38-116 broken wire in sub-chassis - Printable Version

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+--- Thread: 38-116 broken wire in sub-chassis (/showthread.php?tid=13576)

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RE: 38-116 broken wire in sub-chassis - murf - 12-09-2015

Hi Terry,
Checked voltages on both 6L6 tubes and are as follows.
Tube 1
Pin 2 6.5 ac
Pin 3 220v
Pin 4 244v
Pin 5 -7.4v
Pin 7 checks 0 volts ac(should be 6.3)

Tube 2
Pin 2 6.5v ac
Pin 3 243v
Pin 4 244v

Tested both 6L6 tubes also,
Tube 1 checked 4000 (mut cond = 5000)
Tube 2 checked 3500
Pin 5 -31.6v
Pin 7 checks 0 volts(should be 6.3)

High voltage a little low
6.3 ac missing on pins 7
Irregular voltage on pins 5
Tubes check low on my hickok tester.

What do you make of this?
murf

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RE: 38-116 broken wire in sub-chassis - Radioroslyn - 12-12-2015

(12-09-2015, 08:47 PM)murf Wrote:  Hi Terry,
Checked voltages on both 6L6 tubes and are as follows.
Tube 1
Pin 2  6.5 ac
Pin 3  220v
Pin 4  244v
Pin 5  -7.4v
Pin 7 checks 0 volts ac(should be 6.3)

Tube 2
Pin 2  6.5v ac
Pin 3  243v
Pin 4  244v

Tested both 6L6 tubes also,
Tube 1 checked 4000 (mut cond = 5000)
Tube 2 checked 3500
Pin 5  -31.6v
Pin 7 checks 0 volts(should be 6.3)

High voltage a little low
6.3 ac missing on pins 7
Irregular voltage on pins 5
Tubes check low on my hickok tester.

What do you make of this?
murf

Hi Murf,
Well, The mismatch between the two control grids is a problem. According to the  RCA tube manual it should be close to -22vdc. Would check the 10K resistors in series with the grids and two secondary winding of the driver transformer, you may find one is open.

Terry

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