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MEP-805A voltage issues

Guyfang

Guyfang

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No relay controls the coolant temp gauge. Can you read schematics? There is a wire direct from MT6 to M6. It passes through a plug and TB, but no relay.
 
jmenende

jmenende

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Guyfang said:
First off, did you test the fuse?
If so and its good, then when you hold S1 in the start position, On the A1 volt regulator, pins 7&8, you should get about 65-68 VAC, if the exciter is good and the A1 senses AC at the main gen. The 68 VAC comes through that fuse. So we need to know if the fuse is good, and if so, try and start the set. Hold the S1 in the start position. Also know, to get this set to work right, you have to hold the S1 up longer then what you are used to. So hold it up 6-8 seconds at least.
Click to expand...
Hi Guy, I have the same undervoltage problem with my 805a. The voltage drops once I release S1 even after 10 seconds. I have a libby AVR and changed the capacitor for good measure but Im only getting 60VAC on pins 7&8. The hertz show low but when tested its adjustable to 60hz and speeds up the engine. The rheostat shows no effect when turning the dial. Mi model is older and does not have the upgraded external fuse. any ideas as to why im not getting 65-68 VAC ? Thanks.
 
Guyfang

Guyfang

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Is this gen set new to you?
Have you ever seen it run right?
Do you have the TM's downloaded for this gen set?

I would advise doing the Quad fuse improvement, ASAP.
Have you worked on this set? Or someone else?
You say its a Libby A1. Have you looked to see if all the other components of the volt regulation system are Libby parts? The attachment is a list of parts to check.
 

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jmenende

jmenende

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Guyfang said:
Is this gen set new to you?
Have you ever seen it run right?
Do you have the TM's downloaded for this gen set?

I would advise doing the Quad fuse improvement, ASAP.
Have you worked on this set? Or someone else?
You say its a Libby A1. Have you looked to see if all the other components of the volt regulation system are Libby parts? The attachment is a list of parts to check.
Click to expand...
Will check each part. I learned about this mix and match the hard way. I have two 805a, one libby and the other trc. I put the TRC avr on the libby and the avr started smoking. Yikes. 🤪
 
jmenende

jmenende

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Location
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Guyfang said:
Is this gen set new to you?
Have you ever seen it run right?
Do you have the TM's downloaded for this gen set?

I would advise doing the Quad fuse improvement, ASAP.
Have you worked on this set? Or someone else?
You say its a Libby A1. Have you looked to see if all the other components of the volt regulation system are Libby parts? The attachment is a list of parts to check.
Click to expand...
I cant find R16 in my 805a control box. Can you point me in the right direction please. The manual has no mention when I search for it.
 
Guyfang

Guyfang

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jmenende said:
All my libby parts match exept r16 which i could not find. These are the test results. I think i have en exitor problem.
Click to expand...
The T1 wire on the reconnection board, (TB1). TB1 is located inside the right rear top door. There are about a million wires hooked to it.

I dont think its a excitor problem. The main gen makes power. Just not enough.
 
jmenende

jmenende

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Guyfang said:
The T1 wire on the reconnection board, (TB1). TB1 is located inside the right rear top door. There are about a million wires hooked to it.

I dont think its a excitor problem. The main gen makes power. Just not enough.
Click to expand...
I agree, tested the exitor leads and got a 28.2 reading. Close enough to the 3 ohms.
 
Guyfang

Guyfang

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There is probably a Diode function on you multimeter. Its more or less like checking ohms. What you want to see is continuity in one direction, and none in the other.
 
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