OD stage problem

marcinzales · Post by **marcinzales** » Fri Oct 15, 2010 7:38 pm

Hi!!!

A few time ago I build my Dumble style amp. It work great!!! Clean and Drive sounds delicious!!!! And now suddendly the drive stage didn't work. I don't now why. 3 monts works ok. I play it yesterday. Today I plug it and i can't hear any signal from guitar only humming like "FM radio tunning". Clean stage works fine. When you switch to drive channel didn't work. I change tubes and nothing changes. It's confused me. Everything work fine and suddendly something like this. If you have any ideas plese help me. Sorry for my english.

Best regads.

Martin

Structo · Post by **Structo** » Fri Oct 15, 2010 7:50 pm

Check your relay and switching for the OD channel.

marcinzales · Post by **marcinzales** » Fri Oct 15, 2010 8:03 pm

Thanks!!!

I check the relay soon as I can. I used a brand new Finder relay. And if it's not relay?
Do you have any ideas?

fp2000 · Post by **fp2000** » Sat Oct 16, 2010 2:53 pm

did you play with the tubes?

marcinzales · Post by **marcinzales** » Sat Oct 16, 2010 6:23 pm

Yes I play with the tubes and nothing changes.

Structo · Post by **Structo** » Sat Oct 16, 2010 7:10 pm

When you probe for voltages and touch the V2 plate resistors with your red probe, do you get a pop through the speaker?
Likewise on the grids?

marcinzales · Post by **marcinzales** » Sat Oct 16, 2010 8:39 pm

No when I touch the V2 plate resistors I don't get a pop through the speaker.

Structo · Post by **Structo** » Sat Oct 16, 2010 10:39 pm

Are you getting plate voltages on V2?

Are your grounds correct on V2?

Can you switch to OD manually with a panel switch?

Not too many things to go wrong if your tube is good and the proper voltages and grounding is present.

Or like I suggested first, perhaps the relay is faulty.

I would check the voltage at the coil of the relay and if that is correct, I would probably simply plug another relay in.

ChrisM · Post by **ChrisM** » Sat Oct 16, 2010 11:22 pm

marcinzales wrote:No when I touch the V2 plate resistors I don't get a pop through the speaker.

That is good, look for problems before this then. Everything past and including V2 is good then.

marcinzales · Post by **marcinzales** » Tue Oct 19, 2010 8:06 pm

HI!!!

Today I removed relay from the amp. I connected OD stage straight ahead. And I tell You THIS IS NOT RELAY PROBLEM. I check the wiring inside the amp and solder points. And it still not work. Plate voltage on tube is ok.

Structo · Post by **Structo** » Tue Oct 19, 2010 8:34 pm

Take it to a qualified technician.

marcinzales · Post by **marcinzales** » Tue Oct 19, 2010 8:46 pm

Ha Ha!!!

Sorry I lived in Poland. We don't have qualified technician.

M Fowler · Post by **M Fowler** » Tue Oct 19, 2010 9:36 pm

Ha Ha!!!

Sorry I lived in Poland. We don't have qualified technician.

Marcinzales,

You have been officially selected in your community as the guy to go to for amp debugging. Get used to the title

Mark

Structo · Post by **Structo** » Tue Oct 19, 2010 10:43 pm

Divide and conquer.

Start at one end of the amp and move through it with your meter.
Only probe with one hand to avoid a heart stopping jolt!

It can only be a few possible things, so think about how it happened and where the likely area is that is the culprit.

Drumslinger · Post by **Drumslinger** » Tue Oct 19, 2010 11:27 pm

can you post some gut pictures? could be the footswitch pedal, cable or the footswitch connection. do you have a din, xlr, stereo 1/4 inch connection on the back of the amp. I have seen that plug go bad and the cable go bad. just something else to check.

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