Resistance Check [resolved]

Ctoy15 · 1503

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Offline Ctoy15

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on: August 30, 2018, 04:43:37 PM
So I just finished building my BHC and started on the resistance checks, and it did not go well at first. I read some other posts from this forum and checked a few things including my solder joints. When all was said and done, I got most of the resistances to be correct but a few were still not quite right. Here is a list of what I got:

Terminal       Resistance       Measured
 
1           *          *
2           *                 *
3           0 ohms          0 ohms
4           *          *
5           *          *
6           2.4K ohms       1.2K ohms
7           2.9K ohms       2.9k ohms
8           0 ohms          0 ohms
9           2.9K ohms       2.9K ohms
10         2.4K ohms         1.2K ohms
12        0 ohms          0 ohms
13        * will climb slowly toward 270K ohms
14        0 ohms          0 ohms
20        0 ohms           0 ohms
22           0 ohms              0 ohms
 
B3         2.9K ohms       2.9K ohms
B6         2.9K ohms       2.9K ohms
 
RCA jacks:    (Nothing listed?)
Ground lug        0 ohms          0 ohms
Center pin        90K ohms—100K ohms  0 ohms

Any help in solving this problem would be much appreciated as I cannot see anything that would be obviously wrong. Sorry if the formatting is not quite perfect.
« Last Edit: September 01, 2018, 09:52:30 AM by Caucasian Blackplate »

Chris Toy


Offline Paul Birkeland

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Reply #1 on: August 30, 2018, 07:05:56 PM
6           2.4K ohms       1.2K ohms
This will happen if the resistor at the headphone jack and the 3K resistor are somehow in parallel.  Is there a connection somehow between terminals 6 and 7?  This resistance reading that you've given also indicates that you've had this kit for a while ;)
10         2.4K ohms         1.2K ohms
This is the same as above.

 
It is a little curious that your resistances at 7 and 9 are OK, this would make me suspect that there isn't a wiring issue on the octal socket.  If you attempt to measure the 2.49K resistors themselves, what do they read?

That pesky solder joint on the headphone jack where the black wires meet is notorious for causing weird voltage and resistance issues, do be sure that all the wires there are soldered to the jack.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline fullheadofnothing

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Reply #2 on: August 30, 2018, 07:16:19 PM
The 0Ω on the RCA jack is usually caused by a solder blob or other conductive material bridging the center pin and the ground tab.

Joshua Harris

I Write the Manuals That Make The Whole World Sing
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Offline Ctoy15

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Reply #3 on: September 01, 2018, 09:41:49 AM
This resistance reading that you've given also indicates that you've had this kit for a while ;)

Haha I have not personally had this for that long, but I purchased it a while back from a Redditor who had not ever found the time to build it so he sold it to me for a really good deal. It is a Crack 1.0 from what I'm told.

This will happen if the resistor at the headphone jack and the 3K resistor are somehow in parallel.  Is there a connection somehow between terminals 6 and 7?
If you attempt to measure the 2.49K resistors themselves, what do they read?

I checked terminals 6 and 7 and did not see anything that would have caused a problem. You mentioned to measure the 2.49K resistors, so I did and they read 1.2K. From you saying the bit about them being in parallel, I looked around and found that the inbound Tip and Ring terminals on the headphone jack had a drip of solder connecting them, so I cleaned it up and the resistances now check out.

The 0Ω on the RCA jack is usually caused by a solder blob or other conductive material bridging the center pin and the ground tab.

There was a blob of solder that I needed to clean up, so I did and now it measures as it should.

Thanks again to both of you for the help! I just finished the resistance check and then moved on to the voltage checks and everything is as it should be so the only thing left to do is plug in my headphones and see how it sounds! I am very excited!

Chris Toy