The new dumble modded bassman build video series... begins!

[Aaron]

Lucky you got off light! It’s a scary feeling, glad you’re good.

Aaron

[pompeiisneaks]

Yes the entire schematic and layout are here: https://ampgarage.com/forum/viewtopic.php?f=4&t=33721

It was my attempt to put together a layout from the schematic aaron had posted, with work from forum members to confirm all components etc. My layout didn't match the schematic, per the error I found, and updated. It is now a working amp with some demo clips coming... of course after I finish getting the doghouse installed

~Phil

[pompeiisneaks]

Lucky you got off light! It’s a scary feeling, glad you’re good.

Aaron

Yeah, It was the worst way you can do it, going through the body... I hit it with my left hand while trying to toggle the bright switch it went through my arms to my right hand on the guitar strings. Coulda hit my heart... coulda died... glad I didn't

I realize now I think I know what happened. The amp fell over as this happened, I thought it was my hand that touched the B+ that caused the amp to tilt. After thinking it over, it might have been my pushing the toggle that caused it to tip into my hand instead... and part of why it was a super short big pop and done... as it fell past my hand after the contact.

~Phil

[pompeiisneaks]

Some photos of the finished build.

PXL_20210710_050813035.jpg

PXL_20210710_050831757.jpg

PXL_20210710_050843692.jpg

~Phil

[Bombacaototal]

Looking good Phil, and sorry to hear about your shock. I had from the mains a couple times, forgot to unplug the amp and hand accidentally touched it, and ouch, arm was ticklish and numb for some time..btw nice EVM on the back

[professormudd]

Very nice.

[pompeiisneaks]

Looking good Phil, and sorry to hear about your shock. I had from the mains a couple times, forgot to unplug the amp and hand accidentally touched it, and ouch, arm was ticklish and numb for some time..btw nice EVM on the back

Thanks, yeah I've hit 120VAC a couple times not only in amp building but doing work on mains in the house and thinking a socket was down etc. It feels quite different from DC let me tell you... there's somewhat of a 'buzz' feeling to the AC, probably about 60Hz of it, but DC is just like someone slapped you hard but all over the place.

~Phil

[alkuz1961]

Once upon a time I was engaged in the repair of tube TVs... should note, 25 kV from the kinescope give a good boost of energy)))
After such a shake-up, you become very careful... for a while ))

[Bombacaototal]

Looking good Phil, and sorry to hear about your shock. I had from the mains a couple times, forgot to unplug the amp and hand accidentally touched it, and ouch, arm was ticklish and numb for some time..btw nice EVM on the back

Thanks, yeah I've hit 120VAC a couple times not only in amp building but doing work on mains in the house and thinking a socket was down etc. It feels quite different from DC let me tell you... there's somewhat of a 'buzz' feeling to the AC, probably about 60Hz of it, but DC is just like someone slapped you hard but all over the place.

~Phil

Here in the UK it was 240V but from what you are describing I am glad I never had one like you did. It must be a humbling experience, and a reminder that one can never be too careful. Glad you are fine!

[pompeiisneaks]

So I don't know if I mentioned but there was some pretty significant hum from the amp. After toying around with a plastic tool to find the best way to 'impact' it, I discovered it was what I'd already feared, the AC going up to the filter board to be rectified was too close to the signal in the PI output to the power tubes. I checked with the scope and it was almost exactly 60hz.

I did realize I had more of the standoffs and they're the type you can stack on one another for more height. After adding those in, the hum is almost completely gone.

Had something get into the main gain level pot (first one in the drive channel) and cleaned it and retested and the scratchy, inconsistent behavior is gone... looking good, just got to pull together a demo now.

~Phil

[pompeiisneaks]

A few pictures of the guts now that it's doing nicely:

I plan on doing a demo video here soon... and I've recorded a video of the power on testing etc.

PXL_20210901_193901327.jpg

PXL_20210901_193906496.jpg

~Phil

[dorrisant]

Looks great Phil!

Glad you have it up and running well.

[Colossal]

Nice, man!

[Reeltarded]

It looks great!! CRANK IT UP!!

I have once elbowed the corner of 100w 800 board where the power string connects are after the drain came off.. I recreated it to see how much voltage that was. 90VDC hurts worse than wall service. It only lasts a flash though. I still have a little tiny black dot at the point of ill returns!

[Reeltarded]

It looks great!! CRANK IT UP!!

I have once elbowed the corner of 100w 800 board where the power string connects are after the drain came off.. I recreated it to see how much voltage that was. 90VDC hurts worse than wall service. It only lasts a flash though. I still have a little tiny black dot at the point of ill returns!

If you dont have an amp cradle, get a box of deck screws, a box of washers, and a 2x8 or 10 cutoff to make end legs. Works with all amps you just have to imagine it.