G07 ... aaaaaaand I'm stumped.

Scucci

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Okay, here's the deal. I was working on getting one of the monitors from the "graveyard" up and going. G07 is SEVERE Ms. Pac burn, but whatever... monitor's a monitor.

Anywho, width coil is broken off... I have replacement coils, but not bothering with that till I get SOMETHING on the screen.

I hook the monitor up to my Pole Position... turn it on, and I get a high pitched squeal out of it... sounded like what I heard last time a cap blew up in my face.

Anywho, I get the meter.. check the voltages on the big resistor... you know the one, I can't remember the number for it off the top of my head. I get 150V on my side, 35V on the CRT side. So... booboo'd. I check all the 900 diodes and transistors, they're good... unless I missed one.

Then, going by the flowchart here, I check C511, it's lose... the guy that had the monitor before me did half a cap kit apparently and managed to lift the trace on the + side (no idea how he managed that one). I repair that, and hook her back up... same measurements but the squeal is gone (thank God).

I've never had the flowcharts fail before... they're usually spot on. What else could cause under voltage to the extent I'm seeing?

Side note... the resistor (the big white one... ... you know the one), got hot as hell REALLY fast... I turned the monitor off after a few seconds and a good 2 mins later it was still hot enough to burn my finger. ... think that guy's failing? I've managed to bring several monitors back from the dead, and if that's the case... this would be the first time I've ever seen that resistor do anything buck kick ass, as intended.
 
With the resistor getting hot like that, I'd look for a shorted component further along in the circuit. Time to start measuring just about everything after that resistor, that would be my only advice from what you've said.
 
I would test the reg 2SC1106, it may be bad.

Checked it... brain's no away right now, just woke up...

But I get 300ohm resistance from the case of the regulator to the chassis... not good. I checked another chassis I have sitting here and I get about 18K... in diode test I get a beep with the chassis I'm working on from the case to the chassis (reading of .450), with the other chassis, I get 1.8 and no beep. Neither of them show O.L like I would hope.

Then again, neither chassis is actually working, so... can't really trust either one too much. ... I actually don't have a single working G07 here minus the 13" in my Ms pac... ... I'm starting to see a pattern. lol
 
You don't even need the chassis hooked up to the tube to test the Reg or the HOT. Diode test should provide roughly 1200 to 1800 as a reading on a good Reg or HOT. OL, anything under 1200, or beep tone is usually bad. Here are a couple of pics that you may or may not find useful.

http://forums.arcade-museum.com/showthread.php?t=126760

I know what you mean about not being awake, working on second cup of coffee now, preparing to go jump in the shower.
 
You don't even need the chassis hooked up to the tube to test the Reg or the HOT. Diode test should provide roughly 1200 to 1800 as a reading on a good Reg or HOT. OL, anything under 1200, or beep tone is usually bad. Here are a couple of pics that you may or may not find useful.

http://forums.arcade-museum.com/showthread.php?t=126760

I know what you mean about not being awake, working on second cup of coffee now, preparing to go jump in the shower.

Yeah, I swapped them and the problem didn't follow the parts... there's something else down the line screwing up... the only thing I can see is X901, and I just pulled that again, tested it again, and it's still good (again).
 
Yeah, I swapped them and the problem didn't follow the parts... there's something else down the line screwing up... the only thing I can see is X901, and I just pulled that again, tested it again, and it's still good (again).

Do you mean X01? the HOT 2SD869?
 
Sorry, I meant the regs. Swapped from one chassis to the other, and the problem stayed on the chassis... didn't follow the part.

Ahh ok, X04 regulator 2SC1106. Test R902, and see if it is open. It is located just to the left of the filter cap.
 
Woke up enough to get the idea to compare the two chassis from a single point.

The only thing I see acting different is the filter cap... I'll just swap those and check again I guess.


EDIT: Nope... no change.
 
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Ya know, I had a chassis a while back that did the same thing - side resistor got super hot and I even burned my thumb on it 2 minutes after I cut the power. Pissed me off, too.

Can't remember what I did to fix it. Might have posted about it here, but I don't think so...
 
Ya know, I had a chassis a while back that did the same thing - side resistor got super hot and I even burned my thumb on it 2 minutes after I cut the power. Pissed me off, too.

Can't remember what I did to fix it. Might have posted about it here, but I don't think so...

This one is really starting to piss me off...

I've pulled X901, and R903... even took the orange wire off of the reg's frame.. everything that SHOULD isolate the reg from ground... but I'm still getting the exact same readings.
 
Okay... fun stuff...

Put everything back in... checked again... same shit.

When I remove the wire from the regulator's cap to the resistor above it (the big white one... you know the one)... I get a good reading from the cap to ground. 1.2 on the diode test, 11Mohm+ on resistance.

The resistor itself still checks out fine though 119.5ohm.

Walked around and started randomly checking stuff out... pulled C518 and the diode test reading from the can to ground jumped to .985... sooo... weird.
 
I forgot to update this one... figured it out.

Bad wire going to the HOT of all things... wasn't getting a good connection. After I fixed that, I started getting good readings.

... figure that one out, eh? Weird.
 
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