This is my first post and I am almost completely new to BO! Having had some Tandberg and diverse Danish vintage equipment, I recently has become very interested in BO as well.
I recently bought two Beomaster 1000's. One with white keys and one with black. Both need restoration. I really want to make these work. I am specially interested in the earlier version with germanium transistors.
I opened the white one up today, and it seems a transistor was burned (marked AC128,3). There was black dust above it on the wood cabinet inside. I wonder if this is possible to replace..? Is there any hope?
There may be other problems as well, I don't know yet. But this seems serious.
Where do you find more rare spare parts for your vintage machines?
How wonderful that there was a little envelope on the inside with schematics inside it!
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Restoring a Beomaster 1000
Thank you Chartz and Sören Mexico!
I have located and ordered the transistor on ebay, you were right, many available. Now I need to change capacitors, still not sure about the best place to get high quality components (live in Sweden). I do hope very much I will be able to bring it back to life!
Yesterday I disassembled it and took out the burned transistor. I don't know if you will find this interesting, or odd, but the fried transistor was made of plastic, while AC128s usually seem to have a metal cover (and all AC128's I found on ebay). I found that odd. It was also not soldered on the board but attached with wires and electrotaped (as insulation) and inserted in a heatsink like thing. However that is maybe standard. Could it be so that BO used a non standard component that subsequently failed..? I attach a photo.
That mess is definitely not standard.
Martin
That mess is definitely not standard.
Martin
A silicon transistor here? No way!
Good find, keep on and carefully check everything, someone was in there without knowing what he did
Location: Mexico city
Printing machine technician
Restored various 1960-70 items
Rock and Roll music
Collecting Vinyl
Restored Jukebox Wurlitzer 1050
Thanks to you all!
I was right in thinking this was odd then.
I'll post a follow up later.
The transistors bias resistor(s) could have been changed too in an attempt to compensate.
Better check the whole circuit.
Martin
It seems nothing else has been changed. The resoldering of the AC128 is obvious though from beneath the board, so it has been exchanged.
I am not sure what this transistor does.. Anyone knows?
Attached is the schematics with it marked. And a photo of the inside of the cabinet..
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Yes, it's part of the voltage regulator circuit.
As a minimum, check also AC126-5 and AD149-5, resistor 906 and Zener 908.
They all work closely together with AC128-3.
Martin
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