Author Topic: Jamma to scart problem  (Read 9791 times)

Vnera

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Jamma to scart problem
« on: October 24, 2011, 03:03:33 PM »
http://www.youtube.com/watch?v=GfIVj0P_JhM

I have a beast busters that has a busted monitor. So i wanted to replace it whit a new tv. So i made a jamma to scart connector and hooked up to the tv and got the result you can see in the link above.

The harness worked whit other tv's but the one i want to use has this weird problem. Any advice?

Also got a ram error on the board any tips? already checked the +5 volt and it seems oke.

level42

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Re: Jamma to scart problem
« Reply #1 on: October 25, 2011, 12:35:46 AM »
So the beasts busted the monitor eh....:P How busted is it and what monitor is it ?


That looks like a sync problem. Try to find a pot for it inside the TV.

On the other hand, since the Video RAM has a problem....it could be the board too...


Did you use the required resistors to adapt the voltages (I know many people skip them and usually it works, but it's NOT according to SCART specs.)

Vnera

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Re: Jamma to scart problem
« Reply #2 on: October 25, 2011, 09:01:15 AM »
So the beasts busted the monitor eh....:P How busted is it and what monitor is it ?


That looks like a sync problem. Try to find a pot for it inside the TV.

On the other hand, since the Video RAM has a problem....it could be the board too...


Did you use the required resistors to adapt the voltages (I know many people skip them and usually it works, but it's NOT according to SCART specs.)

the monitor was so busted that it needs a  new Lopt (transformator)? i looked for a new one but the start at 130 euro and then there is the problem that its made for a smaller monitor. they try to compensate this bye adding a fan but its doomed to fail.

I have used all the resistors in my adapter and even found out that most tv's only have RGB on scart input 1. (took me some time to find that out)

i have also tested it whit a other board that dosnt has a vram error but sprite issues and has the same problem.

So time to bust the beast open and see if i can find a pot!

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Re: Jamma to scart problem
« Reply #3 on: October 25, 2011, 10:30:04 AM »
Look for "Vertical hold" pot...

Vnera

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Re: Jamma to scart problem
« Reply #4 on: October 25, 2011, 01:32:36 PM »
I have opened already and i couldn't find any pots.  :-[ Only one but that was on the sound part of the board. Also the lop contained 2 pots but those ain't the pots where looking for  :lol:

Also found out the monitor fixing holes are allot difference 5cm in the length and 3 in the with but thats a problem when i'm gone fit it in the cabinet.

If pics of the inside could help i have made some.

PunkRockCaveman

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Re: Jamma to scart problem
« Reply #5 on: October 25, 2011, 01:46:17 PM »
Often tvs are "calibrated" at the factory and there are no pots for h/v-hold or other stuff you can regulate on an arcade monitor chassis. I had some tvs that had fixed resistors for some settings that easily could be exchanged with pots and voila ... manual settings were possible ;)

You need the schematics of that chassis for that reason and have to locate the (missing or fixed) resistors for h/v-hold in order to swap them with pots. Sometimes the pots are just fixed with glue or something ... maybe have another look to find that ones. You will need the schematics anyway to see, where the different settings are made.

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Re: Jamma to scart problem
« Reply #6 on: October 25, 2011, 02:36:23 PM »
how old is that tv ? maybe it has an electronic set up ( through service code and menu's)

Vnera

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Re: Jamma to scart problem
« Reply #7 on: October 30, 2011, 09:24:45 PM »
how old is that tv ? maybe it has an electronic set up ( through service code and menu's)


Jup and i found it! relay happy that i found it. dident test it yet but gone do next weekend because i have  exams :evil: so no time to fiddle around whit arcade cabinets. Cant wait to finsh the monitor and start focusing on the pcb.

Vnera

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Re: Jamma to scart problem
« Reply #8 on: November 06, 2011, 02:38:02 PM »
now my examen's are over its time to start working on this beast again. I found the service code in this document http://dc205.4shared.com/doc/yKDDd2SC/preview.html

Try ed allot of settings but non of them seem to do the job. Then i found auto set and try ed that but that was even worse. Its weird to me that you can set all sort of crazy things in the tv but the vertical and horizontal sync are nowhere to be found. It must be somewhere but i cant seem to find it  :-[

Vnera

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Re: Jamma to scart problem
« Reply #9 on: November 23, 2011, 03:26:19 PM »
Oke so i'm aboding the idea of fixing this problem in the Menu of the tv its self. so i'm going for the suggestion PunkRockCavemand made

Often tvs are "calibrated" at the factory and there are no pots for h/v-hold or other stuff you can regulate on an arcade monitor chassis. I had some tvs that had fixed resistors for some settings that easily could be exchanged with pots and voila ... manual settings were possible ;)

You need the schematics of that chassis for that reason and have to locate the (missing or fixed) resistors for h/v-hold in order to swap them with pots. Sometimes the pots are just fixed with glue or something ... maybe have another look to find that ones. You will need the schematics anyway to see, where the different settings are made.

I found the schematics here http://www.scribd.com/doc/26784858/GRUNDING-C7-C8-chassis

Now i understand electronic schematics but i don't yet understand the working of a tv good enof to find the resistor that dos the job of the vertical sync part.

I think i need to chance the resistor thats on page 23 and on the big chip right side 4 and 5 for the top.

Is there somebody who could say if thats the good resistor? Thx in advance.

Also found a other monitor same size that doesn't has this problem but has a dirty scratch in the middle  you don't notice it when you play for longer then 1 minute but it isn't ideal what your your thoughts on that?

Blanbek

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Re: Jamma to scart problem
« Reply #10 on: November 24, 2011, 12:52:09 PM »
Hello  :)

André may be right, Tries with a resistance like this ?

pin20: 390 Ohms ( sync )
pin 16: 560 Ohms ( +12v )

pin 15 red, pin 11 green, pin 7 blue, pin 8 +12v, pin 5,9,13,18 negatif -




Here is the full link, it works well for me:

http://www.arcade-system.com/index.php?option=com_content&view=article&id=433%3Asupergun-construisez-votre-propre-acade-systeme&catid=36%3Amontage-de-composants-conversions-a-creations&Itemid=27&limitstart=3

level42

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Re: Jamma to scart problem
« Reply #11 on: November 24, 2011, 01:15:29 PM »
Hello  :)

André may be right,

Are you doubting me ?  ::) ::) ;D ;D

Quote
Tries with a resistance like this ?

pin20: 390 Ohms ( sync )
pin 16: 560 Ohms ( +12v )

pin 15 red, pin 11 green, pin 7 blue, pin 8 +12v, pin 5,9,13,18 negatif -




Here is the full link, it works well for me:

http://www.arcade-system.com/index.php?option=com_content&view=article&id=433%3Asupergun-construisez-votre-propre-acade-systeme&catid=36%3Amontage-de-composants-conversions-a-creations&Itemid=27&limitstart=3


Those resistors are there to adjust the voltage of the signals coming out of a classic arcade board to SCART norm levels. Inputting higher voltages can damage the TV. Maybe not right away, maybe only after a long time,maybe not at all, this all depends on what is on the input side of the TV. Personally, I hate MAYBE's so stay safe and use the resistors !

If you want my elaborate view on it:
http://forum.arcadecontrols.com/index.php?topic=77370.0

However, they have no relation to what VNERA's problem (and one of my reasons for not using TV's) is.

VNERA can you mail me the schematic, looks like I have to pay for it ? Please just send me the part where that resistor is and I'll see if I can give an educated guess ;)
« Last Edit: November 24, 2011, 01:23:27 PM by Level42 »

Blanbek

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Re: Jamma to scart problem
« Reply #12 on: November 24, 2011, 03:59:21 PM »
Quote
If you want my elaborate view on it:
http://forum.arcadecontrols.com/index.php?topic=77370.0

I know this little drawing with 100 ohms resistance, it is with this that I build my first MameCab, soft 15khz, modelines, etc ...  :D




Vnera

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Re: Jamma to scart problem
« Reply #13 on: November 25, 2011, 05:20:37 PM »
I used the wiring schematics polderacade once posted. I spoke to him on eurocade and told me it worked great for him.
 
VNERA can you mail me the schematic, looks like I have to pay for it ? Please just send me the part where that resistor is and I'll see if I can give an educated guess ;)

Thanks allot! i have sended you the schematics to your email.

If more people would like to see the schematics just pm me your email and i will send the zip file.