Hantarex Polo dim green color

nassekova · Jan 6, 2026

I have Hantarex Polo which @nem recapped and fixed for me on my Tekken cab, and it's been working for years. Recently it has started to have issues with green color. When booted cold, it works for a 5minutes or so and then it start to loose green color.

I have re-seated cables and wiggled them when the cabinet is on, and it has no effect.

You can see the issue here

But when I crank the brightness pot up from the "remote" it clearly still gets the green signal, it's just very dim.

So before I jump the gun with the chassis and service manuals, any one have had similar issues and know "usual suspects" for this kind of issue? I know some missing colors could be caused by damaged transistors on the neck board, but it's not like the green is completely missing. More like some resistor/pot is giving too much resistance on the green?

So all the hints and tips are welcome! I just had my Haunted Castle clearance run on going and I don't want to continue it without green :cursing:

nem · Jan 6, 2026

Double check that it's not the game board, so you don't waste your time trying to diagnose the chassis.

For chassis, could be a failing color drive transistor or some other component on the neck board. Try comparing parts between the different color circuits with a multimeter set to diode test and resistance. Should be able to narrow it down.

nassekova · Jan 6, 2026

nem said:
Double check that it's not the game board, so you don't waste your time trying to diagnose the chassis.

For chassis, could be a failing color drive transistor or some other component on the neck board. Try comparing parts between the different color circuits with a multimeter set to diode test and resistance. Should be able to narrow it down.

yea it's not the game board, this comes with all the games now. I first thought it was my CPS2 multi since it had this issue first, but now it's all the games.

I will check the neckboard next!

nassekova · Jan 7, 2026

I measured all three transistors and those big resistors from the neckboard but all were giving me same results. I have that one broken Hantarex Chassis (that was sold "as is" on Ebay) and it has a pretty botched up neckboard (jump wires and such fixes), but I took green RGB transistor from that to be extra sure that it's not the issue.

But the issue remains

First 5minutes it works fine and then it looses green color.

nem · Jan 7, 2026

The schematic is here:

https://media.recreativas.org/manuales/hantarex-polo-monitor-schematics-25-28-manual.pdf

There's more than just the big drive transistor and the big resistor. You need to check all of the components after the video amplifier (LM1203, top right corner of the schematic). Pin 20 on the amp is for green output, 16 and 25 for blue and red respectively.

If everything checks out, try swapping the amp from your donor neckboard.

nassekova · Jan 9, 2026

Well I could not find anything measuring those components so I just took that IC1 video amplifier from the donor board. While this was there on the desk, I also switched C2 capacitor to new (even it was changed while re-capped).