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Beomaster 1900 bass,treble and balance lights not working

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Woodcod
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Woodcod posted on Fri, Sep 11 2020 7:41 PM

Hi I have ordered a lamp kit from Beoworld, but before I start replacing lamps, i wondered if anyone can offer some words of wisdom. All three lamps on the bass,treble and balance light module are not working. All other lamps working. I used my fluke across the lamps and got a beep so assume the lamps are intact, is this so or could I be picking up a different path? Also is there any other causes for the lamps not to be working?

I also have no sound out of the right speaker ports so have ordered a new part for the balance potentiometer as that seems to be the most common cause. Thanks Dave

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jhjove
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jhjove replied on Tue, Sep 15 2020 1:30 PM

I'd  check the board  power connections.

These lamps are just hanging off the 15V supply (with individual 68ohm dropping resistors). Might be just a bad connection. 

--Joe

Woodcod
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Thanks Joe, I’ll do some more checks, just a thought are the lamps in series as When I looked one of the resistors had some black marks on the board and I wonder if this might be the cause. Thanks Dave

Woodcod
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Hi Joe thank you just a thought are the lamps in series as I noticed some burning on one of the resistors closest to the power connections thanks Dave

jhjove
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The 3 lamps and their resistor are in parallel. 

Hopefully the attached snippet of the schematic shows this. 

 

 


--Joe

Woodcod
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Thanks Joe as all lamps appear intact think I will look at the transistor TR31 and see if I have 15v

thanks Dave

jhjove
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jhjove replied on Wed, Sep 16 2020 12:01 PM

Dave, have you checked the 68ohm resistors? Possibly they are open or now failing high resulting in very little current flow (not enough current to illuminate the lamps)?

If the 15V supply is suspect I would think other parts of the receiver would not be functioning as well. 

 

--Joe

Woodcod
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Hi Joe success, measured the failed lamps and they were 90 ohms against a new lamp at 20ohms, replaced all three and now working, just need to sort the right channel with the potentiometer upgrade on the balance slider and hopefully that will fix that, thanks for your help and advice.

jhjove
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jhjove replied on Thu, Sep 17 2020 12:39 AM

That's great.

I too have yet to purchase the slider repair kit.  I did a "kludge" fix using "crazy glue" on all 3 slides for mine.  So far it works.... at least well enough for both channels to pass through from tone control to power amp stage.  But I know through use this fix will fail,  however the receiver plays nicely in the meantime. 

--Joe

Woodcod
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Woodcod replied on Fri, Sep 18 2020 10:25 PM

Hi Joe just finished doing the potentiometer upgrade on the balance slider and both channels working now so can recommend purchasing the kit If you are considering it.

all the best Dave

jhjove
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jhjove replied on Sat, Sep 19 2020 12:37 PM

Very good, congrats on getting the receiver  to "sing" again.

This slider repair kit and replacing the old trim pots (idle adjustment) are on the "to-do" list. I just don't want to open the unit just yet. I'm enjoying my own success and the disassembly then the reassembly of  the receiver is not that enjoyable. 

--Joe

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