Beomaster 7000 getting hot in standby

[Marto]

Hi all, few days ago I bought a set of Beomaster 7000 with Beogram CD 7000. The cd needs the usual caps and now working flawlessly. I read here the mod for preamp on BM ( removing of some ceramic caps) and desolder them. Yesterday i touch the Beomaster and it feels warm on the back part of the top cover. By the way it’s connected only to Beolab Penta. I start reading about similar problems here again and do the following. Change the capacitors on the power supply board C8, C9, C14 and another 10uF capacitor which was like a bridge on the R57 and R20 ( don’t know if it’s C22 i didn’t see it on the schematic anyway) all four was way off specs. After this replacement i do the no-load current to 11mV and put everything back together. I went out for few hours and when I come back home touch the Beomaster and again it is warm on top back. Please give me some advice what else can cause this warming without using the BM.

Martin

[Dillen]

Resolder the relay for the amplifier.
Its solder joints for the coil cracks, making it impossible to pull the relay and close down the amplifier.
– Yes, this relay is active when the Beomaster is in standby.

Still no luck – replace the relay (new relay here).

Martin

[Marto]

Thanks for this suggestion Martin. I can hear and see the relay clicks, anyway I resolder it, but still no luck with warming. I think that something else is the reason. The problem should be somewhere on the right side, around the big caps, but still can’t find it. Wondering what else stay on in the standby mode.
Thanks

Martin

[Dillen]

Is it only the far right side of the cooling fin that is warm?
And how warm?

Martin

[Marto]

All the cooling fins are hot, maybe around 50 degree C. It’s like no matter is it ON or Standby, the temperature is the same.

Martin

[Dillen]

Replace the standby relay. It must be hanging (welded contacts), allowing the output stages to be powered even in standby.

Martin

[Marto]

I spend some time for observation and it was actually start to getting hot from the far right side of the cooling fin. The relay is working well for now without any suspicious. So maybe my problem is somewhere in these transistors in the end of the pcb.
Any ideas?

Thanks

Martin

[Die_Bogener]

The “far right” side is the power supply. Especially the 5V supply.

The CPU unit has a funny cap inside, throwing its rubber cap and exploding with a nice bang..n getting pretty hot with a small short circuit…

You see the golden Roederstein cap?

 

[Marto]

Thanks guys. I’ve change all the capacitors that You’ve mentioned and now everything seems to work like it should. There is more that i need help for:
1. I can’t find capacitor C22 that everybody mentioned in the PowerSuply board. If somebody can help me find it out.
2. I’ve bought 18 – 1uF 100V Nichikon Fine Gold capacitors for the Pre Amp board, but still considering changing of all Elnas and Rubycons on that board. What is Your opinion about that.
Many Thanks once more.
Martin

[Die_Bogener]

Really?

*Jöööörg…*

Polarized caps… 100V … 1uF… magnetic…. loss of signal…  lifetime limited… +50%-20%….WHYYYY?

WIMA: not polarized. Non magnetic, no magnetic loss of signal. 50V is more than enough. 5mm footprint. 5%.  Lifetime unlimited… perfect. *Mmmmmhmmmm*

[Marto]

Hi Die Bogener. I agree with You and I will find those on Wima, but can You please tell me where is this C22 on the power supply board? It was mention to be changed with other 3 caps – C8, C9 and C14.
Thanks
Martin

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