Ibanez TSA15H Low volume

[mikeskory]

Grids 40 p to p. Output at speaker. 2-3 p to p

[Helmholtz]

Grids 40 p to p. Output at speaker. 2-3 p to p

Does the speaker signal look like the grid signal on the scope?

What are plate and screen DC voltages (both tubes)?

[mikeskory]

Signal at grids of 6v6s is good. Same as what we saw at the PI. At the 6v6s I get -29v at both pin 5s, 357v at both pin 4s. 357v at both pin 3s

[Helmholtz]

Signal at grids of 6v6s is good.

My question was about the shape of the signal at the spesker output.

[mikeskory]

Shape looks ok. Past 3/4s volume it starts distorting at the bottom. It will start oscillating at near full. Want a pic?

[Helmholtz]

Shape looks ok. Past 3/4s volume it starts distorting at the bottom. It will start oscillating at near full. Want a pic?

Yes, please post pics of grid signal and output signal with scope settings.

[mikeskory]

Here you go. Top 3 input to grid. Bottom 3 outpt to speaker

[Helmholtz]

Here you go. Top 3 input to grid. Bottom 3 outpt to speaker

Grid signal is below 30Vpp.
Speaker signal is asymmetrically distorted but not clipped. Def. too small.

I would test the OT using the neon flash test.

Did you check idle currents?

[mikeskory]

I used a Eurotubes bias probe earlier in the week to see what that showed. It was ok.

[Helmholtz]

I used a Eurotubes bias probe earlier in the week to see what that showed. It was ok.

So what were the plate currents?

[mikeskory]

23 ma when I calculated it it should be 27 ma FYI https://www.premierguitar.com/the-su...sformer-tester

[Helmholtz]

I prefer the neon test below:

[Enzo]

Have you tried a different speaker connected? And have you tried plugging speaker into all the various output jacks?

[mikeskory]

Hey Enzo! Yes tried different speakers, dummy and all the jacks. I also pulled out the small output board to examine, resolder and clean the switching jacks. Now I'll look for a trans. It's a store-stock item so I don't think they"ll want to spend a lot on it.