Goldstar ffh-8900a Service Manual adjusments troubleshooting

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CH1 CH2

Speaker Out

Playback Mode

Head

Test Tape MTT-114

L ch

R ch

GND

Dual-trace synchroscope

Electronic Voltmeter

L out

R out

Unit

This set has been aligned at the factory and normally will not require further adjustment. As a result, it is not recommended that any attempt is made to modificate any circuit. If any parts are replaced or if anyone tampers with the adjustment, realignment may be necessary.

IMPORTANT

1. Check Power-source voltage.

2. Set the function switch to band being aligned.

3. Turn volume control to minimum unless otherwise noted.

4. Connect low side of signal source and output indicator to chassis ground unless otherwise specified.

5. Keep the signal input as low as possible to avoid AGC and AC action.

ADJUSTMENTS

Deck Mode Test Tape Test Point Adjustment Adjust for

A Deck Playback MTT-114 Speaker Out DECK Screw Maximum B Deck Playback MTT-114 Speaker Out Azimuth Screw Maximum

2. MOTOR SPEED ADJUSTMENT

Figure 1. Azimuth Adjustment Connection Diagram

Figure 2. Motor Speed Adjustment Connection Diagram

Head

Playback Mode

Unit

Speaker Out

GND

L out

R out

Record/Playback head

Test Tape MTT-111

Frequency Counter

Deck Mode Test Tape Test Point Adjustment Adjust for Remark

Normal Speed MTT-111 Speaker Out VR201 3kHz ± 1% Hi-Speed MTT-111 Speaker Out more than 5.4kHz High-Speed Dubbing Mode

TAPE DECK ADJUSTMENT

1. AZIMUTH ADJUSTMENT

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3. RECORD BIAS ADJUSTMENT

Head

Unit

PN202

GND

Record/Playback head

Test Tape MTT-5511

Record/Playback and Pause Mode

Frequency Counter

Deck Mode Test Tape Test Point Adjustment Adjust for

Rec/Pause MTT-5511 ERASE HEAD Wire(PN202) L203 90kHz±5kHz

Figure 3. Record Bias Adjustment Connection Diagram

Figure 4. Tuner(S curve) Adjustment Connection Diagram

4. TUNER ADJUSTMENT

Unit

Signal Generator

GND

Electronic OSCILLOSCOPE

FM Antenna Terminal

Speake

Item Test Point Adjustment Adjust for

DC Voltage Checker Pin TP1, TP2 L106 0V±50mV

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TROUBLESHOOTING

Turn power on.

Is power on?

Does initial read work?

Does it play?

Does it output audio?

Check power supply circuit.

(Check PN 701)

Check laser circuit.

Check focus circuit.

Check disc.

Check tracking servo circuit.

Check audio circuit.

YES

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Fails to initial read

1.3V

A B

YES

NO NO NONO

Does laser light?

Disc motor turns.

Does RF waveform appear?

TP 801(RF)

Does tracking servo work? Lower envelope of TP801(RF) waveform is flat.

Does signal appear at TP801(TEO)?

Does signal appear at IC 803 Pin and Pin ?

Does GFS (IC802 pin 󱈁) show as below?

Is rotation normal?

Is there no dropout of RF signal?

Does TE2 signal appear at pin of IC801?

Defective IC 801, pick up and/or open wire.

Detective pattern.

Defective IC 801 and/or IC 803

Defective pick-up and/or connector.

Defective IC 801.

Scratch in disc initial read area.

Defective pick-up adjustment focus offset.

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Laser does not light.

Is “3.5V” applied to pin of IC 801?

Is power supplied to laser Q801?

(Q 801 collector: about 1.8V)

Does laser current flow?

1.0V across R801

Is data transferred from MICOM IC ?

Does voltage appear at IC 803 pin ⑪, ⑫?

Defective MICOM.

Defective connector.

Defective IC 801, 803

Defective slide motor and/or connector.

Defective LMT SW and/or connector.

Defective Q 801 and/or laser.

Defective laser and/or connector.

Did pickup return to

innermost circular?

Does it stop at inner pick circular after shift?

Is defect output from LM SW applied to pin ② of

PN803?

R801≫1.0V

R801≪1.0V

YES

OPEN

YES

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Does lens move up/down?

Does IC 801 out focus search signal?

IC 801 pin (FEO)

Is focus search signal applied to pin , of CN801?

Laser lights.

Confirm

initial

read with

disc

Defective IC801

Defective IC803

Defective IC 801.

Open activator and/or connector.

Open connector and/or defective IC 801.

Incorrect turntable height. Degraded laser diode.

Does TP 801 RF signal appear even in low level?

Is laser output adjustment correct?

Does FOK(focus ok) signal appear?

YES

TP801 (RF)

IC801 pin (FOK)

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FER

ISTAT(SENSE)

Start mode

Does FE1 signal appear? IC 801 pin

Does FZC signal (focus zero cross signal) appear at pin of IC 801, ISTAT (SENSE) terminal?

Does SMON signal appear at pin of IC 802?

Does SMPO signal appear at pin of IC 802?

Is drive voltage applied to disk motor?

Defective IC 801.

Open pick diode

Defective IC 801.

Defective Pattern between IC 801 and IC 802.

Defective IC 801, 803 and/or peripheral circuit.

Defective disk motor and/or insulation.

(Focus servo turns ON by FZC signal of FOK mod.)

YES

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(CH1)

(CH2)

WAVEFORMS OF MAJOR CHECK POINT

1. HF signal (RF signal ) waveform (Test Point TP801) during normal play

2. EFM signal (pin IC 801)waveform during Normal Play

3. Focus coil drive waveform(Pin NO

① , ② of IC 803)

·When focus search failed or there is no disc on the tray

·Focus coil drive waveform(pin NO ①, ② of IC803) and

FOK (pin NO of IC 801) when focus search is accomplished

4. Tracking coil drive waveform (pin NO , of IC 803) and TEO during track traverse (1) When time division is 20nS/div

(2) When time division 0.5nS/div.

(During forward track traverse)

(3) When time division is 0.5nS/div.

(During backward Track Traverse)

5. Feed motor drive waveform(pin NO

⑪, ⑫ of IC 803)

During normal play

CH1 : FOCUS COIL DRIVE

SIGNAL 2V/Div.

CH2 : FOAK

CH1 : TEO(TP801)

1V/Div.

CH2 : TRACKING COIL DRIVE

SIGNAL 2V/Div.

CH1 : TEO(TP801)

1V/Div.

CH2 : TRACKING COIL DRIVE

SIGNAL 2V/Div.

CH1 : TEO(TP801)

1V/Div.

CH2 : TRACK COIL DRIVE

SIGNAL 2V/Div.

0.5V/Div. 500nS/Div.

2V/Div. 500nS/Div.

0.5V/Div. 500nS/Div.

OV (CH1)

(CH2)

(CH1)

(CH2)

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MEMO