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MEP-805B - no power to the ADC100 Electric Actuator

Guyfang

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Now I am going to tell a story. In 1986, I inherited a shop with a gen set in the corner. Haven't run for two years. I had the guys replace a million parts that had been robbed off the thing and then started troubleshooting. Same problem as yours. No gov control. So no start. Naturly we changed the gov. Then the electric Actuater. Then the mag pickup, what you know as MPU. Nothing. Cranks, no start. We had our plate full with fielding Patriot, so I shoved it to the side. Every now and then we fooled with it. My boys started to change every part on the set. At last my boss gave up. "Change the engine, we need to get rid of that gen set". I didn't want to give up, but the commander is the boss. I had two troublemakers who could change an engine faster then lightning. Weren't worth two cents for anything else, but boy could they do engines. Before I could blink, the engine was hanging from the hoist. Everyone went to Linda's Jet to eat lunch, and I hung out at the shop. I walked over to look at the engine one last time. While doing that, I noticed that the mag pickup was still screwed into the engine. BUT, the end of the mag pickup was NOT showing through the bell housing. Upon closer inspection, I found a burr in the hole threads. So I screwed the mag pick up as far in as I could, and the burr kept it from being never enough to the ring gear to count the teeth. Felt like it was bottomed out, but wasn't. I cleaned up the hole, screwed the mag pickup out and had the boys put the engin back in. About had to horse wip them, as they all thought I was insane. But it started right up. So why am I boring you with this story? Well, I can not believe you bought a bad mag pickup. And a mag pickup has no moving parts. It simply works on an electrical Princeble of inductance. When the end of the mag pickup, (with its tiny magnet on the end) is near the ring gear and it turning, IT HAS TO do what it does, because that an electrical law. It can't do otherwise. So, if your new mag pickup will not produce AC voltage, and it indeed screwed in close enough to the ring gear, then something ELSE is the mater. Can only be a few things. One, is that the teeth on the ring gear is full of trash. Since the set has ate at least one mag pickup before, this could be the problem. Two, the ring gear is worn/or ground away? If the engine turns, this is highly unlikely. Or, something is preventing the mag pickup from being close enough. In and case, I might take a good flashlight and take a look see at the hole.
 

155mm

Chief and Indian
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Another description for the MPU is a tachometer for the computer. Yes we could enginerd some way to produce 2.5vac, but that would only tell the computer that the engine is cranking at 300rpm. then when the engine starts the MPU produces (pretend b/c I have never measured) 4.1vac at 1300rpm. Magnetic pickups work at exceptionally close tolerances because it senses very small changes in the voltage and adjusts as needed.

So we adjust it to 2.5vac but the computer really sees 2,500,000 microvolts (1V=1million uV) thats why the governor can maintain 60hz so well.

I know its so easy to throw your hands up and say stupid piece of junk and walk away, but there isnt anything that cant be repaired.

If I get some time today, I will pull my 805 up and throw it on the load tester. I will post the video of going from 0 load to 33Kw load, there is very minimal Hz droop due to the mpu compensating so quickly to the rpm drop. I would love to go more load but 33kw is max on my load tester.
 
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Guyfang

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Mesure how many ohm's you get on the mag pickup. In the meantime, I will look it up. I simply can not believe you bought a new one and it didn't work, and that you used a known good one, and got no joy from it. The problem does not lie in the mag pickup. If the mag pickup is in order, properly adjusted, then it can NOT fail to produce AC voltage.


Looked in the bible. Ohm's reading should be 800-1100 ohm's. This is the very first step you should have taken when you got no AC out of the mag pickup. And when you tried a known good one.
 
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GIJoeCzar

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Gentlemen, thanks very much for your replies! I did in fact test the original mpu for ohms and got no reading whatsoever. I'll test the new mpu tomorrow to determine if it produces any ohm reading.
 

GIJoeCzar

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Tested both again. Old MPU has zero ohms. New MPU has 180 ohms. My guess is that I have to find this specific MPU to produce the correct AC voltage? Manual calls for a MPU model number MSP675C ... there are MSP675s all over the web, but not MSP675Cs (msp675 has a much smaller diameter) ...

If either of you know where I can get a new or used MSP675C I'd certainly appreciate it.
 

155mm

Chief and Indian
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Take your mpu to Kenworth, tell them you need a speedometer sensor for an 03 kw w900 with an 18 speed, its exact including the plug
 

GIJoeCzar

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"speedometer sensor for an 03 kw w900 with an 18 speed, its exact including the plug" -- that's exactly what I did and they sold me the part number that I posted earlier ... plugs didn't match, so I've already changed that, so at this point the plug doesn't matter (I'm going to replug whatever I can find that works) ...
 

155mm

Chief and Indian
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"speedometer sensor for an 03 kw w900 with an 18 speed, its exact including the plug" -- that's exactly what I did and they sold me the part number that I posted earlier ... plugs didn't match, so I've already changed that, so at this point the plug doesn't matter (I'm going to replug whatever I can find that works) ...
I dont know why it would be different, unless KW did a substitute. The 2 that I got from KW were exact fits, and functioned correctly
 

GIJoeCzar

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Well, would you be willing to give me the exact part number of the two that you got from KW??? I did in fact just receive the what I thought was a good cross reference from Governors of America, but of course it was 5/8 when what I need is 3/4 (and of course the thread size is different.

Also, I spoke with Dave at Governors of America and he said that a "typical" MPU would put out about 140 Ohms at 78 degrees ... they do have one that 1,200 Ohms at 78 degrees, and that might be the one, but I have to check the thread size before I order another one (I'm now sitting on nearly $150 in three MPUs that don't fit:(

Having the exact part number that you got from KW would be extremely helpful.
 

155mm

Chief and Indian
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Q21-6005 is the sensor, there is an extension cable (you dont need now, you changed plug) p92-6972

Screenshot_40.png



That sounds like our KW here,oh here the computer says..... I want the olden days from 20 years ago when you had real parts guys that you walked in, and before you could get the part out of the rag, they were walking back to pick up the new one.
 
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