CRT Fetish Thread

[Tempest]

It all depends. Even if all the grounds are tied together inside the machine that doesn't mean that whatever the SCART is plugging into is the same. Usually the PVM has the video grounds tied together but on mine it doesn't handle audio so if my cable only had audio ground then I'd have a problem.

Try adding a piece of wire from the audio ground to the shield of the SCART, if you can't solder to the shield(some don't) then solder to a video ground like 13, 9 or 5.

There's a wire soldered to the casing on the 9-pin side. It goes to the Audio Ground on the SCART. Is that basically the same thing you're suggesting or does this also need to be done on the SCART end?

I'm by no means an authority, or even all that knowledgeable on the subject, but in fiddling around attempting to make a VGA->SCART cable, I couldn't get any type of picture on my PVM without having at least 1 of the video grounds connected and even then it was really noisy. That could be part of the problem right there.

It appears that the Audio Ground is connected, but none of the others. That makes me very suspicious.

I'm still curious as to why I can get the all yellow picture if I half pull out and tilt the 9-pin connector. Am I shorting something when I do that?

 

[Yodd]

Am I shorting something when I do that?

More than likely that's it.

You need someone experienced to open the system and cable up and fix all this. Sounds fubar otherwise.

 

[Tempest]

More than likely that's it.

You need someone experienced to open the system and cable up and fix all this. Sounds fubar otherwise.

I don't know. The system should be fine, as I said it worked before (unless the guy wired up that 9-pin connector wrong). I'm 99% sure the cable is just something minor like a missing ground or something. Still, if I can find someone who has a RGB monitor and is willing to look at this for me I wouldn't mind shipping it out.

 

[Yodd]

I don't know. The system should be fine, as I said it worked before (unless the guy wired up that 9-pin connector wrong). I'm 99% sure the cable is just something minor like a missing ground or something. Still, if I can find someone who has a RGB monitor and is willing to look at this for me I wouldn't mind shipping it out.

Well, I meant more like check the wiring to the 9 pin connector.

There is no reason for him to have wired all those different grounds up on the 9 pin connector on the console side (or did he?). And you mention composite sync. Was it amplified? Or is it actually composite video?


On scart cables, I typically wire for ground pin 21 (the shell), 18 and 4 (audio ground). There are separate ground pins for each of the RGB wires but it really isn't necessary to wire them. Most 3rd party console cables don't.



Maybe some pics of the wiring to all of this would help us?

 

[Jibbajaba]

Tempest, if you can, wire all of the grounds together in the SCART hood. Pins 4, 5, 9, 13, and 21. Then use a continuity tester to make sure that they are connected to ground on the machine side.

I seem to remember having a problem similar to yours one time on a SCART cable that I bought, and the issue was that shit wasn't grounded.

 

[skate323k137]

Tempest, if you can, wire all of the grounds together in the SCART hood. Pins 4, 5, 9, 13, and 21. Then use a continuity tester to make sure that they are connected to ground on the machine side.

I seem to remember having a problem similar to yours one time on a SCART cable that I bought, and the issue was that shit wasn't grounded.

That's my vote as well, at least for starters.

 

[Tempest]

Tempest, if you can, wire all of the grounds together in the SCART hood. Pins 4, 5, 9, 13, and 21. Then use a continuity tester to make sure that they are connected to ground on the machine side.

I can do that, that's an easy first step and the most obvious. If they're not, would soldering the wire to the metal sleeve on the SCART connector ground it? I do have a cheap volt meter (like the kind they give high school science kids) but I really have no clue how to use it. Are most cheap volt meters the same?

Well, I meant more like check the wiring to the 9 pin connector.
There is no reason for him to have wired all those different grounds up on the 9 pin connector on the console side (or did he?). And you mention composite sync. Was it amplified? Or is it actually composite video?

The sync should be amplified. Like I said, this thing worked before so I assume all the wiring inside the Duo is correct. The wiring on the 9 pin looks alright, I didn't see any wonky wires and they all went to the appropriate pins on the SCART connector so that looks ok. The only iffy thing is the lack of grounds other than the Audio Ground pin on the SCART connector which goes to a wire that is soldered to the casing on the 9-pin connector side.

On scart cables, I typically wire for ground pin 21 (the shell), 18 and 4 (audio ground). There are separate ground pins for each of the RGB wires but it really isn't necessary to wire them. Most 3rd party console cables don't.

Pin 21 isn't wired to anything, maybe that's the problem?


I'll get some pics tonight. The cable looks really well made so I'm guessing something just didn't get grounded appropriately (he said he had no experience with making SCART cables so he might not have known).

I know I've derailed this thread a bunch, but I really appreciate everyone's help.

 

[Skips]

I can do that, that's an easy first step and the most obvious. If they're not, would soldering the wire to the metal sleeve on the SCART connector ground it? I do have a cheap volt meter (like the kind they give high school science kids) but I really have no clue how to use it. Are most cheap volt meters the same?



The sync should be amplified. Like I said, this thing worked before so I assume all the wiring inside the Duo is correct. The wiring on the 9 pin looks alright, I didn't see any wonky wires and they all went to the appropriate pins on the SCART connector so that looks ok. The only iffy thing is the lack of grounds other than the Audio Ground pin on the SCART connector which goes to a wire that is soldered to the casing on the 9-pin connector side.


Pin 21 isn't wired to anything, maybe that's the problem?


I'll get some pics tonight. The cable looks really well made so I'm guessing something just didn't get grounded appropriately (he said he had no experience with making SCART cables so he might not have known).

I know I've derailed this thread a bunch, but I really appreciate everyone's help.

If pin 21 is not connected and none of the other grounds were not as well you pretty much have a scart cable with no ground. Pin 21 and 18 (or pin 17 depending on your switch/other cables) must be wired. Pin 21 is main ground and 18/17 are sync ground. The RGB grounds usually don't need to be connected however the main ground and sync ground for sure need to be. Personally I just connect all of them by jumping them off pin 21 when I make cables.

 

[Tempest]

If pin 21 is not connected and none of the other grounds were not as well you pretty much have a scart cable with no ground. Pin 21 and 18 (or pin 17 depending on your switch/other cables) must be wired. Pin 21 is main ground and 18/17 are sync ground. The RGB grounds usually don't need to be connected however the main ground and sync ground for sure need to be. Personally I just connect all of them by jumping them off pin 21 when I make cables.

That's probably it then. The only ground is to Audio Grnd (pin 4). His notes say "(really all the grounds are tied together inside the machine)", but I'm not sure what the heck that really means. I'll ground 18 and 21 and if that doesn't work I can add 17.

Since pin 4 is (audio grnd) already grounded, can I just wire those grounds into that pin? Or is it better to do each one separately? What's the best way to ground something? He grounded pin 4 by soldering a wire to the metal sheath on the 9-pin side. Any reason I can't do this on the SCART connector side (is the metal sheath on the SCART connector not grounded or something)?

 

[MtothaJ]

That's probably it then. The only ground is to Audio Grnd (pin 4). His notes say "(really all the grounds are tied together inside the machine)" , but I'm not sure what the heck that really means.

He is basically saying that the machine is a common ground device i.e. all grounds - whether its video, audio, sync etc. - are one and the same i.e. one reference point is used in relation to all signals and they are all joined together (i.e. there is continuity between the grounds at the machine end).
Take also into account that on a scart switch or a TV with a scart socket or a PVM / BVM all the grounds are common ground anyway so even if you connect a single ground it should be transposed to all the other grounds on the display end.

 

[Tempest]

He is basically saying that the machine is a common ground device i.e. all grounds - whether its video, audio, sync etc. - are one and the same i.e. one reference point is used in relation to all signals and they are all joined together (i.e. there is continuity between the grounds at the machine end).
Take also into account that on a scart switch or a TV with a scart socket or a PVM / BVM all the grounds are common ground anyway so even if you connect a single ground it should be transposed to all the other grounds on the display end.

Hmm... So maybe that's not it after all? Well, it's an easy test to do anyway so I might as well rule it out.

 

[Jibbajaba]

Like I said, I had the same problem and it was ground. I would say that the R, G, B, and audio grounds are probably tied together inside the machine, but they are also tied together in the hood when you buy any decent-quality SCART cable. I think what you just need to make sure of is that ground from the PVM side is connected to ground on the console side, and the way to do that is to tie them all together, instead of some dude (not you but the dude who made your deal) making assumptions about what is grounded to what.

I just stripped the ends off of short, maybe 1" long pieces of wire, twisted the ends together, and daisy-chained all of the grounds together inside the problematc SCART cable that I had. And are you sure that pin 21 isn't connected to the outer shield of the SCART connector? I don't think I've ever seen one that wasn't.

 

[Tempest]

Like I said, I had the same problem and it was ground. I would say that the R, G, B, and audio grounds are probably tied together inside the machine, but they are also tied together in the hood when you buy any decent-quality SCART cable. I think what you just need to make sure of is that ground from the PVM side is connected to ground on the console side, and the way to do that is to tie them all together, instead of some dude (not you but the dude who made your deal) making assumptions about what is grounded to what.

I just stripped the ends off of short, maybe 1" long pieces of wire, twisted the ends together, and daisy-chained all of the grounds together inside the problematc SCART cable that I had. And are you sure that pin 21 isn't connected to the outer shield of the SCART connector? I don't think I've ever seen one that wasn't.

It might be, I'll need to check tonight. I'm going from memory here. It's also possible that it was at one point and broke off. When I got the cable the metal sleeve on the SCART connector was pushed way in and wouldn't make contact correctly with the connector. I think it was banged up in shipping or something. I opened it up to fix that, but I might have jarred loose or something. I'll also take a pic of the cable if I get a chance.

I'm sure the audio is grounded because that pin is connected to a wire that goes all the way to the 9-pin side and is soldered to the metal casing. So what I'll do is daisy chain all the grounds to that pin. Either that or daisy chain them to the outer shield of the SCART connector. Dumb question, but is it possible to use something like tape to hold everything in place while I experiment with this? I'd rather not try soldering everything until I know it's going to work.

 

[opt2not]

Got my Shinybow 4x2 Matrix from a member over on the shmups forum, now setup with my PVM's:

Sorry for the crappy iphone pic.
Here's a better one up close:

I wasn't planning on getting the Matrix, since i bought the Bandridge Scart switch and was going to try just splitting the video signal from the cables. But this is cleaner and more error-proof! If anyone is interested in my Bandridge Switcher I'll be selling it off since it's no longer needed. Just shoot me a PM.

 

[skate323k137]

tempest, just solder it dude, it's not going to hurt anything.

 

[Tempest]

tempest, just solder it dude, it's not going to hurt anything.

Alright I'll stop being a pussy is just solder the thing. Even I can't screw this up!

(save this post for future comedic effect)

 

[skate323k137]

haha right on man. I know it's a long haul, but if you ever need to swing by for testing (or to play on some cabs) let me know

 

[Tempest]

haha right on man. I know it's a long haul, but if you ever need to swing by for testing (or to play on some cabs) let me know

If I can't get this working on my own, I might take you up on that offer.

 

[Tempest]

Pictures. Sorry they suck.

This is the top of the SCART cable. The Yellow wire on the left is Video In (pin 20).


This is the bottom the SCART cable. You can see that Pin 21 (ground) appears to have no attachment to the sleeve.


This is the top of the 9-pin. That wire soldered to the metal casing goes to audio ground.


And this is the bottom of the 9-pin.



So the plan this evening is to attach Video In Ground (pin 18) and Ground (pin 21) to an actual ground. I think I'll go for Audio Ground (Pin 4) since I know that goes to something that's grounded (as evidenced by the third picture). Unless I should attach these wires to the metal sleeve of the SCART connector or something like that.

EDIT: Looks like this will have to wait until thursday. I did try and 'fake it' by just wrapping wires around the pins but that didn't work. However when knocking something around on the SCART connector end I did get a perfect picture for a moment. I wonder what the heck I shorted together? Now I'm convinced that this is something as simple as a missing ground.

 

[city41]

Giving PVMs one last chance. Picked this new vertical one up from Bazookaman last night

The photo is crappy, this PVM is top notch, best picture I've seen yet out of a PVM. It's my fourth PVM, two others died. I can definitely say the 20M4U puts out a better picture than the other models I had (can't remember one model, but one was a 20M2U)

If either of these two die, I'm going XRGB.

 

[Jibbajaba]

Dude you need to adjust the horizontal and vertical size and centering on that shit. Have some respect.

 

[city41]

Dude you need to adjust the horizontal and vertical size and centering on that shit. Have some respect.

I've pretty much given up on that, as every PCB and system I have needs this tuned differently. It gets old quick.

 

[Jibbajaba]

I've pretty much given up on that, as every PCB and system I have needs this tuned differently. It gets old quick.

 

[Nyder]

Yeah, the 800 tvl 20M4U is something else compered to a 600 tvl.
Now you can't go back.

 

[cdamm]

I've pretty much given up on that, as every PCB and system I have needs this tuned differently. It gets old quick.