Warning: DB37 repair unreliable

[de_]

Having done the repair, swapped 2 digital sidecars that had erratic behavior, swapped to a previous year cable (which the DS's worked fine), inspected and re pressed the repair which then failed a pin by pin continuity test, re- did the repair again with an experienced mentor which again failed the test, we believe the posted repair instructions lead to unreliable repairs and potential huge frustrations and or loss of matches, especially for teams without strong mentor support. The problem is the center of the plastic connector bends in the vice as the steel hood bends leading to insufficient pressure on the center to properly penetrate the ribbon cable.

My recommendations are
- find someone who has the proper tool if possible
- UPDATE: as mentioned in a below post, do the fix on the FEMALE end, not the MALE end as per in the instructions. The female end does not have the metal hood to bend. Or do it with the female and male as a unit.
- do a continuity test of all 37 pins no matter what
- if you have a choice, use a previous years cable or a new cable (see Andy Mark or see item 390387142016 on Ebay) if possible no matter what the continuity test says (a weak connection could become intermittent with vibration).
- we ended up putting a piece of thin plywood (or metal) along the full length of the connector between the 2 rows of male pins as a support beam and used the vice against the support beam. There was no bending of the plastic body and so there was consistent penetration of the cable insulation across all 37 pins and immediately all pins passed the continuity test.

[Kevin Sevcik]

Was your piece of metal between the pins on the DB37 connector, or the pins on the IDC side of the connector?

If it was on the DB37 side of the connector, then a female crimp DB-37 housing like this or this would work even better. You could probably find one at your local fancy electronic components store, or just order from Mouser above. I think I'll be getting one to help with repair at the regionals I attend.

Also, it seems a mite riskier, but you could use the female side of the cable you're repairing to act as the support as well. Plug the female side into the male side, line up the red stripe with the opposite red stripe, and squish in a vise.

[Mr. Lim]

A few additional tricks:

1) Repair the female end of the cable instead of the male. The female end holds up to being crushed in a vise much better. The male end is likely to just have the shield and pins collapse before you apply enough pressure to properly close the connector.

2) If you MUST repair the male end, plug the female end into the male end, and squeeze BOTH connectors in a vice at the same time.

3) Make 100% sure that the ribbon cable is lined up and perpendicular to the connector. If not, the pins won't connect to the right wires.

4) Cut the ribbon with a good sharp pair of scissors or shears. A dull or low-quality knife will pull the copper conductors out of the insulation, and possibly cause shorts.

These cables are tricky little buggers to get going, but once you do, they are great!

[Joe Ross]

It doesn't just happen on repaired cables. We had a pre-made DB37 cable that was not fully crimped. It took us half an hour to figure out why PWM 3 wasn't working, but everything else was. A minute in the vice and everything was working again.

[de_]

The FIRST repair doc example shows the fix on the male end for some reason so thats what the student did (actually a junior mentor). At that point, we were stuck fixing the male end. You are quite right if we had fixed the female end, it probably would have worked as there is no metal hood to buckle (spread apart) under vice pressure. Good idea re doing the repair using a pair of connectors.

Just another hair pulling FIRST adventure a day or two before bagging

[Ether]

Originally Posted by de_

The FIRST repair doc example shows the fix on the male end for some reason

I think it's because that's the end which was installed incorrectly.

You can do the female end instead, and it will work fine, but the marking on the wire won't be correct (if you care).

[Alan Anderson]

Originally Posted by Kevin Sevcik

Also, it seems a mite riskier, but you could use the female side of the cable you're repairing to act as the support as well. Plug the female side into the male side, line up the red stripe with the opposite red stripe, and squish in a vise.

That's exactly what I did. I also used a couple of thin strips of wood between the vise and the connector to try to avoid damaging the plastic.

[SuperBK]

Tricky for sure. I can't count how many bad or backwards ribbon cables I have seen over the years. But, we have several old round DB37 cables so I figured we could always go back to one of those.

Thanks for the heads up, I'll get some students to take it off and check each pin.

[wireties]

These things are tricky to tear apart and re-assemble. If you were unsuccessful, don't take it too hard. Strictly speaking, they are not made to be taken apart. In a professional setting, one would never re-use a ribbon cable "repaired" in such a manner.

If teams can afford it, I recommend buying connectors and making a new cable of optimum length. Or buy a manufactured cable.

HTH

[Bruce Meyer]

we used monoprice.com to get a couple of DB37 molded cables that have been used in the past - around $5. Some are out of stock, but for another $2 -$3 you can get gender changers.

http://www.monoprice.com/products/se...d=db37&x=0&y=0