DE powersupply blowing 7amp fuses

Grbgemen

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I picked up a JP awhile back that had a few burnt connectors and cold solder joints.

After fixing the above, played a few games and it quit half way through the 5th game. Found one of the 7 amp SB fuses was blown. Replaced it and got a really loud buzz on power up. Checked other 7 amp and it was also blown. Replaced that and game booted but first 7 amp quickly blew and the other 7 amp got orange hot.

Next I unplugged all the connectors off the psu except the power coming in and tested the 3 test points at the top.

+5 was low around 4.5v
+12 unreg was around 13
-12 unreg was around 1.5

Now just as I pulled my head away to shut the machine off, a cap exploded(will have to check location). 1000uf 25v. Replaced it but still blowing 7 amp fuses.

Didnt really find a whole lot on DE powersupply repair.
 
F1 and F2, the 7 amp fuses, go right to the bridge rectifier. My first thought would be that it might be shorted. Do you have a DMM and can you check the rectifier?
 
Looks as if the bridge rectifier had a cold solder joint. Resoldered it and tested it.

With black lead on - leg, I should get .4 - .6 on each of the AC legs correct? Only getting correct voltage on one AC leg. Other leg is zero. Same with black lead on + leg. One AC leg in range while other is not.

This BR is a 35amp 200v right?
 
Looks as if the bridge rectifier had a cold solder joint. Resoldered it and tested it.

With black lead on - leg, I should get .4 - .6 on each of the AC legs correct? Only getting correct voltage on one AC leg. Other leg is zero. Same with black lead on + leg. One AC leg in range while other is not.

This BR is a 35amp 200v right?

you are correct, 3502, but you can use all the way up to a 3510, 1000v

a bridge rectifier is essentially 2 diodes back to back

so depending on the combination your using as test points, some will read .4 and one will read .8 to .9

i had a issue on my lw3 with the power supply, and turned out that a small cap and diode just below the heat sink were the culprits, if my memory serves me there are 4 10000uf 25v caps on that board as well
 
Would be okay to use a wire lead BR instead of a lug lead? Buddy in town had the wire lead version so I soldered it in just to see if that was the issue and it was.

Game boots fine now. No more blown fuses.

Should I order the lug lead version or will the wire lead be fine?
 
Good deal, glad you are back in business.

As for the bridge, if you did a good job of soldering and clipping the leads so nothing shorts, I'd say you are fine. Every time you heat up the pads to remove and reinstall a component you run the risk of messing things up. Not that it couldn't be fixed, the pads for the bridge are pretty easy to work around if they get lifted. Yeah, technically it isn't right, but why risk it if you have a good connection that is going to hold up just fine.
 
Good deal, glad you are back in business.

As for the bridge, if you did a good job of soldering and clipping the leads so nothing shorts, I'd say you are fine. Every time you heat up the pads to remove and reinstall a component you run the risk of messing things up. Not that it couldn't be fixed, the pads for the bridge are pretty easy to work around if they get lifted. Yeah, technically it isn't right, but why risk it if you have a good connection that is going to hold up just fine.

i agree, the only difference is the type of lead, if its working now and you got good clean joints , no worries!
 
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