Ensoniq Corporation EPS User's Manual

April 15, 1989

THIS BULLETIN COVERS:

. EPS DIAGNOSTICS .

EPS - THE 7501 MAIN BOARD AND THE 10002 MAIN BOARD

EPS DIAGNOSTICS

A number of a faulty power supply. The following are the most common problems which could be caused by a faulty power

SUDDIV:

,. ,

To Transformer-

EPS’s

have been incorrectly diagnosed as having a faulty main board when the real problem was

Back

4.0

Amp, 250 V

4.0 Amp, 250 V

of Unit

Heat Sink

1.5 Amp,

1 .

PROBLEM: Hum or buzz in audio output; EPS crashes randomly; or problems develop after memory expander.

SOLUTION: Check the voltages on the power supply at J4 with the power supply loaded (main board

and display board connected). Using pin 11 as ground, the voltages on pins 14, 16, and 16 (of J4) should be

+4.75

+5.25

VDC. The AC ripple on these pins should be less than 50mV. If the voltages are not

within this range or the AC ripple is greater than

2. PROBLEM: EPS is dead on power up. SOLUTION: Perform solution I above. If no problem is found, check the voltages on the power supply at J3. voltages are not within this range, replace the power supply. pin 25 (of J3).

3. PROBLEM: EPS has disk drive loading problems.

SOLUTION: Perform solution 1 above. If no problem is found, check the voltages on the power supply at J2. Using pin 11 of J4 as ground, the voltage on pin 22 (of J2) should be ripple on this pin should be less than 50mV.

greater than

Using pin 23 as ground, the

It should be -29 to -37.2 VDC. If the voltage is not in this range, replace the power supply,

50mV,

replace the power supply.

1.5Amp.250V

VOltageS

250 V 250 V

To Main Harness

Heat Sink

inserting

50mV,

replace the power supply.

on pins 27 and 28 (of J3) should be -22.7 to -315VDC. If the

If no problem is found, check the voltage at

+11.4

+12.6

VDC. The AC

If the voltage is not within this range or the AC ripple is

THE 7501

Unitswnh &&al

-lWtlN

BOARD AND THE 10002 MAIN BOARD

numbers 16582 or higher (240V- 502603) contain a new version of the EPS Main Board. The

10002 board is a new layout of the 7501 Main Board with: the tower board included: a new square gate array chip that replaces several individual chips; and a different size RAM chip. When replacing a main board, you should replace ii with the same version that is in the unit. Replacing a 7501 Maln Board

board should be done only when 7501 maln boards are not

,avallable

to you. The 10002

with

a 10002

board has all of the connectors (except the disk drive connector, J2) in a different place from the 7501 board. If you must replace a 7501 Main Board with a 10002 Main Board, three cables must be replaced. D

attempt to switch boards without

acqulrlng

these cables from

ENSONIQ Cbstomer

not

Servlce:

Keyboard Cable, Main Board Power Cable (attached lo main harness), and SCSI Cable (if applicable),

Remove the 7501 Main board as described in the EPS Service Manual.

Clip the four wire ties that hold the main board power cable

Insert

the new 10002 Main Board as described in the EPS Service Manual.

Attach the new main board power cable to the power supply at J4 and to the main board at

Reconnect the cables from the display board

Use two wire ties to bundle the new main board power cable out of the way. NOTE: Leave the wheels

(J8),

wheels

(g-pin)

to the main harness.

(J9),

and disk drive (J2).

Discard this cable.

JlO.

cable out of the wire ties.

If applicable, install the new longer SCSI cable (the

34-pin

ribbon cable from the SCSI board to the auxiliary

expansion, connector J6 on the main board).

8. Replace the existing keyboard cable on the keyboard with the new longer keyboard cable.

Re-install the keyboard as described in the EPS Service Manual.

10. For best results, boot the unit with the latest OS. disk (2.35 or higher).

March 20, 1991

This Bulletin Covers:

Soldering jumper wires between the two Poly-Key Keyboard Coil Boards that have a twelve-pin single not need to be hardwired.) This bulletin should only be done after performing Service

Bulletin

row

connector. (A twenty-pin dual-row connector was used after November 1990 and does

#9B

to ensure that the unit has the latest KPC version and resistors.

To form an absolute connection between together using remove six keys from the middle of the keyboard to expose the solder side of the connectors.

Tools Needed:

2.5mm

PhiIlius

soldering iron

hex wrench

screwdriver

the

wires provided. You will need to remove the keyboard

the

two coil boards, you

small flat blade screwdriver

zynr

CONNECT(QDS

wires from ENSONIQ

Remove

these six keys

SINGLE-ROW

(12)

COlL :

BOARD

COIL

iBOARD

will be hardwiring the coil boards

from

the

uu;t and

then

only

COILS

Service Bulletin #I I - Poly-Key Keyoard Coil

(over)

Boards

9TGC

CO86 01 -A

A. Remove the Keyboard from the unit

;;

Remove Using a

Place

all

external cables connected to the unit. including the Power cord.

2.5mm

hex wrench, remove the four (4)

the

unit upside

down

scr~s

that fasten the control panel and raise

the

panel.

Carefully mm the unit right side op. Raise the

the main board. paying particular attention to the polarity.

Remove the keyboard from the case by gently lifting up

Once the

keyboard cavity.

B . Remove Middle D through

rear

of the keyboard has

cleared the

(

contxol panel

control

(see figure on p. 1)

Place

the

keyboard with the keys up on

Remove

b. Push

Remove

a. b.

IMPORTANT!

c. While

the

key springs:

Insen a small Phillips screwdriver

down

expand the

the springs in a

the

keys to expose the coil boara connecmrs Just below the key number (near the There is a clip that holds

lifting up on the back of the key (near

the

keyboard to release

safe

These.

pressure, contact

spring,

place. they

the

clips do not need a lot of pressure to be released.

the

spring

key in place.

ENSONlQ

clip.

hole) on

Insert

Customer Service for a replacement key.

C. Solder the connector leads together

Hardwire

the connector leads together If there are two rows of leads on each a better

co~ector and does

not need to be

(horizontally).

board.

do not solder them together.

hardwised.

and disconnect

the

front of it while pulling it toward

panel

mounting tabs, the keyboard can be removed

(wnxe Keys nrst):

the

key there is a

a small/thin flat blade

the

spring hole) push

the Z&pin

rectnngular

scmwdriver

If a clip breaks due to

the

top

The

keyboard ribbon cable

opening.

into the opening.

the

screwdriver toward

twenty-pin dual-row connector is

the

front of the unit

from the

tco

much

the

f?om

back of

D. Reinstall the keys:

Put the black keys on

2)3)Place the Place

To reinstall screwdriver into the spring and push down and out to expand it. Then move the bottom

frame.

front

of the key on fast, then press

the

white keys back on in order. Make

the

first.

They go on where

springs, place the spring

there are the sure that

into

its hole on the key (open side up). Insert the

single keystops.

back of the

kejj

down

zm!i! the c!ip

the clip for each key is engaged.

catches and holds it in place.

small/thin

the

spring into

Phillips

the

keyboard

E. Install the Keyboard into the unit

Making note of

IMPORTANT!

Insmt

the keyboard rear fust

rear

of the unit, lowering the

slightly to be sure that the keyboard cable lies flat beneath the keyboard and is not pinched under the keyboard frame.

Tom

the unit upside down on a soft surface and replace

Power up, test the unit, and close

page

the

proper polarity, connect the keyboard ribbon cable to the main board.

If the ribbon cable is

into the

front

the

mispirmed,

unit at

the front

the

keyboard as needed to clear the control panel mounting tabs. Lift the keys

control panel.

fuses F3 and F4 on

the

keyboard cavity. Gently slide the keyboard toward the

the

ten (10) screws

the

power supply will blow.

that secure rhe

keyboard to

the

case.

Service Bulletin #II

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