Blast City screen issue

[Retro77]

Hi all,

One of my Blast city machines has developed a screen fault. Around every minute or so the screen looks to very quickly turn off and on again. There is also the occasional line that appears too. Not sure how else to describe it.

I have swapped out the remote board for another one as the pots (particularly the vhold) is very sensitive but this didn't work. I also swapped out the PSU thinking that it is maybe a voltage issue but this didn't fix it either (unless I guess, maybe both of my PSUs are on the way out).

I have had a look inside and can see an earth cable next to the VGA cable that isn't connected to anything. But as I said, it has only recently started doing this.

Does anyone have any idea what the cause of this is and (fingers crossed) if it is repairable.

Cheers

 

[Vamino]

I've never had much luck with Wei Ya/Makvision/Rodotron.

The soldering on these is not the best so try checking for dry solder joints. Also read that cooling the chassis and neckboard with fans prolongs their life.

Hopefully someone else chimes in and can give you more insight in resolving the issue.

 

[Retro77]

Thanks for the advice, Vamino.

I have been back to the cab. When it is on I think I can hear a tiny clicking sound that is more regular than the screen issue (maybe every 10 seconds or so).

It is really faint. So not sure if it is the monitor making the noise or the PSU as that is a bit noisy when sat close to it.

 

[Funhouse71]

That blue JunFu 35v 1000Uf cap looks like it's leaking also JunFU is on the list of bad caps @ badcaps.net

https://www.badcaps.net/forum/showthread.php?t=388

Maybe worth recapping the chassis?

 

[Lurch666]

That blue JunFu 35v 1000Uf cap looks like it's leaking also JunFU is on the list of bad caps @ badcaps.net

https://www.badcaps.net/forum/showthread.php?t=388

Maybe worth recapping the chassis?

Isn't that just epoxy to hold the cap in place?

 

[gunblade]

i think your flyback is failing but it could be a vertical fault

 

[Retro77]

Are they issues that can be fixed, Gunblade?

 

[robotech]

Ive got a couple of spare used fly backs here if you can solder and want to try one
Out

Might be worth a try if grant thinks its the flyback

These are not very good monitors in my opinion though poor quality soldering caps relays and pcb/traces

robotech2020-12-11 21:21:34

 

[gunblade]

yes they can be fixed, they are ok chassis once serviced- not in the 2931 or tosh quality group but as good as a polostar imo

 

[Retroman839]

i was reading on arcade projects that H V leakage can come from the fly diode lead , right where it leaves the top of flyback cas. as if the sheathing of the anode lead is not properly shielding.
they used builders silicone to reinsulate that area.. and it worked for them.

i have a monitor doing the same thing and i have not got round to doing it yet, but i am going to give it a try as read yeh great results for them using this remedy.

my monitor doing tis also makes a crack sound each time..

and yeh pic just drops for a split second as crack sound.. but like gunblade says hv leakage probly is the internals of the flyback also failing/ destroying its self

 

[Retro77]

Thanks for all the help, chaps. I have a fix arranged.

Does anyone have any tips for removing the chassis? I assume the whole CRT has to be removed. It's not like working in the back of a standard jamma cab.

Cheers