In search of crt goodness. So close, but so far..

[capretta]

Hi, first i would like to curse you all for sending me on this quest for crt perfection. I now have whiplash from checking junk piles for discarded scart tvs, and I am over come with sadness when i see a crt that only has svideo inputs as if seeing a child grow up to waste their potential.

Secondly, I would beg of you some advice.
During groovy arcade setup i managed to get a passable, if slightly wavy (interlaced) image, and commenced setup during which i turned the tv off. When i turned it back on this is what i was greeted with.

Picture is fine in svideo albeit squished and black and white, so it cant be the tube right?
I have subsequently tried every thing i could think of to remedy the problem, bought a new scart cable, installed crt emudriver over win xp 64, resoldered joints.. 
One thing i noticed on the 2 1k resistors im reading continuity values of 1000 on one cable, and 1005 on the other. I followed this diagram could that have caused this?
I am at my wits end, im hoping someone with more crt experience can help.

Specs: e8400 cpu
rv370 (x300) gfx card
grundig st70 670 top tv
vga to scart cable


photo pre screwing up


cable im using

[adder]

ok try this:
- dont use pin 14 on the vga connector. leave it unused.
- connect pin 13 from the vga connector to pin 20 of the scart cable, without any resistors.

EDIT: actually  looking at this again, i notice in your picture of your wiring that you have not made a connection between one of the black (ground) wires from the pc molex cable to one of the ground points on your vga/scart wiring (eg. vga pins 5,10 - scart pins 17,18). you need to do that. so do that first and then see if you get a steady image.

[PL1]

One thing i noticed on the 2 1k resistors im reading continuity values of 1000 on one cable, and 1005 on the other.

One is exactly 1K Ohm, the other is 0.5% higher.

Assuming the tolerance color code band on the resistor is the much more common silver (+/-10%) rather than gray (+/- 0.05%), it seems to be well within acceptable range of values.   


Scott

[capretta]

Hey Scott, yeah they are brown black black brown Brown iirc, tolerance of 1%. it's less than you'd find on the 10% tolerance ones but it seemed like it was a sync problem , so I thought my telly may have just been sensitive.

@jadder, thanks for your reply, I have seen no stuff online about hooking a ground up to those wires, I assumed the sync grounds did it themselves through the video card. I will hook the sync ground up to pin 21 on the scart which is chassis ground, then try Molex as well. might not get to it today though, yesterday was my no kids dick around with tv's with the back off day.

Any thoughts as to why it worked for 15 odd minutes without the ground attached?

[adder]

@jadder, thanks for your reply, I have seen no stuff online about hooking a ground up to those wires

have a look at the pic at the bottom of the first post of this thread here:   http://forum.arcadecontrols.com/index.php/topic,77370.0.html

Any thoughts as to why it worked for 15 odd minutes without the ground attached?

sorry, not sure on that one

[capretta]

Huh, I've actually read that thread probably 6 times..  oh man, I really don't have time to muck around with it this arvo but I don't see how I'll be able to resist just flicking it on and pressing a wire here and there.. I mean seriously, how much time could it possibly take! Thanks again, I'll keep you posted.

[capretta]

Sad news (for me) to report. Attaching ground via Molex to either 17/18 or 21 had no effect at all. Even jumping chassis ground on the Vga to the 21 case pin on the scart did nothing. The only appreciable effect I got was when I accidently touched the 5v wire with the ground 😵 I'm beggining to think maybe my rgb input is fried somewhere along the way on the tv. Gonna have to do some more screwing around. Thanks for your suggestions in any case, you got me quite excited!

[u-man]

buy this, less pain:

http://arcadeforge.net/UMSA:::15.html?language=en

or this:

http://www.ebay.de/itm/VGA-RGB-ARCADEVGA-TO-SCART-CABLE-ADAPTER-1-6M-EUROCONECTOR-for-JAMMA-system-/141538519026?pt=LH_DefaultDomain_0&hash=item20f45a67f2

considering how much time you spent, to get it working, it is a "cheap" solution.

[capretta]

Posting once more for completion.. I stand before you a broken man. I rewired to specs on the the post on the monitor forum with ground from the pc, no change. I changed to another tv, a Sony kd32nx200.. no change. I scrounged up another x300 from the tip. No change. Convinced it was my cable I threw myself into learning everything about scart and Vga plugs and can now recite the pinouts on both from memory. I used no resistors on the sync cables. I used matched resistors from the 1k packet to ensure the resistance was identical. I rewired a new cable that was almost the same barring pin 18 having a seperate ground supplied by the computer for the  voltage and the Vga cable only provided a common ground for the rgb. No change. I installed power strip and forced negative sync voltages. No change.

I wouldn't be so confused if it hadn't worked for that beautiful 10-15 minutes early on.

I do appreciate those like the above poster and others who pm'd saying just buy the usma scart thing but that's not what would satisfy me. I see now though that it's my only choice. Thanks everyone for answering a first time posters "it doesn't work, fix it" thread.

I'll go back to lurking now.

[Calamity]

FWIW, what your video shows is clearly an H-sync problem. I'd say the problem could be the composite sync you're producing by wiring the sync cables together plus the 1k resistors is not good enough. If you look at this post from Paradroid, he's adding a specific c-sync circuit:

http://scarthunter.blogspot.com.es/2012/04/how-to-make-vga-to-scart-cable.html

Probably the scheme you're using is good for other TVs. I'm curious of what happened with the Sony... same messed up picture? Blue screen?

If I had seen your video and you told me it's an arcade monitor, my instinct would be adjusting the H-freq pot.

[capretta]

 
Well i didnt want to needlessly update this thread, thanks calamity for your input. I did make up the c sync circuit but the instructions are somewhat incomplete ( ie vero board diagram does not show c sync out ) but i had a stab and didnt get any picture at all.
After this I had somewhat of a medical issue and while lying in hospital the voices of all those telling me i was wasting valuable time kept echoing in my ears. So I ordered a UMSA scart adaptor. Finally it came today and I plugged it in to my loewe and what do you know...

identical issue.
Also the sony was similarly afflicted.

for some reason the sony doesnt display much of the colour, maybe due to better signal processing.


In desperation I thought maybe the polarity of the 5 v power supply for the umsa was the wrong way around, so I switched that round and subsequently blew it up.

I dont think a crt arcade unit is in my future.

[capretta]

Tried a few more things, wiped xp and 're installed groovy arcade, the install screwed up and just hangs on the intro screen. I ran it from the live CD and in the pal setting I got the horizontal rolling the slowest it goes, but it's still unreadable. here is a video of the new telly (grundig sedance 72 sorry not a Loewe) starting up through bios into groovy arcade. I never seem to get even the doubled picture I'd expect from 31khz ..
sorry about the music, I needed something calming at this point.

Grundig groovy arcade screen from power on.:

[adder]

sorry to hear of the ongoing problems
can i ask regarding your X300 card, is this the only card you have used so far. is it possible for you to get an ATI HD4xxx card from eg. ebay
also, regarding the current vga to scart setup you are using, could you post a diagram/picture/explanation of exactly what pins on the vga and what pins on the scart you are using plus any resistors and so on

[Calamity]

sorry to hear of the ongoing problems
can i ask regarding your X300 card, is this the only card you have used so far. is it possible for you to get an ATI HD4xxx card from eg. ebay

+1

I was about to answer the same thing. The fact that the UMSA didn't work either is pointing to the only thing that we were excluding because it's so unlikely that it's faulty: the video card. Your video still shows the hsync being off. It could be the corresponding pin is damaged, or just the crystal is damaged and can't go down to low dotclocks reliably.

Sorry to hear that and hope your health is fine now.

[capretta]

sorry to hear of the ongoing problems
can i ask regarding your X300 card, is this the only card you have used so far. is it possible for you to get an ATI HD4xxx card from eg. ebay
also, regarding the current vga to scart setup you are using, could you post a diagram/picture/explanation of exactly what pins on the vga and what pins on the scart you are using plus any resistors and so on

Hey, thanks for the reply. I am using 2 different X300s and after reading your post I went digging around for an old nvidia I had and, well ,the bastard worked. Kind of. I get a picture now when doing groovy arcade setup, but it won't launch into live CD launcher. I tried a 5770 I picked up at the markets, but I think it might be doa, cause I can't get anything out of that so I've bit the bullet and bought a 4850. Picking it up on the weekend.

Here is some pics of the 2 cards I've been using and the nvidia one that worked, plus the fail screen for posterity.

http://imgur.com/a/AMvFt#5urMLmw

[capretta]

Sorry to hear that and hope your health is fine now.

Ha , thanks, nothing like this project to make me feel sanguine about ones own mortality.