Please help diagnose a Legacy PowerMaster (6-37146) issue

Anyone?  Any ideas?

George

Assuming you have followed the troubleshooting tips on page 21 of the manual, I suspect there could be a failure.  Whether it's worth repairing, that would be a question for the repair folks.  I looked for a factory reset in the manual and didn't see one.

Is it possible it's not receiving a good signal?  Maybe try to relocate it?

Thanks for weighing in, Marty.  Unfortunately, all troubleshooting efforts yielded no change.

George

Does the Legacy PowerMaster have a programmable "stall" voltage like the PM-1 PowerMaster?  Is it possible it's set at the 16.7 volts?

I'm new to the Legacy experience but I know it calls out for a specific grounded plug to prevent problems. Any chance something is wrong there and it's causing the Powermaster to come to life?

That's all I got. What's inside a Powermaster? maybe contact is being made somewhere unexpectedly? I'm really grasping for straws here haha

If the Powermaster directly passes the full input voltage through to the output, it could be that both FET's have failed. They usually fail in a shorted open condition. Each FET controls half the voltage. If you open it up, the FET's are the 3-legged components attached to the massive aluminum heat sink. Replacements can be ordered at a reasonable cost. Installation is relatively straight forward with basic soldering skills. And when you are done fixing or replacing it, I would recommend attaching a TVS diode across the output terminals to give it some extra protection in the future.

@ADCX Rob posted:

Does the Legacy PowerMaster have a programmable "stall" voltage like the PM-1 PowerMaster?  Is it possible it's set at the 16.7 volts?

It's worth checking this - try setting the LPM in conventional mode, and see what the min and max voltage you can dial it to.

It's not quite clear from your post whether you have the LPM in conventional or command mode, and what the difference is between "the main layout power switch" being on and "the layout is turned on."

Does the LPM stay on when you press the e-stop key on the CAB-1?  

@ADCX Rob posted:

Does the Legacy PowerMaster have a programmable "stall" voltage like the PM-1 PowerMaster?  Is it possible it's set at the 16.7 volts?

Part of the troubleshooting procedure.

To me it sounds like the FETs are simi shorted closed. I’d mess around with the CMD-COV switch to see if that effects anything. I suppose it could be the driver but if it’s out of warranty trying a couple new FETs can’t hurt. Just need to pop it open to see what they used but they can be had for pretty cheep

OK, so originally the LPM was in Command mode.

I changed it to Conventional mode and hit Tr 7, Boost.  It showed 17.4.  I was able to use the CAB-1 remote to dial it up to 18.1.

Returning it to Command mode, the best I can get is 17.4.

And this tells us, what? 

George

Is the PowerHouse outputting 18v?  A low line voltage (e.g. 115 vs 120) can lower the low voltage value.

@MartyE posted:

Part of the troubleshooting procedure.

The troubleshooting section mentions nothing about the stall voltage, only the max voltage.

@Tracker John posted:

Is the PowerHouse outputting 18v?  A low line voltage (e.g. 115 vs 120) can lower the low voltage value.

In command mode, the LPM outputs a max of 17.4 VAC.

In conventional mode, I am able to spin the red dial on the CAB-1 and get 18.2 VAC.

George

George, in conventional mode can you dial it back to zero, or is it stuck at a minimum of 17.4?  If it's stuck at 17.4 then yeah, that can't be good.