Broken 7800... Will not run 7800 games but will run a few 2600 games

[MMarcoux66]

Bought another 7800 off eBay to give to a family member. Hooked it up and it will not play any 7800 cartridge. I cleaned the cartridges and the port, still will only work with Mario Bro 2600 and a few older titles. Ms Pacman 2600 will not load... just lines on the screen. Contacted the seller but curious if this may be an easy fix. I tried using the power supply for my working 7800 and it did not help. Was able to test all carts in my working 7800 and they worked fine.

 

Alos noticed that in Mario Bros, the screen seems to bounce a bit.

 

Any help would be greatly appreciate.

[+-^CrossBow^-]

Could it be you have a PAL 7800?

[MMarcoux66]

Could it be you have a PAL 7800?

 

No, I opened it up and it is an NTSC one.

[SoundGammon]

My bet it's the cartridge connector that's the problem. Seems like an address line isn't making contact.

[MMarcoux66]

My bet it's the cartridge connector that's the problem. Seems like an address line isn't making contact.

 

Could be. Any way to check it? I was trying to figure out how to remove the plastic around the cartridge slot to see if there just needs to be some cleaning.

Edited October 1, 2018 by MMarcoux66

[+-^CrossBow^-]

There is usually tape on the bottom that covers the Phillips screws that hold that cart sleeve on. Just scrape or cut that tape away and take out the screws and the whole sleeve will come right off.

[MMarcoux66]

There is usually tape on the bottom that covers the Phillips screws that hold that cart sleeve on. Just scrape or cut that tape away and take out the screws and the whole sleeve will come right off.

 

Awesome, found the screws. Thanks. Checking the traces. Found a few scrapes but no broken traces.

Edited October 1, 2018 by MMarcoux66

[+-^CrossBow^-]

Check the two sets of pins on the far right and left of the cartridge port itself. Those are the pins specific for 7800 use.

[CZroe]

Try leaving it on for 15 minutes then cycling the power. If that works, remove the RF/EMI shield and see if that eliminates this warm up time:

 

https://youtu.be/XNOQk1nQaEQ

[MMarcoux66]

Check the two sets of pins on the far right and left of the cartridge port itself. Those are the pins specific for 7800 use.

 

They look clean from what I can tell. I did clean them with some alcohol.

[MMarcoux66]

Try leaving it on for 15 minutes then cycling the power. If that works, remove the RF/EMI shield and see if that eliminates this warm up time:

 

 

I'll give this 15 minutes on a try. I have already taken it apart and removed the RF shield with the same results without waiting 15 minutes. Would be interesting if that works.

[MMarcoux66]

 

I'll give this 15 minutes on a try. I have already taken it apart and removed the RF shield with the same results without waiting 15 minutes. Would be interesting if that works.

 

Same issue. Only a few 2600 carts work... no 7800 carts work. I just noticed that the voltage regulator was a bit loose, so I replaced it but no change.

[CZroe]

 

Same issue. Only a few 2600 carts work... no 7800 carts work. I just noticed that the voltage regulator was a bit loose, so I replaced it but no change.

Wish I knew what caused my issue because I bet it’s still related somehow, since yours has the exact same behavior (rolling bars/lines for 7800 games; works with 2600 games).

 

I can’t do any further testing because I traded it away (yes, the recipient was aware).

[+-^CrossBow^-]

Only other issue would be something in the bios not switching over to the Maria or the Maria itself? I have found at least one 7800 that crossed my path that had a faulty Maria IC in it.

[+DrVenkman]

 

Same issue. Only a few 2600 carts work... no 7800 carts work. I just noticed that the voltage regulator was a bit loose, so I replaced it but no change.

 

Do you have a multimeter to confirm continuity from all the connector pins on the 7800 to the next-in-line component or via? Also, and tangentially related, have you examined the pins themselves under magnification looking straight down into the cartridge port to confirm that there's no conductive debris down inside the connector.

 

Unfortunately, I see your 7800 is fully-soldered; if you've got a bad MARIA (and/or bad TIA or RIOT) it's going to be a pain in the butt to replace.

Edited October 1, 2018 by DrVenkman

[MMarcoux66]

 

Do you have a multimeter to confirm continuity from all the connector pins on the 7800 to the next-in-line component or via? Also, and tangentially related, have you examined the pins themselves under magnification looking straight down into the cartridge port to confirm that there's no conductive debris down inside the connector.

 

Unfortunately, I see your 7800 is fully-soldered; if you've got a bad MARIA (and/or bad TIA or RIOT) it's going to be a pain in the butt to replace.

 

Yeah, the fact it is soldered limits what I am willing to do. I will check the connectors under magnification just out of curiosity.

[+Mitch]

If half of the 2600 games don't work then it probably isn't the cart connector or the Maria chip. More likely a marginal TIA or CPU.

 

Mitch

[MMarcoux66]

If half of the 2600 games don't work then it probably isn't the cart connector or the Maria chip. More likely a marginal TIA or CPU.

 

Mitch

 

Great insight... does make sense, Mitch. I am going to try to get another 7800 board that has issues to see if I can make 1 working board between the 2. Maybe I will luck out and both boards will not have the same issues... lol....

[+-^CrossBow^-]

In the case of the TIA and other main chips, you can usually use a 2600 to get those parts since they are the same. I've used quite a few 2600s to repair 7800s that had faulty TIA and RIOTs in them at least.'

[MMarcoux66]

In the case of the TIA and other main chips, you can usually use a 2600 to get those parts since they are the same. I've used quite a few 2600s to repair 7800s that had faulty TIA and RIOTs in them at least.'

 

Another great idea. If I go that route, I will probably buy sockets so that I can easily remove the chips. All the current ones chips are soldered in the 7800 which I will have to clean up if I desolder them out. I could also try them in a 2600 to see if they work as well.

[Shawn]

If half of the 2600 games don't work then it probably isn't the cart connector or the Maria chip. More likely a marginal TIA or CPU.

 

Mitch

 

THIS. Mitch is almost certain to be correct here.

 

EDIT: I have a full set of 7800 brains (including a TIA and MARIA, 84 BIOS, RAM, ect.) and a cart connector to spare if you end up looking

to buy replacement chips for your machine. Socketing it all like you mentioned is a very good idea.

 

Edited October 3, 2018 by Shawn

[MMarcoux66]

 

THIS. Mitch is almost certain to be correct here.

 

EDIT: I have a full set of 7800 brains (including a TIA and MARIA, 84 BIOS, RAM, ect.) and a cart connector to spare if you end up looking

to buy replacement chips for your machine. Socketing it all like you mentioned is a very good idea.

 

DSCF8500.JPG

 

Thanks. I may take you up on it. What would you be looking to get for them? I'm not sure I would need everything but understand if you need to sell as a set. I might just sell the broken 7800 and get another working one but I do love tinkering with things. So weighing in options. Also, where are you guys getting the sockets?

[john_q_atari]

 

Thanks. I may take you up on it. What would you be looking to get for them? I'm not sure I would need everything but understand if you need to sell as a set. I might just sell the broken 7800 and get another working one but I do love tinkering with things. So weighing in options. Also, where are you guys getting the sockets?

 

Not sure where others get them but I love ordering sockets and other parts from arrow.com. Cheap, and free next day shipping! (Netherlands will take a few days but still free shipping).

 

going only by Shawn's picture, it seems this is what you would need:

 

3 of these:

https://www.arrow.com/en/products/ar24hzl7-tt/assmann-wsw-components-inc

 

3 of these:

https://www.arrow.com/en/products/ar40hzl-tt/assmann-wsw-components-inc

 

1 of these:

https://www.arrow.com/en/products/sa486000/on-shore-technology

Edited October 4, 2018 by john_q_atari

[MMarcoux66]

 

Not sure where others get them but I love ordering sockets and other parts from arrow.com. Cheap, and free next day shipping! (Netherlands will take a few days but still free shipping).

 

going only by Shawn's picture, it seems this is what you would need:

 

3 of these:

https://www.arrow.com/en/products/ar24hzl7-tt/assmann-wsw-components-inc

 

3 of these:

https://www.arrow.com/en/products/ar40hzl-tt/assmann-wsw-components-inc

 

1 of these:

https://www.arrow.com/en/products/sa486000/on-shore-technology

 

Perfect, thanks for the list. I've bought stuff from them in the past as well.

Edited October 5, 2018 by MMarcoux66

[Shawn]

 

Thanks. I may take you up on it. What would you be looking to get for them? I'm not sure I would need everything but understand if you need to sell as a set. I might just sell the broken 7800 and get another working one but I do love tinkering with things. So weighing in options. Also, where are you guys getting the sockets?

 

$25 USD plus exact shipping.