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Author Topic: Smashup on testing 2 of 8 LEDs not lighting  (Read 1254 times)

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Offline nirvanashot

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Smashup on testing 2 of 8 LEDs not lighting
« on: June 22, 2016, 09:30:43 AM »
I arrived at the end of the steps of the Smashup Manual and began testing the voltage.
the 2 LEDs near the front of the chassis on the A side are not lighting, while the other 6 LEDs are lighting.

from 29, 17U is reading 215V

On the A side PCB:
     IA is reading 215V should be 180-220V
     OA is reading 64V should be 150V
     IB is reading 64V should be 150V
     OB is reading 64V should be 45-75V
     Kreg(B side) is reading 4V should be 3-5V
     Breg(B side) is reading 64V should be 150V
     +reg(B side) is reading 64V should be 150V
On the C side PCB:
     IA is reading 215V should be 180-220V
     OA is reading 215V should be 150V
     IB is reading 215V should be 150V
     OB is reading 64V should be 45-75V
     Kreg(B side) is reading 4V should be 3-5V
     Breg(B side) is reading 215 should be 150V
     +reg(B side) is reading 215 should be 150V

B1 is reading 0V as defined
BT is reading 64V when it should be 150V
B3 is reading 4V within the 3-5V range
B4 is reading 0V as defined
B5 is reading 215V when it should be 150V
B6 is reading 4V within the 3-5V range

I am wondering if it is a simple matter of rechecking my solders on the A side board relative to the to LEDs. From the final exposed side they look good.
Looking forward to discovering what I missed or did incorrectly.
Thanks.

Offline Doc B.

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Re: Smashup on testing 2 of 8 LEDs not lighting
« Reply #1 on: June 22, 2016, 09:41:43 AM »
Make sure you have not accidentally swapped the PN2907 and the LM431, and make sure you have not swapped the 37.4 ohm and 49.9 ohm resistors
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline nirvanashot

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Re: Smashup on testing 2 of 8 LEDs not lighting
« Reply #2 on: June 22, 2016, 04:02:08 PM »
I did good on my transistors, but on the A side I had swapped my 37.4 and 49.9 resistors.
I corrected that, but am still getting odd numbers:
On the A side PCB:
     IA is reading 218V should be 180-220V
     OA is reading 215V should be 150V
     IB is reading 215V should be 150V
     OB is reading 48V should be 45-75V
     Kreg(B side) is reading 2V should be 3-5V
     Breg(B side) is reading 215V should be 150V
     +reg(B side) is reading 215V should be 150V
On the C side PCB:
     IA is reading 217V should be 180-220V
     OA is reading 215V should be 150V
     IB is reading 215V should be 150V
     OB is reading 48V should be 45-75V
     Kreg(B side) is reading 1V should be 3-5V
     Breg(B side) is reading 215V should be 150V
     +reg(B side) is reading 215V should be 150V

B1 is reading 0V as defined
B2 is reading 215V when it should be 150V
B3 is reading 2V within the 3-5V range
B4 is reading 0V as defined
B5 is reading 215V when it should be 150V
B6 is reading 1V within the 3-5V range
B7 is reading 2V while B8 is reading 5V and am wondering if this is correct.

I see in further review of the schematics that the transition from 220V down to 150V that the resistor path may be the culprit. From 29 through 17 and on to IA, I see that the voltage should still be in the 180-220 range, and it is. However, all of the readings after that, which should be in the 150V range, are in the 180-220 range. I also see that that after the MJE5731A, on the schematic,the voltage should be 150V. And, apparently, given that both channels are acting the same, that I have done something incorrect on both sides. Any ideas as to what I probably did wrong?

I reviewed the removal of objects from the base Smash and confirmed that was done correctly.
I tried to measure other contacts based on the values in the core smash instructions, but ran into issues at contacts 3 and 10 where the ohm values were supposed to be 475K, they weren't. going back up the line, it appears I need to first correct what it causing the discrepancy in the volts.

I'm looking at it further, but if you can provide additional probable cause, that would be really appreciated.

..and please correctly me if my analysis is misdirected.
Thanks for your help.
« Last Edit: June 26, 2016, 08:21:53 AM by nirvanashot »

Offline Paul Birkeland

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Re: Smashup on testing 2 of 8 LEDs not lighting
« Reply #3 on: June 27, 2016, 05:19:36 PM »
It is generally quite helpful to post photos of both sides of your PCB's. 

Does your 6SN7 tube glow when the amp is on?

The Kreg voltage on the A side should have gone up, not down, when you fixed the R1 resistor issue.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline nirvanashot

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Re: Smashup on testing 2 of 8 LEDs not lighting
« Reply #4 on: June 28, 2016, 03:32:17 PM »
Yes, yes, I missed a note. I missed that there was a different vacuum tube for this Smashup. The OD3 was still in place. As soon as I put the 6SN7 in all of the voltages were exactly as specified.

Sorry for taking your time and thank you for my patience.
I am still learning, but the success I am having with this, despite my oversight, is motivating.
On to the next upgrade, the SmashQuiet.
I hope to not be bothering you.

Thanks for a great product. It is already exceeding my expectations.

Offline Paul Birkeland

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Re: Smashup on testing 2 of 8 LEDs not lighting
« Reply #5 on: June 30, 2016, 02:51:33 PM »
I'm glad you got it all sorted out! You can save the 0D3 for a future night light project.

-PB
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man