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Beocord 5000 (492x) _ No sound

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dahiyas
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dahiyas posted on Tue, Aug 11 2020 5:46 AM

Hello,

I just replaced the belts and a fusible resistor (R20) on a Beocord 5000 (thanks to Martin). Everything tested ok. Played a whole side of cassette without any issues. Put it in standby. 30 min break. Switch on and play cassette - Noticed that the LED for VU meter were not lit for Left side. Right side was OK. music was playing from both speakers. So I switched off the unit, switched on again but this time there was no sound from speakers when cassette was played.

So the player is playing the cassette. All tape functions work ok. The connected BC9500 switches on when beocord 5000 is switched on and responds normally.

Two visible issues -

1. No sound on play.

2. VU meter  - All LEDs come ON when cassette is playing. The LEDs go off if tape is switched off.

Any help/guidance will be appreciated.

Thank you !!

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Dillen
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Dillen replied on Tue, Aug 11 2020 1:42 PM

Check the ref. voltages and capacitors 4C1 (10uF) and 2C3 (220uF)

Martin

dahiyas
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Thanks Martin..Both the caps seem to be ok. I replaced them anyways

No change in issues.

dahiyas
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Martin..I see 7.2v on pin 5 of IC101 and IC201.

On closer look I found C2 on the PCB 2 was 470uf but the service manual shows it as 100uf ?

Thanks.

Dillen
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Dillen replied on Thu, Aug 13 2020 10:17 AM

Check that the Dolby circuit board is connected properly under the main board.
Check the record/playback relay contacts (or replace the relay).
Check the 14VA and -15V supplies to the audio line amplifiers.
Check the ground connections to the tapeheads.

Martin

dahiyas
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Thanks for your guidance Martin. I'll check the items you have listed.

Also should I leave the 470uf cap or replace with 100uf ?

 

Dillen
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Dillen replied on Thu, Aug 13 2020 5:45 PM

470uF is fine.

Martin

dahiyas
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Martin...weird one...the beocord seems to be erasing the tapes when I play them Confused. I tried the tape I am using on the defective player on a BC9500 and found its erased. I can hear some music at very high volume but its faint.

I am 100% sure I have not pressed the record button at any point. Put another old tape and same fate.

Does that point to a specific component failure ?

 

Thanks !!

dahiyas
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Removed the Relay and tested with 3v. Seems to be working fine. Have ordered another one that should show up later this week. But relay doesn't seem to be the issue.

Check that the Dolby circuit board is connected properly under the main board - Took out and reconnected multiple times. Looks ok.
Check the 14VA and -15V supplies to the audio line amplifiers. - All voltages as per schematic check ok.
Check the ground connections to the tapeheads. - Verified.

 


dahiyas
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I finally did get some time to work on this.

I have another Beocord 5000 and I compared the two units and confirmed the following -

1. I swapped the PCB 2 from bad unit to good unit and the good unit worked fine. So PCB2 is not an issue.

2. On the bad unit the E of TR112 is reading 3.7V and the good unit is about 40mv.

Any next steps ?

 

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