The Amp Garage

So I fired it up and it seems to be running as it should. Sounds good for a $200 amp. So for anyone else who comes across this thread because their triple rectifier is blowing fuses, it’s always the tubes. I replaced all the power and the preamp tubes and switched to solid start recrifiers and this ...

It's pretty faint but I can hear it. I'm pretty sure it's 120 HZ. According to the nets, it could be plate vibration at twice the fundamental frequency, which would be 60 HZ. With all voltages ready for the most part correct, is it possible for there to be a short in the PT?

Ok, so I fired it up but have only turned standby off for a few seconds to take quick voltage measurements. So far everything seems to be running about 6-8V high. Not sure if that’s an issue. Also, there is a low hum from OT when in standby that goes away when standby is switched off and then a diff...

I’m sure everyone is tired of this post by now but I put the amp back together, put in the preamp and 4 brand new power tubes. I did not have a 4A slow blow so I put in a 3A. I plugged into the lightbulb limiter with the 100 watt bulb and turned on power and turned off standby. The lightbulb stayed ...

Again, I cleaned it with alcohol and there is no sign of carbon residue anymore but the solder still looks gray like a cold solder. Here are some pics I snapped of the underside of the main PCB. The bottom pic around where the 18 pin IC is located is where the charing occurred. All the circuit trace...

Yup, I pulled the board and realized V1 does not share the same filament as the other preamp tubes and the schematic confirms this.

With B+ not running to the preamp, I got suspicious that this may be a problem with the filament power. Just for shits I took resistance measurements from pin 5 of one tube socket to pin 5 of the next and likewise with pin 9. All were around 2 ohms except for V1 from V2. That measurement low and wou...

I tried a 2 amp fast blow and it turned on but I turned it off after a few seconds because I realized I was not plugged into speaker. When I turned it back on, the fuse blew immediately. My speaker cab was plugged into the 4 ohm jack if that is somehow important information. There were no tubes in t...

So, I bought a 100 watt incandescent bulb and turned the amp on(still with the OT center tap and the 2K7 resistor disconnected) and it was dim. The mouse piss theory makes sense. The chassis sits at the bottom of the head box so if the mouse pissed while inside the amp, it would leak through onto th...

Does anyone know what the Tarif will be on tubes from Russia? I heard they will be importing them again but now they will have a Tarif.

Here is the schematic I've been using. So far it's been correct.

I do not have access to a 100W incandescent light bulb at the moment but I did pull the OT center tap as well as the 2K7 resistor. I was already using a 3A fuse since I was out of 4’s. I turned on power to see if there was any difference in how bright the light was and there was not. It was still br...

I just picked up a REV C Triple Rectifier that the previous owner was told by his local shop tech needed a new preamp board. I opened it up as soon as I got it home and the inside looked like new, untouched and no mods. Plenty of mouse turds though. Not believing the bad preamp board diagnosis, I pl...

I found these https://www.marshallforum.com/threads/need-help-with-jmp1h.114305/ detailed picks of the main PCB for the JMP-1 and while I have not confirmed every single part of the schematic, what I could see looked accurate. At the end of this thread, https://ampgarage.com/forum/viewtopic.php?t=27...

Hey MATEC, was the PDF Cassoulet sent you what was used to draw up your JMP1 schematic?