Solarus --no output

[Valvehead]

Ok---i found it.....................the freakin power tube sockets must be really dirty or corroded , (i cleaned them) or need tensioned . I pulled the el34s out and stuck in a diff pair just to try that--amp fired right up ! The original pair now works too.


Now onto the rest of the Bolloks.........pretty bad low freq hum going on..its there with Master at 0, and whats weird is it kind of goes away when turrning the Master vol from 3 -6 , then it returns at 7-10 real bad ! All the high voltage electrolytics / filter caps are new


The trem circuit works ! The reverb = i can hear it trying if i bang on the tank...but no verb out of the speaker. The cables seem to be ok..

[Helmholtz]

is that trans dead then ??

Not clear yet.The DCR readings are not suspicious, but a shorted turn won't show in DCR readings. I recommend the neon bulb test.

[Valvehead]

I just took resistance readings on a Dynaco 40W amp that sits near my computer as a chrome monument. Plate to plate, 185 Ohms. One side to center tap, plate 102.4 Ohms, screen 34.2 Ohms. Other side, plate 88.3 Ohms screen 29.6. One side went crazy with my meter, had to clip a short across the secondary.

is that trans dead then ??

[Valvehead]

What about the secondary?

OR1 TO BLK 1 OHM

OR2 (not used ) TO BLK 0.8 OHM

YELL TO BLK 1.2 OHM

PRIMARIES TO SECONDARIES `---OPEN

[loudthud]

What about the secondary?

If you really gotta know,

4 wire measurements to the black common wire (no averaging):

4 Ohm tap, 0.36390
8 Ohm tap, 0.48331
16 Ohm tap, 0.71211 (1047 Ohm feedback network in parallel)

[The Dude]

What about the secondary?

[Valvehead]

I just took resistance readings on a Dynaco 40W amp that sits near my computer as a chrome monument. Plate to plate, 185 Ohms. One side to center tap, plate 102.4 Ohms, screen 34.2 Ohms. Other side, plate 88.3 Ohms screen 29.6. One side went crazy with my meter, had to clip a short across the secondary.

These readings are very close to what i just measured on mine !

also 1 side plate to other side plate = 300 ohms
1 side screen to other side screen = 102 ohms

[loudthud]

I just took resistance readings on a Dynaco 40W amp that sits near my computer as a chrome monument. Plate to plate, 185 Ohms. One side to center tap, plate 102.4 Ohms, screen 34.2 Ohms. Other side, plate 88.3 Ohms screen 29.6. One side went crazy with my meter, had to clip a short across the secondary.

[The Dude]

^^^^^^ That! Another good reason to do the resistance checks. It might lead you to a simple transformer repair instead of replacement.

[Enzo]

Well, once you decide it ha to come out, pull it, and take the end bells off and try to check the connections between winding wire and the insulated lead wires. Might have a failed connection or a broken wire.

[The Dude]

That's not bad. To be honest, it's been a long time since I looked for a replacement OT for a UL amp.

I'd still make some resistance measurements on your OT. You hate to spend that much money and the problem is elsewhere. I always do every check possible before I shoot an output transformer.

[Enzo]

$140 is a lot less than I would have guessed.

[Valvehead]

Sadly, this is looking like a bad OT. Check primary and secondary resistances and see if you can spot an obvious failure- i.e. open winding, etc. If it is the OT, it's not going to be cheap since this is an ultra-linear amp. It would probably be cheaper to reconfigure/modify the circuit and use something more standard.

thanks-- i dont know if i want to go that route . I think the Dynaco replacements are $140 ?

[The Dude]

Sadly, this is looking like a bad OT. Check primary and secondary resistances and see if you can spot an obvious failure- i.e. open winding, etc. If it is the OT, it's not going to be cheap since this is an ultra-linear amp. It would probably be cheaper to reconfigure/modify the circuit and use something more standard.

[Valvehead]

I'd unhook the yellow and orange taps from the OT secondary and hook a speaker directly to one of them to eliminate a possible jack or jack wiring issue.

tried that---nothing

the 1k/ 2w and 680 ohm/2w are good ---right by the OT in the scem