHRINK TUBE 2:1 .50ID B AR
29 780-123-00 INSULATOR PCB M2600 A 1
30 780-133-00 INSULATOR VAMP SHLD M2600 A 1

NOTE: The Item numbers in
the first column refer to the
Amplfier/Heatsink Assemby
Drawings on pages 17-19

21

055-129-00 Rev A Channel 1 board

Part # Description Value Reference Designator

040-261-00 RIB 28GA TRAN 10C .1 3IN J1
040-262-00 RIB 28GA TRAN 40C 3IN J6
040-265-00 DIS 14GA BLK/ WHT 4.5IN QD J4
040-266-00 DIS 14GA BLK/ WHT 6IN QDX2 J1 2
040-267-00 DIS 14GA WHT 6IN QDX2 J 8
040-268-00 DIS 14GA BLKWHT 6IN QDX2 J9
121-077-00 RESISTOR MOF 15 0 5% R58
123-013-00 RESISTOR MOF 0.33 5% R40-55
123-045-00 RESISTOR MOF 6.8 5% R60-68
123-056-00 RESISTOR MOF 20 5% R59
123-125-00 RES MO 3W 5% 15K OHM 15K 5 % R70-73
150-009-00 RES FUS .25W 5% 2.2 OHM 2.2 5% R3 R5-6 R8 R11 R13 R16 R18 R21 R23 R25

R29 R31 R33 R36 R38

150-037-00 RES FUS .25W 5% 33 OHM 33 5% R1 R4 R7 R9 R12 R14 R17 R19 R22 R24

R26-28 R30 R32 R34 R37 R39 R57 R69
150-045-00 RES FUS .25W 5% 68 OHM 6 8 5% R2 R10 R15 R20 R35 R56
150-066-00 RESISTOR, FUSABLE, 1/4W 5 10 5% R75
200-036-02 CAP, METALIZED POLY, T/R .1uF 10% C22 C27
200-041-00 CAPACITOR POLY HI-CURRENT 0.01 10% C24
205-003-02 MICA 330PF 5% 500V 330pF 5% C30-31
211-003-00 CER .001UF 10% 50V AX 0.001 10% C1
211-009-00 CAPACITOR CERAMIC AXIAL 0.1 10% C2 C4 C6 C8 C15 C17
220-011-02 CAPACITOR LYTIC RADIAL T&R 100UF 10% C14 C16 C18 C20
220-025-00 CAPACITOR LYTIC RADIAL 1,000UF10% C21
220-027-02 CAPACITOR LYTIC RADIAL T&R 10UF 10% C25-26
220-047-00 LYT 47UF 20% 160V RAD 47UF 20% C19 C23
301-009-00 DIODE POWER 1N4004 D5
301-010-00 DIODE POWER 1N5404 D1-2
302-003-00 DIODE ZENER 1N4745 D3-4
310-033-00 TRANSISTOR PNP MJL21193 Q13-14 Q16-17 Q19-20 Q23-24
310-034-00 TRANSISTOR NPN MJL21194 Q2-5 Q7-8 Q10-11
310-042-00 TRANSISTOR NPN MJE15032 Q1 Q6 Q9 Q1 2
310-043-00 TRANSISTOR PNP MJE15033 Q15 Q18 Q21 Q25
310-049-00 XSTR PNP 2SA794A 2SA794A Q29
310-050-00 XSTR NPN 2SC1567A 2SC1567A Q22 Q28
310-055-00 XSTR NPN 2SA1480 2SA1480 Q27
310-056-00 XSTR PNP 2SC3790 2SC3790 Q26
400-077-00 HEADER STR LCK SHRD 20P .100 X 2 J5
400-129-00 FUSE CLIP 0.25 DIA PC MNT Z1-4
400-231-00 HEADER, 2X5, MATE-N-LOCK J2
400-242-00 CONNECTOR,STR,3P,.098 X 1,SHRD J3
400-243-00 CONNECTOR,STR,2P,.098 X 1,SHRD J7
450-129-00 PCB, M2600 CH-1 AMP Z5
490-021-00 MAGNET, .2THK .5DIA Z6
501-003-00 RELAY, SPDT T9AS5D12-24 K1
510-041-00 FUSE 25A FB 3AG 25 A F1-2
601-006-00 INDUCTOR, AIR CORE 1uH 10% L1
601-008-00 INDUCTOR 10uH L2-3

22

Components noted with this symbol shall be replaced only by the component
specified.This is required to maintain product safety.

055-130-00 Rev A Channel 2 board

Part # Description Value Reference Designator

040-262-00 RIB 28GA TRAN 40C 3IN J3
040-269-00 DIS 14GA RED 6 IN QDX2 J5
040-270-00 DIS 14GA BLKRED 6IN QDX2 J6
121-077-00 RESISTOR MOF 15 0 5% R60
123-013-00 RESISTOR MOF 0.33 5% R40-55
123-045-00 RESISTOR MOF 6.8 5% R61-69
123-056-00 RESISTOR MOF 20 5% R70
123-125-00 RES MO 3W 5% 15K OHM 15K 5% R58-59 R73-74
150-009-00 RESISTOR, FUSABLE, 1/4W 2.2 5% R2 R4 R7 R9 R11 R15 R17 R19 R22 R24 R27

R29 R32 R34-35 R37
150-037-00 RES FUS .25W 5% 33 OHM 33 5% R1 R3 R5 R8 R10 R12-14 R16 R18 R20 R23

R25 R28 R30 R33 R36 R38 R56-57
150-045-00 RES FUS .25W 5% 68 OHM 6 8 5% R6 R21 R26 R31 R39 R71
150-066-00 RESISTOR, FUSABLE, 1/4W 5 10 5% R75
200-036-02 CAP, METALIZED POLY, T/R .1uF 10% C21 C26
200-041-00 CAPACITOR POLY HI-CURRENT 0.01 10% C25
205-003-02 MICA 330PF 5% 500V 330pF 5% C29-30
211-003-00 CER .001UF 10% 50V AX 0.001 10% C1
211-009-00 CAPACITOR CERAMIC AXIAL 0.1 10% C7 C9 C11 C13 C15 C17
220-011-02 CAPACITOR LYTIC RADIAL T&R 100UF 10% C14 C16 C18 C20
220-027-02 CAPACITOR LYTIC RADIAL T&R 10UF 10% C23-24
220-047-00 LYT 47UF 20% 160V RAD 47UF 20% C19 C22
301-009-00 DIODE POWER 1N4004 D4
301-010-00 DIODE POWER 1N5404 D1-2
302-003-00 DIODE ZENER 1N4745 D3 D5
310-033-00 TRANSISTOR PNP MJL21193 Q15-16 Q18-19 Q21-24
310-034-00 TRANSISTOR NPN MJL21194 Q2-3 Q6-7 Q9-10 Q12-13
310-042-00 TRANSISTOR NPN MJE15032 Q1 Q5 Q8 Q1 1
310-043-00 TRANSISTOR PNP MJE15033 Q14 Q17 Q20 Q25
310-049-00 XSTR PNP 2SA794A 2SA794A Q29
310-050-00 XSTR NPN 2SC1567A 2SC1567A Q4 Q28
310-055-00 XSTR NPN 2SA1480 2SA1480 Q27
310-056-00 XSTR PNP 2SC3790 2SC3790 Q26
400-077-00 HEADER STR LCK SHRD 20P .100 X 2 J2
400-129-00 FUSE CLIP 0.25 DIA PC MNT Z1-3 Z5
400-173-00 CONN QUICK DISC .250 J4

W/STABLE-LOK TABS
400-231-00 HEADER, 2X5, MATE-N-LOCK J1
450-130-00 PCB M2600 CH-2 AMP Z4
490-021-00 MAGNET .200 THK X .50 DIA Z6
501-003-00 RELAY, SPDT T9AS5D12-24 K1
510-041-00 FUSE 25A FB 3AG 25 A F1-2
601-006-00 INDUCTOR, AIR CORE 1uH 10% L1
601-008-00 INDUCTOR 10uH L2-3
706-033-05 STANDOFF, SWAGE, 4-40 X .312L H1-4 H6

Components noted with this symbol shall be replaced only by the component
specified.This is required to maintain product safety.

23

055-131-00-01 Rev A Input board

Part # Description Value Reference Designator

DO NOT STUFF C22 C24
040-258-00 RIB 28GA TRAN 20C .1 5IN J6
040-259-00 RIB 28GA TRAN 20C .1 6IN J5
040-260-00 RIB 28GA TRAN 20C .1 20IN J11
100-027-00 RESISTOR CF 12 0 5% R23 R28-29 R50-51 R65
130-062-02 RES POT 12MM HORIZ DUAL 50KC R11 R66
140-078-00 RESISTOR TF SMT 1K6 5% R7 R67
140-082-00 RES TF SM .1W 5% 2K4 OHM 2 K4 5% R9 R69
140-089-00 RESISTOR CF 4K7 5% R24-27 R52-53
140-090-00 RES TF SM .1W 5% 5K1 OHM 5 K1 5% R80-81
140-095-00 RES TF SM .1W 5% 8K2 OHM 8 K2 5% R8 R68
140-123-00 RES TF SM .1W 5% 100K OHM 100K 5% R77-79
145-318-00 RESISTOR MF SMT 2K00 1% R4 R6 R38-41 R72 R74
145-331-00 RESISTOR MF SMT 2K49 1% R35 R59
145-346-00 RESISTOR MF SMT 3K57 1% R14 R17 R44 R47
145-389-00 RESISTOR MF 10K0 1% R3 R5 R21-22 R32 R56 R63-64 R71 R73
145-397-00 RESISTOR MF 12K1 1% R1-2 R12-13 R16 R18 R30-31 R36-37

R42-43 R46 R48 R54-55 R60-61 R75-76
145-406-00 RESISTOR MF SMT 15K0 1% R20 R62
145-426-00 RESISTOR MF SMT 24K3 1% R15 R19 R33-34 R45 R49 R57-58
200-025-02 CAPACITOR MYLAR T&R 0.56 C10-11 C38-39
200-029-02 CAPACITOR MYLAR T&R 0.22 C12-13 C20-21 C28-29 C36-37
212-001-00 CAPACITOR CERAMIC SMT 0.01 10% C4-5 C14-19 C23 C25 C30-35 C41-42
212-004-00 CAPACITOR CERAMIC SMT 220PF 5% C3 C6-7 C40 C43-44
212-009-00 CAPACITOR CERAMIC SMT 47PF 5% C1-2 C45-46
220-001-02 CAPACITOR LYTIC RADIAL T&R 22UF 10% C8-9 C26-27 C47-48
300-003-00 DIODE SIGNAL SMD DL4148 D1-6 D9-16
302-002-03 4.7V DL5230B D7-8
320-006-00 OPAMP 2068E NJM 2068 U1 U11
320-012-00 OPAMP NJM4560M NJM4560M U2-4 U6 U8-10
329-012-00 OPTO-ISOLATOR,LED/CDS VTL5C10 U5 U7
400-041-00 CONNECTOR XLR PC MTG VERT MALE J7 J10
400-214-00 CONNECTOR JACK 1/4” VERT PC J3 J12

MOUNT W/1MM LW
400-223-00 CONNECTOR XLR PC MTG VERT FML J4 J13
400-269-00 TERM QDISC RTA .250 PCMT J1
450-131-00 PCB, M-2600 INPUT Z1
500-023-00 SWITCH 4P3T SW1-6
706-013-00 STDF NO.4 X .978L M/F H1-2

24

055-132-00-01 Rev A Display board

Part # Description Value Reference Designator

130-070-00 RESISTOR POT 9MM HORIZ 5KB 20% R2 R34
140-057-00 RESISTOR CF 220 5% R17
140-065-00 RESISTOR CF 470 5% R35 R41
140-068-00 RESISTOR TF SMT 62 0 5% R11 R24
140-076-00 RESISTOR CF 1K3 5% R25 R43-49 R51
140-081-00 RESISTOR CF 2K2 5% R1 R33
140-083-00 RESISTOR TF SMT 2K 7 5% R12-13 R19-21 R50 R52
140-087-00 RESISTOR CF 3K9 5% R16
140-092-00 RESISTOR CF 6K2 5% R15
140-094-00 RESISTOR CF 7K5 5% R18
140-106-00 RESISTOR TF SMT 24K 5% R5 R10 R29 R31
145-389-00 RESISTOR MF SMT 10K0 1% R4 R7 R23 R27-28
145-454-00 RESISTOR MF SMT 47K5 1% R37 R39-40 R42
145-472-00 RESISTOR MF SMT 73K2 1% R8 R26
145-480-00 RES MF SM .1W 1% 88K7 OHM 88K7 1% R3 R22
145-527-00 RESISTOR MF SMT 274K 1% R14
145-547-00 RESISTOR MF SMT 442K 1% R6 R9 R30 R32 R36 R38
212-001-00 CAPACITOR CERAMIC SMT 0.01 10% C1 C3 C 6 C10-11 C14 C19-20 C22-23
212-025-00 CAP CER .1UF 25V 10% X7R .1UF 10% C7-9 C12-13 C15-16
220-002-02 CAPACITOR LYTIC RADIAL T&R 47UF 20% C2 C4-5 C17
220-014-00 CAPACITOR LYTIC RADIAL KS 2.2UF 10% C18 C21
300-003-00 DIODE SIGNAL SMD DL4148 D13-20 D27
304-070-02 LED RED T1 W/.550 SPCR T/R RED D1 D7 D21-22 D24-26
304-071-02 LED GRN T1 W/.550 SPCR T/R G RN D2-6 D8-12 D23
311-002-00 X-SISTOR PNP SMD IMBT4403 Q1-2
320-012-00 OPAMP NJM4560M NJM4560M U1 U6
323-002-00 I.C. QUAD COMPARATOR SMD LM339 U2-5 U7
400-077-00 HEADER STR LCK SHRD 20P .100 X 2 J1
450-132-00 PCB, M2600 DISPLAY Z 8
706-033-08 STANDOFF, SWAGE, 4-40 X .665L H1-3 H5-7

25

055-133-00-01 Rev A Power distribution 120V

Part # Description Value Reference Designator

040-137-00 DIS 18GA GN/YL 96IN QD LUG J11
121-077-00 RESISTOR MOF 15 0 5% R3
125-020-00 RESISTOR WIRE WOUND 8 2 5% R1-2
200-023-00 CAPACITOR, POLY BOX .001uF 20% C1-2
200-024-00 CAPACITOR, POLY BOX .01uF 20% C3-4
301-009-00 DIODE POWER 1N4004 D1
400-129-00 FUSE CLIP 0.25 DIA PC MNT Z1-2
400-173-00 CONN QUICK DISC .250 J1-10 J12-15
400-173-00 CONN QUICK DISC .250 J16-17

-00 AND -02 ASSY ONLY

400-173-00 CONN QUICK DISC .250 J18

-01 ASSY ONLY
400-242-00 CONNECTOR,STR,3P,.098 X 1,SHRD J23
450-133-00 PCB, M2600 PWR DISTRO & AC-INRUSH Z3
501-003-00 RELAY, SPDT T9AS5D12-24 RL1
510-017-00 FUSE 20A SLO-BLO -02 ASSY ONLY F 1 Z4 (100 VOLT MODELS ONLY)
510-018-00 FUSE 15A SLO-BLO -01 ASSY ONLY F 1 Z6 (240 VOLT MODELS ONLY)
510-033-00 FUSE 25A SLO-BLO -00 ASSY ONLY F 1 Z5 (120 VOLT MODELS ONLY)

26

Components noted with this symbol shall be replaced only by the component
specified.This is required to maintain product safety.

055-170-00 Rev A, Voltage amplifier and protection

Part # Description Value Reference Designator

TEST POINT, PART OF PCB J1-9 J11-16 J24-26
100-025-00 RESISTOR CF 10 0 5% R11 R30 R37-38
105-369-00 RES MF .125W 1% 6K19 OHM 6K19 1% R141-144
130-021-00 RESISTOR POT TRIM HORIZ 10KB R162
130-053-00 RESISTOR POT TRIM HORIZ 200 R163
140-053-00 RESISTOR TF SMT 15 0 5% R12-13 R22-23
140-057-00 RESISTOR TF SMT 22 0 5% R6
140-061-00 RES TF SM .1W 5% 330 OHM 330 5% R159
140-073-00 RES TF SM .1W 5% 1K0 OHM 1 K0 5% R16 R19
140-076-00 RES TF SM .1W 5% 1K3 OHM 1 K3 5% R160
140-077-00 RESISTOR TF SMT 1K5 5% R105
140-082-00 RESISTOR TF SMT 2K4 5% R104 R140 R156
140-084-00 RESISTOR TF SMT 3K0 5% R103 R139
140-090-00 RESISTOR TF SMT 5K1 5% R48-49 R53 R77 R86 R102
140-092-00 RES TF SM .1W 5% 6K2 OHM 6 K2 5% R110 R152
140-093-00 RES TF SM .1W 5% 6K8 OHM 6 K8 5% R121
140-095-00 RESISTOR CF 8K2 5% R7 R47 R51
140-099-00 RESISTOR TF 12K 5% R41-42 R67-68 R97-98
140-111-00 RESISTOR TF SMT 36K 5% R10 R26 R57 R76
140-113-00 RES TF SM .1W 5% 43K OHM 4 3K 5% R122
140-116-00 RESISTOR TF SMT 56K 5% R120 R158
140-117-00 RESISTOR TF SMT 62K 5% R59 R88 R155
140-120-00 RES TF SM .1W 5% 82K OHM 8 2K 5% R147 R150
140-123-00 RESISTOR TF SMT 100K 5% R45 R60 R123 R148-149
140-126-00 RESISTOR TF SMT 150K 5% R3 R31 R36 R54 R107 R116
140-130-00 RESISTOR TF SMT 200K 5% R1 R101 R106 R126 R129-130
140-140-00 RESISTOR TF SMT 510K 5% R8 R55-56 R108 R115
140-143-00 RESISTOR TF SMT 680K 5% R28
140-147-00 RESISTOR TF SMT 1M 5% R9 R33 R92
140-152-00 RESISTOR TF SMT 1M6 5% R5
145-000-00 RES TF SM .1W 0 OHM 0 5% R15 R20 R40 R43
145-182-00 RESISTOR MF SMT 76.8 1% R93-94 R99-100 R145
145-266-00 RESISTOR MF SMT 57 6 1% R112 R114
145-308-00 RES MF SM .1W 1% 1K58 OHM 1K58 1% R46
145-318-00 RESISTOR MF SMT 2K00 1% R14 R21 R39 R44 R63 R72 R146 R151 R157
145-331-00 RESISTOR MF SMT 2K49 1% R52 R64 R71 R111
145-389-00 RESISTOR MF SMT 10K0 1% R50 R58 R61-62 R73-74 R124 R128 R136

R138
145-414-00 RESISTOR MF SMT 18K2 1% R83 R132
145-418-00 RESISTOR MF SMT 20K0 1% R25 R29 R32 R34-35 R75 R78-80 R82 R84

R127 R133 R137
145-422-00 RES MF SM .1W 1% 22K1 OHM 22K1 1% R119 R125
145-426-00 RESISTOR MF SMT 24K3 1% R2 R4 R65-66 R69-70 R90-91 R95-96 R109

R117
145-427-00 RESISTOR MF SMT 24K9 1% R113
145-435-00 RES MF SM .1W 1% 30K1 OHM 30K1 1% R118
145-439-00 RESISTOR MF SMT 33K2 1% R17-18 R24 R27
145-469-00 RESISTOR MF SMT 68K1 1% R87 R89 R135 R161
145-531-00 RESISTOR MF SMT 301K 1% R81 R85 R131 R134 R153-154

27

055-170-00 Rev A, continued
Part # Description Value Reference Designator

200-011-02 CAPACITOR MYLAR T&R 0.0022 5% C59
200-036-02 CAP, METALIZED POLY, T/R .1uF 10% C31-32
205-006-02 MICA 30PF 5% 500V T/A 30pF 5% C60
210-017-02 CAPACITOR, CERAMIC, T/R 470pF 5%/Y5E C45
212-001-00 CER .01UF 10% 50V X7R SM 0.01 10% C20 C25
212-006-00 CAPACITOR CERAMIC SMT 470PF 5% C46
212-007-00 CAPACITOR CERAMIC SMT 0.047 5% C4 C6 C8-10 C12-13 C22-23 C27 C30 C33

C35 C37-39 C41-42 C52-58 C61-62
212-008-00 CER .22UF +80/-20% 25V SM 0.22 5% C1 C3 C47 C51 C63
212-016-00 CAPACITOR CERAMIC SMT 1000PF 5% C5 C21 C24
212-018-00 CAPACITOR CERAMIC SMT 10PF 5% C43-44
212-019-00 CER 150PF 5% 50V SM 150PF 5% C11 C14
212-025-00 CAP CER .1UF 25V 10% X7R .1UF 10% C15-18 C66
212-029-00 CAPACITOR CERAMIC SMT 270PF 5% C34
220-001-02 CAPACITOR LYTIC RADIAL T&R 22UF 10% C7 C48-49 C64-65
220-004-02 CAPACITOR LYTIC RADIAL T&R 470UF 10% C50
220-014-00 CAPACITOR LYTIC RADIAL KS 2.2UF 10% C2 C19 C26 C28-29 C36 C40
300-003-00 DIODE SIGNAL SMD DL4148 D1-6 D11-14 D16-25 D27-36 D38-39

D41-42 D44-45 D47-52 D56-57
300-010-00 DIODE SIGNAL SMD RLS245 D26 D37 D40 D43 D46 D53-55 D58-60
302-009-00 DIODE ZENER SMD DL5260B D7 D10
302-010-03 DIODE ZENER SMD DL5232 D8-9 D15
310-042-00 XSTR NPN MJE15032 MJE15032 Q1
310-043-00 XSTR PNP MJE15033 MJE15033 Q2
311-001-00 X-SISTOR NPN SMD IMBT4401 Q13 Q22 Q25
311-002-00 X-SISTOR PNP SMD IMBT4403 Q7-8 Q21 Q24 Q28
311-007-00 TRANSISTOR PNP SMD 2SA1415 Q4 Q9-10 Q20
311-008-00 TRANSISTOR NPN SMD 2SC3645 Q3 Q11-12 Q15
311-009-00 TRANSISTOR PNP SMD 2SA1552 Q6 Q2 6
311-010-00 TRANSISTOR NPN SMD 2SC4027 Q5 Q2 7
311-011-00 TRANSISTOR PNP SMD 2SA1740 Q14
311-012-00 TRANSISTOR NPN SMD 2SC4548 Q23
311-019-00 TRANSISTOR PNP SMD 2SB792 Q16-17
311-020-00 TRANSISTOR NPN SMD 2SD814 Q18-19
320-012-00 OPAMP NJM4560M NJM4560M U5-6 U8-9
323-002-00 I.C. QUAD COMPARATOR SMD LM339 U2-4
329-014-00 IC, DEG C TEMP SENSOR LM35DZ U1
329-036-03 NJM4200M ANLG MULTR SM NJM4200 U7
400-143-00 CONN, HDR, 3-PIN, UN-SHROUDED 0 .100 J21-22
400-171-00 CONN, HDR, 2-PIN, UN-SHROUDED, 0 .100 J17-20 J23
400-186-00 CONN HDR 40P .100 X 2 STR SHRD J10
450-170-00 PCB, M2600 V-AMP & PROTECTION Z1
550-369-00 BRACKET, L H1-2
601-008-00 INDUCTOR 10uH L1-2
712-021-01 RIVET Z4-7

28

055-171-00-01 Rev A Power supply board

Part # Description Value Reference Designator

100-077-00 RES CF .125W 5% 15K OHM 15K 5% R10-12
123-109-00 RESISTOR MOF 3.3K 5% R1-8
150-037-00 RESISTOR, FUSABLE, 1/4W 3 3 5% R9
200-036-02 CAP, METALIZED POLY, T/R .1uF 10% C15-22
211-009-00 CAPACITOR CERAMIC AXIAL 0.1 10% C23-24
220-006-00 CAPACITOR LYTIC RADIAL 2200UF 10% C9-12
220-029-00 CAPACITOR LYTIC RADIAL 2200UF 20% C13-14
220-041-00 CAPACITOR LYTIC RADIAL 15,000uF20% C1-8
300-001-00 DIO SIG 1N4148 100V 500MW 1N4148 D19-20
301-009-00 DIODE POWER 1N4004 D1-5 D10-16
301-010-00 DIODE POWER 1N5404 D6-9
301-015-00 DIODE BRIDGE 25A D17-18
310-007-00 XSTR NPN 2N4401 2N4401 Q1
400-060-00 FUSE CLIP PCMT 5MM DIA Z1-3 Z5
400-133-00 HEADER, 2X3, MATE-N-LOCK J6
400-173-00 CONN QUICK DISC .250 J3-5

W/STABLE-LOK TABS
400-231-00 HEADER, 2X5, MATE-N-LOCK J1-2
450-171-00 PCB, M2600, POWER SUPPLY Z4
510-026-00 FUSE 5X20 T-3.15A F1-2

055-172-00-01 Rev A Speaker output board

Part # Description Value Reference Designator

400-138-01 SPEAKONS HORIZ 4 CKT J2-4
400-173-00 CONN QUICK DISC .250 W/STABLE-LOK TABS J5-8
400-237-00 CONNECTOR, QUAD BANANA J1
450-172-00 PCB, M2600, OUTPUT Z1

Components noted with this symbol shall be replaced only by the component
specified.This is required to maintain product safety.

29

055-186-00 Rev A 15 Volt supply/fan drive board

Part # Description Value Reference Designator

TEST POINT, PART OF PCB J1-2
100-031-00 RESISTOR CF 180 5% R8
100-049-00 RESISTOR CF 1K 5% R7
100-056-00 RESISTOR CF 2K 5% R10
100-061-00 RESISTOR CF 3K3 5% R6
100-066-00 RESISTOR CF 5K1 5% R2
100-068-00 RES CF .125W 5% 6K2 OHM 6K2 5% R5
100-069-00 RESISTOR CF 6K8 5% R4
100-073-00 RESISTOR CF 10K 5% R9
100-078-00 RESISTOR CF 16K 5% R3
100-080-00 RESISTOR CF 20K 5% R13
100-090-00 RES CF .125W 5% 51K OHM 51K 5% R12
100-097-00 RESISTOR CF 100K 5% R11
121-081-00 RESISTOR MF 2K2 5% R14
130-021-00 RESISTOR POT TRIM HORIZ 10KB R1
211-009-00 CAPACITOR CERAMIC AXIAL 0.1 10% C3 C5 C7-8
220-001-02 CAPACITOR LYTIC RADIAL T&R 22UF 10% C2 C4 C9
220-027-02 CAPACITOR LYTIC RADIAL T&R 10UF 10% C1 C6
300-001-00 DIODE SIGNAL 1N4148 D5-7
301-009-00 DIODE POWER 1N4004 D1-4
310-002-00 TRANSISTOR PNP 2N4403 Q3
310-024-00 TRANSISTOR PNP 2SB817 Q1
310-050-00 TRANSISTOR NPN 2SC1567A Q2
320-011-00 I.C. LINEAR NJM 4560 U3
321-001-00 I.C. LINEAR NEG 3 TERM VOLTAGE LM 7915 U1

REGULATOR
321-002-00 I.C. LINEAR POS 3 TERM VOLTAGE LM 7815 U2

REGULATOR
400-078-00 CONNECTOR STR LCK SHRD 10P .100 X 2 J4
400-171-00 CONN, HDR, 2-PIN, UN-SHROUDED, 0 .100 J3
450-186-00 PCB, M2600, +/-15V SUPPLY & FAN DRIVE Z1
550-369-00 BRACKET, L H1-2
601-013-00 CHOKE, POWER AXIAL 470uH L1-2
712-021-01 RIVET Z4-7

30

M•2600 amplifier modification instructions

Models affected: All M•2600 amplifiers with serial numbers “AU” or those less than DX10017.

Add this mod as part of your normal repair procedures.

Symptom: No signal, dead channel or distorted output.
Possible Cause:

1: Transistor Q5 on the V-amp protection boards may be shorted to an adjacent trace.
2: Transistors Q3 and Q4 on the V-amp protection boards may oscillate under certain conditions,

causing V-amp board failure, and/or failure of R57 on Ch.1 amp board and R56 on CH.2 amp
board (33Ω fuse).

Solution: Rework both V-amp circuit boards (055-170-00) as follows:

1: Replace Q5 with a new transistor and make sure it is postioned further down, away from the trace,

or : cut two traces and add a jumper wire (to bypass any possiblity of a short).

2: Replace R14, R15, R20 and R21 with new value resistors (to improve the reliability of the final class A

stage, comprising of transistors Q1 to Q6 and associated resistors, diodes and caps).

Safety Warning:

Caution! These instructions are for use by qualified personnel only. To avoid electric shock, do not
perform any servicing unless you are qualified to do so. Refer all service to qualified personnel.

Tools Required:

Sharp pointed X-acto knife, Phillips screwdriver, Torx and Allen drivers, needle nose pliers, safety glasses,
soldering iron suitable for surface mount work.

Parts Required:

Insulated jumper wire

311-010-00 2SC4027 Transistor, NPN, SMD Q5
140-057-00 220Ω Resistor, 0.1W, 5%, Thick film, SMT 0805 R15 and R20
140-084-00 3KΩ Resistor, 0.1W, 5%, Thick film, SMT 0805 R14 and R21

Procedure: (The following modifications must be performed on both V-amp boards)

1/ Remove all cords (including the power cable and speaker outputs) from the amplifier.
2/ Remove the amplifier subassembly from the chassis.
3/ Remove the two V-amp boards (055-170-00) from the amplifier subassembly.
4/ Replace R15 and R20 (from 0Ω to 220Ω).
5/ Replace R14 and R21 (from 2kΩ to 3kΩ).
6/ Follow step A, or follow step B, whichever you find easiest.

A/ If you have a new transistor in stock, replace Q5 and make sure it is positioned further

down, so the left leg is fully on its pad and not over the trace. Note: a new transistor is
required because unsoldering and repositioning the original transistor will thermal-stress
and weaken the part.

B/ Carefully cut the trace in two places on each board. See the diagram on the second

page. The trace should be cut exactly in the locations shown. It is not easy to get to, and
you may have to scrape off some of the white silkscreen lines in order to see the trace.

Solder a jumper wire in the position shown, on each board.
7/ Reassemble the V-amp boards onto the amplifier subassembly.
8/ Reassemble the amplifier subassembly into the chassis.
9/ Perform a complete specification and safety test. Refer to the service manual for details.

M•2600 modification SSE July 2000

M2600mod.pdf, page 1 of 2

THE MACKIE FIXER  MACKIE DESIGNS SERVICE NEWS

Amplifier
Subassembly

055-170-00 V-AMP board

Solder
here

Cut trace here

Change R20 and R21

Change R14
and R15

Cut trace here

Solder an insulated wire here

M•2600 modification SSE July 2000

M2600mod.pdf, page 2 of 2