Solid vertical white line on UAV modded 2 port 5200

[Elysiom]

This is a 2 port 5200 that I acquired recently, it seems to be pretty clean - the motherboard doesn’t have any noticeable corrosion, leaky capacitors etc.

 

Originally I thought this was some weird overscan or incompatibility issue with a LCD TV, I connected it to a CRT set and it has the same issue.

 

When modding the system I left the 4050 in place and soldered the UAV on top, I didn’t remove the shielded RF module as you probably would with a 7800.

 

If you take a peek at the few uploaded images there is a solid vertical white line down the right side of the screen at boot and if you look at Pole Position that line seems to shift to the left a bit and its almost a clone of the red and white center line, not shown but it does this in other games like Super Breakout.

 

Thinking the basics - could this be some bad ram or week power supply?

 

Thank you for your time in advance!

 

[+-^CrossBow^-]

Since you left the 4050 in place, did you leave the RF intact as well? Do you get the same results on RF to the CRT?

[Elysiom]

1 hour ago, -^CrossBow^- said:

Since you left the 4050 in place, did you leave the RF intact as well? Do you get the same results on RF to the CRT?

Yes - I left RF intact and just disconnected the coax cable, I'm about 90% sure it had this issue beforehand, I remember I was hoping it would go away with the UAV mod.

 

I've tested a few other games and oddly it doesn't have this issue on the title screen in some games but its then visible on the play screen, I'm thinking its something involved with processing and when the system is under load - bad ram, GTIA, ANTIC.

 

I've uploaded some other images - Joust at boot, Joust title screen and finally Joust play screen.

 

Thank you.

[+-^CrossBow^-]

Well...you are basically correct in that it is likely a RAM issues or the ANTIC or GTIA chips. To test if the RAM is at fault is pretty easy. Just swap them around and see if the issue changes. Because if it does, then you know one of the two last ram chips you just moved is at fault and can isolate further from there.

 

After that you have to look at the ANTIC and GTIA chips which, are the two large ICs above and below where the 4050 is.

 

The ram can still be found easily enough, but the ICs are custom and you would have to go through Best Electronics for NOS replacements or pull them from donors. 

 

I keep a working 4 port on hand outside of its case just for the purposes of chip swapping.

 

[Elysiom]

I recently purchased an Atarimax cart, so I now have the ability to run the diagnostic ROMs.

 

PAM Diagnostics Version 2.3 - it passes CPU, RAM, ROM but GTIA and ANTIC have soft errors 24 01 - I'm guessing this could be a result from running it from a flash cart.

 

Seems like the ANTIC could be at fault - it doesn't seem to match any of the test patterns I've seen, there is a block / character out of place.

 

 

[+DrVenkman]

Definitely an ANTIC or GTIA issue. Fortunately, major chips in 5200’s are all socketed so should be an easy fix.

[+-^CrossBow^-]

5 hours ago, DrVenkman said:

Definitely an ANTIC or GTIA issue. Fortunately, major chips in 5200’s are all socketed so should be an easy fix.

I've had more than a few 2 port units that didn't have all the ICs in sockets. I think the last one I did only had the pokey in a socket and I thought that was quite odd.

[Elysiom]

2 hours ago, -^CrossBow^- said:

I've had more than a few 2 port units that didn't have all the ICs in sockets. I think the last one I did only had the pokey in a socket and I thought that was quite odd.

 My two port is socketed and like most of the Atari hardware of that age it has it quirks and if I remember there is a bodge fix.

 

I've cleaned and reseated both ICs - figured it wouldn't help and it didn't so I'll look at sourcing replacements.

[Elysiom]

It ended up being the ANTIC - I found a 'as is, not tested' 2 port 5200 on eBay that ended up working just fine.

 

My bad ANTIC is C012296D-01 - made in Korea

 

 

Once I get a working part to make the parts system functional again I'll put it up for sale with a fair price here or trade.