Crown RC3020-30:
Sporadic PMT for FWD/REV

I have an RC3020-30 that will go forward and reverse but then randomly go out either direction and do the PMT before completely dropping out where you have to turn the key off and back on. Sometimes after turning the key off and then back on it will fix it and other times it won't. After sitting for the weekend not running at all, it was dead in the water this morning again. Finally after turning it off and on several times I was able to get it going. I changed out the third snubber from left and it started working for half a shift but then it is back to doing the same problem. Any advice would be greatly appreciated.
  • Posted 23 Aug 2022 03:45
  • Discussion started by tg0486
  • Missouri, United States
Showing items 16 - 28 of 28 results.
I know I came in late with advice and haven't spent any time in a manual. So I'm tossing out ideas. Things are starting to sound like a PMT driver issue. Testing drivers by the book is a little tricky and replacement was what we did due to having spares on hand. In a previous post, you mentioned disconnecting the card terminal strip got it reset one time. Not sure if that was a coincident or a clue.
I do seem to be shooting from the hip and it's been quite some time since fighting an EV1, Not very often does the driver fail intermittently. The card on the other hand, more intermittent. If you're savvy with the book troubleshooting, test the PMT driver.
  • Posted 24 Aug 2022 05:50
  • Reply by ErichO
  • Washington, United States
Even when it does the PMT and gives out but before I get it reset, voltage is correct and is half of the battery voltage. I checked voltage at the card, 1 Rec, and also changed out each snubber filter since i had a spare with no change.
  • Posted 24 Aug 2022 02:27
  • Reply by tg0486
  • Missouri, United States
When it will not reset, check the T2 voltage. Should be 50% of battery voltage. Locks out at 70% or higher.
  • Posted 24 Aug 2022 02:06
  • Reply by ErichO
  • Washington, United States
Let me know how things go....

There are other problems areas that will cause a weird PMT to occur.
  • Posted 24 Aug 2022 01:45
  • Reply by LaGrange
  • Missouri, United States
Strong in mind, Strong in Health.
Battery is fully charged. I also tested the capacitor and had a pretty strong spark from it so i'm guessing it is good.
  • Posted 23 Aug 2022 20:43
  • Reply by tg0486
  • Missouri, United States
You can test the Capacitor while the battery is charging.

Remove the console and remove the 2 wires that are connected to the Capacitor.

Next, use a short screwdriver and touch both posts at the same time, you will see a fairly strong blue spark 9f the Capacitor is good.

No spark means it's bad.
  • Posted 23 Aug 2022 07:09
  • Reply by LaGrange
  • Missouri, United States
Strong in mind, Strong in Health.
Once the battery is fully charged, we can start up again.
  • Posted 23 Aug 2022 07:05
  • Reply by LaGrange
  • Missouri, United States
Strong in mind, Strong in Health.
Yes it did
  • Posted 23 Aug 2022 05:23
  • Reply by tg0486
  • Missouri, United States
One thing I have found, when it does the PMT and it quits moving, when you turn the key off and back on it rarely fixes it and usually does a PMT again, but if i just unplug the wiring harness on the right side of the control card and plug it back in it will get it back going again for a period of time before it drops out again. I thought maybe it was a connection there but everything there seems tight and a good connection by my readings.
  • Posted 23 Aug 2022 05:22
  • Modified 23 Aug 2022 05:22 by poster
  • Reply by tg0486
  • Missouri, United States
Did the charger turn on and stay on ?
  • Posted 23 Aug 2022 05:21
  • Reply by LaGrange
  • Missouri, United States
Strong in mind, Strong in Health.
The battery shows about half charged so I will put it on the charger now and will make sure water levels are correct after fully charged.

I do have a new capacitor I could try.
  • Posted 23 Aug 2022 04:16
  • Reply by tg0486
  • Missouri, United States
Pull out the battery and check water levels for each cell.
  • Posted 23 Aug 2022 04:08
  • Reply by LaGrange
  • Missouri, United States
Strong in mind, Strong in Health.
Is the battery fully charged ? Test battery volts.

You might have a weak capacitor or a weak #1 rectifier.
  • Posted 23 Aug 2022 04:07
  • Reply by LaGrange
  • Missouri, United States
Strong in mind, Strong in Health.

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