Possible 7800 mod problems

[Lendorien]

I recently purchased Longhorn's prebuilt 7800 AV mod. I'm quite pleased with it overall, but something popped up today that raised some concern.

 

I have a Psyclone game switch that I use to hook multiple systems up to my TV. Today I went to play my 7800 and found that the S-Video port on the switch longer worked. I tried other devices in it and it didn't work for them either. This went for the audio jacks too

 

I got a little suspicious, so I got out my multi-tester and tested the S-video port on the 7800 touching a ground and the choma and luma wires. The port appears to be outputting 1.4 DC volts. I opened the console and traced the leads back to the mod board and it's definitely coming through the board itself.

 

I tested some of my other games systems which also use S-video. None put out a current like that. I'm not really an expert in this sort of thing, but the 1.4 volts coming out of the S-video port seems to be unusual. I have no other modded console to test the voltage on and I'm not an electronics guy. I'm concerned that that sort of current burned out the SVideo and audio ports on the game switch. I don't know how much voltage is OK.

 

I'm hesitant to use my 7800 in any other ports or with my TV if that current is unusual and might be the cause of my problems. It could be a coincidence, but I'm afraid it's not.

 

Is it possible I wired something wrong? I went over the instructions and checked everything and so far as I can tell, I have everything as Longhorn instructed. Pictures available on request. Anyone else with this mod able to see if they have the same voltage thing going on?

 

I have sent an e-mail to Longhorn, though I know he's busy, being the end of the school year and all.

 

Thank you for helping me out with this.

Edited May 7, 2010 by Lendorien

[Lendorien]

Bumping this.

 

I've got my 7800 unplugged until this is resolved. I don't want to risk killing my TV's S-video ports if the voltage through the zvideo port might be the cause. If anyone can help me out, I'll be grateful.

[jaybird3rd]

I can't say I noticed this problem on any of the three Longhorn mod kits that I've built so far, although it never occurred to me to put a multimeter on the S-Video connector to check for it. I'd try it now if I had any of those kits left, but I've sold them all.

 

My only advice is to look over the mod board very closely to check for any extra beads of solder that might be causing a short somewhere. Check the wires going to the console mainboard and the jacks, too, to make sure they aren't touching anything they shouldn't be.

 

I've got some more mod kit boards on order from Longhorn, but I haven't heard from him about them in a few weeks. I know he's been busy with school, but given that the semester is probably over by now, I wish he would respond to his e-mail more often.

[Lendorien]

I can't say I noticed this problem on any of the three Longhorn mod kits that I've built so far, although it never occurred to me to put a multimeter on the S-Video connector to check for it. I'd try it now if I had any of those kits left, but I've sold them all.

 

My only advice is to look over the mod board very closely to check for any extra beads of solder that might be causing a short somewhere. Check the wires going to the console mainboard and the jacks, too, to make sure they aren't touching anything they shouldn't be.

 

I've got some more mod kit boards on order from Longhorn, but I haven't heard from him about them in a few weeks. I know he's been busy with school, but given that the semester is probably over by now, I wish he would respond to his e-mail more often.

 

I have a brother who's in his senior year as a mechanical Engineer. I know how busy things can get when you're approaching the end of the year. One has to prioritize. I've sent Longhorn an e-mail as well but have yet to get a reply.

 

I have checked over my work. Nothing obvious is wrong. For kicks I checked the board with a multitester at various points. There's definitely that 1.4 volts going into the board. I'm not good enough with such things to trace the voltage back. I have lent out my multitester for the moment anyway.

 

This situation really sucks because I love my 7800 and want to play it. I just got Dig dug. I could haul out my 2600 to be able to play on RF, but I like playing Centipede on the 7800 and don't have the 2600 cart (well ok, I do have a harmony. I should use that...).

 

It might just be the game switch. The audio has gone out on it too, but I have no idea, which is why I don't want to use the thing until I get a more concrete answer onw hether that voltage is normal or not. All I need is someone with the mod and a multitester to check theirs.

Edited May 10, 2010 by Lendorien

[Lendorien]

Bump.

 

Anyone have any suggestions?

[Lendorien]

Still could use help with this. Longhorn is incommunicado. Anyone able to use their multitester to see if this voltage thing is normal?

[Longhorn Engineer]

Still could use help with this. Longhorn is incommunicado. Anyone able to use their multitester to see if this voltage thing is normal?

 

I will check mine today. 1.4V on the Luma or chroma lines?

[Lendorien]

Still could use help with this. Longhorn is incommunicado. Anyone able to use their multitester to see if this voltage thing is normal?

 

I will check mine today. 1.4V on the Luma or chroma lines?

 

Well, from both it seems. If the positive is on the luma or chroma lines and negative on the ground.

 

I'd double check but I lent out my tester.