P&H v1.1b Q1 is grounding all injectors to MS case

[jsdevel]

Hi Jean,

My injectors stopped working, so I put my MS2 on the JimStim to troubleshoot. I noticed that all of the injector grounds were grounding to my MS case. On a hunch I disconnected Q1 from my MS case and the injector grounds are no longer grounding at the case. What would cause this to happen? Does it look like I have them installed properly?

IMG_20170726_230906.jpg (1.77 MiB) Viewed 1247 times

[rickb794]

Have you resolved your problems?

Did the problem appear on all 4 injection channels?

See http://forum.jbperf.com/viewtopic.php?f=4&t=1652 jean's reply at the bottom?

And

http://forum.jbperf.com/viewtopic.php?f=4&t=1636

[jsdevel]

Have you resolved your problems?

Not yet.

Did the problem appear on all 4 injection channels?

Yes. All 4 are grounded and aren't working.

I'll checkout the links. Thanks!

[jsdevel]

Also, I have tested without the driver board using LEDs on a bread board, and I'm getting proper 5v signals on each injector. So basically, none of them are working through the board.

I did make the mistake of grinding off part of the screw attached to the heat sink with a dremmel. Is it possible I fried the TIP42C via static electricity? My Zener appears to be working properly.

[jsdevel]

I ruled out Q1 as an issue. I really wish Jean were around. I could use the schematic.

[jsdevel]

I figured it out! Turns out that all the TIP121's were fried. Ordered some compatible TIP122's from DigiKey and BOOM!

I was able to rule them as the issue when I had voltage at the base when testing the LM1949n's.

The lm1949n datasheet was extremely helpful.