Hantarex Polo 20 issues

[mappy24]

Hi all, I've got a Hantarex Polo 20, mounted horizontally, with the following issues:

1. It has the shakes....

Again, at around 4-5 seconds in on this one....

The shaking stops if the V. Amp is reduced so the picture doesn't fill the screen vertically.

2. At interlaced resolutions, if the V. Amp is adjusted so that the picture fills the screen the alternate lines don’t line up unless I adjust the H.Phase to the left a bit, again, turning down the V.Amp fixes this, but then the picture doesn't fill the screen....

3. Adjusting the H. Phase causes weird corruption....

Has anyone seen anything like this before? I've got an identical monitor in another cab that doesn't behave like this, I've swapped the remote boards over and fault remains, so it's nothing to do with the remote board.

Cheers

 

[gunblade]

have you tried a different game board?

 

[mappy24]

Both cabs have the same DIY raspberry pi board as detailed here http://www.ukvac.com/forum/diy-pi2jpac-jamma-adapter_topic361469.html

I've swapped the boards over and the problems stay with the monitor. I've also got a raspberry jamma/Arpicade board that exhibits the same issues with this monitor yet works perfectly in the other cab.

Just shrinking the vertical size fixes everything but I'm wondering if this can be fixed somehow.

 

[gunblade]

whats the b+ on each chassis?

 

[gunblade]

also have seen real odd arse issues with screwy vertical lineraity pots so maybe worth giving that a tweek

 

[mappy24]

B+ measured on TP6 is similar on both:

Good chassis: fluctuated between 120.3-124.1 then settled at 123.7v
Bad chassis: fluctuated between 122.5-123 then settled at 122.7v

 

[gunblade]

its ok at that level but should be 130v, i doubt that causing the issue

perhaps the problem could related to the vertical ic or it circuit, maybe a bad cap or even the ic breaking down - is the 24v supply stable

 

[mappy24]

Sorry, but where do I measure the +24v?

 

[gunblade]

tp8

 

[mappy24]

23.6v stable on TP8 in the menu, rises to 23.7v stable when in game.

Assuming I look at caps first, c137, c139, c142 and c144?

 

[gunblade]

yes

also check reading of r177

 

[mappy24]

Thanks, as always!

 

[mappy24]

R177 is testing at 3.0 ohms, on the schematic it’s listed as 1r8 1/4w 1-2% tolerance, so it’s out of range?

 

[gunblade]

i have also marked as 2r7, what are the colour bands?

 

[mappy24]

Brown, Grey, Black, Silver, Brown - digikey lookup agrees - 1.8 Ohms 1% is what I have at R177 and it's testing at 3ohms.

Matches up with the schematics I'm using at https://arcarc.xmission.com/PDF_Monitors/Hantarex%20Polo%20Schematics.pdf

mappy242022-02-15 12:13:59

 

[gunblade]

replace it then

 

[mappy24]

Replaced r177, c137, c139, c142, c144 problem remains.

Suspect TDA1675 next?

 

[mappy24]

I replaced the TDA1675A, powered on and the problems were all fixed, no more interlaced issues and no more shaking! Put everything back together and put the cab back in position. Job done!

Then after a 10-15 minutes of being powered on, this **** happens:

While changing the IC the cable did fall out of the CRT socket on the neckboard, I pushed it firmly back in again before reinstalling. It's one of those crap CRT sockets that I've replaced before so I think I'll replace it anyway.

mappy242022-02-27 17:20:07

 

[gunblade]

have a look at the 470uf 35v cap in power supply section

 

[mappy24]

Will do, but I'm going to have to replace the CRT socket first, it fell off again while taking the chassis out and the wire has snapped off inside