Atari Jnr graphics screwed! Help

[mamejay]

Hi everyone,

 

Just wondering if anyone can give some advise of my problem.

 

I tried to perform a CD4050 AV mod on my PAL Atari Jnr console which from another thread in the hardware section.

I did get display but could not get the colours correct.

I decided to reverse the mod which was just desoldering all the cables etc.

When I connected back up VIA RF the graphics are now screwed up and I do not get any audio.

 

I am suspecting that the TIA or CD4050 chips may be fried. Can someone take a look at the screen shots and tell me what they think could be the problem?

The games are missile command and River Raid.

On the River raid you can see the colour is all wrong as well graphics screwed like with the Activision logo at the bottom of the screen.

Also for Missile Command the cursor displays on both sides of the screen and cannot be moved.

 

I have found some CD4050 chips but they have different letters at the end of them.

CD4050BCM HEX NON-INVERTING BUFFER

CD4050BCMX HEX NON-INVERTING BUFFER

CD4050BCN HEX NON-INVERTING BUFFER

CD4050BCSJ HEX NON-INVERTING BUFFER

 

Would any these be able to be used? I checked the data sheets and the inputs and outputs look the same as from as screenshot of thread http://www.atariage.com/forums/topic/128279-cd4050-av-mod-on-pal-atari-2600/

 

If it is a TIA chip I will just get one from Best Electronics.

 

Thanks everyone

[GroovyBee]

CD4050BCN HEX NON-INVERTING BUFFER

 

This is a DIL part number which is what you want.

[mamejay]

CD4050BCN HEX NON-INVERTING BUFFER

 

This is a DIL part number which is what you want.

Sweet. I can get that chip locally. Do you have any thoughts on what the issue could be? I am thinking more the TIA as the CD4050 is just a buffer chip from what i understand.

[GroovyBee]

Did it work OK before you did the AV mod?

[mamejay]

Did it work OK before you did the AV mod?

Yes it was working fine beforehand.

[GroovyBee]

Have you repaired any cut tracks and put any removed components back? How did you attach wires to TIA's legs?

[mamejay]

Have you repaired any cut tracks and put any removed components back? How did you attach wires to TIA's legs?

There where no cut tracks for this mod. I only attached the Chroma to the bottom of the resister that was coming from PIN 9 of the TIA. The LUMA and SYNC was coming from the CD4050 chip and attached to the resisters coming from that chip.

 

I may have attached the Chroma signal wire to pin 9 directly of the TIA just by holding it on and switching the thing on to see if I got a better result.

[GroovyBee]

Unless the console has some sentimental value it might be cheaper to get another one from eBay.

[mamejay]

Unless the console has some sentimental value it might be cheaper to get another one from eBay.

They are getting a little tricky to find here in Australia.

If its just a $10 fix I would prefer to try and do that.

[GroovyBee]

OK. Looks to me like your machine's TIA is probably cooked (based on the fact that graphics and control methods are messed up). Did you use any anti-static precautions when handling the PCB/chips to add the AV mod?

[mamejay]

OK. Looks to me like your machine's TIA is probably cooked (based on the fact that graphics and control methods are messed up). Did you use any anti-static precautions when handling the PCB/chips to add the AV mod?

 

 

No I did not which I know is not a good thing. So the TIA controls the graphics as well as the controls? Now I am definitely thinking its the TIA.

 

So just replacing it should hopefully give me a good result? What do you suggest I do to reduce static when working with these things?

[GroovyBee]

No I did not which I know is not a good thing. So the TIA controls the graphics as well as the controls? Now I am definitely thinking its the TIA.

 

TIA does the video, buttons and paddles. RIOT does the stick movement and console switches.

 

So just replacing it should hopefully give me a good result? What do you suggest I do to reduce static when working with these things?

 

Make sure you have a good connection to earth with a suitable anti-static wrist strap. Wear natural fibre clothes. Avoid working on carpeted floors (the kitchen table is probably best).

 

http://en.wikipedia.org/wiki/Anti-static_wrist_strap

 

Make sure you are using a modern soldering iron too.

[mamejay]

No I did not which I know is not a good thing. So the TIA controls the graphics as well as the controls? Now I am definitely thinking its the TIA.

 

TIA does the video, buttons and paddles. RIOT does the stick movement and console switches.

 

So just replacing it should hopefully give me a good result? What do you suggest I do to reduce static when working with these things?

 

Make sure you have a good connection to earth with a suitable anti-static wrist strap. Wear natural fibre clothes. Avoid working on carpeted floors (the kitchen table is probably best).

 

http://en.wikipedia.org/wiki/Anti-static_wrist_strap

 

Make sure you are using a modern soldering iron too.

 

Thanks for all your advice. I have emailed Best Electronics and asked about stock etc for the PAL TIA. Hopefully they will get back to me soon.

 

Anyone here got any PAL TIA chips they wanna sell?