G07 driving me crazy

LyonsArcade

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I have a G07 that I got in unknown condition. It had a blown 901 fuse. I put the ultra super duper rebuild kit from Bob in it; a new flyback, a new hot, all new caps, two new fuses.

Powered up, looked great. So after a day, the monitor went dead. The 901 fuse was blown. So, I thought about it, and I hadn't put any thermal compound on the HOT. So I put a new hot in, with thermal compound and a new Mica Insulator.

Upon power up, it blows 901 again.

So, I thought maybe I've got a bad, new, flyback. So I checked the diodes in the rectifier area, everything's fine. I checked the voltage regulator, it tests fine and nothing's shorted out. The new hot is dead on shorted out everywhich way but sunday, both posts are shorted (I think the resistance was about 100 ohms) and the case is shorted to the ground 1 ohm resistance.

So, I removed the HOT and checked the large electrolytic caps at the back of the board that all this ties into, none are shorted. There's about 8k resistance across that bridge there (5 of them bridge two solder traces together).

I put a new HOT in with thermal grease this time, and after bolting everything in checked continuity. HOT checked good in circuit, nothing was shorted together, nothing was touching, all the insulators were installed, etc. I put a brand new flyback in, again.

Upon power up, the HOT and the fuse 901 send sparks all over the inside of the cab as they blow again!

Anybody have any idea what I'm missing here? Could it be the degauss ring?
 
Are you putting the mica insulator between the HOT and the frame?

Are you using the proper thermal compound? I think there was some mention a while back of a thermal compound that had silver in it...
 
I am putting the insulator between the frame and the hot like I said, yes.

The thermal compound has 10% silver in it. However, after I installed it, I checked continuity and there was none. If that was shorting it out, it'd be shorted out before I ever turned the switch on.
 
Well then, if you're blowing up the HOT and the fuse, it's possible you are wiring it up improperly, or something else connected to the hot circuit is messed up...
 
By popular Demand, and since Dokert's such a nice guy I have posted these following 4 blurry pictures. LOL

I don't think the pics will help, but maybe! A few comments: 1st, the chassis was working after I put a fly hot fuse caps in it... then the next day stopped. So if I had a cap backwards or something, I would think that would have prohibited it for working the first day.

Second, the 1st 'new' flyback that I took out of it, I put in another board, along with a hot, and a capkit, and a fuse, and got that chassis working, and it's now powering the game & tube that this was in and blowing it's fuse in (thrice!). So I think that eliminates cab or tube or yoke or degauss coil issues since i'm sitting here looking at another board working just fine in it.

I've looked over everything in that circuit and checked the power rectifier diodes with a diode checker, I can't find anything that doesn't look right. Also last time when I said that the two center posts on the hot were shorted, in circuit they always look shorted (I've since discovered) there's only about 1ohm resistance between the two posts in the circuit.

Here's the pics, it's just sitting here so if you see anything else I can take a blurry picture of let me know.
 

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Your Horizontal width coil looks sketchy at best. The large disc cap on the HOT in pic 2 looks like it is touching the frame. At a minimum I would heat up that big disc cap and move it closer to the end of the leg on the HOT.
 
I just checked, it's not touching just an optical illusion. The width coil is definately shot, but the game it was in the width was pretty much right where it needed to be so I never replaced it.
 
Well, besides the fact that G07's are well known not to work well around NES carts ;) , it looks like the HOT you have on there is a 2SD571.

attachment.php


If that is the case, then it appears you have the wrong HOT installed. It should be a 2SD870 (19") or 2SD869 (13").

The 2SD571 has:

Collector to emitter max peak voltage = 50

The 2SD870 has:

Collector to emitter peak voltage = 1500

That might have something to do with it...
 
BTW - the pic is blurry, so it might say 2SD871 instead. if so, then it's probably okay...
 
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