Let's Get Technical > Troubleshooting Problems

MP1 v 1.38 no sound can someone help me out?

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Wormwoody:
Haven’t checked this in a few days I expected an email notification if there was a reply. Anyways I will crack the case again and check out these things tonight.

Rnolan—I did do some work on the tube board. Changed some caps mainly if I remember right.  Also now that I think about it I also removed the main signal wire out or in (not sure which) in order to more easily swap caps on the tube board (with it connected it was tight). I extended that wire with a piece of scrap in order to more easily remove tube board in the future. Thankfully MJMP caught this when I sent him a pic and told me to put it back to normal. I did ring it out with my ohmmeter and seems as if connection there is good. Thanks all of you I’ll reply back when I have checked voltage and looked if the tubes are glowing (if I remember right they are). I believe all the tube board connections are as they should be, is there any I should check in particular?  I did not change out the old xfmr.

Thanks MJMP I’ll check voltage at those points.

I am an electrical contractor so I can do some of these things easily but I am new to PCBs and soldering in general.

Thanks again gents.

rnolan:
Unfortunately email comes and goes (but just for some of us), I'm not getting any notifications at the moment either, best to check the site from time to time  :thumb-up:

Wormwoody:
The tubes are lit up. I have 189V to ground on the incoming power side of both R1 and R4 and 174 V to ground on outgoing side of both R1 and R4. So power is getting onto the tube board through R1 and R4, and to the tubes (if they’re lighting up) but somewhere else on the tube board (or afterwards) it is not getting to the outputs. Where could/ should I look next for power/ signal?

Wormwoody:
Does anyone have any additional suggestions to troubleshoot this mp1?  A while back MJMP suggested my five pin LED things (can’t remember their name) that I replaced may be bad. I bought them from a website called Pedal parts, or a similar named company. Anyways as per his suggestion I tested them (as per pedal parts test procedure using 9v and a resistor) and they tested good. Are there any resources showing a signal chain out of the tube board that I can use to troubleshoot, or does anyone have any further ideas?  I’d like to find the problem myself (with help from you guys), but if I can’t figure it out can I send it to one of you to be looked at?


Thanks again!

MarshallJMP:
Those led things are called vactrol's. So those voltages look good to me.
Do you have access to a oscilloscope?

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