Power Supply Test

oguinn · 768

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Offline oguinn

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on: January 10, 2020, 10:54:27 AM
Alright, got past the first power supply test. Voltage was 6.2 VDC. Now on to the 275 VDC test, and I’m getting a slow climbing reading in the mV range. I turned it off after a minute and it was at 670 mV. I’m thinking it might be that I’ve missed the pads with the alligator clips. The reason I think that is because I had something similar on the 6V pad and readjusted and it worked. I’ve tried twice with the 275 pad.

Is it possible to use probes for this test? Or would that be super dangerous given how long the power supply stays energized?

Jameson O'Guinn

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Main System: Schiit Bifrost MB, Rega Planar 6 with Exact cartridge, Eros 2, BeePre, Kaiju/Stereomour II, Jagers, Mainline

Desktop System: Crack with Speedball


Offline Paul Birkeland

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Reply #1 on: January 10, 2020, 11:01:58 AM
I would use probes.

You can improve the performance of test leads by soldering the ends.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline oguinn

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Reply #2 on: January 10, 2020, 11:08:42 AM
Ok. Probed it. Same situation. I assume it should read 300-500 VDC pretty immediately, right? I’ll post some pictures in a few minutes once the power supply has de-energized.
« Last Edit: January 10, 2020, 11:12:07 AM by oguinn »

Jameson O'Guinn

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Main System: Schiit Bifrost MB, Rega Planar 6 with Exact cartridge, Eros 2, BeePre, Kaiju/Stereomour II, Jagers, Mainline

Desktop System: Crack with Speedball


Offline oguinn

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Reply #3 on: January 10, 2020, 11:29:40 AM
Here’s an album of the power supply. Are there any glaring errors? Anything to try out? https://imgur.com/a/wYmhnmy

Jameson O'Guinn

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Main System: Schiit Bifrost MB, Rega Planar 6 with Exact cartridge, Eros 2, BeePre, Kaiju/Stereomour II, Jagers, Mainline

Desktop System: Crack with Speedball


Offline Tom-s

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Reply #4 on: January 10, 2020, 11:49:19 AM
It's not that the HV is rectified with the Schottky diodes and the heaters with the other diodes?
As i'm missing the shottky's on the board?

Don't have a Eros, don't know what the supply looks like.  :-X

Because this could explain the problem and the voltages you get.

Edit;' and what the board looks like (underneath).
« Last Edit: January 10, 2020, 11:51:51 AM by Tom-s »



Offline oguinn

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Reply #5 on: January 10, 2020, 11:51:15 AM
God I’m dumb. That’s it. Thanks for that. Good eye.

Jameson O'Guinn

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Main System: Schiit Bifrost MB, Rega Planar 6 with Exact cartridge, Eros 2, BeePre, Kaiju/Stereomour II, Jagers, Mainline

Desktop System: Crack with Speedball


Offline Tom-s

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Reply #6 on: January 10, 2020, 11:55:46 AM
The 135Vac should double-up, but it needs some direction to do so  :P



Offline oguinn

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Reply #7 on: January 10, 2020, 12:04:38 PM
That fixed it. I feel very dumb.

Jameson O'Guinn

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Main System: Schiit Bifrost MB, Rega Planar 6 with Exact cartridge, Eros 2, BeePre, Kaiju/Stereomour II, Jagers, Mainline

Desktop System: Crack with Speedball


Offline Tom-s

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Reply #8 on: January 10, 2020, 12:10:04 PM
You've learned from this how your PS works and that your HV has a working CRC filter  :P



Offline grufti

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Reply #9 on: January 10, 2020, 12:38:54 PM
While you're at it you might want to chop the short section wire that's sticking out at T12. It looks like it is long enough to contact T11 accidentally, if it is ever bent over that way.



Offline Paul Birkeland

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Reply #10 on: January 10, 2020, 12:58:56 PM
The 270K resistors should rest against the board too.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Deke609

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Reply #11 on: January 10, 2020, 01:41:34 PM
The 270K resistors should rest against the board too.

@PB - Just curious: why do they need to be against the board? I assume that they are bleeders for the HV power supply caps, and so don't need to be raised from the board b/c they don't dissipate much if any heat. But why is it a bad idea to have them raised?  Does the extra lead length risk picking up noise?

many thanks, Derek



Offline Paul Birkeland

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Reply #12 on: January 10, 2020, 01:57:41 PM
If they can move around, it becomes difficult to predict what they might touch that they shouldn't.  If they are up off the board, it's more likely that they will break loose, and if one resistor breaks loose and the other does not, that will cause some problems with the DC voltage balance across those power supply caps.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Deke609

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Reply #13 on: January 10, 2020, 05:23:56 PM
Many thanks PB. Makes sense.



Offline oguinn

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Reply #14 on: January 11, 2020, 04:48:39 AM
Thanks, everyone. I’ve shared that all up and made it past the shunt regulator tests. Waiting for the power supply to de-energize, then onto the audio circuit

Jameson O'Guinn

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Main System: Schiit Bifrost MB, Rega Planar 6 with Exact cartridge, Eros 2, BeePre, Kaiju/Stereomour II, Jagers, Mainline

Desktop System: Crack with Speedball