Hantarex Polo Lines on Left-SOLVED!

mikerk

Well-known member

Donor 2013
Joined
Feb 2, 2011
Messages
872
Reaction score
96
Location
Virginia
I dont know if any of you Polo 25 folks have solved the "vertical black/white bars" problem on the left or right side of the screen but in this case, it was the replacement flyback!

After I resoldered a working original back in the chassis the lines disappeared. Most likely cause is the internal diodes were weak or the capacitor (although the schematic shows no internal capacitor).

Then I researched this problem and in EVERY POST I READ this problem occurred after a capkit/new flyback install.

However, Im also certain this can happen to the original flybacks as well I just havent heard about it yet.
 
I actually has this problem with a brand new flyback that was faulty. Chad had to get rid of all of his flybacks for the polo.
 
Necrobump... Are there any replacement fkybacks that don't cause this issue? I bought 3 fkybacks a couple years back I ended up havering to replace fkybacks on 2 chassis and they both got the black lines on the left.
 

Attachments

  • PXL_20230514_140655508.jpg
    PXL_20230514_140655508.jpg
    4.5 MB · Views: 48
Necrobump... Are there any replacement fkybacks that don't cause this issue? I bought 3 fkybacks a couple years back I ended up havering to replace fkybacks on 2 chassis and they both got the black lines on the left.
yes, you turn down your brightness. you shouldn't see anything in a black area of the picture, it should be solid black. if I recall you have to find a happy medium between Screen and Brightness adjustments to remove the lines.
 
yes, you turn down your brightness. you shouldn't see anything in a black area of the picture, it should be solid black. if I recall you have to find a happy medium between Screen and Brightness adjustments to remove the lines.
Thank you I got most of it out. It's not noticable during game play but on some screens you can see the white horizonal lines some on the left.
 
I remember this being a thing with the Bob Roberts flybacks some 12-13 years ago, I didn't know it was still a problem. I don't remember white horizontal lines like in your picture being an issue, unfortunately monitor adjustments are so second nature to me a lot of steps in the process I don't even notice.
 
I remember this being a thing with the Bob Roberts flybacks some 12-13 years ago, I didn't know it was still a problem. I don't remember white horizontal lines like in your picture being an issue, unfortunately monitor adjustments are so second nature to me a lot of steps in the process I don't even notice.
Well if I stilled lived in Texas you could come adjust it for me :). I need to go purchase a floor mirror so I can see what I'm doing. It's hard when your behind a row of games and trying to use your phone to see what your adjusting, it dosn't work so well. I do appreciate your help, thank you.
 
On the original Polo flybacks made by Eldor (1242.5001) the HOT collector is coupled to pin 1 (just look at the schematics) while on the replacements made by HR Diemen (HR7191) it's coupled to pin 4:

https://www.hrdiemen.com/reparation/flyback/scheme/7191

https://forums.arcade-museum.com/threads/hantarex-polo-25-jailbars-confirmation.288456/post-2731301

The different inductance of the primary side (3-4 vs 3-1) shows up as a ringing effect (what you call jailbars). It's quite possible that the allgedly defective 'Bob Roberts flybacks' are in fact reproductions of the HR Diemen design and a simple pin/trace rerouting could make them work fine.
 
On the original Polo flybacks made by Eldor (1242.5001) the HOT collector is coupled to pin 1 (just look at the schematics) while on the replacements made by HR Diemen (HR7191) it's coupled to pin 4:

https://www.hrdiemen.com/reparation/flyback/scheme/7191

https://forums.arcade-museum.com/threads/hantarex-polo-25-jailbars-confirmation.288456/post-2731301

The different inductance of the primary side (3-4 vs 3-1) shows up as a ringing effect (what you call jailbars). It's quite possible that the allgedly defective 'Bob Roberts flybacks' are in fact reproductions of the HR Diemen design and a simple pin/trace rerouting could make them work fine.
Thank you MKL. This is great information.
 
yeah. or PNL fixes your Polo and puts a Polo/2 flyback on it. Chad's seen it and I still have the Polo/2 flyback in my Polo box from when I sent one of mine to them to fix years ago. I don't even understand how those mutts are still in business.

I was able to mute the lines by finding some happy medium with the Screen and Brightness pots though. I forgot about the trace routing @M K L mentioned. all my flybacks are original now, the Polos I had with Bob Roberts flybacks went in games I sold off years ago.
 
I got my flyback from Arcade Parts & Repair less than a year ago. Im able to mute the line but kind of sucks not being able to have the screen brighter...

Is possible to test the inductance of the primary side to see if its (3-4 vs 3-1), Is it a matter of testing continuity between the flyback pins?
I would do the trace routing if needed.
 
I measure 3.5mH across 1-3 and 4.3mH across 3-4 on both Eldor 1242.5001 and HR7191 so the HR is an exact reproduction. But I'm talking about *original* HR7191. I can see the one in the link above is not original. Just because a repro has a sticker with the same numbers it doesn't mean it's the same. Stuff needs to be measured to be sure. If you don't have a tool to measure inductance (like an LCR meter), you could reroute the traces and see. The flyback doesn't need to be desoldered, you can just cut the trace near pin 1.
 
I measure 3.5mH across 1-3 and 4.3mH across 3-4 on both Eldor 1242.5001 and HR7191 so the HR is an exact reproduction. But I'm talking about *original* HR7191. I can see the one in the link above is not original. Just because a repro has a sticker with the same numbers it doesn't mean it's the same. Stuff needs to be measured to be sure. If you don't have a tool to measure inductance (like an LCR meter), you could reroute the traces and see. The flyback doesn't need to be desoldered, you can just cut the trace near pin 1.
ok thanks, I do have an LCR meter. So if understand, the inductance should match and it should be fine. Otherwise it requires the re-routing of the traces. I will give that a try and report. I put back the original flyback last night and Im not getting the jailbars either, so that's not a good sign.
 
Allright, so both flybacks are off the pcb. I took some measurements and pictures:

Original Polo Flyback ELDOR 1242.5001. 1-3 = 3.526mH, 3-4 = 4.176mH
IMG_0699.JPGIMG_0697.JPGIMG_0698.JPG

New Replacement Flyback. 1-3 = 3.927mH, 3-4 = 4.584mH
IMG_0702.JPGIMG_0704.JPGIMG_0706.JPG

Comparing both results with the values you mentioned: 3.5mH across 1-3 and 4.3mH across 3-4.
Even though the original one is old (showing 1992) and possibly a bit off specs due to extended use, the values of the Eldor are much closer to what you are getting.

I guess the next step would be to put back the replacement flyback, bend pin 1 and re-routing the trace to see if that fixes the jail bars. Whether its using 3-1 or 4-1, I guest that cant hurt anything since the re-routing will force 4-1 anyway. So either it will be fixed or just like before.
 
Last edited:
FYI here's a quick video showing the Eldor original flyback installed. No issues at all, everything cranked to the max... the problems only happen when using the replacement flyback purchased recently.

Replacement flyback (Brightness and contrast maxed)
441250158_450002344055232_2000426106719250665_n.jpg

Original flyback (Brightness and contrast maxed)
IMG_0711.JPG

Spoke to someone who fixes a lot of monitor about the issue, he was well aware of it but was under the impression the jailbars were due to a weak tube. However as you can see, using the same chassis (fully refurbished), same tube... the only variable is the flyback (original vs replacement). Its safe to say that even to this day the replacements are subpar and the modification described on this tread is still needed: https://forums.arcade-museum.com/threads/hantarex-polo-25-jailbars-confirmation.288456/#post-2731301

Hope that helps anyone having the same issue. Of course you could dim the brightness and contrast to get rid of the bar but that's not ideal... The goal is to get a nice and bright image.

UPDATE: Just got a word from Peter (Arcade parts and repair) and he is aware of the issue. Apparently some reproduction flybacks have the jailbars, some don't. He has been working on new samples that work and don't cause jailbars but they wont be for sale for about a year from now. they will be updated to closer specs. In the meantime re-routing the traces is a good workaround he said.
 
As 3-4 (4.1mH) of the original flyback is close to 3-1 (3.9mH) of the replacement, I would first try and see how the original works with 3-4 and if there's no jailbars, I would try the replacement with 3-1. Replacement with 3-4 (4.5mH) as a last resort (unlikely to work).

Cutting the trace is better than bending the pin IMO:
zzzzz.jpg
 
I just finally got around to doing this fix. I ended up bending pin 1 back and jumping to pin 4. I have a desoldering station so it was not bad. If you don't have a desoldering station the cut trace may be the easiest was to get it done.
 
I can tell you guys I never would have figured out such an issue on my own. Not to mention I'd be pissed that the new fly I just installed now needs to come back out...

Thank you so much for sharing this!!
 
Back
Top Bottom