Shunt Regulator Voltage Test Fail [resolved]

Why1504 · 1991

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Offline Why1504

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on: January 22, 2017, 07:44:17 AM
First the voltage for D1 never dropped below 326.6. Only the 2 LEDs on the A side lit up.

D6 settled at 224.3 but again only 2 LEDs lit on the A side.

Please advise.
« Last Edit: January 23, 2017, 10:24:03 AM by Caucasian Blackplate »


Online Paul Birkeland

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Reply #1 on: January 22, 2017, 09:22:13 AM
Can you post the IA, IB, OA, OB, and both Kreg voltages?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Why1504

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Reply #2 on: January 22, 2017, 10:20:56 AM
I can't now.  I have left my office where I am working on it.  I will go in early and check them and post tomorrow.


Offline Why1504

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Reply #3 on: January 23, 2017, 01:12:01 AM
Can you post the IA, IB, OA, OB, and both Kreg voltages?

IA. 327
IB.  327
OA. 224
OB. 325
KREG A. 4.999
KREG B. 32.25


Online Paul Birkeland

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Reply #4 on: January 23, 2017, 08:54:26 AM
Can you confirm that you have a 431 regulator in the slot for Kreg B?  That voltage makes me think that it's in backwards, or an MPS4250 is installed in its place.

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Why1504

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Reply #5 on: January 23, 2017, 09:01:33 AM
The 431 is installed the same way on both sides with the flat to the outside.  Pins are installed the same on both.


Online Paul Birkeland

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Reply #6 on: January 23, 2017, 09:06:25 AM
Well, little to no current is being drawn by half of the 12BH7.  This can happen due to a wiring or part installation error on the PC board, or a failure of the solder joint on pins 4 and 5 of that 9 pin socket.

Another issue that I believe will cause this type of problem is if Breg and +reg aren't jumpered on that side.

To check the pin 4/5 issue, you can look at the 12BH7 and see if there are amber glowing dots on each plate structure.

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Why1504

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Reply #7 on: January 23, 2017, 09:11:45 AM
I see 2 dots glowing on the top and 2 near the base of the tube.
« Last Edit: January 23, 2017, 09:13:29 AM by Why1504 »


Online Paul Birkeland

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Reply #8 on: January 23, 2017, 09:13:45 AM
The next step I would recommend is to post some photos of that area.

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Why1504

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Reply #9 on: January 23, 2017, 09:15:12 AM
The jumper between the BReg and the +Reg is in place


Offline Why1504

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Reply #10 on: January 23, 2017, 09:26:54 AM
One of the 110k resistors wasn't soldered good.  As I was taking pictures it popped out.  Voltage now settlers to 223 and 224 respectively. All 4 LEDS light.

I think I am good.  Thanks for the help.


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