Cartdrige port cover screw size

[SmakyTaky]

I have just bought a 7800 console to mod it for Composite video. The console has a loose cartridge cover as it is missing the two screws it should have. By any chance anyone knows the type and size of screws I should put there?

 

Thanks.

Edited May 26, 2021 by SmakyTaky

[+-^CrossBow^-]

It arrived without those screws? So someone has been inside this before then? I'm not sure the exact size but I might be able to find out later. However, even without them, with the top cover on, the cartridge sleeve should still stay in there pretty secure.

 

[CPUWIZ]

Really interesting, I recently received a dead board from someone, which also had them missing.  I wonder what the reason is.

[+-^CrossBow^-]

I will admit that there might be 2 or 3 that I've worked on where those screws are missing. But that is also because the plastic those screws used to screw into...is also missing. Done to allow tigervision and super charger carts to seat in fully.

 

[Dopy25]

I will have to check but I am pretty sure mine does not have screws either. I was going to remove the guide to clean it up but it is attached by some serious adhesive strip, no screws. Also am pretty sure nobody had been in it before.

[+-^CrossBow^-]

1 hour ago, Dopy25 said:

I will have to check but I am pretty sure mine does not have screws either. I was going to remove the guide to clean it up but it is attached by some serious adhesive strip, no screws. Also am pretty sure nobody had been in it before.

I've yet to come across one that didn't have screws in the cart sleeve and I can safely say, I've seen the insides of a LOT of 7800s at this point. I'd be curious to know what revision 7800s these are being found in because I'm pretty sure I've worked on most if not all the variants and haven't seen any without the screws. In fact, I'm the one that usually cuts out the old masking tape that was used to cover the screws originally. But if the snap tabs on the sides were made a little larger to fit the space more, they wouldn't have needed to use the screws and could have kept the opening hollow to allow more 3rd party 2600 games to fit.

 

 

[Dopy25]

41 minutes ago, -^CrossBow^- said:

I've yet to come across one that didn't have screws in the cart sleeve and I can safely say, I've seen the insides of a LOT of 7800s at this point. I'd be curious to know what revision 7800s these are being found in because I'm pretty sure I've worked on most if not all the variants and haven't seen any without the screws. In fact, I'm the one that usually cuts out the old masking tape that was used to cover the screws originally. But if the snap tabs on the sides were made a little larger to fit the space more, they wouldn't have needed to use the screws and could have kept the opening hollow to allow more 3rd party 2600 games to fit.

 

 

I can post pics when I get home.

[+-^CrossBow^-]

3 hours ago, Dopy25 said:

I can post pics when I get home.

I'm not saying I don't believe you, I'm just stating that I've worked on AT84 models through X model 7800s and haven't seen any that didn't have screws in the bottom attaching the small plastic space and cartridge sleeve together. So when one is found that way, I have to suspect they have been worked on before. They should have small machine screws with masking tape originally covering the access to those screws from the bottom of the PCB between the PCB and screw.

 

[SmakyTaky]

9 hours ago, -^CrossBow^- said:

It arrived without those screws? So someone has been inside this before then? I'm not sure the exact size but I might be able to find out later. However, even without them, with the top cover on, the cartridge sleeve should still stay in there pretty secure.

 

It seems so, as there was a lot of flux on all the pins of the cartridge port. I guess it was replaced at some point and probably that's when the screws were removed/lost. My concern is the cartridge sleeve is a bit loose.. every time I take a cartdrige out, I am worried I may end up pulling it out.

[SmakyTaky]

This is my motherboard. The flux I mentioned before is gone as I have thoroughly cleaned it with IPA on both sides as I noticed lots of flux on it. I have already started to mod it for composite video (thus the missing RF modulator). Also replaced the push buttons as the original ones were somewhat faulty.

 

Console works just fine, however, the cartridge sleeve is a bit loose without the screws.. just wondering the size they should be and probably I may be able to get something similar.

Edited May 27, 2021 by SmakyTaky

[Dopy25]

29 minutes ago, -^CrossBow^- said:

I'm not saying I don't believe you, I'm just stating that I've worked on AT84 models through X model 7800s and haven't seen any that didn't have screws in the bottom attaching the small plastic space and cartridge sleeve together. So when one is found that way, I have to suspect they have been worked on before. They should have small machine screws with masking tape originally covering the access to those screws from the bottom of the PCB between the PCB and screw.

 

Oooooooooooooohhhh. That might explain why I thought there was some serious adhesive! I might not get to it tonight but I thought that tape was an adhesive strip. What you're saying makes more sense. 

[+-^CrossBow^-]

10 hours ago, SmakyTaky said:

It seems so, as there was a lot of flux on all the pins of the cartridge port. I guess it was replaced at some point and probably that's when the screws were removed/lost. My concern is the cartridge sleeve is a bit loose.. every time I take a cartdrige out, I am worried I may end up pulling it out.

I wouldn't worry about it falling loose. It has to come up way to high for that and the top shell is designed so that the lip around the top of the sleeve molding sits just under where the top shell opening is. In other words, the plastic around the top of the sleeve holds it in place against the top shell. Even if loose, it can't fall through the top opening and again, there isn't enough of a gap between the top shell and the sleeve for the sleeve to come up high enough to come loose. Worse you have to deal with is perhaps having to wiggle the carts a bit to ensure they are seating in square.

 

Lots of flux on the cartridge port is actually pretty normal. In fact, lots of flux residue on the entire bottom side of the main board is normal. Doesn't seem Atari took much care in making sure the boards were clean after the solder wave bath. It is also why the panel switches tend to get flaky over time is because often, that flux actually seeps inside the switches and starts to corrode the internal contacts. 

[SmakyTaky]

Thanks... any clue on the size of the screws? I would like to put them there if at all possible.

[+-^CrossBow^-]

Okay, so I'm finishing up a 7800 now as we speak, and part of what I do when servicing them, is to remove the cartridge port sleeve to allow better access to the pins to clean them. Meaning..

 

They appear to be:

 

6mm x 2.5 - 3mm using my ruler on my work mat. #1 philips head or it is the other way around at 3mm x 6mm.

 

 

 

[ChildOfCv]

I guess metric is possible, especially for later consoles.  But I do wonder if it's a standard American size though.  Maybe a truss head "type B" screw, or else the hi-low style.

[+-^CrossBow^-]

2 hours ago, ChildOfCv said:

I guess metric is possible, especially for later consoles.  But I do wonder if it's a standard American size though.  Maybe a truss head "type B" screw, or else the hi-low style.

Well, that is what the screw measured when I placed it up against my ruler on my service mat.

[Bratwurst]

I just took apart a stock 7800 console and measured the screws while I'm in there cleaning the cartridge port.

 

Standard American size screw is #4-40 and 5/16" long from tip to top of screw head.

 

This thread pitch and diameter is practically identical to M3, and 6mm long from tip to underside of screw head, or 8mm long from tip to top of screw head.