Paramount pops and sparks [resolved]

[Paul Birkeland]

So with the red high voltage wire disconnected from the power supply PC board, you still blow the 270 ohm resistor?  If this is the case, that would indicate that something on the board is causing excessive current draw in the second power supply filter stage and blowing out the 270 ohm resistor. The next step would be removing the power supply board and removing that set of filter caps, putting the board back in, then firing it up.

This is a rather challenging amount of work if you don't have a powered solder vacuum, as getting the board out without one is likely to destroy the board.  You're going to want something like the Hakko FR-301 in order to continue debugging, or you'll have to send it to me for repairs.

[notbent]

Here's my rig.

I really want to save it!

[notbent]

Sorry text crossover.

I've already had the power supply board off twice to replace the diodes using solder sucker wire no probs.  I think.

I'll replace the filter caps tomorrow and get back.

Thank you for your help

Cheers, Andy

[Paul Birkeland]

Do consider the possibility that it may not be the filter caps.  An important step in diagnosing would be firing up the board without the second bank of filter caps.  I think with the solder sucked off that you can just smoosh the board back onto the pins on the power transformer to see if the 270 ohm resistor gets toasty.

[Karl5150]

Andy, that is a beautiful setup, hope you get it sorted soon - back to the music.
Karl

[notbent]

OK I'm ready to pull the PS board and remove the second bank of filter caps.

Which ones are they?

[Paul Birkeland]

Circled in blue.

[notbent]

Thank you.

I've removed the two caps, and smooshed the back on.

Before I power up, are the black wire to PC2 and the red to terminal 16 supposed to be connected?

[notbent]

I went ahead and powered up.. blew the 5W resistor again.

Black to PC2 is connected, red to terminal 16 disconnected, and the two circled caps removed.

[Paul Birkeland]

Interesting... Can you slide the board back off and post some photos of it in detail?

[notbent]

I took this pic just before I smooshed it back on.

It's starting to look pretty beat up...

[Paul Birkeland]

That board has lost traces and is no longer usable (in my opinion).

You can contact me at pb(at)Bottlehead(dot)com regarding repair options.  I have produced small batches of Paramount power supply boards in the past for refreshing kits, so there are still plenty of pathways to get you back on the road.

[notbent]

Thanks Paul I'll send an email.

[notbent]

Well I sent Paul an email and he supplied me with a new PS board.

I installed all the parts from the old board and now it's singing as sweet as it ever did!

Thanks to everyone who helped me out!

Cheers, Andy