How Do You Fix Broken Ports For v5?


#1

We, team 8931J, have now had two ports die within the last month. The first we thought was an accident. Since the second one died just this week I decided to look on here for any help. The ports that have died have died being connected to a wire that is about three to four feet long, we made it. In these ports, the brain recognizes that the motor is there but it is not moving the claw. We are making a desperate move, we are changing our arms so that they do not need such a long cord. As for the weather, it is not very good at the moment. We also have had little no static this year, unlike my other two years of robotics, Starstruck and In The Zone. However, we just found that we damaged the wire in the slightest, with a dremal accident. We thought that we had only taken off the black outside covering, we actually took off a little of the inside wire coverings and some of the copper wire is exposed. We now do not know if we were short-circuiting the wire or if it is the same problem you are all having. I can say this, the part that was damaged was not touching the metal at any point, we also used electric tape to cover the now exposed wires, and it still does not work.

Now, another team in our club has had the exact opposite problem as us. They have had to switch all of their wires to custom length because some of the vex given wires have burned out their ports. I do believe that they burned out only one port before they decided to switch to all custom length wires. I have not heard of them having any more problems with ports. This team is also a senior team so it was not a rookie mistake as far as I know.


#2

Investigation of V5 issues is ongoing, both by a nonzero number of community members and, almost certainly, VEX too.

As far as I know, there is currently no known fix for the seemingly common scenario of death of Brain ports. You just need to contact VEX and get a replacement Brain.


#3

Thanks, however since we operate in a club do you think they would send 4 new ones for the brains that have ports that are messed up.


#4

Who should I contact? Address and addressee? How can I do this?


#5

All the contact information can be found on vexrobotics.com. If I remember correctly the email you are looking for is sales@vex.com


#6

You’re better off just calling. Their email response time is pretty slow relatively.


#7

@Cavelero as everybody else said above, there is no easy fix for dead ports and the easiest option is to send V5 brain back to VEX for replacement.

However, I couldn’t miss this chance to answer your question as if that wasn’t an option. Anecdotal evidence is that RS-485 driver chips (SN65HVD1782) are burning out since they don’t have enough ESD protection. There is one driver chip per each motor port.

https://vexforum.com/index.php/attachment/5c04c45609a19_v5brain-internal-power-distribution-RS-485-driver.jpg

These ICs come in SOIC-8 package (~5x5 mm in size) and cost about $4.30 (or $2 for volume buyers). SOIC-8 is not impossible to replace in home and school lab with a good temperature controlled soldering iron and hot air gun, but requires a lot of skill.

If there are multiple dead ports the easier option would be to replace entire power distribution PCB, which is likely what VEX is going to do to refurbish all the V5 brains that are sent back.


#8

It’s really disappointing that they didn’t do a better job with ESD protection, especially since this was a problem with Cortex.


#9

also surprised that protection wasn’t added after reports of weak ESD protection were reported during beta (so I hear)


#10

The production release of V5 was too soon after the beta period to reasonably make any hardware changes, whether or not VEX wanted to make any changes.


#11

SN65HVD1782 There are many specific models, such as:SN65HVD1782DR SN65HVD1782D SN65HVD1782DG4 …What’s the difference between them? Which model should I buy?


#12

As far as I know, additional letters after the IC part # refer to the packaging options. Both the physical package (SOIC, PDIP, etc…) and how it is shipped (tube, tape, reel, …)

For example, at the Mouser there are several options for SN65HVD1782 with one being PDIP-8 and rest SOIC-8 in various packaging options, with some of them only shipping in quantities of multiple thousands.

You could get any SOIC-8 variant if you have someone with experience doing soldering on surface mounted components. However, this will void the warranty and make V5 brain non competition legal. If you have no other options, except doing repairs yourself, you may just as well add a couple of TVS diodes between the ground and each data line. I found a really good deal on SMBJ43CA here.


#13

=

I don’t know anything about electronic circuits. I’ve broken 11 ports. Official maintenance is too long. I can’t wait.