Voltage measurements off and tubes not glowing [resolved]

mrequalizer · 1745

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Offline mrequalizer

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Hello,

i am andreas from germany and this is my first every DIY soldering kit.

yesterday i finished my Bottlehead Crack Kit (240VAC) but sadly there is something wrong.

UPDATE: Resistance measurements look good now. I tried a different MM now and now everything looks good on the resistance part.

Resistance
Terminal / Suggested / Actual:
1 / * / fluctuating numbers
2 / * / fluctuating numbers
3 / 0 ohms / 0 ohms
4 / * / fluctuating numbers
5 / * / fluctuating numbers
6 / 2.4K ohms / 2.49k ohms
7 / 2.9K ohms / 2.96k ohms
8 / 0 ohms / 0 ohms
9 / 2.9K ohms / 2.91k ohms
10 / 2.4K ohms / 2.48k ohms
12 / 0 ohms / 0 ohms
13 / * will climb slowly toward 270K ohms / yes it climbs slowly toward 270k ohms
14 / 0 ohms / 0 ohms
20 / 0 ohms / 0 ohms
22 / 0 ohms / 0 ohms

B3 / 2.9K ohms / 2.96k ohms
B6 / 2.9K ohms / 2.92k ohms

RCA jacks:
Ground lug / 0 ohms / 0 ohms
Center pin / 90K ohms—100K ohms  / R 108k ohms - L 111k ohms

--

The tubes wont glow and i also measured the voltages. From what i have read in the forums my high voltages would be explained by the fact that the tubes are not drawing any voltage because something is not working correctly. Also the two LEDs wont light up.

Voltages
Terminal / Suggested / Actual:
1 / 75-90 / 225
2 / 170 / 225
3 / 0 / 0
4 / 170 / 225
5 / 75-90 / 225
6 / 0 / 0
7 / 100 / 0
8 / 0 / 0
9 / 100 / 0
10 / 0 / 0
11 / 0 / 0
12 / 0 / 0
13 / 170 / 225
14 / 0 / 0
15 / 185 / 225
20 / 0 / 0
21 / 206 / 225

A1 / 90 / 225
A2 / 0 / 0
A4 / 0 / 0
A5 / 0 / 0
A6 / 90 / 225
A7 / 0 / 0
A9 / 0 / 0

B1 / 90 / 225
B2 / 170 / 225
B3 / 100 / 0
B4 / 90 / 225
B5 / 170 / 225
B6 / 100 / 0
B7 / 0 / 0
B8 / 0 / 0

Thanks for any help in advance!
« Last Edit: March 08, 2016, 09:28:24 PM by Caucasian Blackplate »



Offline fullheadofnothing

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Reply #1 on: February 28, 2016, 10:05:49 AM
Tubes not glowing is usually caused by a miswire or soldering issue on terminals 4 and 5 on the transformer or B8 and B9 on the octal socket.

Joshua Harris

I Write the Manuals That Make The Whole World Sing
Kit Packer Emeritus


Offline mrequalizer

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Reply #2 on: February 29, 2016, 12:35:41 AM
Thanks for the quick reply fullheadofnothing.

I updated my resistance measurements using a different MM to measure. Everything looks good now on the resistance part.
First post update with new measurements.

I will check the mentioned terminals for miswire.

Is there a way to make sure that the problem is not one of the tubes?

New measurements:
- Transformer terminal 4 <-> B8 about 0 ohms
- Transformer terminal 4 <-> A4/A5 about 0 ohms
- Transformer terminal 5 <-> B7 about 0 ohms
- Transformer terminal 5 <-> A9 about 0 ohms

tried not to measure on the cables but on the pins of the sockets or terminals instead to avoid getting a false right connection.
« Last Edit: February 29, 2016, 12:43:40 AM by mrequalizer »



Offline Doc B.

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Reply #3 on: February 29, 2016, 07:13:11 AM
I'm heading in to the office in a bit and I will offer some suggestions when I get there.

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


Offline mrequalizer

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Reply #4 on: March 05, 2016, 12:08:07 PM
Got it sorted my crack is working now :)

I did some more measurements with a different DMM but this has not shown any difference. Looking at the wireing also did not reveal any problems.

Then i tried to check the tube pinout to be able to validate that the tubes are working.
The information i found was that the tube should be feeded with 6.3V at pin 8, so i took a closer look and i saw that B8L was not soldered o.O

Rechecking the manual revealed that there are no wires missing on B8L but that there is no clear instruction to solder B7L and B8L, maybe this should be added to the manual?

Thanks for your help! :)

ps. enyoing my Crack now with a Sennheiser HD600 attached!