Quote from: Keijo on August 23, 2017, 07:31:38 AMOne time I found 2 diodes in one amp that were both open. But I didn't need a DMM to find that out.  :duh

That's like hitting the Jackpot right there!!

I can't actually recall a time that I ever found an open diode. Plenty of shorted ones but never open.

Here is the service manual and the 17-11 board is pg18-19. Not sure this the one you are searching for...??

Edit: Well looking closer this one says 1971 and the one I think your looking for is for 1972 and later generation 2 or something. I will keep a look out for anything on the matter.

Better yet. Download Gimp image editor and save your jpg (image) files in formats that are small enough to upload to the actual SSguitar.com web server. I get tired of 3rd party hosting sites where someone even deletes linked files or forgot about the account, which they disappear.

Try this one out...

Quote from: Erich on August 12, 2017, 02:38:17 PMThe board in the one I have has 10 different spade terminals in the area where the power supply hooks up and none of them are marked with a color / voltage

Oh yeah Enzo I am with you 100%. I know those amps pretty well and they are clearly marked with P3, P4, and P5. I only requested a picture as the OP was almost implying that there are no markings on the board or something. Of course they are not marked with a color or voltage and that does not mean he said they are not marked with a P3 or other designators. However, he never even acknowledged that input. It's almost as if Erich thought Red and Red/Yellow on the board but those are just the color of the wires.

Quote from: Erich on August 12, 2017, 02:38:17 PMHey, I think I may have found he problem: The transformer outputs look like they have been hooked up wrong. I've checked the schematic I have and I can't tell from it (it's a crappy copy and I can't find another one) if the Xformer leads are attached to the board correctly. Does anyone have a picture of the fully connected board / power supply?

But to look at a picture of his amp we all could tell him right away if the transformer is connected correctly.

Quote from: Erich on August 12, 2017, 02:38:17 PM
The board in the one I have has 10 different spade terminals in the area where the power supply hooks up and none of them are marked with a color / voltage

I think we need a picture to understand better what you are looking at.

Well don't hold me to this completely, but this is where my search took me. I found this link here>>>
http://soundelectronic.ch/shop/index.php?main_page=product_info&cPath=4_37&products_id=493&zenid=pq7k3lmfpdchjng85hu8kfv526

At that point it confirmed B79-1 and it showed Model: 657179. It even had that it was made by Wulitzer. Which I think just means that Model: 657179 relates to Wulitzer. At least it shows something that might help you figure this out, good luck.

No. Reversing neutral and hot plugs on the amp will not make any REAL difference in this case. The safety ground being removed just means if there is leakage somewhere in the amp, to ground, the primary path will now only be the possibly grounded human guitar player. 

Stop trying to make a theory of what happened exactly. There are trained pros in the business of repair that can't EXACTLY tell you a WHICH transistor finally died when an amp suffered a major failure.

Edit: Just divide and conquer. Troubleshoot the amp by looking for obviously bad parts and replace. Test things (Transistors, Diodes, etc) in circuit with meter and see what might be bad. If a capacitor has started bulging then it is time to replace that guy.

Yeah it does look like something nasty sticky fell in the amp. Try using a q-tip and some 99% isopropyl alcohol to give it a good cleaning. That 220uf electrolytic cap needs to go on a diet his body broke right out of his outfit.  :lmao:

Try this out. It seems Digikey is now my go to for Sanken type transistors.

https://www.digikey.com/products/en?keywords=2sa1294

https://www.digikey.com/products/en?keywords=2sc3263

Funny thing is I had to call Fishman for a schematic recently too and it was just the fastest phone call ever. I love companies that support their products at the consumer level so the owner has options for independent repair. Makes ownership a privilege rather than an inevitable headache that comes with trying to repair something without the roadmap.

Quote from: Enzo on July 11, 2017, 08:56:44 PMWhenever I have to replace outputs, I change the drivers, yes even if they test OK.  They are getting stressed by the power transistor failures.  And your meter puts a tiny current at a low voltage through the part.  The circuit puts substantial voltage on the parts and draws substantial current through them.  Your meter can't test for that.

Amen to that one brother!! The idea is that you are already in there so you might as well. With amp repair we constantly hear don't just replace parts such as throw in a new set of caps before isolate and fix the REAL problem. But when you have transistors near a point of failure it sometimes pays off big time replacing those questionable parts. I owe a lot to the pro repair guys online as I just know to replace those pre-drivers after a major failure. Their experience saved me from finding out the hard way many times.  :trouble

I recently had to call Fender for a schematic a few weeks ago and it was very quick & easy. However, he did mention something about how he only sends it if the person sounds like they know what they are doing. Seems like I did good job fooling him!!  :duh

Quote from: aaron on June 20, 2017, 03:14:53 PMWhat I ended up doing was cannibalizing a small heat sink from another circuit board, applied thermal paste, attached it to the resistor, and voila!

I'd like to see a picture of that.