In Need of SA-7800 Schematic

Congratulations, greap. I knew you could do it. It's a lot of tedious work, electronics repair. A lot of desoldering, testing and resoldering. I'm glad you didn't give up, a few posts back it sounded like you where ready to toss in the towel. I'm sure Mark is happy and proud to help, his assistance is invaluable. Enjoy the amp. CC

Thanks Charlie. I wasn't going to give up but didn't want Mark to feel obligated with all of his time. He is very patient and it's only because of him it's where it is right now.

Outstanding! It "sounds" like you're making progress to me! I love these kinds of threads. :thmbsp:

Just to update everybody, the search for output transistors continues.

The hangup is that Pioneer again used some advanced transistors (1979 ring emitter) with a unique case. The things are soldered onto the pcb traces on the pc board and mount to the heatsink with a pair of screws 24 mm apart.
The originals were:
Fujitsu 2SA1075 and 2SC2525 and were probably 34.1mm x 16.2mm square with mounting holes 24mm apart.
The amp currently has:
Toshiba 2SA1389 and 2SC3546 34.1mm x 16.2mm square with mounting holes 24mm apart, with two dead ones.
We tried to get some GOOD replacements which were:
Sanken 2SA1216 and 2SC2922 36.4mm x 21.4mm square with mounting holes 24mm apart from Amplabs.

Well that 2.6 mm difference on the bottom and the top ((21.4 - 16.2 / 2 = 2.6 mm ) bit us in the a$$. I didn't look closely enough at the dimensions on the datasheet (the fujitsu's mech drawing had a CRAPPY background that obscures the numbers) to see there was a problem.

The pc board overlaps the case 2.6 mm and the top 2.6mm of the case interferes with other stuff mounted on the heatsink.

Michael form Amplabs is helping us look for replacements.

And YES, we (I) HAVE been corresponding with EchoWars.

Well Digitron Corp. supposedly has in stock 2SA1075 with the complimentary 2SC2525 so I sent them an email for pricing last night and I did not get a reply back from them today. The transistors have a production date of 2003.

Could these be knockoffs was my question for them or maybe even restamps which you normally see in PC processors? Do you think I pissed them off?:scratch2:

Digicorp finally got back to me. They are a company of 55 strong that resell and also fabricate their own semiconductors. The price on the 2SC2525's are 12.50 and the 2SA1075's are a whopping 42.50. They are built by digicorp to the original specs and guaranteed for form. fit and function. The company personnel that I dealt with were very helpful and pleasant. I have ordered two of each and will post pictures once I receive them and also after I have installed them. I should be receiving them in a few days.

Well the transistors have arrived from Digitron Electronics and as you can see in the attached images they were very well packaged by this I mean they came in a 8X6X3 box bubble wrapped and then individually wrapped as shown here. The dimensions are an exact match to the Toshiba substitutes that were on the SA-7800 and also the data sheet for the original 2SA1075 and 2SC2525 that Pioneer originally had installed.

I will be installing these in the next couple of days and will post images for all those that care to view them.

Wow, I'm pulling for you. That seems like a lot of dough, If in the end it sings for another 25-30yrs, plus the satisfaction of doing it yourself, it will be worth it. good luck. CC

You're right but I also bought this amp right for about $35 plus I have a friend that's offered me a decent amount if I want to part with it but you hit the nail on the head the satisfaction of doing it myself of course with a lot of help from Mark and also EW. But really for me this is more therapy kinda keeps the mind busy so I don't have them anxiety attacks. Also I wanted to not have to rig it by altering boards or drill new holes and move things around.