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WG K7000 dead... flyback? (SOLVED)
MKFan4Life:
Hi guys. I have a WG K7000 series (K7197 to be exact) chassis that is in my Mortal Kombat 1 cab. I recapped it about 2 years ago, but did not install a new flyback.
A few days back I was playing it for an hour or so and it glitched for a second and went out.
There is no neck glow and no high voltage whine I detect. No static really on the face of the tube either, however, when you first power it up, I seem to hear static and high voltage for a second and then nothing, along with no neck glow.
I figured, time to replace the flyback, but also wondered if this might be high-voltage shutdown? I checked the AC voltage coming in which is fine, and then the fuse which is ok, too. I haven't removed the chassis from the tray yet, but when I do, I figured I'd check for shorted diodes at D19, 20, 21, & 22 (as I have read they can short) and then check for an open R103. And then I would check the HOT also. (figured Bob Robert's repair kit with the flyback, fuse, HOT, and a backup cap kit would be a cheap investment at $28)
Does this in any way sound more like HV shutdown? The flyback has no visual signs of trauma I can see.
A note: This chassis was originally mated with another tube, a Zenith G-A63ADG25X and I paired it up with a different tube (the original had a bad blue gun). The new tube was from a K7400 monitor and was a Zenith A63AGD01X. They had close resistance on the horizontal and vertical coils, and it's been running great for about 7 months until now. Just thought I'd include this info as some people say mismatched yokes and chassis types can cause problems.
Thanks for any insight.
Sarver Systems:
I don't have an answer for you, sorry, but I am subscribing to this post because I have the same chassis that I just recapped, and it shuts off after about 5 minutes.
I am anxious to see what others have to say about your issue so I can hopefully track down my issues.
D19,20,21,22 and R103 are something I will need to check on mine. THanks for the info!
lilshawn:
MKFAN: the place to start is your regulator...check to make sure you are getting B+ if it pops up and then shuts off, you'll have to check more into the system, it's shutting down cause it's overloaded (shorted cap or bad flyback)... if the voltage is not popping up at all (dead dead), it's gone bad on you and will need to be replaced...
SARVER: your regulator might be overheating causing it to shut down. check the thermal interface and make sure the regulator 1) bolted down good 2) grease is not all dried up yucky. (which can act as a heat insulator more than a conductor)
you could have a component going bad that increases in resistance before it loads down the B+ supply enough to make it shut off (overload protect)
BOTH OF YOU:
you must not run this monitor outside the cabinet. it needs to be isolated from the AC by the cabinet transformer. if not, the monitor chassis blow up on you.
MKFan4Life:
--- Quote from: lilshawn on December 04, 2013, 02:40:36 pm ---MKFAN: the place to start is your regulator...check to make sure you are getting B+ if it pops up and then shuts off, you'll have to check more into the system, it's shutting down cause it's overloaded (shorted cap or bad flyback)... if the voltage is not popping up at all (dead dead), it's gone bad on you and will need to be replaced...
SARVER: your regulator might be overheating causing it to shut down. check the thermal interface and make sure the regulator 1) bolted down good 2) grease is not all dried up yucky. (which can act as a heat insulator more than a conductor)
you could have a component going bad that increases in resistance before it loads down the B+ supply enough to make it shut off (overload protect)
BOTH OF YOU:
you must not run this monitor outside the cabinet. it needs to be isolated from the AC by the cabinet transformer. if not, the monitor chassis blow up on you.
--- End quote ---
Thanks for the reply. I will check that as soon as I get a chance. The chassis has never ran without being connected to the ISO in the MK1 cabinet. ;)
MKFan4Life:
--- Quote from: lilshawn on December 04, 2013, 02:40:36 pm ---MKFAN: the place to start is your regulator...check to make sure you are getting B+ if it pops up and then shuts off, you'll have to check more into the system, it's shutting down cause it's overloaded (shorted cap or bad flyback)... if the voltage is not popping up at all (dead dead), it's gone bad on you and will need to be replaced...
--- End quote ---
I checked for B+ at the large resistor (180 Ohm 25 Watt resistor) on the bracket the voltage regulator is mounted against (on the opposite side). I have read that you can read each side of that resistor for input and output (B+). It's reading 179.5 VDC on one side and 177.7 VDC on the other. (ARGH!)
I know it's best to check on IC4 Pin 4 (positive lead) Pin 3 (negative lead) right? Just so darned hard to cram my hand there and make good contact with the chassis mounted in place at the moment.
What do you think? :-\