Help: Ergodox Multimeter troubleshooting

[Diggity]

Hey all,

I tried my hand at sourcing my own Ergodox and it has been troublesome

The right hand side is working. However when I plug in the TRRS cable the entire keyboard dies (which suggests a short circuit).

I have replaced several parts, soldered, re-soldered and hunted all over the board to try to find the problem to no avail.
I have checked the continuity of the diodes across the board and they all check out.

Pictures here: (I cleaned it off for easier viewing) http://imgur.com/a/7Ha7h

I suspect at this point the problem is the TRRS connectors themselves, however I do not know how to confirm this with the multi-meter.

So general question: How can I utilize the multi-meter to find the problem beyond continuity checks?

Any help is greatly appreciated

[suicidal_orange]

I'm pretty sure you're not supposed to plug in the second half with it powered on as the TRRS temporarily shorts damaging something, did you?  If so have a read, that's all I know on the topic.  The other prime candidate that can't be verified from your pics is are you sure the IO expander chip isn't in backwards?  That wouldn't work well.

Also neither of your TRRS connectors connect to the middle holes, but I'm not sure they should as I see no gold - did you buy TRS ones instead, maybe because that's what you need?  If so are you using a TRRS cable?  Either way it might be missing a connection.

Other than that it looks like a very tidy build so I'll have to leave it to an Ergodox expert.  Problems in the matrix will just look like stuck keys, so no need to spend time checking them yet (though it sounds like you already did)

[Diggity]

I'm pretty sure you're not supposed to plug in the second half with it powered on as the TRRS temporarily shorts damaging something, did you?
 

I plugged the entire keyboard in (with cable connected) and plugged it in with the cable removed. I did not plug it in while it was powered.

are you sure the IO expander chip isn't in backwards?
 

Yea I checked it over and the IO expander is facing the proper direction (as labelled on the PCB)

Also neither of your TRRS connectors connect to the middle holes, but I'm not sure they should as I see no gold - did you buy TRS ones instead, maybe because that's what you need?  If so are you using a TRRS cable?  Either way it might be missing a connection.
 

I purchased the connector straight from digikey off the ergodox main site. (http://www.digikey.com/product-detail/en/SJ-43514/CP-43514-ND/368146)

Other than that it looks like a very tidy build so I'll have to leave it to an Ergodox expert. 
 

Thank you for the help anyhow

[OldDataHands]

Have you checked the voltage present when the keyboard goes dead?

I've had USB ports go wonky on my laptop where the keyboard (wireless mouse too)
would stop working on that particular port, but would work fine on another port.

Are you running it off of a non-powered hub, or perhaps an overtaxed hub?

Does it work on another system? Have you measured the current draw through
the KB during this state?

Checking for continuity, and lack of short circuits amongst the 4 signals on the TRRS
is all that you need in order to suss out whether or not it is the problem.

Not quite sure what's going on under the bottom of your USB connector where the
wires going to the teensy are soldered... Maybe those are tails of the wires that could
be trimmed to avoid possible shorts?

[Diggity]

Have you checked the voltage present when the keyboard goes dead?

How would I go about doing that?

Are you running it off of a non-powered hub, or perhaps an overtaxed hub?

I am not sure if the hubs are powered or not. Does it make a difference?

Does it work on another system?

On a mac laptop I have it gives me a message that its drawing too much power.

Checking for continuity, and lack of short circuits amongst the 4 signals on the TRRS
is all that you need in order to suss out whether or not it is the problem.

What should the proper continuity read out be from pin to pin?

Not quite sure what's going on under the bottom of your USB connector where the
wires going to the teensy are soldered... Maybe those are tails of the wires that could
be trimmed to avoid possible shorts?

I cut off the tails just be safe. Good recommendation. However it does not effect the end result.

[OldDataHands]

On a mac laptop I have it gives me a message that its drawing too much power.

This ought to mean that you have a short circuit power to ground on the left half somewhere,
or perhaps in the cable. Is it a 4 conductor cable? (TRRS v TRS i.e. Tip Ring Ring Shield = 4 conductor
while TRS = 3 conductor. They look very similar, but would cause severe trouble like this if
you used the wrong one.)

Checking for continuity, and lack of short circuits amongst the 4 signals on the TRRS
is all that you need in order to suss out whether or not it is the problem.

What should the proper continuity read out be from pin to pin?

Using the multimeter you should turn on the continuity beep mode, or just measure resistance.
You should  measure just the cable from end to end on each of the 4 conductors to make certain
that there is just a few ohms (say less that 5) through the cable on one conductor, and that from
conductor to conductor you always have much more than 100,000 Ohms.

Then do the same thing when the cable is connected to both halves.

[Diggity]

This ought to mean that you have a short circuit power to ground on the left half somewhere,
or perhaps in the cable. Is it a 4 conductor cable? (TRRS v TRS i.e. Tip Ring Ring Shield = 4 conductor
while TRS = 3 conductor. They look very similar, but would cause severe trouble like this if
you used the wrong one.)

I believe that this is the problem.... (TRS vs TRRS on the cable) Thank you