WG K7000 blowing fuse

THE COUNT

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I recently got an untested WG 25" k71957.I hooked it up to test it and it immediately blew the chassis fuse. I've done several flybacks and cap kits and fixed soldering issues on K7000s, but this is my first one to blow a fuse. I checked out the sticky in this forum and went through Randy's flowchart as best as I'm capable of. This is what I've done/tested:

-replaced flyback with a fairly new/working flyback (old one was cracked badly)
-replaced the HOT with a working one (old one tested good I gave it a shot anyway)
-removed C36, C38 and C69 to test, they tested good
-unpluged degaussing connector
-tried chassis with another compatible tube (just in case)
-verified it isn't a cab issue by hooking another monitor up to it (j/i/c)

No luck, still blowing the fuse. All I get is a quick attempt to power up and then it blows I have a cap kit for this chassis but I'm assuming that won't have anything to do with issue? What's my next step? Please be somewhat specific about testing procedures for anything you post, since this is the farthest I've ever had to dig into a monitor chassis.
 
Replaced the B+ regulator? If so, did you use the correct type number?

You remembered to use a mica insulator and silicone heat sink grease on the horizontal output transistor? Same goes for the B+ regulator if replaced.
 
I will try that next, I have a working donor chassis here for parts to help diagnose this.

I do not have any heat sink grease, but I did make sure the insulator was there when reinstalling, and it was still pretty greasy. Is that good enough? If not, do Radioshacks or stores like Home Depot/Lowes carry this grease? Radio Shack is the closest thing to an electronics store near my neck-of-the-woods.
 
You may want to also make sure the bridge rectifier diodes are good....they can also cause the fuse to blow. Those diodes can be damaged by hooking up the monitor without an isolation transformer. Since you don't really know what any previous owners did to it, it certainly wouldn't hurt to rule it out. I believe they are diodes d1-d4.
 
Replace the B+ regulator only with the same type number as what is in yours now. There were 4 different ones used during the production run. If yours has a STR30130 then replace it with an STR30130.
 
Replace the B+ regulator only with the same type number as what is in yours now. There were 4 different ones used during the production run. If yours has a STR30130 then replace it with an STR30130.

I have one of the same p/n, it is STR30130.

I got to testing diodes and came up with this.

D1 - D4 test good

D20 & D21 test SHORTED

D19 & D22 test good

Will the shorted D21 & D22 cause the fuse to blow, according to the flowchart they will? Would the values for D1 & D22 on this 25" K7000 be the same as on a 19" K7000? If not can someone tell me what kind of diodes to buy to replace them?
 
O.k., I replaced D20 and D21 with ones from a working chassis, they are the same p/n. It still blows the fuse. Both diodes were testing shorted on the board, after removing them only D20 tested shorted, but I replaced them both anyway. Now D19-D22 all test good. While I was at it I threw in a cap kit as well. Whats next?
 
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VR has been replaced. HOT still tests good. I swapped C36 out with another and it still blows the fuse.

The C36 I have is the 2 legged blue cap that reads:

JL .00361
PDS1600v
9211

I removed and check it and it reads 5nF (.005uF). I tried the one from my working chassis and it read 4nF (.004uF) which is closer to is printed value. It still goes pop???
 
O.k., I replaced D20 and D21 with ones from a working chassis, they are the same p/n. It still blows the fuse. Both diodes were testing shorted on the board, after removing them only D20 tested shorted, but I replaced them both anyway. Now D19-D22 all test good. While I was at it I threw in a cap kit as well. Whats next?

If you give up, I'm not that far away if you want me to fix it...
 
Sometimes when those diodes blow, they also take out that big white vertical resistor there on the corner...
 
There's a diode that sits behind the yoke plug (sorry, I don't remember it's number....it's right beside the plug). This diode runs hot, and I've seen quite a few develope cold solder joints.....and/or short. Check it.

Edward
 
There's a diode that sits behind the yoke plug (sorry, I don't remember it's number....it's right beside the plug). This diode runs hot, and I've seen quite a few develope cold solder joints.....and/or short. Check it.

Edward

That is D18 and it tests good. Keep the ideas coming.
 
So like I had said before, this was my first monitor to ever pop a fuse. The chassis had a 2amp fast burn fuse in it when I got it. I initially started using 2amp slow burn fuses, which it also popped 4 of them durning testing/changing parts. Yesterday BEFORE I found D20 shorted, I had switched to fast burn fuses that I had on hand, since I ran out of slow burns. This morning I decided to go get 2 packs of 2 amp slow burns to replace the ones I robbed from other games. I decided "what the hell" and put one in the chassis. It has ran for about 15 min. and not blown the fuse so far *fingers crosses*

I know D20 was shorted, and the flyback was cracked pretty bad. I assume I fixed the problem with replacing them and just didn't know it because I was using the wrong fuse type. I'll post back after further testing.
 
O.k. I've ran this monitor for about an hour now while doing some pic. adjustments and it isn't blowing the fuse anymore. It has a bad blue drive pot on the neckboard I have to replace and needs all the pots replaced on the remote board (I've been using a donor for testing), but otherwise seems to be fine.

Thanks to everyone who posted for your help and advice. :)
 
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