Guitar Cable Tester

Stompboxes circuits published in magazines, books or on DIY electronics websites.
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Ripdivot
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Post by Ripdivot »

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.
Attachments
Guitar Cable Tester.bmp

mitchelr
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Post by mitchelr »

Is there a PCB layout for this cable tester

Axldeziak
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Post by Axldeziak »

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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Ichabod_Crane
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Post by Ichabod_Crane »

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).

mozz
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Post by mozz »

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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x-tn
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Post by x-tn »

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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Ichabod_Crane
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Post by Ichabod_Crane »

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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kusi
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Post by kusi »

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.

mozz
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Post by mozz »

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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