The Amp Garage

Thanks a lot!
I will get to it asap.

I have a Fender Blues Deluxe (1993, 1st generation). These have a fixed bias via resistor R87. The bias is reportedly set 'cold'. I want to install a potentiometer instead of R87, but where on the pcb can I test ma current? Another solution would be a different resistor value, the current one is 27k...

This forum is known to me having very patient and often helpful members. I indeed lack active knowledge, but I managed to build several tube amps so far. As I love this amp also very much, I'm looking for solutions; a point from where to start, to make it work again, but I think this problem is over...

I think you mean NOT working? Thanks dad I'll be fine, I'm just not used to reading schematics every day.
I'll figure it out and learn somewhere else.
Thanks

That lack of a ground is a big issue! That fuse blowing is on one side of the power supply rail so either the negative or positive side. This in tern means one side of the output stage now has at least a bad output Transistor or two if it's over a 50 watt amp and maybe that section of the output st...

I have this wonderful Lab Series L7 that I bought cheap. The only thing not working is the compressor. So I opened it up, detached the front board hoping to find a quick solution like corroded leads etc. Couldn't find anything so I fired it up and got a loud noise, probably due to lack of grounding ...

The other day I bought a Fender Frontman 25R for about $ 25,-. The fuse was blown so that was an easy fix.
However there is a strange ticking noise every 2 seconds. Could this be a diode gone bad?

The new tubes came in and it works and sounds fine now!
Thanks all for your help.

I wil try that. First I will put in a whole new set of tubes.

I cleaned all the tube sockets with contact fluid. This seemed to work but after a while the problem comes back.

The owner told me that with the mentioned problems, the amp also makes a loud pop when turned off. It didn't do that before.

Poking around did not help either..

Thanks.
I forgot to mention that I swapped out all of the tubes.
And the owner says that hitting it hard often cures the problem for a while.
I did not tested that..

A friend asked me to look at a problem in his Koch Twintone 2 guitar-amplifier. https://en.audiofanzine.com/tube-combo-guitar-amp/koch/twintone-ii/user_reviews/ It's very sensitive to even the slightest touch, notably when tapping on the powertubes and some of the pre-amp tubes. I built some amps a ...

martin manning wrote: ↑Sat Sep 28, 2019 3:07 pm Do you have more preamp tubes to try? Failed heater-cathode insulation can cause hum like that.

I swapped all the tubes, but only swapping V2 for 12AT7 yielded less hum. A 12AU7 even less.
Could this be a lead?

Moving and redressing the heater wires does not alter the hum in any way..

I made a little clip of the amp (please don't mind burned thumb)

https://www.youtube.com/watch?v=h56IoVuqFHQ

Thanks. I got the kit from a reputable source. It's not clearly visible on the photo but I can assure you that the mains safety ground is very firmly soldered to a pre- roughed up (steel) surface with a big (clumsy) wattage iron, including flux, so well flowed. I tried to take it of by force, but it...