97 GTX 787 MPEM diode

[miltonedens]

I have researched a bunch and admit i measure twice and cut once. I have seen pics and diagrams of a lot of machines but not a 97 GTX. I have sene all kinds of opinions where to find the diode. The one i want to believe most is holding the MPEM ,with the fuses to the top one inch to the right of the fuses. Now on my part #278-001-200--correct for my 97 GTX as best i can determine there is a round thing ( 1/4" dia x 1/2" long with an indented ring closest to fuse) right in that location--sort of too good to be true. Writing i can see says on it says (M) 105 C with 6(2) under it. looks like printing on some heat shrink as it appears to repeat. Is that the diode i am after?? I have also read it will be the first component from the 5 amp fuse. This item would be right in line with the 5 amp fuse but 1/2" clear separation between fuse holder and end of component. Before i start cutting i would like to know what i am after. Thanks

 

[LouDoo]

Can you post a picture?

Lou

 

[miltonedens]

I can if i can. never done that before on this site

 

[Robj]

How I did my repair was first remove it from the plastic case and remove the epoxy from the back and then dig out the epoxy from around the diode, unsolder it from the board and solder in the new one. It looks like the diode, but hard to tell from the picture. Once you access the back of the board check continuity od the diode. If you get it both ways it is the shorted diode.

 

[miltonedens]

The bottom fuse is the 5 amp and everything i can find says the diode is close to the 5 amp fuse. The round thing an inch to the right of the 5 amp fuse does not look like the picture of the component available on line. but the thing is in there somewhere

 

[miltonedens]

how did you remove from the plastic case i tried some but did not seem to be something that was going to happen very easy.

 

[miltonedens]

been working on removing the block of epoxy from the plastic case. cutting aroung the edges and i do not see it coming out. am i missing something here or a trick i do not know.

 

[Robj]

Use a heat gun on the epoxy, softens it right up and then pick it off in chunks. Set of dental tools comes in real handy.

 

[miltonedens]

i can see that working but getting the whole chunck out of the plastic case???

 

[Robj]

i can see that working but getting the whole chunck out of the plastic case???

I used the heat gun, warm up the case and it came out. You need to access the back of the circuit board to solder in the new diode.

 

[miltonedens]

thanks I saw a post that if the black wire to the 5 amp fuse was not a dead short the the mpem was good. my old one dead short my new one not so may be something to that theory. i know a bad diode will show a dead short but way to measure without digging has so far eluded me and a lot of others. I now think i have a bad ground from somewhere to somewhere. if anyone has had that problem and found a bad ground please let me know where it was.

 

[Robj]

How to check the diode is measure the continuity between the fuse socket and ground. A bad diode will cause a short to ground that is why tje fuse is blowing.

 

[miltonedens]

my fuse is not blowing. the machine will not recognize any key not my key or the dealers programmer key. And i realize you are correct. i went from the fuse to the black wire which is attached to the MPEM right at what i think is the diode. with that wire disconnected from the ski. there is another black with attached to the mpem maybe black and some other color. Both tests showed resistance--not dead short. But some of the other wires to the mpem were hooked up. all colored wires. I have an MPEM out of the machine. if i go from either black wire to the fuse socket i get dead short. So i guess i am confused. do i test the MPEM with some wires hooked up or pretty much out of the ski.

 

[LouDoo]

If the mpem is not blowing the 5amp fuse you have another problem other than the diode. I'm afraid you've got a bad mpem. The best thing for you to do is buy a good used mpem. Send a PM to minnetonka4me or 99spxxx and see if they have a good used one.

You're gonna spend all summer farting around with this thing, time you could spend on the water.

Lou

 

[miltonedens]

The diode is laying right beside the 5 amp fuse. I mean right against it. And perpendicular to the fuse holder. Now my problem. removing the diode the direction of current was scratched off the old one. Can someone tell me the direction to put the other one in. The round thing with brown shrink wrap is a capacitor. Stay away from it. My part number is same as yours.