MPH1

OK, We have a 1987 version MPH1 that if the car runs for 13 seconds we get a DS10 that stops the car in flight returns to bottom landing opens the doors and takes itself out of service till a manual reset. A year ago we had the same problem and replaced the NSP (noise suppression board)and the problem went away. When it came back we changed the NSP board and again the problem went away but for only 2 weeks. We canged the board again and again the problem goes away but this time only for one week!The original prints do not have a designation for DS10 but are manuals show it as Oil Temp over/under. So we disconnected the thermostat. And we stll have the same problem. We have changed every board we can and also the power supply. We have also removed the valve coils so no movement of the car is possable and the car still times out at 13 seconds.We then kept the motor from starting and again at 13 seconds the car shuts down. This only happens between 1 and 2 because of the floor height. From 2 to 3 and 3 to 4 the car runs fine. We know that replacing the NSP board will cure the problem but they do not last long enough to be a practice solution. Any ideas we are fresh out?????

Check all your grounds?

I know it's not much, just throwing it out there.

Just throwing it out there...
Have you checked the low oil timer?

Seriously...

Does the status of the service tool say
"Whew. It's Hot!!"

If so, add more oil to the tank.

If you put in a motor that has a varistor temperature sensor, when the control is wired for bi-metallic, (or visa-versa), you will have problems. Change the pump motor lately? Check the motor thermal anyway.

Sorry I didnt cover all the things we tried. We have jumped the motor thermal and that is not the problem. We are heading back today (Its about an hour and a half from shop) To install another NSP board and I will send the old one to a repair shop where I can find out what they are fixing to see if we can back track the problem. We have been getting them from Adams for a core and I cant find out what they are fixing.

If R18 1K resistor on the NSP PCB is open will give a DS10 Temp condition because K55 (DS38) never turns on when 5 picks. But I thought it happened immediately. There's also a C18 cap that can short and take out that resistor. The 13 seconds and why the resistor is going bad is weird.

hey same as vic. go thru your earths(grounds) on your controller.it also sounds like a power supply issue maybe a suspect motherboard connection or solder connection.you could also be a wire from this that has a broken insulation on it.

You cant just jump the motor varistor. The thermal relay is looking for a certain resistance, but not a short

Does it have a TH relay? Usually up at the top left side of the controller?

We found the problem. We had an open resistor on the NSP board for 5 (starter picked input) so even though the car ran there must be a watch dog program that shuts the car down at 13 seconds if the 5 input is not seen. The only thing in this circute is the started coil so we are replacing it and adding noise suppression.

R18? I've seen the starter pickup and drop back out with that resistor open, which is why i said immediately in my prior post.

Great news, Dan!

hey, e-man, I have 2 different mph1 prints one that shows the k55 input with a r18 resistor in front, and one that shows no resistor. Is this noise suppression circuitry something that was added on in the field, or was it added to newer mph1 controllers in the factory, or maybe both. have looked at a lot of these controllers, and never caught that small difference in the prints. good post to learn from.

The job prints we have didnt show any of the NSP connection so my guys couldnt tell where things went. So when we got prints that showed NSP connections we were better off. E-man shindler has changer that resistor from 1K ohm to a 10 ohm???? Also why it is opening stays a mystery. We disconnected the starter coil so everthing was passing thru the resistor and it didnt even get warm???? We replaced the coil and added surge protection but time will tell 1 week or 1 year who knows. When Adams tec support finally answered they said the same resistor had been opening when Otis had the job. They are checking to see how many of the 75 boards they sold last year had the same problem...

NSP PCBs were on the earlier MPHIs. If you look on a later version MPHI that just has the 2 PCBs (MPH and HR2), you'll see those resistors/capacitors incorporated in the HR2 PCB under the relays and the HR2 PCB is a little taller. I have both styles on my route. I've had that same resistor open (on different cars older and newer versions) about 3-4 times in the last 12 years. I bought a pack of them from Radio Shack and keep them in the truck.

Not sure about the 10ohm, I'll have to check. Is there any evidence of frequent releveling?

no holds solid no relevels and the hi low oil thermostat was disconnected and a tank heater added. Like I said this is a hour and a half out of town and a OG account so we only get a call when she is down or to do yearly inspection. Building mantenance man is over your shoulder every minute. So we have to send him for something important to get anything done! I also got a 10 pack of resistors from radio shack stached in the macineroon.