6G6B Bassman, airbrake, blown OT, tears

[mr_hankey]

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[JazzGuitarGimp]

After removing the end bells from the OT, does it smell like it's burnt?

[JazzGuitarGimp]

Where did your Airbrake schematic come from? It doesn't look anything like the one in the Trainwreck Files section.

[jelle]

Hi Hagenees, you should be sent to de Koepel.
The readings are not too suspect. I assume the secondary reading is done with the negative feedback disconnected. But it could still mean that the ot has a huge internal short. Can you scope the amp to see where the signal disappears?



This is the test to do now.



Arie-Jan from FNS used to do rewinds of transformers, good luck!!

Jelle

[mr_hankey]

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[jelle]

Marble amps in Renkum.

[jelle]

My guess is that you fried something else. Are all resistors still good? And the choke? Tubes?

[Reeltarded]

I am not convinced the tranformer is blown. Thos readings don't look open or burned. Measure each wire's resistance to ground instead of pri/sec pairs.

Ok, this sounds degenerate. Get a long straw up your nose and sniff around very slowly in and around every other part of the amp.

You'll need: 1 long straw

[JazzGuitarGimp]

I am not convinced the tranformer is blown. Thos readings don't look open or burned. Measure each wire's resistance to ground instead of pri/sec pairs.

Ok, this sounds degenerate. Get a long straw up your nose and sniff around very slowly in and around every other part of the amp.

You'll need: 1 long straw

I once had a massive guitar rack system. One day, something in the rack fried. Turns out a standard drinking straw is a perfect fit for a 1/4" jack.... Didn't take long to sus out the TC2290 as the culprit.

[Reeltarded]

You can also grind each component and smoke it in a water pipe. If it doesn't taste like ozone and carbon it already burned. I used to know a guy...

[mr_hankey]

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[mr_hankey]

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[jelle]

Visual tests do not count. I do not see a rationale for removing the OT at this point. Please put it back in. Smoke coming from the center could still be the choke. Please get your ohm meter out and stop guessing. This should be a 10 minute trouble shooting job.

Most importantly, check the voltages throughout the amp. Are voltages ok?

If all test fine, replace tubes. If that does not work, have the amp checked with a scope before taking parts out. This will save you a lot of time and frustration. Good luck!!! Jelle (originally from The Hague as well)

[vibratoking]

That ain't an airbrake schematic, that's for sure. It does attenuate as you noticed. On the bedroom setting, the load seen by the amplifier is anywhere from about 30 Ohms to 250 Ohms. This is safe, but not at all optimal. There is basically no attempt at impedance matching with this design. I would guess that it sounds bad, especially with that 0.1uF cap. I'm guessing it's really fizzy.

The real airbrake does make an attempt at impedance matching. The impedance match is not great, but it's much better than the circuit you posted.

I would suspect that the loadbox you used did not cause the problem if it's really wired the way you showed. Have you checked the impedance of the box with a multimeter to verify you correctly implemented the circuit? I would not continue with that circuit if it were me. Build something that is at least trying to match impedance.

[mr_hankey]

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