HT Club 40 preamp issue

[b00ker]

I have a club 40 with a volume issue. Everything is working, but the volume is very low, with levels cranked all the way up. It is not an issue with the tubes, they have been replaced. I am suspecting it's something in the solid state component of the preamp. I haven't opened it up and checked out the board yet. Wondering if anyone else has had this issue.

[b00ker]

Ok, I got it opened up and someone before me has tried to mod this thing or repair it poorly. The input Jack is not the original and there is a burned out trace between c50 and L1 with a piece of wire reconnecting it on the underside of the board. Not sure if the cap at c50 is the correct one or is just a poor soldering job, which it definitely is. I will post pics later today.

[b00ker]

image2.JPG (49.36 KiB) Viewed 13219 times

image1.JPG (35.8 KiB) Viewed 13219 times

Any idea what was going on here?

[b00ker]

Same issue when using emulated output, so I think that eliminates an issue in the power amp

[dsmmrm]

Have you tried plugging a line level input into the effects return? That might confirm the power amp's health. By the same logic you can try the loop send into another amplifier source as a preamp test. Other than that I got nothin.

Not sure if this model needs to see something in the input before the effects loop is active but you might need to plug a cable in the front to test the loop.

[thephantum]

Since the issue exists at the emulated output, the problem is most likely in the preamp. You can try the above and slave the HT-40 to another preamp just to confirm that the power amp is working.

I'm not 100% positive, bit I think the HT-40 does have a sort of standby built into the jack...that way if you unplug the guitar cable there's no sound. If I had to guess, someone tried to replace the jack with a non original one and then attempted to bypass the cutoff. In the process, they obviously screwed something up. My guess is a burned component.

It would be easy to pinpoint it with an o-scope and signal generator. Failing that, you're kinda stabbing in the dark.

[b00ker]

Thanks for the reply, I'm pretty sure that it is not the original jack. The sound that does come out does kind of sound like the cable is not connected properly, Like when you have a broken cable that needs jiggling. Poking around, I was able to get it to produce a loud buzz, as though a cable was plugged into the amp but not connected to an instrument if that makes sense. The loudness of the buzz leads me to believe that it is jack related. I may be able to get access to an oscope, but not sure. I have a multimeter, not sure if that is going to help or not. I have not tried anything through the effects loop.

[b00ker]

If anyone cares, I have solved the volume issue. there were a couple more jumpers needed on the jack. Now I am left with the hum which is apparently common with these things. I will be doing some reading on that.

[b00ker]

Hum gone, was a grounding issue that I now have sorted and everything is sounding good. Thanks for the help thephantum and dsmmrm!