Where to find 6000uF 50V replacement cap cans??

[saturated]

I'm trying to figure out what you did

grounded my O-Scope to the Hi input jack

you connected the scope probe or the ground clip on the scope probe

Also...dude...stuff happens don't stress out about it

[RG100ESROX]

I'm trying to figure out what you did

grounded my O-Scope to the Hi input jack

you connected the scope probe or the ground clip on the scope probe

Also...dude...stuff happens don't stress out about it

I attached the grounding probe of the O-Scope to the ground of the Hi input jack. And when I touched the other probes to the .62R to take a bias reading...well, that's when it happened.

Understand that the o-scope/signal generator/DMM I was using are all one unit. If they had not been. I don't think this would have happened. To this unit as a whole, a ground is a ground...and pop!!

Now she just kinda hums/buzzes all mixed into one when you turn it on with a speaker hooked up.

I'm thinking I more than likely have blown a few of the first 1N5484's in the preamp. Not sure though. I hope like hell I didn't blow the thermistor.🙏🏻

However, while the power transistor were removed. I took some voltage readings per the schematic, and they were all as to be expected.🤷�♂️

Ya know? Couldn't I put the DMM on that thermistor and give it a little heat and see if the reading acts as expected???

[g1]

See if the hum is DC or AC at the output.  If it's DC that is more serious.  If it's AC you may have just lost a ground somewhere (like a burnt or blown ground trace).
Any kind of DMM that has black probe connected to ground is potential trouble.  I only use fully floating battery powered DMM's.
Sounds like basically you grounded out which ever end of the 0.62 resistor you connected the black probe to.
Also, bias is only checked under no-signal conditions, and is a DC voltage reading at emitter resistors of output transistors.  So no scope or signal generator should be connected when checking idle current.
If looking for crossover distortion, that is with signal gen. connected to input, and scope connected at amp output.  It is not a bias measurement.

[RG100ESROX]

See if the hum is DC or AC at the output.  If it's DC that is more serious.  If it's AC you may have just lost a ground somewhere (like a burnt or blown ground trace).
Any kind of DMM that has black probe connected to ground is potential trouble.  I only use fully floating battery powered DMM's.
Sounds like basically you grounded out which ever end of the 0.62 resistor you connected the black probe to.
Also, bias is only checked under no-signal conditions, and is a DC voltage reading at emitter resistors of output transistors.  So no scope or signal generator should be connected when checking idle current.
If looking for crossover distortion, that is with signal gen. connected to input, and scope connected at amp output.  It is not a bias measurement.

What's the best method of checking for AC or DC at the output jacks? In detail if ya don't mind. I wanna be sure I'm doing this right.

Thanks in advance.

[g1]

One meter probe (black) to chassis, one meter probe (red) to the 'tip' connection of the output jack.  Set meter to DC volts, then check again with meter set to AC volts.

[RG100ESROX]

One meter probe (black) to chassis, one meter probe (red) to the 'tip' connection of the output jack.  Set meter to DC volts, then check again with meter set to AC volts.

Okay. Great. I didn't know it was just that simple. It usually isn't. That's why I asked.

Am I running the risk of any further damage by power the amp up in its current state??

[g1]

Not sure what the 'current state' is.  Seems we have gone back and forth a bit on whether the output transistors are installed.
There is a sticky post regarding 'lightbulb limiters'.  You should read it and build one, it will help protect from damage during repairs.
https://www.ssguitar.com/index.php?topic=2093.0

[RG100ESROX]

One meter probe (black) to chassis, one meter probe (red) to the 'tip' connection of the output jack.  Set meter to DC volts, then check again with meter set to AC volts.

Well, it's not good...

I got about 8.67 VDC on the + output jacks.

Now what?? What's this an indication of?? Or do I really want to know???

While I wait for your reply. I guess I'll get the PCB ready to access the the other side.

[RG100ESROX]

Not sure why I didn't see this before now, but I found a burnt cap right around where I saw the smoke.

All I have to replace it with is a 102 2KV ceramic cap. Hope this will work...

Thoughts???

[saturated]

Nice find 

but is that not a resistor ?

Maybe not
I wonder what that diode symbol means

[RG100ESROX]

Nice find 

but is that not a resistor ?

Maybe not I wonder what that diode symbol means

It's a cap. Why it's marked like that I have no idea.

Here it is on the schematic...(see below)

I just measured it and it measured correctly (1.12n)....I wouldn't use it though.

All I have is the ceramic cap in that value and voltage rating. So, I soldered it in to see if it helps fix the issue. It should be fine, no??

[RG100ESROX]

Well, you were right on the money when you said "probably a broken trace on the back of the board..."(see pics below)

Kuz that's what it was. At least I hope this is the extent of the damage.

We'll see.

I soldered the .001uF (or 1000pF) ceramic cap in place of the burnt box cap. Didn't trust it being burnt and all...

So, I'll Fire her up and see what happens.

I'll report back.

[RG100ESROX]

Well, no sound. Other than the somewhat  diminished hum/buzz that I had previously.

I tested the thermistor and it worked very well when heat was applied. So, I don't think this is my issue.

I changed both TIP32C's and the one TIP31C. And both 1N5484's located near the bias trim pot.

Any thoughts??

What should I be checking next??

[saturated]

That is some good work.  I would chill out and wait for the big dogs to help you get this sorted out 

[RG100ESROX]

That is some good work.  I would chill out and wait for the big dogs to help you get this sorted out 

Thank you.

And you're right. I'm gonna wait for the professional's to chime in...