First time builder - failed voltage check [resolved]

shroomalistic · 7919

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Offline shroomalistic

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Hi guys,  having issues.  Something is definitely not right here

T01: -.9
T02: -.9
T03: 0
T04: -.9
T05: -.9
T06: 0
T07: 0
T08: 0
T09: 0
T10: 0
T11: 0
T12: 0
T13: -.9
T14: 0
T15: -.9
T16: 0
T17: 0
T18: 98.4
T19: 98.4
T20: 0
T21: 241
T22: 0

I get errors when i try to attach a picture
« Last Edit: May 05, 2023, 03:55:01 PM by Paul Birkeland »



Offline Paul Birkeland

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Reply #1 on: April 19, 2023, 06:00:41 AM

T15: -.9

T21: 241

Terminals 15 and 21 are connected with a 270 ohm resistor. One end of that resistor is loose or poorly soldered.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline shroomalistic

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Reply #2 on: April 19, 2023, 06:05:27 AM
Terminals 15 and 21 are connected with a 270 ohm resistor. One end of that resistor is loose or poorly soldered.

I thought there was something wrong with that resistor,  its dead.  solders are great on it,  it got super hot and i burnt my finger on it.



Offline shroomalistic

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Reply #3 on: April 19, 2023, 06:13:33 AM
any suggestions where to buy replacement?



Offline Paul Birkeland

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Reply #4 on: April 19, 2023, 06:18:28 AM
That resistor will only die if there's a catastrophic short, which should show up in your resistance checks.  Just buying another one and replacing it will lead to more dead resistors.  Is the other 270 ohm resistor in-tact?  Usually that is the one that fails first.

Is that black wire that's supposed to go to 14U going to 15U instead?  How were your resistance checks?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline shroomalistic

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Reply #5 on: April 19, 2023, 06:25:04 AM
resistant checks were all spot on.  its the insulation pulled back off the wire there,  its going to 14u



Offline shroomalistic

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Reply #6 on: April 19, 2023, 06:30:19 AM
looks like both resistors are dead.  getting  nothing from both when checking them



Offline Paul Birkeland

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Reply #7 on: April 19, 2023, 06:37:21 AM
Are pins 1 and 2 touching on the 9 pin socket?

Having both resistors burnt means that your resistances at terminals 2, 4, B2, and B5 should not measure correctly.  Can you let me know what resistance values you get at those terminals?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline shroomalistic

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Reply #8 on: April 19, 2023, 06:50:06 AM
it does nothing when i measure between 12u and 2,4,b2, b5.  man i hope im not reading my meter wrong.  does the * in the manual mean there should be no resistance?

a1,and a2 dont touch  pretty close but there is room for movement and still not connect



Offline Paul Birkeland

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Reply #9 on: April 19, 2023, 06:55:03 AM
No resistance would be 0 Ohms, which would be a short.  If your meter says "OL", that would mean infinite resistance, which is desired.

For the resistors to go from 270 ohms to open without the cement housing cooking and falling off means they were shorted to ground, so this issue has to be found before replacing them. This doesn't happen on its own without a cause.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline shroomalistic

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Reply #10 on: April 19, 2023, 06:58:23 AM
would the cap being reversed do that,  i had the wrong cap on 14u, 15u.  didnt realize it they were all different.  I then switched it with the right one and put it in backwards but I thought i caught it before powering up



Offline Paul Birkeland

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Reply #11 on: April 19, 2023, 07:19:17 AM
Yes, a backwards electrolytic will create a dead short. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Doc B.

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Reply #12 on: April 19, 2023, 08:00:18 AM
Just to clarify the electrolytic caps aren't all different. There are just two values supplied in the kit. The caps in the power supply around the power transformer are three 220uF 250V capacitors and the output coupling caps by the 6080 socket are two 100uF 160V capacitors.

Once power has been applied to a power supply filter cap that has been installed backwards it has been stressed to a point that it should probably be replaced even if it still seems functional.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline shroomalistic

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Reply #13 on: April 19, 2023, 08:36:48 AM
so i should buy new caps too?

Sorry,  Im completely blind in one eye and a my other is going bad from old age.  Its making this a real challenge for me even with magnifying glass

do you have suggestions on where to buy the parts?
« Last Edit: April 19, 2023, 08:38:22 AM by shroomalistic »



Offline Paul Birkeland

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Reply #14 on: April 19, 2023, 08:42:31 AM
You can e-mail replacementparts(at)bottlehead(dot)com regarding these parts if you'd like to get them from us. 

Otherwise these are what you need:
https://www.mouser.com/ProductDetail/Xicon/280-CR5-0.27-RC?qs=SXXIg1eCKOp1bN5Y9Kl0jA%3D%3D
https://www.mouser.com/ProductDetail/Nichicon/UCY2E221MHD3?qs=Ajmft%252BTTukEz8LAZjX8PHg%3D%3D


Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man