G07 chassis..not recapped...can you identify the problem?

Smart Bomb

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G07 chassis..not recapped...can you identify the problem?

11 second vid attached

I have a ton of G07's I am randomly trouble shooting and now I am focusing on this one. I installed it into my Dig Dug which, lately, seems to be the guinea pig for G07 testing..

I have not recapped this chassis yet (I do plan on it) and the b+ is zeroed in at 120.3

I have messed with all of the pots and the image you see is the best i can get out of it.

So im just wondering if anyone can identify off hand what may be the cause of what you see in the vid.

https://www.youtube.com/watch?v=tI_SCmW75cE&feature=youtu.be
 
i would check the vertical transistors but personally i wouldn't even start diagnosing this before doing a cap kit and reflow.
 
i would check the vertical transistors but personally i wouldn't even start diagnosing this before doing a cap kit and reflow.

i know..it was more of an exercise...im just trying to learn more things about chassis repair and wanted to post a raw chassis with all original parts and see what others had to suggest....i absolutely plan on doing a recap.
 
i know..it was more of an exercise...im just trying to learn more things about chassis repair and wanted to post a raw chassis with all original parts and see what others had to suggest....i absolutely plan on doing a recap.


i understand but when your dealing with a 35+ year old monitor with original caps no tech should ever start in the middle and should always start at the beginning otherwise you end up chasing your tail in circles. if your working on a different model and brand of monitor you may not start with caps but on a G07 with original caps YES start at the beginning and cap it and then diagnose any problems if they are still there. to properly learn you also need to have a process you follow that makes sense for each model/brand of monitor otherwise all your doing is random guessing.

IF you want to see what exact component that caused the problem then pull caps one at a time measure the capacitance and esr rating on all of them, but remember the cause could be multiple caps so unless your going to retest after replacing each individual cap you still won't know which exact cap or caps were the culprit.
 
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That looks like you have lost vertical sync. Especially since the vertical hold won't lock it in.

Reflow the solder on the 3 pin and 6 pin video input headers and install a cap kit first and see what that does. Then test X306 and R317. Replace IC501 as a last resort.

You also may want to invest in a TPG if you are going to work on monitors.
 
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oh boy!!...so I removed all of the caps to test and also to prepare for a future cap kit....there were a lot of wrong caps all over this thing....wow...my first time encountering something like this...what were they thinking??!!...i will list the ones that were not to spec:

C107 calls for a 10uf250v....installed was a 10uf350v..I know u can go higher on the v but i just listed this one to show a difference than what is spec.

now it gets good...

C504 calls for a 1uf50v....installed was a 4.7uf50v

C403 calls for a 100uf25v..installed was a 100uf16v

C701 calls for a 100uf25v...installed was a 100uf6.3v

C517 calls for a 100uf25v...installed was a 220uf50v

C302 calls for a 220uf25v..installed was a 220uf16v

C518 calls for a 220uf25v..installed was a 100uf50v

C506 calls for a 33uf25v..installed was a 33uf16v

I am surprised i even got a screen to be honest with all the out of spec caps installed...

I hope these wrong caps didn't ruin something else on the board.
 
yup, i would not even looked at it on a tube without a cap kit.

i know the cap kit get preached a lot, but this is a good example of why.
you never know what the status of a chassis or one of it's most important consumable parts that cause problems are.

what is your result after the kit?

Peace
Buffett
 
All of those caps are either factory issued , or within spec (the 4.7 even works in place of the 1uf). Those cap values and voltage ratings are not the problem.
 
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yup, i would not even looked at it on a tube without a cap kit.

i know the cap kit get preached a lot, but this is a good example of why.
you never know what the status of a chassis or one of it's most important consumable parts that cause problems are.

what is your result after the kit?

Peace
Buffett

No cap kit yet..need to order it...actually i need to order about 8 cap kits..i have a ton of g07's to refurbish..5 stand alone chassis and three for my games....im only current addressing 3 as u may have seen from my threads this week...im on a week vacation from work...im trying to diagnose these three while on vacation..i put them off for a year.
 
I got this one working!!!....i have tons of spare caps left over for various recaps from the last 2 yrs..TONS!!!...this morning i went thru A LOT of caps testing them ....ditched the bad ones.....when i was done i went and installed the correct caps in the list i made earlier in this thread.....threw that sucker in the guinea pig dig dug arcade and tada!!..perfectly good board now! That means I just may get pole position up and running by this evening...I want to do it now but i have to go visit parents for xmas.....but when i return this evening im going to work right on the PP....the board works and i did do the 5volt mod...i just need to install all of the boards.....i put it all together and hopefully i will have another game to add to my arcade.
 
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