help with old amp please

[zendixie]

 hi everybody. I have an old Electro M8-E that has a fried PT and I need some help replacing it with the right one. I bought this amp a few years ago and had never opened it up. it sounded great and I just never saw a need to look at it. it looks like the PT and the OT  had been replaced with some pretty cheap parts and now that it's not working, I'd like to find the correct ones. if you're not familiar with this amp, it's a little 5 watt single ended job with a 5Y3 rectifier, a 12AX7 pre and a 6V6 power tube. the speaker is a 4 ohm 8 inch jensen. according to a schematic I found, it looks like the 5Y3 should get 325 volts. I'd like to replace the bad PT with a decent one like a hammond maybe. same goes for the OT. any suggestions?

[Platefire]

How have you determined the existing transformers are bad? Very seldom does both go out at the same time. Doug at this site  has SE champ type PT and OT. Platefire

[xm52]

I'm thinking that a transformer set for a fender champ would work well. These Fender replacement transformers are available from a lot of sources.

Fender output transformer 125A35A, 8W, 3.2 ohm speaker impedance, 7K primary impedance.
Fender power transformer 125P1B, 325-0-325@70mA, 5V@2A, 6.3V@2A.

Since you asked about Hammond, they sell replacement transformers for vintage amps: PT: 290AX, OT: 1750C.

[plexi50]

Have you removed the 5Y3 and checked the secondary voltages of the power transfomer leads soldered at the rectifier tube? Does the  the mains fuse blow?

[zendixie]

I should have mentioned how it got damaged. I had agreed to help a friend provide some music for a neighborhood barbeque . we had done this several times before and never had a problem. when we got there someone had run a power outlet to within 20 feet of the area we were to play in. once again, this was typical. well, I now think they had screwed up and ran 220 volts into the outlet by mistake. when we plugged everything in, it all came on briefly and quit. i suspected a bad power strip/surge protector and asked if there was another around. someone handed me a small, cheap five outlet strip. when i plugged it in, it shot sparks and made a nice pop. the other gear was modern and was better protected than the old amp I was using . when i tried to replace my fuse, it just blew again. like I said, I had never looked inside the amp before and was amazed to find that the PT hadn't even been soldered in. most of the leads were just wrapped around and twisted onto posts. it looked as if it had been done in a hurry. I'm pretty sure it has the wrong OT too. I had looked at the hammond 290AX and thought the specs looked right, I just wanted to make sure. I guess I'll try it and see what happens. there are no amp techs in my neck of the woods. the closest guys are about 50 miles away and don't have the greatest reputation. thanks for the suggestions guys. it's a dinky little amp but, it sounds great in a studio with the right mic in front of it.

[plexi50]

Have you tested the 5Y3 rectifier tube?  Pull the 5Y3. Does the amp still blow the fuse? Chances are you may have just blown the 5Y3 rectifier tube. Rule out one thing at a time throughout the power supply first. Pop was probably one or both of the 40uf power supply capacitors. Is the 10K power supply resistor burnt black or reading open? Sparks flying was the 5Y3. Tell us if the 5Y3 is DOA

[PRR]

FYI: the B+ connections on that drawing are reversed; also the 6V6 cathode resistor is surely 250-300 ohms, not _K_ohms.

Yes, it is a different-maker Champ, and essentialy a high-class 1939 radio minus the tuner. Champ iron will be fine.

[billcreller]

Electro IS Rickenbacher, from what I know.  Their old guitars have Rickenbacher Electro on them also.

That old amp is likely worth more on Ebay than it is to keep it !!