7800 av mod question

[Neogeoman]

I recently bought an av modded 7800 that was completely recapped and overhauled. I went to hook it up to my Samsung LCD and after making all the connections and switching the tv source to av I was getting no signal. The av plug the system came with is a standard 3 color male plugs on one side that's plugs into the tv and the other end has one male plug that goes into the 7800. Never saw this set up before all other av connections I've seen have 3 color plugs on both ends. Anyway I removed and plugged in the one male plug on the back of the 7800 several times and was finally able to get a picture but moving the 7800 ever so slightly  loses the picture. I tried this on another Samsung LCD and the same thing. Am I doing something wrong? Is it the system or wire? Any help would be appreciated. 

[john_q_atari]

Pictures of the cable connections would help.

[Lord_of_Sipan]

The plug that goes into the system is the same as the 3 that go to the TV? That would be strange if they are all RCA plugs on coax cables for composite not sure how that would work.

 

As the poster above me said, photos would help.

 

Edit- if the system is losing picture when moved try to move the cable subtly while holding the console still with your other hand. That would let you know if the cable has a fault that is resulting in problems when moved slightly. 

Edited November 12, 2022 by Lord_of_Sipan

[+x=usr(1536)]

1 hour ago, john_q_atari said:

Pictures of the cable connections would help.

If it's what I think it is based on the description, it's a TRRS (tip-ring-ring-sleeve) 3.5mm plug, similar to the ones used on headphones.  Like this:

 

 

@Neogeoman, the problem is very likely going to be either with the cable or the jack that it plugs in to.  Without knowing how the jack is mounted or if other systems show the same effects when using the same cable as your 7800, tracking down an exact culprit may be a case of trial and error.

 

If you replace the cable and the problem stays, then you know the problem's not in the cable.  How adverse are you to opening the 7800 up and getting some photos of the modifications from inside the machine?

[Lord_of_Sipan]

Just spitballing here but it is possible that the modder hot glued the wires that connect the board to the trrs female output if that is what it is. That usually works ok but it may have the video wire coming loose. The fact that it outputs an image at all rules out the mod being installed with wires to the wrong parts of the trrs female connector.

 

I feel dumb not assuming the mod used a trrs hook up to get 3 different outputs via one plug to make a composite out.

[+x=usr(1536)]

9 hours ago, Lord_of_Sipan said:

Just spitballing here but it is possible that the modder hot glued the wires that connect the board to the trrs female output if that is what it is. That usually works ok but it may have the video wire coming loose. The fact that it outputs an image at all rules out the mod being installed with wires to the wrong parts of the trrs female connector.

At this point, anything's possible and nothing's ruled out.  This is precisely why seeing photos of the inside would be a good idea.

9 hours ago, Lord_of_Sipan said:

I feel dumb not assuming the mod used a trrs hook up to get 3 different outputs via one plug to make a composite out.

No need to feel dumb: for whatever reason, it's not as common as mounting RCA / S-Video jacks to the case.  Not that there's anything wrong with either approach, and the only reason I remembered the TRRS cable was that I happened to have been looking into them earlier today

[+DrVenkman]

We definitely need to see the insides of the system to get an idea of how everything is connected (and what may be loose).

 

[+-^CrossBow^-]

Yeap pics are going to be needed and I'm going to guess that if you just remove the top cover, that the RF shielding was likely not put back in so it should make it easier to see everything. Does the single port for the output happen to be mounted in the spot where the RF used to come out? If so, it is possible that it is using the TFW8bit kit as that seems pretty common and their kit instructions advise mounting their TRRS jack PCB in that location since the RF modulator is removed as part of the installation process.

 

I personally and NOT a fan of TRRS jacks because they provide a single point of failure and I don't feel they are nearly as robust/reliable as separate RCA jacks are. The other issue if that not all of those 3.5mm composite+audio cables are wired up the same. So if you lose the cable in the future or it gets broken in some way and you have to replace it, then you have to figure out which ring goes to which RCA so you can find a proper cable to match. This is why I provide the dongle adapters for component installs when I'm forced to use 3.5mm TRRS jacks.

 

[Neogeoman]

On 11/12/2022 at 1:09 AM, x=usr(1536) said:

If it's what I think it is based on the description, it's a TRRS (tip-ring-ring-sleeve) 3.5mm plug, similar to the ones used on headphones.  Like this:

 

 

@Neogeoman, the problem is very likely going to be either with the cable or the jack that it plugs in to.  Without knowing how the jack is mounted or if other systems show the same effects when using the same cable as your 7800, tracking down an exact culprit may be a case of trial and error.

 

If you replace the cable and the problem stays, then you know the problem's not in the cable.  How adverse are you to opening the 7800 up and getting some photos of the modifications from in

Sorry I didn't get back to you sooner I had a busy weekend, thanks for your help. Those are the exact cables I have. Unfortunately I cant open the 7800 because theres a tamper proof sticker over one of the screw holes and it'll void the warranty. I wanted to make sure I wasn't doing something wrong before I filed a claim to return it. I know for some setups you have to buy an upscale to get a picture but an av hookup should be straightforward as I dont have any issues with my other av modded consoles on the same tvs. I have a feeling its the wires or the mod itself

[Neogeoman]

And thank you to everyone who got back to me

[Silver Back]

That's the exact cable I have for my modded 7800 and I'm not a fan. For one the cable that was sent with mine didn't work. He said something about sending the wrong cable because he had purchased the wrong ones and his assistant grabbed from the wrong pile blah blah blah. I'm a cable junkie who buys and keeps every cable I can find so I had another and while it did work with the new cable it's real finicky. Sound will stop playing in one speaker or the other if I bump it etc.  So I have to be very careful not to bump that console. 

 

I should've returned it and looked for a different one but at the time I had many 7800s and didn't want to bother.  My recommendation to you is to return it and look for one with rca out on the console. 

[+-^CrossBow^-]

And I'm curious who did the work and thinks a security sticker is enough? Didn't we just pass laws here in the US no long ago stating that crap like this doesn't actually mean anything anymore? I use security like stickers myself, but I don't use them to cover holes in the consoles and instead I hide them inside as my badge of having been inside it to service it in case someone else has to get into them later and then they know who to reach out to or curse when they have to service it.

 

I get it that RCA jacks are big and bulky and a pain to install. But they work well and are reliable and cabling for them is crazy easy to get cheaply. It is also worth noting that most of the common simple composite only installs tend to look better on CRTs vs modern displays and upscalers. That is why I've had a few 7800s and 2600s sent to me to have the common kits removed and replaced with UAV setups.

 

[Lord_of_Sipan]

I am by no means a specialist in console related tinkering but I do have quite a lot of experience with audio equipment and synthesizers and I have had issues with designs in that realm that use TRS and particularly TRRS connections for various functions. I have never had a problem with either size of TS jack/patch cable with any equipment no matter how jankily made in some garage but I have had some problems with TRS/TRRS stuff. I've seen stereo connections wired with left and right audio reversed off of TRS stuff and I want to say I had something in my collection at some point that was supposed to use a trrs out for simultaneous mono audio out, CV pitch control out, and clock out but it didn't work at all if I remember right. Always had to run audio out of the headphone monitor out and make sure it would be the final instrument in the chain so to speak if I was using synchronized clock signals.

[+-^CrossBow^-]

21 minutes ago, Lord_of_Sipan said:

I am by no means a specialist in console related tinkering but I do have quite a lot of experience with audio equipment and synthesizers and I have had issues with designs in that realm that use TRS and particularly TRRS connections for various functions. I have never had a problem with either size of TS jack/patch cable with any equipment no matter how jankily made in some garage but I have had some problems with TRS/TRRS stuff. I've seen stereo connections wired with left and right audio reversed off of TRS stuff and I want to say I had something in my collection at some point that was supposed to use a trrs out for simultaneous mono audio out, CV pitch control out, and clock out but it didn't work at all if I remember right. Always had to run audio out of the headphone monitor out and make sure it would be the final instrument in the chain so to speak if I was using synchronized clock signals.

My HDRetrovision cables on my Genesis developed an issue about 6 months after I got them where I was hearing some odd static and audio channel cut outs when playing games. Isolated it to the 3.5mm jack that they have you plug off of to your AV receiver or TV. I did away with it since I have actual RCAs installed on the back of my Genesis and just have those plugged directly to the audio input on my OSSC. Which, oddly enough is also a 3.5mm jack but so far has been fine on all of the inputs.

 

[Neogeoman]

On 11/14/2022 at 9:54 AM, Silver Back said:

That's the exact cable I have for my modded 7800 and I'm not a fan. For one the cable that was sent with mine didn't work. He said something about sending the wrong cable because he had purchased the wrong ones and his assistant grabbed from the wrong pile blah blah blah. I'm a cable junkie who buys and keeps every cable I can find so I had another and while it did work with the new cable it's real finicky. Sound will stop playing in one speaker or the other if I bump it etc.  So I have to be very careful not to bump that console. 

 

I should've returned it and looked for a different one but at the time I had many 7800s and didn't want to bother.  My recommendation to you is to return it and look for one with rca out on the console. 

Taking your advice and everyone else and sending the 7800 back. Bought a set of new cables which didnt correct the problem, signal still goes in and out and often gets corrupted. I hate this setup anyway and now I'll look for an av modded 7800 with 3 av male plugs on both ends. My av modded 5200 has this setup and fires up perfectly every time. Thanks again 

[mimo]

1 hour ago, Neogeoman said:

signal still goes in and out and often gets corrupted. I

Could be the TV you are using doesn't like the signal from the 7800. 

Not saying it is, but I've experienced it in the past so don't rule it out 

[Silver Back]

9 minutes ago, mimo said:

Could be the TV you are using doesn't like the signal from the 7800. 

Not saying it is, but I've experienced it in the past so don't rule it out 

Quoted the wrong user. Just ignore this post. 

Edited November 16, 2022 by Silver Back

[Neogeoman]

On 11/16/2022 at 12:53 PM, mimo said:

Could be the TV you are using doesn't like the signal from the 7800. 

Not saying it is, but I've experienced it in the past so don't rule it out 

Yea tried it on 3 different tvs including a CRT, also used different cables and carts nothing work so I gave up. Seller is taking it back. Going to try and get a modded 7800 with a different setup