Are my resistance and voltage readings OK? [resolved]

cddc · 1802

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Offline cddc

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on: December 06, 2016, 03:31:53 PM
Here are the readings of my resistance check:

Terminal --- Resistance Reading
T1---1.4-1.3...1.1M ohms...
T2---2.7-2.6...2.4M ohms...
T3---0 ohms
T4---5.0-4.9...4.0M ohms...
T5---55-56-57---60K ohms...
T6---2.48K
T7---2.93K
T8---0 ohms
T9---2.92K
T10--2.48K
T12--0 ohms
T13--280-270-260K ohms...
T14--0 ohms
T20--0 ohms
T22--stayed at the initial reading of 1 (the reading when multimeter is set to resistance check). Then I found there is a fiber washer between T22 and the plate. So I think the reading of T22 can never be zero ohm. The zero ohm for T22 from the manual is more likely an error, I believe.

B3---2.93K ohms
B6---2.92K ohms

RCA jacks:
Ground---0 ohm
Center Pins---101K ohms for red jack, and 106K ohms for black jack

I'd really appreciate it if someone could help me confirm:
1. whether the zero ohm for Terminal 22 from the manual is not correct?
2. whether the rest of my resistance readings are OK?


« Last Edit: December 14, 2016, 02:37:42 PM by Caucasian Blackplate »



Offline cddc

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The above resistance check seemed OK to me. The 0 ohm of T22 is more likely an error from the old manual I believe (the fiber washer will never make the zero ohm happen).

Anyway, I proceeded with my voltage check and it seemed OK as well.

Here are my voltage readings:

1=90V
2=180V
3=0
4=180V
5=87V
6=0
7=115V
8=0
9=113V
10=0
11=0
12=0
13=180V
14=0
15=203V
20=0
21=226V

A1=87V
A2=0
A4=0
A5=0
A6=90
A7=0
A9=0

B1=89V
B2=180V
B3=115V
B4=86V
B5=180V
B6=112V
B7=0
B8=0


The above voltage check also seemed OK to me.

After powering up, I also noticed the voltage changes at the headphone jack within the first 10 seconds.

So everything seems OK.

« Last Edit: December 06, 2016, 09:03:57 PM by cddc »



Offline cddc

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At last...I connected the Crack to my DAC. Plugged in my Senn HD650 and threw some Bach on it.

The background is dead silent. The Crack sounds fantastic. The Starker's unaccompanied cello suites are sublime.

I am enjoying the music now.  :) :) Will complete the Speedball upgrade within the next couple of days. :)
« Last Edit: December 06, 2016, 09:12:44 PM by cddc »



Offline Paul Birkeland

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It's not super critical if 22 does not read 0 Ohms.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline cddc

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It's not super critical if 22 does not read 0 Ohms.

Indeed! My Crack worked pretty well after powering up.

I believe T22 can never read 0 ohm. There are 4 fiber washers between the power transformer and its 2 strips. So the T22 can never go down to 0 ohm since there is a fiber washer between its leg and the chassis plate. I believe it's another manual error for the old Crack manual.



Offline Paul Birkeland

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I believe T22 can never read 0 ohm. There are 4 fiber washers between the power transformer and its 2 strips. So the T22 can never go down to 0 ohm since there is a fiber washer between its leg and the chassis plate. I believe it's another manual error for the old Crack manual.
The ground path goes up the one transformer screw that is grounded, through the transformer cover, then back down the screw that passes through terminal 22. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline cddc

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The ground path goes up the one transformer screw that is grounded, through the transformer cover, then back down the screw that passes through terminal 22.

There is a fiber washer in between T22 and the chassis plate (please see the pic below).

I really couldn't see the ground path here.  :(



Offline Paul Birkeland

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Terminal 22 touches the #8 nut that sits above it.  The bolt that passes through that touches the transformer cover, the transformer cover is grounded through the screw by the IEC inlet.

The insulator is there to control how the transformer is safety grounded.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline cddc

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Terminal 22 touches the #8 nut that sits above it.  The bolt that passes through that touches the transformer cover, the transformer cover is grounded through the screw by the IEC inlet.

The insulator is there to control how the transformer is safety grounded.

Great, I see your points now.

I think the heavy painting on my transformer cap breaks the ground path. I painted both sides of the transformer cap with multiple layers of paint. So it much be the paint on the cap that breaks the ground path from T22 to the #8 ground solder tab connected to the chassis.

However, I think the grounding of the transformer itself in my case is still OK, because on the other side of the transformer the T16 terminal connects the transformer to the ground, and this ground path is not affected by the painting. It's just T22 and the painted transformer cap are not grounded - but I think it doesn't matter.



Offline cddc

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Just measured the ground path for the transformer on the T16 side (touched T16 and one side of the transformer), and got a 0 ohms reading...Hooray  :)
« Last Edit: December 08, 2016, 02:13:13 PM by cddc »