Resistance Check Errors - 22/23

TurbOSquiD77 · 3626

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Offline TurbOSquiD77

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on: January 22, 2017, 11:59:08 AM
Hope everyone is having a great weekend. I'm on the final resistance check of the build and ran into measurements being 0, when they should be *.

Terminal 22, 23 read 0.
I've re soldered joints around this area, and double checked connections.
Thank you very much!



Offline Paul Birkeland

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Reply #1 on: January 22, 2017, 12:48:26 PM
Is your C2A plugged into the wall when you made these measurements?

This is where the 120V power comes in.  With a power cord plugged into the C2A, the neutral wire of your AC mains will provide a path to ground for both these terminals that wouldn't exist without the cord plugged in.

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline TurbOSquiD77

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Reply #2 on: January 22, 2017, 12:58:14 PM
No, I did not have the power cable connected to the wall or the amp.
Tried with the power cord connected to the amp with the  same result.
I am sitting with both feet on the floor, measuring terminals 22 and 23 at 0, and when I lift my feet off the ground I see resistance in the tens of thousands for 1-2 seconds then 0 again, feet still off the ground.



Offline Paul Birkeland

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Reply #3 on: January 22, 2017, 01:08:08 PM
I'd be very interested in seeing a photo of your build in that area, being sure to include the IEC power entry module in the shot.

I would recommend not powering up this amp just yet.

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline TurbOSquiD77

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Reply #4 on: January 22, 2017, 01:11:50 PM
Interesting, I'll grab a photo quick.

But... I did insert the power cord to the IEC, into the wall socket, turned on the amplifier, measurements read right around 1k at 22 and 23. No tubes inserted, nothing else extra I can think of.

Pics inbound.



Offline TurbOSquiD77

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Reply #5 on: January 22, 2017, 01:23:27 PM
pics.



Offline TurbOSquiD77

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Reply #6 on: January 22, 2017, 01:35:53 PM
Unable to post other pics. Getting HTTP ERROR 500 (internal server error).
Troubleshot for a while. I'll keep trying, but seems like a web server issue.
Took a couple tries to get the first 2 pics up. hmmmm
« Last Edit: January 22, 2017, 01:47:48 PM by TurbOSquiD77 »



Offline Paul Birkeland

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Reply #7 on: January 22, 2017, 01:46:04 PM
Well, this will be a little inconvenient, but can you disconnect all of the red and black wires that go from terminals 22/23 to the PT-8 (just pop them off 22/23 and leave them sticking up in the air).

Now, test the resistance between 22 and ground, then 23 and ground.  Also test the resistance between ground and each terminal of the power transformer.

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline TurbOSquiD77

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Reply #8 on: January 22, 2017, 01:58:20 PM
Disconnected the red and black wires coming from PT-8 to 22/23.
Tested resistance of 22/23 and 0Mohms is what I'm getting.
Also 0 for PT-8 1,3,4,6.
This is with the power cable connected to the IEC and the power switch on. Not plugged into wall outlet.

Thank you for assisting, I greatly appreciate it. Can't wait for this, so close!



Offline Paul Birkeland

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Reply #9 on: January 22, 2017, 02:01:43 PM
Disconnected the red and black wires coming from PT-8 to 22/23.
Tested resistance of 22/23 and 0Mohms is what I'm getting.
This can be a little tough to discern.  0Mohms could mean that you're on the mega-ohm scale (1,000,000 ohms is a mega-ohm), or the milli-ohm scale (0.001 Ohms is a milli-ohm) 

Also 0 for PT-8 1,3,4,6.
This is with the power cable connected to the IEC and the power switch on. Not plugged into wall outlet.
Is this 0 Ohms between PT-8 1, PT-8 2, etc. and the chassis?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline TurbOSquiD77

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Reply #10 on: January 22, 2017, 02:04:13 PM
Correct, PT-8 1,3,4,6 and the ground lung/nut by the IEC - 0 (that is with and without PT-8 being connected to 22/23.)
***Actually, my Ohm meter reads nothing I believe. It does not change to 0.0Ohms in K or M (auto mode). It stays at 0.L (part of the tenths "0" is cut off as if nothing were being detected) on 22/23, pt-8 1,3,4,6 while ground being attached to the chassis on the tab next to the IEC. Same reading as if the Ohm meter was not connected to anything.


My input voltage was 118.9ACV  during the test just before the power transformer input wiring.

PT-8 and chassis ground:
1,3,4,6 - 0.L (no change in reading from ohm meter being connected and disconnected)
9 through 15 - settles to 109Ohms
19 and 20 - 5.67MOhms (I believe Mega)

This is with the power cord inserted to the IEC, switch on, disconnected from wall power outlet.

Cheers! :o
« Last Edit: January 22, 2017, 04:34:47 PM by TurbOSquiD77 »



Offline Paul Birkeland

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Reply #11 on: January 22, 2017, 04:33:21 PM
Something isn't adding up here. We're you able to do the line voltage check and power transformer check? If you had 0 ohms to ground at 22 and 23, the fuse would blow as soon as you flipped the power switch.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline TurbOSquiD77

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Reply #12 on: January 22, 2017, 04:37:36 PM
Edited my last post to try and be a bit more helpful, ha.

Yes. I remember very well that I successfully passed both the line voltage, and transformer tests, as well as glow test.

Hmm, pulled the fuse and looks normal.
« Last Edit: January 22, 2017, 04:42:55 PM by TurbOSquiD77 »



Offline Paul Birkeland

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Reply #13 on: January 22, 2017, 04:43:47 PM
Well, if everything else is in order, can you plug the cord in and turn on the power switch, then measure the AC voltage between the chassis plate and 23, then the chassis plate and 22?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline TurbOSquiD77

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Reply #14 on: January 22, 2017, 04:47:10 PM
Sure thing.
23 - 1.61v
22 - 120.8v