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Technical problem with MPM-AP-24

#31348

Technical problem with MPM-AP-24 | 11 November, 2004

We are having a problem with our AP-24x printer. When the vacuum motor spins up we get a 60 hz buzz into the DC drivers for the forcers and the stencle wiper. We also indicate a main power drop from 115 vac to 80 vac. The vacuum motor checks out good by our local motor rebuilder. During the troubble shooting of this electrical problem I ran across a perplexing aspect in the schematics. The main power relay made by Potter Blumfield #PRD-3DY0-24 is a DC coil driven relay. In the schematics this relay is energized by a AC supply. My question is how can a DC activated relay work with a AC supply. Can a AC replacement be substituted for this DC relay. Our configuration is useing 115 vac single phase. Referance AP20/24 referance manual section 6, power schematics, sheet 1 of 43.

Has anybody else experanced this problem. Can a shorted cap in driver supply be causing this problem.

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#31349

Technical problem with MPM-AP-24 | 11 November, 2004

Hello We have been working on the MPM's for over 11 years now. And we have never had any trouble with that circuit, just goes to show you. If you have one of the old, old manuals you will find a lot of errors. They corrected them as they went. We have some newer ones and plenty of replacement parts. Let us send you some and simply plug them in till the problem goes away. Don't waste a lot of energy and down time. Just ask and we will send you what ever you need. What MPM does is that they use 24vdc to hold the 110 vac on. No 24 vdc and the 110vac goes off. The relay is useing the 24vdc to hold the 110 turned on. Don't know if I stated it correctly but I tried.

harry

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#31350

Technical problem with MPM-AP-24 | 11 November, 2004

It's me again just to add. If Ken is looking in thanks for the good comment, on a previous thread. Nice to know that some people are saying nice things and we do appreciate it. harry

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Ken

#31353

Technical problem with MPM-AP-24 | 11 November, 2004

Relay: Yes, you can drive a "DC" relay with AC. As long as the latching threshold is achieved, you can close the contacts. However, if the relay impedence is improperly selected, relay chatter can occur. I am confident MPM selected a correct relay for this application. (reminds me of the time I did a UP3000 software upgrade. MPM Instructions: perform data backup using backup utility. Unfortunatly, the upgrade was to fix the backup utility!)

Is it possible there is an EMI filter missing?

Valueems: Hey, no problem on the kind words. Maybe someday I need a job (wink wink). At the rate EMS is receding domesticly....

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#31354

Technical problem with MPM-AP-24 | 11 November, 2004

Hello There is several items that could cause this problem. And ken don't ever try to upgrade any software unless you are real sure that you have every thing on the hard drive backed-up. MPM just loves to sell the 2D codes over and over. There is so many little tricks to MPM software that I could write a book, nobody would believe it thou. If you own a MPm alsways BACK UP THE HARDDRIVE!!! On this electrical problem-- there has to be something pulling the 110 down to 80v. Start disconnecting items one at a time. Harry

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#31365

Technical problem with MPM-AP-24 | 12 November, 2004

Thanks, That's the direction i'm headed. After by passing relay altogeather, testing large caps for the driver supply, replacing bridge rectifiers, and the MOV's, that's about all im left with. The vacuum motor will run with the software toggle without the machine having to be reset. I plan on opnening the 3 rectfiers in the lower control section one at a time. Although I cant reason what could be causing a voltage drop during load phase of this motor other than the motor it's self. Resistance at the main power relay from carboned and pitted contacts is still my best guess. This machine is 12 years old. Calculating 300 contacts closures per year times 12 years is only about 3,600 cycles. The main relay is rated at about 50,000 cycles. The wireing is 10 gauge on a short cord to a 30 amp circut but i am still going to check for corosion at terminal lugs in the plug. I will post a reply if i locate the problem for all you curious techs. On the down time reply on this thread I will add, that this machine is in production. The noise is only experanced when vac motor starts. Therefore all operators have been informed to disable vacuum function. The machine operates quite well without vacuum.

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KEN

#31366

Technical problem with MPM-AP-24 | 13 November, 2004

Motors are huge producers of EMI.

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