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38-116 Code 121 Powering Up Help
#45

Hi Terry!

Okay with tubes I know that are good, I took measurements of all 15 tubes pins, the interstage transformer pins, neutral and hot of the AC line cord, filter caps (141 & 142), electro caps (140 and 140a and 80a and 80b) choke 136 and choke 138 and the resistor junction of 134 and 135.  here goes.

-- where the line cord enters the chassis I got 110 vac across the hot and neutral.
-- across the power transformer primaries I have 107 vac
-- for the power filter caps 141 and 142 I get 333 vdc positive to negative (should be 385) and I get 281 vdc positive to ground.
-- for electro caps 140a where the positive goes to ground and the negative to the negative of the filter caps, i have -48 vdc (should be -50 vdc I think)
-- for 140 I have 270 vdc
-- for electro cap 80: I have 256 vdc, 80a: 236 vdc, 80b: 85 vdc
-- for choke 136 I have 283 vdc for the pin closest to the front and 270 vdc for the lower one.
-- for choke 138 I have 236 vdc for the black wire and 245 vdc for the white wire
-- at the junctions of resistors 134 and 135 I have -21 vdc
for the interstage transformer I have: pins 1 through 4: -20 vdc pin 5: 236 vdc pin 6: 231 vdc

I f I do not list a pin it read zero. My largest discrepancies are on my oscillator (6A8G) and oscillator control (6N7G) tubes.

Rectifier Tube 5X4G:
across pins 1 and 2 (filaments): 4.85 vac
chassis to plate on pin 4: 341 vac
chassis to plate on pin 6: 341 vac

Output tube #1 6L6G (closest to side):
pin 2: 6 vac (should be 6.3 vac)
pin 3 262 vdc (should be 290 vdc)
pin 4: 267 vdc (should be 300 vdc)
pin 5: -21 vdc (shuold be -20 vdc)

Output tube #2 6L6G:
pin 2: 6 vac (should be 6.3 vac)
pin 3 263 vdc (should be 290 vdc)
pin 4: 268 vdc (should be 300 vdc)
pin 5: -21 vdc (should be -20 vdc)

6J5G Driver tube:
pin 3 230 vdc (should be 260 vdc)
pin 5: -6.8 vdc (not sure what this should be)
pin 7: 6 vac (should be 6.3 vac)

6K7G RF Tube (on RF subchassis):
pin 2: 6.1 vac (should be 6.3 vac)
pin 3 237 vdc (should be 250 vdc)
pin 4: 85 vdc (should be 90 vdc)
pin 5: 2 vdc (should be -3.5 vdc)

6L6G Mixer Tube (on RF subchassis):
pin 3 225 vdc (should be 250 vdc)
pin 4: 90 vdc (should be 90 vdc)
pin 5: 2 vdc (should be -3.5 vdc)
pin 7: 6.1 vac (should be 6.3 vac)

6A8G Osc Tube (on RF subchassis):
pin 3 260 vdc (should be 180 vdc)
pin 4: 260 vdc (should be 110 vdc)
pin 5: 260 vdc (should be 125 vdc)
pin 7: 6.1 vac (should be 6.3 vac)

6N7G Osc Control Tube (on RF subchassis):
pin 3 275 vdc (should be 225 vdc)
pin 4: -3 vdc (not sure what it should be)
pin 5: -3 vdc (not sure what it should be)
pin 6: 275 vdc (should be 225 vdc)
pin 7: 6.1 vac (should be 6.3 vac)

6K7G 1st IF Tube:
pin 3 231 vdc (should be 250 vdc)
pin 4: 85 vdc (should be 90 vdc)
pin 5: -2.6 vdc (should be -3.5 vdc)
pin 7: 6.1 vac (should be 6.3 vac)

6K7G 2nd IF Tube:
pin 3 226 vdc (should be 250 vdc)
pin 4: 85 vdc (should be 90 vdc)
pin 5: -2.6 vdc (should be -3.5 vdc)
pin 7: 6.1 vac (should be 6.3 vac)

6J5G AVC Tube:
pin 5: -5.3 vdc (not sure what it should be)
pin 7: 6.1 vac (should be 6.3 vac)

6K7G 2nd detector Tube:
pin 3: 34 vdc (should be 40 vdc)
pin 4: 18 vdc (should be 15 vdc)
pin 5: 18 vdc (should be 15 vdc)
pin 7: 6.1 vac (should be 6.3 vac)

6J5G Disc. Tube:
pin 3: -0.6 vdc (not sure what it should be)
pin 5: -9.4 vdc (not sure what it should be)
pin 7: 6.1 vac (should be 6.3 vac)
pin 8: -0.6 vdc (not sure what it should be)

6J5G Disc. Tube:
pin 3: -5 vdc (not sure what it should be)
pin 5: -18 vdc (not sure what it should be)
pin 7: 6.1 vac (should be 6.3 vac)

6R7G 1st Audio Tube:
pin 3 69 vdc (should be 70 vdc)
pin 7: 6.1 vac (should be 6.3 vac)

Andy Sorrell
Palmyra, Virginia


Messages In This Thread
38-116 Code 121 Powering Up Help - by AVSorrell - 07-17-2017, 07:12 AM
RE: 38-116 Code 121 Powering Up Help - by morzh - 07-17-2017, 07:21 AM
RE: 38-116 Code 121 Powering Up Help - by morzh - 07-17-2017, 08:47 AM
RE: 38-116 Code 121 Powering Up Help - by morzh - 07-18-2017, 07:57 AM
RE: 38-116 Code 121 Powering Up Help - by morzh - 07-18-2017, 11:05 AM
RE: 38-116 Code 121 Powering Up Help - by morzh - 07-19-2017, 08:08 AM
RE: 38-116 Code 121 Powering Up Help - by morzh - 07-30-2017, 01:49 PM
RE: 38-116 Code 121 Powering Up Help - by morzh - 07-30-2017, 07:10 PM
RE: 38-116 Code 121 Powering Up Help - by morzh - 07-31-2017, 07:42 AM
RE: 38-116 Code 121 Powering Up Help - by morzh - 07-31-2017, 12:27 PM
RE: 38-116 Code 121 Powering Up Help - by AVSorrell - 08-06-2017, 03:15 PM
RE: 38-116 Code 121 Powering Up Help - by Chris h - 09-26-2017, 12:19 PM



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