k4900 issue.

a_wookie

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i went to recap a monitor today in a ms. pac man. I told the owner it was likely a electrohome g07, because thats what come in one originally, but check anyway and let me know.

he emails me back and says "ya this ms pac has a go7 and is a all original machine "


so i take all my tools and parts to his home, a good distance, get the monitor out and notice it is a wells gardner 4906.... just so happens i did have that kit stocked in my parts.


i explain to him the sitch and show him the model number. At this point i replace all the caps, fire it back up and i get nothing. i adjusted the the screen/ brightness adjustment on the flyback a little and could see the thin horizontal red line getting bighter.

at this point i thought must be the hot is bad now, i am 99.9995 percent sure i put the capps in correctly. so i reached up and touched the outside of the hot caseing to see if it was excessively warm and it shocked me pretty good.

i told my customer a had hots, resistors and fuses etcetra for a go7 not a wells.
i of course only charged him for the parts and gas charge, so basically i made no money and put miles on my car for nothing.

so my question is can new caps make the hot go out like that ?????
 
I seem to remember reading somewhere. if the B+ caps got weak at times the OP would just crank up the voltage to compensate, now if you replaced all of the caps with new ones, that Voltage may have been out of spec and popped the HOT.
But that is just a guess.

I personally have never had a HOT pop from doing a cap kit.
They were usually already out when I got the monitors.
 
Did you meter the HOT to see if it was shorted?

And, I don't think that it was shorted, unless the fuse popped.

IIRC the 4900 uses a 2SD870, like the G07.
 
I'm going to give you some advice, and don't take this the wrong way. I'm trying to help you.

sevvvvvvvvvvvveral red flags goin' on here.

1. BIG pain in the ass to work on people's stuff in their home. the reason is because of what you ran into. Problems,... don't have the correct parts, have to make several trips, etc. It's very hard to make money doing that unless you're really good and have a ton of parts.

2. It's also kind of risky to be doing repairs to monitors when you're kind of a novice at it. That's not an insult. I'm not really good at them either, but I'm farther along than you are, just becuase I've rebuilt hundreds and hundreds of them. I'm just saying if you tell somebody you can fix it, then can't... that's going to work out bad.

3. Monitors can be troubleshot (I like that word!) by systematically removing sections of the monitor from the equation. the HOT has nothing to do with your problem. If the HOT goes bad in a monitor, the fuse blows because the only thing seperating the B+ from ground is the diode inside the HOT. If the HOT blows, it shorts B+ to ground and blows the fuse. So if you're getting anything at all on the screen, you know that the HOT is fine.

Another thing: Ms. Pac machines came with all kinds of diferent monitors in them. The manual has schematics, inside it, for a G07, K4600, and K4900, it could have had any from the factory and anything else swapped into it.

Good luck with it.
 
I'm going to give you some advice, and don't take this the wrong way. I'm trying to help you.

sevvvvvvvvvvvveral red flags goin' on here.

1. BIG pain in the ass to work on people's stuff in their home. the reason is because of what you ran into. Problems,... don't have the correct parts, have to make several trips, etc. It's very hard to make money doing that unless you're really good and have a ton of parts.

2. It's also kind of risky to be doing repairs to monitors when you're kind of a novice at it. That's not an insult. I'm not really good at them either, but I'm farther along than you are, just becuase I've rebuilt hundreds and hundreds of them. I'm just saying if you tell somebody you can fix it, then can't... that's going to work out bad.

3. Monitors can be troubleshot (I like that word!) by systematically removing sections of the monitor from the equation. the HOT has nothing to do with your problem. If the HOT goes bad in a monitor, the fuse blows because the only thing seperating the B+ from ground is the diode inside the HOT. If the HOT blows, it shorts B+ to ground and blows the fuse. So if you're getting anything at all on the screen, you know that the HOT is fine.

Another thing: Ms. Pac machines came with all kinds of diferent monitors in them. The manual has schematics, inside it, for a G07, K4600, and K4900, it could have had any from the factory and anything else swapped into it.

Good luck with it.

great advice, just to add if your going to work in a home ask the person to snap a picture of the chassis then you know what your walking into. when I do a house call I bring a replacement chassis and swap them out get my money and repair the broken one at home at whenever I want.
 
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