Hilgen 2502 power transformer

[JOHNNYCOMET]

Hello!
I recently saved a hilgen basso profundo model 2502 from being thrown in a dumpster. It is a project but is mostly complete and original. One key piece that is missing is the power transformer. I got a schematic for it but it does not show voltages. The tubes are GX34 rectifier, 12ax7 pre amp, 12ax7 pi, and a pair of 7591 power tubes. I found a transformer from Hammond that has the right mounting hole pattern, 6.3v, and 5v heater outputs and centertapped +/-300v output. Since Hilgen was a spin-off of Sano and also has some Ampeg influences, I referenced some of their schematics and found that Sano was running the 7591 plates at just under 400v and Ampeg runs them lower at 360v. I am thinking the Hammond transformer through the gz34 would be around 370v at the plates. So my question is: does anyone know what the original high voltage output of the pt was on these amps? Otherwise, what are y'all's recommendations for a replacement?

[LOUDthud]

7591s are good to over 500V B+, but you don't often see them operated that high. What are the filter caps ?

[Phil_S]

Congratulations and commendations on the dumpster dive! I'm going to assume you didn't have any luck searching for the information you'd like to have. You may need to guess.

There isn't quite enough information here to make a complete recommendation. I'd guess that Hammond 300-0-300 through a GZ34 will give B+ around 400V, which is close enough to the 370V you suggest. My main concern about the Hammond is whether is has enough current (Amps) capacity to support the filament requirements and the audio circuit (high voltage secondary.) Do you have a model number for the Hammond? I'm assuming you mean to say you found a current production Hammond, so please find the specs for us and also post to model number. Also, is this the schematic you found?
http://www.hilgenamplifiers.net/uploads ... _rev_a.pdf

There was another post on this or a similar model. You might PM the other person. Assuming he's got an original PT, you might be able to get an confirmation of B+, but, unfortunately, it seems that individual may not be "regular" here and might not see a PM.
https://ampgarage.com/forum/viewtopic.php?t=35318

[JOHNNYCOMET]

The transformer I am looking at is a Hammond 272fx. The specs are: 600v CT @ 172ma, 5v CT @ 3a, 6.3v CT @ 5a. According to the schematic, the filter caps are 40, 20, 20, 20 mfd / 450vdc. The Ampeg j12r with7591's are higher at 70, 40, 40, 20 mfd / 450vdc. The hilgen schematic is a redraw from 2013 and it is my understanding that there were some variations in production of these amps, so I'm not sure it is 100% accurate to the one I have. I'll need to pull out the chassis to read the can cap to confirm.

[Phil_S]

If the bolt pattern matches, then i wouldn't hesitate on that Hammond. I has plenty of filament supply and plenty of mA on the high voltage secondary. The remaining question is whether you want 300-0-300. I'd say, why not? I wouldn't sweat minor differences among the various versions of the amp.

[JOHNNYCOMET]

So far, it seems the amp matches the schematic. I verified the filter cap can matches, looks original, but will also need replaced since it is from 1965. I'm hoping to be able to get it rebuilt and keep it sounding as good or better than it did back in the day - without blowing up any savable original parts such as the output transformer. Thanks for the help! I guess I'll get the power transformer ordered along with caps and tubes and get working on it. Thanks again.