recognize this Supro?....no tremelo...no schematic info on web....?

[skallywampus]

Looking for the reason no tremolo and a beginner at this and no schematic to help sets me back. Do any of you know of a similar schematic I may learn from?
thanks, Skallywampus

[shooter]

Here's Doug's schematic page, find something you like, maybe we can  help start the process

https://el34world.com/charts/TubeAmpSchematics.htm

[sluckey]

Tell us what tubes are in it. Show us some pics of the chassis, inside guts and outside layout.

Your schematic is not complete and the input jacks are connected to ground.

[skallywampus]

thank you ..drawing the schematic as I go....(hurricane outside anyway...)  here are some more pics. There is an ID plate x79202....

[vampwizzard]

Valco tonemaster? https://reverb.com/item/2032134-rare-1956-valco-tonemaster-english-electronics-twin-6l6-15-amplifier

[Latole]

https://el34world.com/Forum/index.php?topic=14581.0


http://www.oldfrets.com/Valco/Schematics.html

[PRR]

The LFO seems taken from Supro 1690T. The fact the audio stage is triode or pentode is probably not very important.

[Latole]

Often with tremolo issue and if tube is good; I replace all tremolo circuit capacitors.
It's aways work....and cost only few $

[skallywampus]

here's the tube layout...

[bmccowan]

That's a pretty rare amp. I think VampW has it right. English Electronics was one of the Chicago music stores that Valco labelled amps for. Folks, including me, have looked for that schematic before. So if you sketch out the schematic, and post pics of the guts, folks here can help you fix the tremolo, and many, me included will be happy to have the schematic.

[ALBATROS1234]

yea thats a bad ass valco wouldnt mind taking a peek at its underbelly. weird how its got the 5979 mini with metal octals. ive seen a few like that with the preamp connected with the umbilical cord to the power supply/power amp. i bet it has the sweet gritty 50s valco sound too.

[bmccowan]

weird how its got the 5979 mini with metal octals. ive seen a few like that with the preamp connected with the umbilical cord to the power supply/power amp.

Yup on the 5879. I thought I'd be able to find a very similar earlier schematic with a 6SJ7 in that position, but I did not. I have three Valco basket cases awaiting rebuilds. Two have separate preamps with an umbilical cord, but they are clearly different circuits. Valcos are hard to work on, what with the crowded terminal strips, but they are a ton of fun and tone! 

[skallywampus]

This is what I have for the tremolo circuit so far....no oscillation.
so...
jumped 22K on off switch.....no change.
jumped 1.5K Cathode 5879 ..no change
raised 1.5K to 3.9K on 5879...lowered volume start tremolo..not sustain
raised 1.5K on 5879 to 1meg....lowered amp volume and tremolo started and does not sustain
Paralleled  47uf cap on 5879cathode...no change
just shotgunning I guess....

[PRR]

> Your schematic is not complete and the input jacks are connected to ground.

Still likely errors in today's plan (cleaned and attached).

The 0.5u cap in the LFO phase-shift seems unlikely; 0.05 or 0.02 more usual.

[vampwizzard]

Pretty interested in getting a working schematic out of this. Keep it up!

[bmccowan]

One of the Gibson GA-40 Les Paul models used a 6SQ7 for the tremolo and a 5879. The portion of the circuit in the sketch look pretty darn similar. Joe Piazza drew a very clean schematic of that amp. Maybe it helps.