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Beomaster 1900-2 no power after disassembly

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This post has 11 Replies | 1 Follower

Sampep
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Sampep Posted: Sat, Apr 28 2018 12:19 PM

Hi all,

Hopefully someone can help me out with this one, I recently attempted to restore a 1900-2 with Martins cap kit and rectifier - thanks by the way - but when I put it all together and turned it on there was nothing. All the lights etc. worked before but when I tested it there were no lights or turning on noise from speakers.

The only thing I soldered apart from the caps was 2/4 wires on the on/off switch so that i could take it apart. The wires are definitely back the right way around!  

Anything I could have damaged in assembly? Or how I can diagnose any common issues? I have pictures, please note I broke one of the fuses on second disassembly so that wasn't the issue but you may see one weird looking fuse on these pictures.

Thanks, appreciate any help, could be something so simple!

Pics here

solderon29
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No standby light either?

Did you reassemble the power switch correctly I wonder?

I've never dismantled that switch,but it seems significant that you had function previuosly?

Regards,

Nick

Dillen
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Dillen replied on Sat, Apr 28 2018 5:15 PM

While replacing the single capacitor on the fuse board, it's quite easy to pull one or more of the stiff wires from the
transformer etc. inadvertently and unnoticed from their solder joints.
They may still sit in their holes in the board but no longer have any connection.
Try pulling them gently one by one - or simply clean and resolder them.

Martin

Sampep
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Sampep replied on Sat, Apr 28 2018 7:15 PM

Thanks for your replies chaps,

Nick, no lights im afraid. I took a photo of.the wiring of the switch before and the wires are in the same places so I don't think that is it.

And Martin, pulling the stiff wires didn't yield anything. What however did budge were the two blue wires that have sleeves to join to the board. (https://imgur.com/a/qj1r9Dl). I will solder these in place but seeing as they still make contact, surely the circuit is in tact?

Please do correct me if I'm.wrong, any other suggestions are appreciated ! Thanks

Sam

Dillen
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Dillen replied on Sat, Apr 28 2018 7:35 PM

AC voltage readings before and after the switch?

Martin

sonavor
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sonavor replied on Sat, Apr 28 2018 7:35 PM

The best thing to do in this situation is start with the power to the Beomaster and proceed to the power supply. Verify that you have correct power voltages (and grounds).

-sonavor

Sampep
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Sampep replied on Sat, Apr 28 2018 9:38 PM

My voltmeter is about as old as the beomaster, only goes up to 15v. Possibly not up to the job?

I have tried the wires blue and black wires that come out the switch and they max it out at 15v, not 100% sure on which ones to test?

However I have just snapped off the switch so will have to revisit this when that is sorted, thanks again guys

Dillen
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Dillen replied on Sat, Apr 28 2018 9:50 PM

AC!
Not DC.

Grab one of the cheap multimeters off Ebay.

Martin 

leafrancis
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leafrancis replied on Sun, Apr 29 2018 10:18 PM

I have been told that the 'mains switch' on the 1900s can fail, possibly more likely if you have been soldering to it... I would simply link out the mains switch and see if that fixes it...

As Dillen says, measure the AC voltages, particularly the low voltage supply wires (2 x copper wires that solder to the main PCB)... These provide the input power to the 15volt power supply (also standby power)...

If you don't have a standby led lit, then there is probably no low voltage power...

£20 will buy you a tidy multimeter... 

Sampep
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Sampep replied on Thu, May 17 2018 9:51 PM

I have finally acquired a multimeter, 243 before switch, 0 after.. guess we have our culprit.

Possible to get a replacement switch or any good alternatives out there? Would ideally have one rather than soulder the wires and bypass it altogether.

Sampep
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Sampep replied on Mon, May 28 2018 3:07 PM

So I bypassed the switch, 240v reading on the brown PCB where the power comes in. 

I re-souldered the thin copper wires that join the main PCB,  which read 0.2v as did just about everywhere else. Replaced fuses too.

Without knowing better it seems like the transformer or whatever the large circular thing is, is not giving power beyond 0.2v.

No idea why or how to fix. never tampered with these parts and the area appears To be intact any ideas? ?

Torinst
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Torinst replied on Sat, Jan 29 2022 9:09 AM

Almost certain you during the assembly have forgotten to insulate TR27 - the transistor that uses the bracket - shilding the big electrolytes - as a cooling plate. Its fastened to the bracked by a small bolt. If not insulated properly the whole unit will be none working including the small red power led. 

Its very easy to miss the insulation - a small square plate insulates the transistor from the bracket AND - a very small plastic washer - insulates the bolt from the transistor - so that the transistor will be perfect insulatet from the bracket. The TR27 might survive the miss treatment and also the whole unit. 

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