V1 & V2 Voltages Help Needed

Info for maintaining and tweaking your amp to perfection.

Moderator: VelvetGeorge

Post Reply
User avatar
white noise
Senior Member
Posts: 263
Joined: Sat Jun 22, 2013 9:09 am
Just the numbers in order: 13492
Location: San Antonio Texas

V1 & V2 Voltages Help Needed

Post by white noise » Mon Mar 28, 2016 12:33 pm

ok, I am at my wits end on this one.

I finished putting a Dual PPIMV on a 2203, did final testing, biased the amp, working perfectly, shut it off, put it in its case and re-test and NO SOUND!

Removed the chassis, and now i am not getting proper Voltages for V1 or V2! :bang:
V3 - V7 all voltages are proper and working.

I have re-flowed all pins for V1 and V2.
Re-flowed all the resistors and caps for V1 and V2.
tested the fuses.
Put new tubes in V1 and V2. Swapped tube for V3 to V1 and also to V2, its not the tubes.
Cleaned out the pins for V1 and V2.
Verified continuity for pins from outside to inside of the chassis for tube sockets.
Verified continuity from pins to all resistors and caps for V1 and V2.


Here are the voltages i am getting for V1 and V2:

V1
Pin 1: -.995 yes negative
Pin 2: -.511 yes negative
Pin 3: 3.15
Pin 4: 3.15
Pin 5: -.952 yes negative
Pin 6: 0
Pin 7: -.359 yes negative
Pin 8: .014
Pin 9: 3.276

V2
Pin 1: -.953 yes negative
Pin 2: -.68 yes negative
Pin 3: 3.3
Pin 4: 3.3
Pin 5: -.953 yes negative
Pin 6: 0
Pin 7: -.98 yes negative
Pin 8: 0
Pin 9: 3.283

Any help would be appreciated!

danman
Senior Member
Posts: 1099
Joined: Tue Sep 10, 2013 9:09 pm
Just the numbers in order: 13492

Re: V1 & V2 Voltages Help Needed

Post by danman » Mon Mar 28, 2016 4:04 pm

With your amp powered up and in playing mode, start checking your B+ voltage from the 10k dropping resistor on down the line. Just follow your board jumper wire, taking readings at each turret that it connects to, and you should be able to find the spot that the voltage stops.

User avatar
white noise
Senior Member
Posts: 263
Joined: Sat Jun 22, 2013 9:09 am
Just the numbers in order: 13492
Location: San Antonio Texas

Re: V1 & V2 Voltages Help Needed

Post by white noise » Mon Mar 28, 2016 8:24 pm

yep am feeling like I am in the twilight zone on this one.
I have replaced the preamp filter thinking it may be bad, but that's not it.

Voltages:
V3 on pin 1 i have 282vdc and at the turret of the plate resitors i have 33vdc.
V3 on pin 6 i have 373vdc and at the turret of the plate resistor i have 35vdc.

tracing back to the bottom turret of the 10k dropping (right side) is reading 436vdc, top of that 10K its reading -.976 (yes negative)

the left side 10K dropping is reading -.976v at the top and .002v at the bottom.

here is a picture:
Image

Tazin
Senior Member
Posts: 794
Joined: Fri Jan 19, 2007 8:54 pm

Re: V1 & V2 Voltages Help Needed

Post by Tazin » Tue Mar 29, 2016 4:35 pm

Check and make sure that 10K/1w dropping resistor isn't an open circuit.

User avatar
white noise
Senior Member
Posts: 263
Joined: Sat Jun 22, 2013 9:09 am
Just the numbers in order: 13492
Location: San Antonio Texas

Re: V1 & V2 Voltages Help Needed

Post by white noise » Tue Mar 29, 2016 5:42 pm

Problem solved! :thumbsup:

The 10K decoupling resistor failed, even after removing there was no reading from it.

Post Reply