SNES no AV video has sound Rf video and sound works Help

[Dragonite | 17]

So I picked up a snes today that I have thoroughly cleaned and I get video and audio through the Rf switch but I only get audio with the AV plug. The AV plug I’m using works just fine on my other snes. My TV is a CRT not a new tv. I have also cleaned and checked the AV plug pins and they look fine. Before I started the deep clean I checked to see if it worked and it had the same issue. Questions I have are:

where should I start the troubleshooting? Does the Rf have a Separate capacitor then the AV plug in, on the board? Could it be a cold solder on the AV port? Any thing else I should consider? Thank you for any and all help.

Edited May 29, 2021 by Dragonite

[darkchylde28 | 1,546]

Do you have any other AV hookups to be able to test?  I ran into this with my childhood SNES years and years ago and believed that there was some sort of issue with the system in that I could get RF out but not AV.  The AV cord I was attempting to use came from an N64 I got off of a coworker which worked fine on the N64, but wouldn't output anything at all on my SNES.  Years later, I dug out the same system and ended up with different AV hookups (first a super cheap audio/s-video cable, then a fantastic third party set meant for GameCube/PS2/Xbox [made by Pelican, maybe?]) which worked just fine on the same system.

I don't know that there would be any sort of compatibility issues between certain system configurations and certain AV adapters, so I'd guess it likely comes down to what's making a good connection or not.  I know you said you checked the pins, but it's often hard to tell when system pins are just dirty enough to cause issues but look just fine to the naked eye, or even after a basic alcohol/q-tip session.  Fingers crossed you figure this out and it works out in your favor!

[Dragonite | 17]

3 hours ago, darkchylde28 said:

Do you have any other AV hookups to be able to test?  I ran into this with my childhood SNES years and years ago and believed that there was some sort of issue with the system in that I could get RF out but not AV.  The AV cord I was attempting to use came from an N64 I got off of a coworker which worked fine on the N64, but wouldn't output anything at all on my SNES.  Years later, I dug out the same system and ended up with different AV hookups (first a super cheap audio/s-video cable, then a fantastic third party set meant for GameCube/PS2/Xbox [made by Pelican, maybe?]) which worked just fine on the same system.

I don't know that there would be any sort of compatibility issues between certain system configurations and certain AV adapters, so I'd guess it likely comes down to what's making a good connection or not.  I know you said you checked the pins, but it's often hard to tell when system pins are just dirty enough to cause issues but look just fine to the naked eye, or even after a basic alcohol/q-tip session.  Fingers crossed you figure this out and it works out in your favor!

So I gave this a try with another set of av plugs actually tried 4 other sets and unfortunately I’m getting the same results. I know the pins are super clean because if I have the Rf switch plugged in instead of the av plug it starts the games every time with no issues. Thank you for the info as it at least ruled out another possibility.

[darkchylde28 | 1,546]

12 minutes ago, Dragonite said:

So I gave this a try with another set of av plugs actually tried 4 other sets and unfortunately I’m getting the same results. I know the pins are super clean because if I have the Rf switch plugged in instead of the av plug it starts the games every time with no issues. Thank you for the info as it at least ruled out another possibility.

Sorry it wasn't a simple fix.  I found this link for you, and the best thought out of it is to use a multimeter to check continuity on the AV port pins and determine if there's any trace rot or not.  I'd follow the traces on the inside back as far as you can and if you ever don't have continuity, visually check the section you're troubleshooting to see if any solder mask or even traces appear to be missing.  I've never seen this on an SNES myself, but have run across it quite a bit on earlier release original XBOXes.  If you end up having a bad trace, it's fairly simple to just solder in a jumper wire to bypass the damaged section of trace and get things going again.  Good luck!

Edit:  A couple of older posts have suggested some folks had the same issue occur due to wonky PSUs.  If you haven't already, try using the PSU from another unit to see if it makes any difference.

Edited May 30, 2021 by darkchylde28

[Pikkon | 20]

Your getting audio/video from the RF so the cpu and both ppu's are working.

If I had to guess I would say some of the caps might be bad,composite cap should be 100uf or 220uf but have no clue which revision snes you have,also look for any broken traces and this schematic should be helpful.

https://gamesx.com/wiki/lib/exe/fetch.php?media=schematics:snes_schematic_color.pdf

Edited May 30, 2021 by Pikkon

[a3quit4s | 4,124]

I was gonna ask what revision the board was as well but it seems some tracework is probably needed here or as someone mentioned try a new power supply as well. If you want to ship it to me I can take a look or just grab you a multimeter and go nuts. 

[Dragonite | 17]

12 hours ago, darkchylde28 said:

Sorry it wasn't a simple fix.  I found this link for you, and the best thought out of it is to use a multimeter to check continuity on the AV port pins and determine if there's any trace rot or not.  I'd follow the traces on the inside back as far as you can and if you ever don't have continuity, visually check the section you're troubleshooting to see if any solder mask or even traces appear to be missing.  I've never seen this on an SNES myself, but have run across it quite a bit on earlier release original XBOXes.  If you end up having a bad trace, it's fairly simple to just solder in a jumper wire to bypass the damaged section of trace and get things going again.  Good luck!

Edit:  A couple of older posts have suggested some folks had the same issue occur due to wonky PSUs.  If you haven't already, try using the PSU from another unit to see if it makes any difference.

I had seen that link when I googled looking to see if I could Narrow down the problem, just wish they would have updated what they figured out LOL. I’m going to start with the tracing the connectivity with my multimeter and move on from there. I will update in a few days how it’s going.

[Dragonite | 17]

2 hours ago, Pikkon said:

Your getting audio/video from the RF so the cpu and both ppu's are working.

If I had to guess I would say some of the caps might be bad,composite cap should be 100uf or 220uf but have no clue which revision snes you have,also look for any broken traces and this schematic should be helpful.

https://gamesx.com/wiki/lib/exe/fetch.php?media=schematics:snes_schematic_color.pdf

Thank you for the link to the schematics. I’m going to start with tracing the connectivity and just move down the line. Thank you for the info. I will update on what I find out and let you know which board I have.

[Dragonite | 17]

1 hour ago, a3quit4s said:

I was gonna ask what revision the board was as well but it seems some tracework is probably needed here or as someone mentioned try a new power supply as well. If you want to ship it to me I can take a look or just grab you a multimeter and go nuts. 

I will let you know which board it is when I jump back into tomorrow. I appreciate the offer to look at it but this unit will be my Guinea pig to learn on. I have always been able to figure out most of the amateur issues but never took them any farther then that but always wanted to. Unfortunately I don’t have another snes power supply to test that.