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Beomaster 2400 - NOT quite the usual volume control problem - I need help!

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StuckInBulgaria
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StuckInBulgaria Posted: Sat, Dec 10 2016 10:20 PM

Hello

Ok this is what I have done so far:

Replaced ALL electrolytic caps with new

Mended the balance (plus the 2 tone control) potentiometer slider pickups

Replaced all lamps with 15v 1w lamps

Replaced the 2 capacitors on the volume control board

Replaced both bridge rectifiers

This has left me with a much improved piece of equipment still exhibiting 1 problem - the volume goes pretty much instantly to max.  The "UP" light is on full and the "DOWN" is very dim.  HOWEVER - touching the "UP" control will dramatically LOWER the volume to probably 1/3 of max.  It will also cause the "up" and "down" lights to balance out in brightness.

 

On TR23 I have 15.4v and on TR26 I have 12.3v - 12.3v being correct.  Im afraid that is where my knowledge runs out, obviously something in the circuit prior to TR23 is allowing two much voltage through but beyond replacing components 1 at a time until I hit on the culprit Im a little lost as to how to quickly identify the culprit.

 

Any and all help much appreciated - I have many hours work in this unit both cosmetic and component and it is driving me nuts I can not crack this final problem so I can listen to it!

Dillen
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Dillen replied on Sun, Dec 11 2016 10:39 AM

If the volume lamps are stuck and not following the actual volume, check the lamp drivers on the volume board.
Also check your work on the volume lamp board (and the lamp that is not lit).

Martin

StuckInBulgaria
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Dillen:

If the volume lamps are stuck and not following the actual volume, check the lamp drivers on the volume board.
Also check your work on the volume lamp board (and the lamp that is not lit).

The lamp is good and the work ok.  The lamp drivers being TR 27 & TR 28?  Would you have the parts specification list for the 128 step volume control board?  I only have it for the 16 step so parts replacement is difficult.

 

Im surprised someone has not started making a replacement volume control board the number of posts on the internet about people desperately trying to get them to work - that functionality is probably available today in 1 IC LOL.

Dillen
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Dillen replied on Mon, Dec 12 2016 9:33 PM

StuckInBulgaria:

Would you have the parts specification list for the 128 step volume control board?

Yes, email me.

StuckInBulgaria:

 that functionality is probably available today in 1 IC LOL.

The whole Beomaster could easily be available as 1 IC.
But it wouldn't be the same, - would it?

Martin

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