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I am at the final hurdle, I believe, to getting this awesome amp fully functional. The last roadblock I'm faced with is when I switch on the overdrive, the volume drops to almost inaudible. I can hear it very faintly, but can't seem to figure out what it could be. Everything else is working including the PAB, the rock/jazz switch, and the midboost. I can hear the OD relay clicking, but again, the sound is almost non-existent. Any ideas on tracking this down ?

Thanks, Mike

I have checked re-checked and re-soldered every joint, replaced the shielded wire connections, but am still without full level sound in OD mode. In going over the amp again, I realize that the LED for the OD side of the relay board is not lighting up, even when I test it manually with a jumper per building guide. I can hear the relay clicking though. The LED did work originally. The PAB LED works both with the foot switch and manually. Is this a possible cause or does the light even matter ? The LED's on the foot switch work. I am just about to the point of admitting it's not within my capabilities to finishing it and taking it to a professional.


The clean channel on this amp sounds amazing, so to say I am bummed that I cannot get it 100% functionality is an understatement.

Thanks, Mike

Heya Mike,

What kind of test equipment do you have? Ideally you’d have a good multimeter, function/signal generator and oscilloscope, but it’s understandable if you don't!

The idea behind asking this question is that we want to trace an input signal through the amp to see where it breaks down. Based on what you’ve got we can tailor further help

Don’t despair. The OD section is worth the time and effort required to debug it!

-b

[quote="bushwhacka"]Heya Mike,

What kind of test equipment do you have? Ideally you’d have a good multimeter, function/signal generator and oscilloscope, but it’s understandable if you don't!

The idea behind asking this question is that we want to trace an input signal through the amp to see where it breaks down. Based on what you’ve got we can tailor further help

Don’t despair. The OD section is worth the time and effort required to debug it!

-b
Thanks for the reply,
I have a good multi meter, but no signal generator. I just plug in a guitar. I have taken the relay board out and checked underneath for anything suspicious, possible solder leaking one to other connections. I re-installed it and the connections and checked for grounding issues on the OD relay side. In this pic, I have drawn a yellow line around 4 connections, that all have continuity to ground. The same 4 connections on the PAB relay do not have continuity to ground and the PAB works great. Could this be the problem ?



I appreciate your help, Mike

Yeah, that's not right. Those points connect the relay to the OD trim pot on the rear of the amp. It could be that the trim pot is wired incorrectly, and in fact there is an error in the documentation about that part of the wiring.

I'd first try setting the OD trim pot (on the rear) to 12 o'clock. The OD level and OD ratio pots should also be at 12 o'clock. Engage the OD switch - do you get overdriven tones?

Can you take a picture of the OD trim pot wiring and how it's connected to the FX loop return jack? There should be a ground wire between the two.

Here's the thread I started about the incorrect OD trim wiring. Coco/Stephen has since corrected the documentation.

viewtopic.php?f=21&t=6824

white wire connects to 220k resistor under the board.



The dark blue arched wire is a continuity fix that Stephen discovered via a FaceTime session.

Sorry Mike, but those photos are what the internet would call "potato quality" ;-) It's really difficult to see anything clearly.

Sorry, do these help. It's a very hard to see area. If these don't show well enough, let me know,
Thanks, Mike

Great news. First of all, thanks for all the help. I appreciate the time taken to help this novice-ish builder. Again, I went through the solder joints, and when I fired it up, it has OD at volume. I did have a bit of a time dialing in the Level, Ratio, and trim controls, but when switching from OD to clean, the volume does not jump from 1 to 10.

There are still a few head scratchers such as the LED on the OD side of the relay does not come on when the OD is engaged. I can get it to light by jumping from ground to one of the two points marked LED. Both LED's on the foot switch do light up, weird.
I made the cab for this amp 3 years ago when I bought it, and will be glad to get it together. I will post pics when that happens. Hopefully, everything will remain working !!

Again, thanks so much for your help, Mike

That is GREAT news!!! Congrats, I'm glad you've got it all working

I too just put my OSD into a cabinet, although Stephen built mine as I have neither the skills nor the tools. Check the Colorado build thread for photos. I'd love to see photos of yours, too.

Just finished installing the OSD build into the cab I built for it 3 years ago when I bought the kit. Sounds great Thanks for the help !!

Wow, that looks the business. Nice job on the cabinetry!

It's Friday, SRV is blasting from my speakers and it's beer o'clock. Looks like a successful week for all concerned.

Congrats on the build. The cab looks great!

_________________
Stephen
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