Perfectly working monitor suddenly went blank.

mikeidge

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Perfectly working Hantarex polo monitor suddenly went blank.

Hi all. i have a hentarex 25" monitor that was working perfectly in a SF alpha 2 cab. out of nowhere it went black. i checked the power cable going to the monitor and it shows 120v. i checked the fuse after the power cable and it is fine too. the tube is not lighting up and it appears that the monitor isnt getting power. the game plays fine and i can hear it working. i even swapped a known working board in and it also was blank so i know its not the game. what should i look at to try and repair this monitor? i am fairly proficient at working with electronics although, monitors are new too me...

also....while im on the subject of monitors. can anyway tell me how to check to see if a monitor has been properly de-energized? the last time i pulled a monitor out....i did the usual method of using a flat head screwdriver with aligator clips and grounding to the chassis. there was no pop, and i did it a few times. even put the cap directly to the chassis to be sure. thinking it was de-energized, i began working and got zapped while touching the neckboard. what is the absolute be all end all to ensure a monitor has no juice stored?
 
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The reason you had a problem is that you were discharging the anode cup. the cup doesn't hold the charge, the tube does. You need to discharge the hole that the cap goes in. And you have to make sure your screwdriver is connected to the monitor frame while doing so.

And even doing so, you may get shocked by a bad monitor if a capacitor on the chassis was charged up, but never had a chance to discharge.

Sounds like you need a monitor rebuild - new caps at least. You may have other problems, but you'll need some basic testing/repair skills to go beyond checking the fuse. if you don't think you can do it, then it's best to just let someone with experience rebuild it for you...
 
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also....while im on the subject of monitors. can anyway tell me how to check to see if a monitor has been properly de-energized? the last time i pulled a monitor out....i did the usual method of using a flat head screwdriver with aligator clips and grounding to the chassis. there was no pop, and i did it a few times. even put the cap directly to the chassis to be sure. thinking it was de-energized, i began working and got zapped while touching the neckboard. what is the absolute be all end all to ensure a monitor has no juice stored?

I would guess the only way to be really sure would be to measure for voltage to be sure all is gone. I assume you were working on chassis removed from the game when you got shocked by the neck board though. If that's correct it's likely due to the filter cap on the chassis still holding a charge. It's always good practice to discharge this cap too after discharging at the anode cap. Of course I mean after the chassis is pulled from the game but before you actually work on the chassis.
 
i am confident i can do any work myself so long as i can discharge the monitor, and or chassis. i did think the anode held the charge, but the chassis was removed when i got zapped. so it wasnt the tube that shocked me. how should i go about discharging this? i cant see why i would need a capkit when the picture was perfect before it just decided to go blank. it was working perfectly and looked bright and vibrant right before it went off.
 
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A cap can go anytime and make the picture go blank. So can a bad fuse, a bad HOT, a bad diode, a bad resistor, etc.

As for getting shocked, it doesn't happen much that way. Typically you see this on the G07. If you're that worried, do the discharge thing you did before, but touch both solder points of any big caps...
 
ok. thanks. is there a way i can test the caps, or the flyback to try and narrow down the problem?
 
If you have an ESR meter, you can test the caps.

Another thing to do would be to pull the chassis and look it over carefully for any obvious problems - burned parts, caps with bulging tops, etc - and get a multimeter and check the transistors and diodes for failed parts. Make sure the fuse it good.

A complete cap kit for a Hantarex Polo 25" (if that's your model) can be had for $7, so it's better to just replace all of them (since they're all the same age) than it would be to just replace a couple...
 
ok..so i replaced the flyback and did a cap kit. still nothing. i have another hantarex polo and swapped chassis' to make sure that the problem is definitly in the chassis. what should i look for now? i dont see any bad solders, and nothing is burnt, etc. the fuse is good too.......im lost.
 
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Check the HOT, it's a large "BU508AF".

When these go out it'll send the monitor into shutdown... you can sometimes hear a FAINT clicking sound coming from the chassis.

Check to see if it's shorted to the chassis. Then pull it and check to see if it's internally shorted or open.

I just got done repairing a 25" Polo, what a pain the butt.
 
i do hear a faint clicking sound. im not sure what you mean by the hot though? i searched that part # and noticed what looks like a few of them. which one should i look to replace?
 
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i do hear a faint clicking sound. im not sure what you mean by the hot though? i searched that part # and noticed what looks like a few of them. which one should i look to replace?

Looking from the back of the monitor, it should be in the upper right hand area of the chassis if my memory serves me right. It'll be secured (hopefully) to the frame with a spring loaded piece of metal IIRC (I didn't pay attention to the original one when I took it off). I do know that the original one uses the chassis as a heat sink. The new ones don't really require that though... the ones I got in to replace the original run so cool they don't have to be heat sinked... but there are still plenty of older ones out there that WILL require a heat sink of some sort.

I originally replaced it with the same type, they fried after 15 mins because they got so hot... actually smoothed out my finger prints on my finger when I felt it. The new ones I got (from Mouser) don't need to be sinked... I've ran the monitor I fixed for 11 hours, and the thing was still cool to the touch.
 
so i replaced the BU508AF and now i have a bright spot in the center of the screen that changes colors. at least something is on the screen now. any idea what to do next?
 
also....i ordered a cheap chinese chassis and basically it looks like shit. i know how to adjust the monitor, but this thing does weird things. its a street fighter game and while im playing the game, the colors are good.....but during the "VS" screen, and character select screens, the colors are MUCH different. i would basically rather buy a new chassis at this point. can someone recommend a good replacement?
 
so i replaced the BU508AF and now i have a bright spot in the center of the screen that changes colors. at least something is on the screen now. any idea what to do next?

Check the adjustment board, the one that controls the size and freq. of the picture... they have really shitty connectors on them. Reflow everything and make sure everything is getting a good connection. The pots on those boards are also known for sucking... check and replace them as needed... or just replace all of them so you don't need that stupid little plastic tool anymore.

You can wiggle the connector while the monitor is on to check the connections... ... again, remember... they REALLY suck.
 
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