Bottlehead Kits > Integration
Something was wrong and then I made it worse. [solved]
corndog71:
I got the shunt regulator board installed and fired it up for testing voltages. I noticed the leds on the shunt board were all lit as were the two on the left channel tube.
The right channel leds on the tube were not lighting up.
I checked the voltage on the metal tabs of each MJE5731.
Left side was 105VDC, right side had 0VDC. I figured I didn't solder it in good enough so I shut it down and resoldered all 3 pins.
I turned it on again and the right tube leds were still not lighting up. I probed the outer pins of the MJE5731 and got 120VDC and then my probe slipped and hit the center pin and I heard a snap. All four leds on the shunt board stopped lighting up.
So the question is how do I figure out which parts I broke?
Paul Birkeland:
--- Quote from: corndog71 on February 22, 2014, 10:09:48 AM ---
So the question is how do I figure out which parts I broke?
--- End quote ---
You don't, you build a new PC board.
(It was very likely the center leg of the MJE-5731A, or an issue with the black jumper)
corndog71:
--- Quote from: Caucasian Blackplate on February 22, 2014, 12:50:26 PM ---
--- Quote from: corndog71 on February 22, 2014, 10:09:48 AM ---
So the question is how do I figure out which parts I broke?
--- End quote ---
You don't, you build a new PC board.
(It was very likely the center leg of the MJE-5731A, or an issue with the black jumper)
--- End quote ---
The black jumper checks out. Are you saying I need to replace all of the parts on the board? Surely some of them are salvageable.
corndog71:
So I took the shunt regulator board out as well as the two 1K resistors, reconnected the B+ wires and turned it on to make sure it still worked in stock form.
The tubes lit up but I thought I heard a slight crackling sound so I shut it down.
Going back to resistance checks I found some off readings.
39 - 7.2K
41 - 7.2K
42 - 8R
50 - 982R
51 - same as 50
52 - 1.952K The reading jumps around but then builds up to here and stays there.
53 - same as 52
56 - 0.6R
57 - same as 56 Bad cap?
58 - 982R It jumps a bit then settles here.
59 - same as 58
The 1K resistors between the power supply caps are still good.
Paul Birkeland:
I guess my biggest question is whether the stock Reduction was functioning or not.
56/57 being 0 and 58/59 being 1K means that you have a short at 56/57.
Can you provide a photo of that region?
It's also possible that one of the red wires leaving that region got moved to a ground connection. (T5 would be the logical mistake here)
Generally, you won't kill one of the power supply caps unless it's in backwards, which is also possible.
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