Metropoulos Forum

Finally got my 2203 kit running. Bunch of gremlins in this one. First the mains fuseholder was bad, then the mains switch had an open, then the mains fuse kept blowing. Eventuallly realized V5 was runaway red plating bad. WTF???? All is well and running now after a tube swap but the PI V3 voltages are still out of whack. Any thoughts guys???

V3 s/b pin 1 - 218 is 246, pin 2 s/b 28 is 54, pin 3 s/b 42 is 95, pin 6 s/b 214 is 244, pin 7 s/b 28 is 60, pin 8 s/b 42 is 95.

The amp actually sounds pretty good, biased at 40ma but the RI Mullard I swapped out in place of the bad jj is showing 70ma???? WTF??????????????
see pics

Killer !
Another one alive ! Man, watch those (RI) Mullards ! Best to use a shit pair that works. Be a shame to loose good tubes!
So you matched it up with a quad of those Black Back's now, didja ?.
A liitle WD-40 on those fingers and how 'bout a little clipatarski of tone, pal ?

-Jimmie

JimiJames wrote:Killer !
Another one alive ! Man, watch those (RI) Mullards ! Best to use a shit pair that works. Be a shame to loose good tubes!
So you matched it up with a quad of those Black Back's now, didja ?.
A liitle WD-40 on those fingers and how 'bout a little clipatarski of tone, pal ?

-Jimmie

Comin', Jimi!!!

What JJ's are you using chief? EL34M or E34L?

I only ask because the E34L are somewhat different by design, and probably not very easily match to anything else.

demonufo wrote:What JJ's are you using chief? EL34M or E34L?

I only ask because the E34L are somewhat different by design, and probably not very easily match to anything else.

Don't know whatever George put in the kit. Most likely the M. They were matched at some point but I didn't plan on keeping them in there long anyway so I didn't pay much attention. Just for fire up and debug.

Pretty sure they're the E34L's, because that's what George was shipping standard with the Plexi kits.

OnTheFritz wrote:Pretty sure they're the E34L's, because that's what George was shipping standard with the Plexi kits.

That would probably explain it. Although I have had different batches of Mullard Reissues that bias vastly different to the other as well.

Did you solve the PI/V3 voltage issue? If not, and you measure (with amp off/unplugged/discharged), from pin 3 or 8 of V3 to ground/chassis for resistance, what reading do you get? Should read around 15K.

If you read higher, look for a bad connection from V3 pins 3/8 on through the 470 Ohmer, the 10K, to the 4.7K on the presence pot to ground. Check values too, for example, check to see if you mistakenly used a 47K resistor on the presence pot instead of a 4.7K (if so, you'd see PI voltages much like you have now, so a good suspect right there).

As to the power tube issues, if a 47K is indeed on the presence pot now, the large amount of NFB resulting could cause stability problems leading to power tube redplating. May also want to check that the jumper there between the 10K PI tail resistor and the 100K NFB resistor isn't able to short (or intermittently short) to the turrets/legs of the PI 220Ks/.022ufs where it crosses very closely by them (melted insulation or such due to tight fit of the bits in those 2 spots).

Any way don't know if you sorted this yet or not, but a couple things to check for starters if not.