Phonoland

Huh. I removed Q17, Q18, Q27 & Q28 (all the driver transistors) & replaced the power supply diodes - I still have a short

Transformer?

Doug,

-Check that the polarity of the new diodes is correct.

- Look for a shorted capacitor in one of the 3000mfd caps (the two standees next to the power tran).

Note that if you find a shorted filter cap be sure to retest the diodes as they can be damaged by a dead short.

Finally, if all passes disconnect the two red wires from the power tran to the diodes to chk the transformer.

It is a really simple circuit and this will take about 5 minutes.

Rob

Fixed the short and the rest of the other issues and I'll be ready to test under power with outputs installed tonight I think

Question... the 2n3055a's that were installed have no mica insulators or teflon bushings. Is this normal for these amps?? I see no mention of this anywhere in either the Seeburg nor Tony's manual.

The installed transistors are marked STM and are in bad shape. I'm replacing them with NTE130's which are a good electrical match.

Doug,
ThatZ THE problem--the outputs MUST have a mica installed, slathered in Dow-Corning #5 heat sink grease !
Mica is listed as an "insulator #375074", on the chassis page, in the electronic parts book, heat sink grease is not--.
PS-- I do not care for the NTE's I have used--I much prefer 2n3055's Ron Rich

I like the real deal's as well, but I had some NTE130's, so for testing, they should work until my new order comes in.

Do you use the bushings as well, or just the mica? A real hero had this amp on their bench before me, for sure.

Just the mica's--screws MUST BE tight !!

Thanks Ron

Transistors in, bias set, here we go...

https://youtu.be/1fXxGqp0k0o

Doug,
OK--I listened to about half of "Tell-star"--what are you attempting to do ??
You should read the set-up instructions for bias--no input/no output when setting it !!
Ron Rich

The bias is steady at 1.6v on the bases, no input or output. Did that before I made the video, just took a few minutes. The video was just a "Thanks guys"! Plus, the Ventures should make any day better.

Doug,
You're welcome !
Ron Ric