Guitar Cable Tester

Stompboxes circuits published in magazines, books or on DIY electronics websites.

Guitar Cable Tester

Postby Ripdivot » 27 Oct 2016, 20:34

I recently purchased a programmable looper for my pedal board. This means I had to assemble about 22 patch cables and I wanted to make sure they all worked properly before I installed them. I decided to build a cable tester for the fun of it. This tester can capture very quick open and short circuits in the cable. It is very easy to build. All you need is a plastic enclosure (you can you a metal enclosure but you will need isolated jacks), a couple TRS jacks 1/4", a 9 volt battery and a very easy to build circuit. The tester turns on when you insert a plug into J1 (just like a pedal). The operation of the tester is on the schematic. I hope this is a useful tool for some of you. This tester is for 1/4" unbalanced mono jacks only as I wanted it to be very simple. You can test other unbalanced cables with adapters.
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287m (28 Oct 2016, 15:40), Axldeziak (07 Oct 2019, 19:54), blackbunny (Yesterday, 02:09), deltafred (28 Oct 2016, 09:06), karul (07 Oct 2019, 10:54), Manfred (27 Oct 2016, 23:23), mitchelr (07 Oct 2019, 10:16), modman (07 Oct 2019, 10:34), mozz (18 Oct 2019, 16:10), swt (03 Nov 2016, 22:05)
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Re: Guitar Cable Tester

Postby mitchelr » 07 Oct 2019, 10:15

Is there a PCB layout for this cable tester
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Re: Guitar Cable Tester

Postby Axldeziak » 07 Oct 2019, 19:53

mitchelr wrote:Is there a PCB layout for this cable tester


Not a PCB but I just made a layout of it.
Image

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Re: Guitar Cable Tester

Postby Ichabod_Crane » 08 Oct 2019, 07:48

Is this layout verified?

It's a nice tool, but I'm wondering if it worths, especially a circuit like this. I mean, it's enough to check the continuity of the cable signal/ground, right?
There are a pair of very simple layouts here: https://tagboardeffects.blogspot.com/20 ... ester.html But I'm not sure those are verified, though very simple.
(Anyway, the idea to build one of this is welcome).
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Re: Guitar Cable Tester

Postby mozz » 18 Oct 2019, 16:09

Just ran into a bad cable last week. Talent wire from parts express. I make my own as needed out of the 100ft spool I bought from them. I've seen better quality and I've seen worse. Modded and temperamental fuzz pedal was making crackling noises as I was trying more mods. Narrowed it down to the 4 ft jumper to the bench amp.

Wierd thing , it was measuring 62k between conductor and shield. Figured the battery in my Fluke was going before the low batt icon comes on. That happens with other meters too, you get odd readings before you get the warning. Batt was fine. Totally other meter gives me the same reading.

So I cut off both ends, resoldered, 1 ft less than before, still getting leakage resistance on cable. Running my hand and squeezing the cable made the resistance change but would not open or short. Very odd failure and hope all the other jumpers I made don't end up having similar problems down the road. Mogami bulk cable next time.
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Re: Guitar Cable Tester

Postby x-tn » 18 Oct 2019, 22:57

mozz wrote:Talent wire from parts express.
...
Wierd thing , it was measuring 62k between conductor and shield.
...
So I cut off both ends, resoldered, 1 ft less than before, still getting leakage resistance on cable. Running my hand and squeezing the cable made the resistance change but would not open or short.

Talent cable says "A conductive PE layer bonded to the dielectric along with a bare copper braid provides excellent protection from electronic interference."
http://www.talentaudio.com/products/cab ... 00-ft.html
Did you know about it and strip that layer?

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Re: Guitar Cable Tester

Postby Ichabod_Crane » 19 Oct 2019, 07:57

mozz wrote:Just ran into a bad cable last week. Talent wire from parts express. I make my own as needed out of the 100ft spool I bought from them. I've seen better quality and I've seen worse. Modded and temperamental fuzz pedal was making crackling noises as I was trying more mods. Narrowed it down to the 4 ft jumper to the bench amp.

Wierd thing , it was measuring 62k between conductor and shield. Figured the battery in my Fluke was going before the low batt icon comes on. That happens with other meters too, you get odd readings before you get the warning. Batt was fine. Totally other meter gives me the same reading.

So I cut off both ends, resoldered, 1 ft less than before, still getting leakage resistance on cable. Running my hand and squeezing the cable made the resistance change but would not open or short. Very odd failure and hope all the other jumpers I made don't end up having similar problems down the road. Mogami bulk cable next time.


It's happend the same to me. I found tha handmade patch cable of a friend made sound the pedal chain muddy and quite. In this cable were between tip and shield just 40 Ohm. I tried to solder it again, but it wasn't it the problem. I open the other jack, it looked ok. I measured resistance bewtween tip and shield again it was perfect. Then I noticed this oddity every time I close (twisting or tightening, depends from the jack) the body of the jack. Sometime there were contact, sometime the resistance were very high 40M-20M or lower, 1M, 300k, and often oscillating. After several minutes to work in these cable I try it on pedalboard, but the sound I can hear was clear and really good.

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Re: Guitar Cable Tester

Postby kusi » 19 Oct 2019, 09:49

x-tn wrote:
mozz wrote:Talent wire from parts express.
...
Wierd thing , it was measuring 62k between conductor and shield.
...
So I cut off both ends, resoldered, 1 ft less than before, still getting leakage resistance on cable. Running my hand and squeezing the cable made the resistance change but would not open or short.

Talent cable says "A conductive PE layer bonded to the dielectric along with a bare copper braid provides excellent protection from electronic interference."
http://www.talentaudio.com/products/cab ... 00-ft.html
Did you know about it and strip that layer?


1+ for that, make sure to cut this layer!
i run into the same problems with other cables, after removing a couple mm of this layer, all problems were gone.

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Re: Guitar Cable Tester

Postby mozz » Yesterday, 13:28

No, I didn't know there was any other layer. New cable made out of the same roll tests fine. I'll have to retest the old piece. Time to get the magnifying glass out. This is what happens when you're out of the field for 30 years. I think I only made a few pedal jumpers out of this cable, will have to check them too.
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