HELP video error

ok i have a stable picture now but its a bit dark (i guess use the rgb under the panel)

UPDATE

it all works fine now the rgb under the panel corrected the colours and it seems that some pcbs do not connect to my jamma harness as well as others. but a bit of a wiggle of the jamma connector and its a perfect picture

cheers for your help aryssor
and to everyone else

 

No worries.

It's not uncommon to have to adjust rgb between pcbs too.

 

up to this point i never had to but we learn cheers once agin.

 

aliens pcb

hi its a aliens pcb problem now I'm getting dots at the top of the screen every time it loads up a level/intro etc they appear but don't last long.also I'm getting lines that appear on this part of the demo but you can't see them in pic 2.

is this a pcb problem or my cab cos i brought the pcb 100% working

aliens on a sega astro city

 

Try adjusting the +5V trimmer on the PSU.

 

OK thats the v.adj little hole thing on the top of the psu i guess.
do i need to take the right side panel off cos its well stuck the screws are on tight.

atb

 

Umm, I don't know what cab you've got!! :lol:



Top control

 

one for a sega astro city i wish my psu looked that easy to adjust

mine is like this but with the buttons on the front
http://slawdog.net/hc//uploads/AstroCity/Inside.jpg

service switch/test switch/demag switch/4afuse-not a switch really-

on top their is a small hole and above that is says v.adj i can't really see inside.
i will see if i can get it open though.

 

Although unlikely, you want to make sure when you adjust the 5V that you do have the board plugged in and working and that you have a multimeter so you know you have 5V. Check the voltage from the JAMMA edge connector on the GND (pins 1&2) and 5V (pins 3&4). This should just be over 5v (say 5.05V).

If possible check the 5V signal from a chip at the bottom of the board. Find a 74 series chip (a 14 or 16 pin version) there will be a notch at the top (or a dot on the top right) with this at the top put the ground lead of the multimeter on the bottom left hand pin of the chip and the positive lead of the multimeter on the top right hand pin of the chip, you want to read between >4.9 and 5.0V. If it is less then 4.6V then this is when you start to get issues.

 

OK cheers for the info i will test this tomorrow.

in pic 2 the lines appear only when Ripley is in the mech i dunno if thats due to it being under voltage i am no expert.

thanks for the help guys

 

Oh, those.

That's a hole for a trimmer tool. Don't take it apart FFS! And use a trimmer tool on live PSUs, not a screwdriver!

 

ok got ya don't take it apart... i am going to test the voltage first to make sure.

 

hi
it looks like I'm getting 5.07 to 5.08 volts on the connector and its stable at 5.07

 

You need to measure it on the PCB while it's under load, it's no good measuring at the connector, the further from the connector the better

 

where should i try on the pcb i don't know where the 74 series chip is really.

 

Probing a graphics ROM would be a good idea ;-) Look up its datasheet for the pinout.

 

the guy is now saying its in the programing so don't worry.but i will test the roms and chips all over the pcb.

 

I tested as much as i could its 5.07 all over.the mask roms and the chips near the conector the chips at the bottom of the pcb and the chips in the middle of the pcb its the same voltage 5.07.

fuck it i will keep the pcb cos its not the first time i have brought a 100% working pcb that had problems...

thanks for you help everyone anyway.