yet another Hantarex Polo 25 issue

timply

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a quick explanation to how i got to this point.

Bought a mk2 cab about 5 years ago, monitor didn't work, i replaced the flyback, hot and did a full recap. It worked for a few years.
monitor went out again a couple years ago, i messed around with it with my limited troubleshooting knowledge couldn't ever get it to work so just sat it to the side.

A couple weeks ago I got a wild hair to fix it. watched mikes amateur arcade monitor repair and got to to work. I found R105 was open and T101 was no good. replaced those and got the lightbulb test to work.
hooked it back up to the monitor and had a very dark screen with looked like sync problems, did some more testing found that R235 was open, replaced it and got an improvement but now we're at this point.


thats what the monitor currently looks like and R219 is getting EXTREMELY hot as pictured below

PXL_20240729_222947647.PORTRAIT.ORIGINAL.jpg

I've replaced all the film capacitors, i've tested as much as i can test, i reflowed everything. I'm kind of lost atm. any help is appreciated.
 
Thats what happens when I turn it on.
I guess it didn't even occur to me until just now that it could be the arcade pcb causing that?
yes

those resistors on the side carry B+ and often the solder breaks down, or rather the solder pads can just break off.

I gathered some intelligence: https://www.arcaderepair.net/hantarex-polo/

but @M K L is the Polo expert
 
i have reflowed both of those big resistors and checked continuity to the pads and everything seemed good. No wobble, no cold joints.

I didnt know if that was normal for a polo. I have never worked on one.

I checked it with a Infrared temp gun and it was bouncing between 170 and 200 degrees f
 
Yes, it's off. When it's on it generates white vertical bars that are superimposed on the picture.

So did you find out if it's the gameboard?

R235 is just there to bleed off a residual charge on the 200V line that supplies the RGB transistor on the neckboard.

As for R219 getting HOT, post a pic of the underside that allows to follow the traces (i.e. not a cloeseup) so I can give you some jumper wiring suggestions.
 
I haven't hooked the monitor up to see if its the game board, but after doing a little research i see others having the same problem and it tends to be the graphic chips on the mk2 pcb. I'll tackle that once I figure out this resistor getting hot issue.
 

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I haven't hooked the monitor up to see if its the game board, but after doing a little research i see others having the same problem and it tends to be the graphic chips on the mk2 pcb. I'll tackle that once I figure out this resistor getting hot issue.
that's like the cleanest Polo I've ever seen lol I would take out those ceramic resistors and sand the legs and solder them back in though.

as for the game, do you have the powerup test disabled? here's the legend of the dipswitches, you want UJ1-7 set to OFF to enable powerup test.

0016.png

you can access this screen by entering test mode -> Diagnostics ->Dipswitch Test. while you're in there, on the Diagnostics menu, choose CPU Board Test. see if any of the video roms show up as bad. if you have a 2 board, ensure that the top rom board is seated correctly. if any roms are missing the labels that cover the UV erase windows you'll want to throw some blue tape on them. if you need additional help tag me or send PM.
 
I think I'm the first person to ever work on the chassis, the whole cabinet is really clean. I'll take a picture once I get it all back together. I reseated all the connections and the game is working correctly again! But after about 10-15 minutes, r219 is reading about 220-240 degrees f. I'll Try sanding and retest!
 
It looks like the scorch marks are connecting directly to r222. r222 is reading 0.6 and r219 is reading 2.1k so its seems both of them are good.
 

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I think it's the primary side of the horizontal drive transformer that is causing that. Very thin wire and weak solder joints prone to failure.
 
is there a way to fix it?
get good at sanding solder mask open and patching traces. when I worked with gamefixer in Texas we had a cup of cut off cap legs, they make great jumpers and are obviously more rigid than wires. I used to 90 degree bend the resistor legs many years ago, to anchor them better cause those solder pads can lift, that's a totally not proper method for doing it.

one of these days I need to find a Polo to cap and do a walkthrough using my lesser knowledge than M K L
 
My soldering skills, in that respect, are pretty good, its my diagnosis and trouble shooting that could use a ton of work. Lol. I did home console mods for years. But the problem with that is I didn't learn the smaller details of electronics. If it worked before the mod it should work after, if done right. I have soldering stations, desoldering stations, hot air stations, I can do SMD work, you name it. I have the skills and equipment, I just don't have the knowledge. But I'm learning. I can do a continuaity test like it's nobodies business. Lol!
 
My soldering skills, in that respect, are pretty good, its my diagnosis and trouble shooting that could use a ton of work. Lol. I did home console mods for years. But the problem with that is I didn't learn the smaller details of electronics. If it worked before the mod it should work after, if done right. I have soldering stations, desoldering stations, hot air stations, I can do SMD work, you name it. I have the skills and equipment, I just don't have the knowledge. But I'm learning. I can do a continuaity test like it's nobodies business. Lol!
that's half the battle
 
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