Big speedball board LEDs near PS in Crack will not light [resolved]

[Paul Birkeland]

Again this is not that you need to take the transistors out and clean them, it's the mounting of the metal tab of the transistor against the heatsink.  There needs to be no continuity between these pieces of metal or you will end up with a short.

Continuing to say "I must have a bad part, so I'll just keep pulling things out at random and replacing them" will lead to a kit that never works, because nothing is diagnosed and you're just constantly guessing.  Similarly you are evaluating whether the kit works based on the LEDs lighting up or not lighting up, when really the operational status of the amplifier is only ascertained by examining the voltages. 

[Galapac]

Transistors are properly mounted with the mica spacer in between the trans and heat sink.

I am only working on your advice and suggestions and trying my best.

You stated, "I must have a bad part, so I'll just keep pulling things out at random and replacing them" - I only did this for the transistors which were not replaced but removed, cleaned, and re soldered.
Also I was advised to remove the large caps and put the original ones in which I have done.
Those are the only parts that have been removed/replaced.

Only one LED lights on the big board now.

Here are the latest voltages from both boards:
Small board:
OA = 66.1
IA = 219
B-AB = 0
IB = 219
OB = 64.6

LARGE BOARD:
OA = 102.8
OB = 98.8
G = 0
B+ = 219

These voltages looked ok so I plugged everything in and now, no sound from either channel. Nothing. Dead silence. Not even a pop from plugging in the headphone.

[Paul Birkeland]

There's also a fiber washer that goes between the screw head and the transistor (which only properly fits one way) that keeps the screw from grounding out the collector tab of the transistor.

Voltages that are correct but on LED that isn't lighting would have me checking the 2N2222 on that side to be sure there are no shorts between pins on that device. 

The no sound in both channels issue is likely completely unrelated to the issue you started with, and is likely to be a loose connection or some kind of hookup issue.

[Galapac]

I have been on vacation so just got back to this.
I took new voltage readings and got the following:

SMALL BOARD
All readings within tolerance

BIG BOARD
One LED is lit and I have the following:
OA = 187.6
OB = 158 <- initial reading but drops in voltage slowly
G = 0
B+ = 218

[Paul Birkeland]

I would suggest ordering a replacement larger board and parts to start over on this.  Please note that if you get 0 resistance between OA or OB on the big board and the G pad, you are going to have the same issue.  This is mentioned in the manual on page 22 with very large lettering in hopes of preventing these kinds of issues. 

Salvaging the board you have now is probably not a good idea, as removing transistors can lift and/or damage traces and make the whole board unusable.

[Galapac]

Thanks Paul I will heed your suggestion and reach out to the parts department for a replacement board and parts.
I will let you know how it goes.
It dumbfounds me as this was a working board/BHC at one point and all I did was add bigger caps but maybe I tinkered a bit too much and will start over with a new board and let you know.
-Greg

[Galapac]

Paul,

 I ordered the replacement board and parts, redid as before, fired it up to check my voltages and all were within spec.
All LEDs were lit as well so it was promising.
Plugged in my headphones and DAP, an Viola! Music in both channels. Everything is working now.

I'm not sure if I will go back to the big caps right now as this is what got me into trouble in the first place, but for now sweet tubey goodness!

Thanks for putting up with my multiple posts but it looks like in the end I just needed a whole new large board with all the parts.

Consider this thread closed, unless you want my old board for inspection?

-Greg

[Paul Birkeland]

I'm not sure if I will go back to the big caps right now as this is what got me into trouble in the first place, but for now sweet tubey goodness!

They can certainly cause some issues!  Thanks for circling back to let us know everything ended up working out.