2204 PI voltages

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ClintN667

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Hey guys,
I'm trying to do my voltage chart on my 2204 build and my pi voltages are off. I have 304v on pin 6 and on pin 1 I only have 74v. V1 and v2 voltages are in a normal range. I'm using the ceriatone layout.
 
PI plate resistors are 82k & 100k? Double check them with a meter.
 
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Since they both share the cathode and power supply node you’d think it has to be either the plate or grid. Or the tube itself.

What is the power supply node voltage? I.E. the voltage on the other side of the 82k and 100k plate resistors (either one, should be the same).
 
syscokid said:
Can just the PI tube be pulled, and then test for voltages?
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Absolutely! Good check too. The plate voltages and the PI node voltage should all the same since no current should be flowing thru those plate resistors with no tube installed.
 
22AE25FE-C070-4EE8-9C84-0E4DBCCC2AD5.jpeg

Is the PI grounded through the presence pot? My voltages were high when I forgot to do that.
 
With the amp OFF, voltages drained, and unplugged; check the resistance from pin 2 to ground. It should measure just over 1M (as should pin 7 to ground but that triode seems to be fine). You did connect the cathodes at the socket (as shown in layout above) right?
 
SpiderWars said:
You did connect the cathodes at the socket (as shown in layout above) right?
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I think this is the pic of his Ceriatone build. Pic is not very clear, but it looks like the cathodes are hooked up right. Can't tell if the PI is grounded properly though. Jumper wire is probably under the board.
20221231_205354.jpg
 
syscokid said:
I think this is the pic of his Ceriatone build. Pic is not very clear, but it looks like the cathodes are hooked up right. Can't tell if the PI is grounded properly though. Jumper wire is probably under the board.
View attachment 153052
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So I put in a new tube and they are measuring a little over around 250
 
I'm getting closer. This has some different options than a standard ceriatone so I'm hitting little snafus from the modifications. I am using an IEC with the mains fuse, the lighted rocker switches and I ommited the half power switch. Not necessarily heavily modified but since this is like my 6 ot 7th build Im hitting stuff that is taken me out of my comfort zone. It's been fun so far. I'm hoping to have everything sorted by the weekend then I'm going to try to build a mata amp GT120 next. I have the PCB and I have sourced the iron just gotta find a proper chassis. I'm hoping this one is a good choice for the next step up. I didn't want to try a yeti, sloclone etc yet
 
Many times, I have chased my tail trying to find the bug in an amp that was misbehaving. Only to finally find out that the problem was a weak tube.

ClintN667 said:
I didn't want to try a yeti, sloclone etc yet
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SLO-clone? I highly recommend C3 Amps. Built their 50 watt version. Excellent quality throughout the whole kit!
 
syscokid said:
Many times, I have chased my tail trying to find the bug in an amp that was misbehaving. Only to finally find out that the problem was a weak tube.


SLO-clone? I highly recommend C3 Amps. Built their 50 watt version. Excellent quality throughout the whole kit!
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I may do that. I've done a mod101 amp, a couple Champs, a valvestorm plexi, a ceriatone plexi, 2 headfirst pcb based 2204, and now this 2204. I've been learning a lot but I'm not doing this enough to feel like I definitely know what I'm doing if that makes sense. I'm definitely not repeating mistakes and learning more and more each build but I feel like I need much more practice. I want to go one step harder but I don't want to go too far above me skill level.
 
Clint, what’s your PI supply voltage? Where the 100k and 82k resistors meet.
 
burger said:
Clint, what’s your PI supply voltage? Where the 100k and 82k resistors meet.
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Hey Jason,
I ended up finding a few mistakes with help from Alex Catlow. My voltages are good now and it sounds killer. I'm hoping to grab a headshell for it sometime this month.
 

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burger said:
Awesome man, congrats. Alex is super helpful and talented,
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yeah he showed me some things he is working on and he definitely isnt scared to go off the beaten path. I think he was rebuilding some transformers from KLD
 
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