Please help me identify these trans....

General discussion area for tube amps.

Moderators: pompeiisneaks, Colossal

Post Reply
User avatar
sonicmojo
Posts: 669
Joined: Thu Mar 03, 2011 3:41 am
Location: Oahu, HI

Please help me identify these trans....

Post by sonicmojo »

I got an older, probably 80s Marshall 50 watt style homemade combo amp that is running 6550s and has a very high B+ (520V). I want to identify the PT and OT so I can decide what to do with it. When I got it, the previous tinkerer had installed 5W 470R resistors on the PT secondaries before the rectifier diodes presumably to lower the B+ but those basically heated up to the point of destruction. I removed those resistors because they seem to be a bad idea and beefed up the filter caps so it can handle the incoming voltage but I don't want to go too crazy on it.

Here are pictures of the codes and I have not been able to successfully cross reference the numbers. Maybe someone recognizes these. Thanks!
You do not have the required permissions to view the files attached to this post.
---------
Bryan
User avatar
pompeiisneaks
Site Admin
Posts: 4244
Joined: Sat Jan 14, 2017 4:36 pm
Location: Washington State, USA
Contact:

Re: Please help me identify these trans....

Post by pompeiisneaks »

From the triode electronics lists of transformer codes:

http://www.triodeel.com/eiacode.htm

Those start with 606 which seems to correlate to Woodward-Schumacher.

606747 and 606746.

I think then the 747 means year ending in 7, 47th week, so it could be 57,67,77 etc. is the year, since you said 80's likley an 87 setup. (this is per that same page above)

~Phil
tUber Nerd!
User avatar
sonicmojo
Posts: 669
Joined: Thu Mar 03, 2011 3:41 am
Location: Oahu, HI

Re: Please help me identify these trans....

Post by sonicmojo »

Yes, I figure it is mid-70s transformers. Would love to figure what they came from. My guess is both came from the same amp. It actually has a 1965 Fender Super Reverb type choke in it too so these parts were probably grabbed from whatever other broken amps were laying around at the time.
---------
Bryan
User avatar
pompeiisneaks
Site Admin
Posts: 4244
Joined: Sat Jan 14, 2017 4:36 pm
Location: Washington State, USA
Contact:

Re: Please help me identify these trans....

Post by pompeiisneaks »

It seems that they're likely all fender transformers, because I was trying to find the part number and didn't find much, but I did see a lot of discussion about fender amps using schumacher's around that time.

~Phil
tUber Nerd!
User avatar
Phil_S
Posts: 6048
Joined: Tue Oct 23, 2007 10:12 pm
Location: Baltimore, MD

Re: Please help me identify these trans....

Post by Phil_S »

Read my post from 11/08/09. https://ampgarage.com/forum/viewtopic.php?f=6&t=3822&p
You'll need to do some guessing. The OT will be easier to figure out than the PT. For the PT, load test it for what you want to do. The only ways to know for sure, unless someone can tell you from the stock number, is to either let the smoke out or unwind it, or both.
I'm no expert. The stock numbers don't look like Fender stock numbers to me. I suspect hi-fi.
User avatar
sonicmojo
Posts: 669
Joined: Thu Mar 03, 2011 3:41 am
Location: Oahu, HI

Re: Please help me identify these trans....

Post by sonicmojo »

Phil_S wrote: Tue Sep 25, 2018 10:59 pm Read my post from 11/08/09. https://ampgarage.com/forum/viewtopic.php?f=6&t=3822&p
You'll need to do some guessing. The OT will be easier to figure out than the PT. For the PT, load test it for what you want to do. The only ways to know for sure, unless someone can tell you from the stock number, is to either let the smoke out or unwind it, or both.
I'm no expert. The stock numbers don't look like Fender stock numbers to me. I suspect hi-fi.
This makes sense! That was a good read and figuring the transformers with math and load tests is more work than I want to bother with for sure. I wasn't even thinking non guitar amp source....The speakers are a pair of old 10 inchers that I think maybe came from a JBL hifi speaker. The shop that did this amp many years ago was called XSDB and rented stuff to everyone for everything audio so who knows? Well, I think my answer is I don't have anything special here and it's not worth making nicer. It is stable and runs okay now with the 6550s and is loud and maybe a good pedal platform but I'll pass it on to someone as is.
You do not have the required permissions to view the files attached to this post.
---------
Bryan
User avatar
Phil_S
Posts: 6048
Joined: Tue Oct 23, 2007 10:12 pm
Location: Baltimore, MD

Re: Please help me identify these trans....

Post by Phil_S »

Speakers are CTS from 50th week of 1968. If you like them, that's great, but there is nothing particularly special about them. I removed one of those from an amp and replaced it with something I liked much better.
I can understand you don't want to do all that work to figure out what you have. Good luck.
Ten Over
Posts: 371
Joined: Mon May 25, 2015 5:27 pm
Location: Central California

Re: Please help me identify these trans....

Post by Ten Over »

The dates indicate UL era if from Fender in the 70's and the high B+ would be consistent. How many wires are coming out of the OT?
User avatar
sonicmojo
Posts: 669
Joined: Thu Mar 03, 2011 3:41 am
Location: Oahu, HI

Re: Please help me identify these trans....

Post by sonicmojo »

Ten Over wrote: Wed Sep 26, 2018 3:00 am The dates indicate UL era if from Fender in the 70's and the high B+ would be consistent. How many wires are coming out of the OT?
Here's the pic I took of the PT wires inside. I did not look too close at things, was mainly concentrating on the red secondaries at the time.
You do not have the required permissions to view the files attached to this post.
---------
Bryan
Post Reply