Quality problems with parts

[RyanN]

Has anyone noticed that the quality of parts distributed this year are worse than previous years?

I haven't been able to spend much time with my team this year due to other obligations at college, but I have had a few strange phone calls that have to due with defective products.

1. The Digital Side Car was defective out of the box. The 6V LED was out and our PWM outputs were intermittent. As I said before, I'm not with my team so I can't see what failed inside the DSC. 6V shouldn't be used for anything except the power pin on the PWM outputs.

2. They purchased the AM-2678 Pneumatic Fittings Kit (http://www.andymark.com/product-p/am-2678.htm) and received some pneumatic tubing from AM, but when using the two products together, every fitting leaked. It wasn't an issue with the tubing not grabbing, but an issue with it just leaking. Apparently the robot was unable to build any pressure at all.

3. The second DSC may also be bad. With nothing connected, our DIO's are reading low, which is causing our compressor to run continuously. I think they're investigating that problem now. This could also be a defective ribbon cable, which was included with the KOP.

4. I've seen some other teams mention it, but our Y-PWM cables did not work. Motor controllers worked fine with just a straight PWM cable, but not with the Y-PWM. This was with Talons.

Not trying to cause a fight or anything, because we do have some great sponsors for FIRST, but I am concerned with what I've been hearing and seeing on these forums this year.

What is everyone elses opinion?

[Nirvash]

I haven't had a chance to use the fittings this year, but these fittings can be a little tricky to get a good connection, the cut needs to be nice and square to the tube and the tube not distorted.

Also, just out of curiosity, was the team sure that the DSC was receiving 12volts from the PDB? Those symptoms sound like it could have been a power issue.

[Joe Ross]

Like Nirvash said, issues 1, 3, and 4 are likely all related to not powering the Digital Sidecar correctly.

[RyanN]

Originally Posted by Joe Ross

Like Nirvash said, issues 1, 3, and 4 are likely all related to not powering the Digital Sidecar correctly.

So the 5V light was on, just not the 6V. Looking at the schematic, the 6V power should have nothing to do with anything but powering servos on the DSC. Since 5V was working, the PWM interface should have worked. To fix #1, they replaced the DSC. The defective DSC came straight from the anti-static bag to the robot.

The tubing cut might have been the issue, but we went back with some that we've had around since my time and they're working just fine.

#3 is still an issue. However, it appears to be more of a controls issue. When the robot is disabled, the input reads correctly in the Periodic Tasks, but when it goes to Teleop, the input just reads low. I haven't had much time to look at the underlying code for this year, but it doesn't appear to be anything the students are doing to cause the problem. In other words, the behavior is completely undefined and does not logically make any sense.

[Alan Anderson]

But was the BAT light on?

Seriously, everything you've described (excepting the pneumatic leaks) points to the Digital Sidecar not getting battery voltage to its power input. It'll get a tiny bit of leakage through the ribbon cable from the DIO module that makes things seem to work, but everything will quickly get flaky, especially if you have only a few motors defined or try to run more than a couple of them in reverse at the same time.