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I have the Schematic for the original Jet City 50 & 100 and the slo schematic and the mod just changes the values of 7 components to bring the preamp and phase inverter sections to SLO spec. I do have the schematic I edited showing the new values in place if you’d like to see it. None of the...

Unfortunately I don’t have a scope yet but that’s on my list of things I need asap. Wiring is pretty straightforward and power supply leads all are routed and attach at the opposite side of the pcb. I’ve moved them around and cleaned that up as much as possible with no audible change in noise...

Also none of the caps in this area caus the buzzing issue just the resistor.

R37 is the grid resistor on the input of V2. If I touch that with anything I’m holding in my hand or in the center of the pins on V2 it makes a ton of noise. This isn’t repeatable on any other part of the board.

Sure I’ll take a few later today and maybe a video. Thanks

I recently powered up and did preliminary checks on my Jet City 50 which is modded to SLO spec. Everything is great except for some noise related to V2. While searching for the source of the buzz/hum, I noticed getting close to V2 made it louder. I swapped the tube out and it is 80% better but...

Just wanted to clarify something from the video. When you say the "NFB in" going to the 39K resistor, is that point attached to the phase inverter or is that where the speaker tap is connected? Attaching an image I made with DIYLC based on the schematic if you have a minute to look. I attached...

Awesome guitar! What pickups are they?

Sorry I thought I replied to you already. I got that schematic online somewhere, I am a member of the SLO Clone Forum but I didn’t get it there. It was listed in a bunch of links to different amp mod schematics and labeled as the Fortin Cali Mod. I do understand that there are a bunch of...

Fantastic man! Appreciate you taking the time to do that video. Nice to see the circuit represented in actual components. Once I see it that way it’s much easier to process.

Awesome info, thanks man! I realize now I was wrong and my range was actually 27K to 127K on my existing NFB control. I will try the circuit with and without the high frequency caps and experiment a bit to see what the difference is.

In this schematic, can someone elaborate on it further and help me understand how the thump and hair switches are affecting the negative feedback, Obviously the the 4.7nf on the pot is a resonance control, but how do the 39K and 47K resistors and 10pf caps affect things? I would like to try this...

This is a 50 watt Jet City amp which I modded to be closer to SLO spec. Attached is a factory replacement from mercury. The 63 VAC tap works just fine for two octal power tubes with half wave rectification. I guess I was just unsure what happens when it’s a separate winding instead of a tap. If...

Just for reference here’s the mercury replacement which is almost identical to the original and I was wrong it’s a 63 volt tap.

This is a 50 watt Jet City which I Modded to be closer to SLO spec. The original PT had a 60 VAC tap on the high voltage windings which worked ok for two tubes. So since the original tap was 60 and worked just fine to bias two octal power tubes after half wave rectification, couldn’t the...

Thanks for the info! Yes familiar with the PT secondaries being AC. On the switching schematic I attached the circuit already has half wave rectification and a filter in place and the PT winding is 5VAC are you suggesting I should implement a completely different rectification circuit and add a...

I’m sure this is pretty common knowledge but based on the diagram, how would I wire the 60V winding to use for my bias supply? I have a bias circuit already on the board which used a 60V tap on the original PT so I’m not sure what to do with the common. I’m assuming it’s supposed to be attached...

Yeah that’s true. Hadn’t really thought of that.

Yes I am also a fan of the .0068 for a lot of the tones I play through. I include .0069 on my 3 way depth switch. Only reason it’s .0069 and not the .0068 is because of how the on-off-on switch gets wired I had to combine a .0047 and a .0022 in parallel. It sounded good so I kept it at 69. My...

I will definitely keep you posted once I've tried it. I added some caaps to my recent parts order but I'm really considering getting a decade box to make tasks like this a bit easier. It does make sense as far as how it works but it also raises some questions for me. So since the depth pot/cap...