rooth's Big Red -- technical worklog

roothorick

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This is more just putting my thoughts down so I don't forget anything, though commentary from the enlightened peanut gallery is welcome. For reference, it's a 4-25 version 3 with the black marquee.

Outstanding problems:
  • I do not like ANY of the games in it :mad:
  • No sound from speakers. Headphones are fine (volume goes up to FREAKIN' LOUD!) though.
  • Monitor has very very weak red and green.
  • Title card lights don't work.
  • DAT CP. Left joystick is utterly unusable, right A button is completely destroyed.

As a precaution, I removed the battery from the mainboard. It looked, frankly, almost brand new. I didn't see any signs of leaking at all. Still, I'm leaving it out. I'll add on a connector and put a displaced battery somewhere in the cabinet (much) later.

Troubleshooted the sound issue a little bit. Speakers meter good -- 8ohms each. Didn't check cabinet wiring. Checked 12V -- 12.15 at edge socket with board connected. Using some shitty unamplified speakers I had laying around, plugged into the headphone jack, as a workaround until I get around to figuring out what happened to the amp.

Played with the monitor a bit too. Green and red respond to cutoff/gain pots but are VERY weak. As I turn up the gain pots, they become visible but very dim, then just bleed out, still very dim. I'm scared for the tube :( still, I'm gonna try swapping around the CDTs.

The marquee lights are not what I was expecting. I was expecting a SMT LED array with a diffuser. What I actually found is what appears to be electroluminescent pads (think EL wire except a solid rectangle), four of them on two PCBs, driven by yet a third PCB mounted behind the marquee. Fascinating shit, I'm gonna have to spend some time with this circuit.
 
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Marquee lights are EL (Electro-Luminescent) panels and are almost always dead on cabinets these days. You can cut some new EL panel material to fit if you can find it.

No audio out = time to recap the audio section. I sell kits on my site if you don't want to dig all the caps up yourself.

Sucky games are easy to replace. There were many many many great titles for the Big Red. Metal Slug (any), Shock Troopers 2nd Squad, and Top Hunter are my faves. Every Big Red needs a Puzzle Bobble game. :D

Good on ya for removing the pesky battery. They cause many MVS deaths.

On the monitor, it's VERY easy to rejuvenate a CRT. If you were closer to me I'd say bring it over and I'd show you how.
 
Marquee lights are EL (Electro-Luminescent) panels and are almost always dead on cabinets these days. You can cut some new EL panel material to fit if you can find it.

So the panels themselves die, it's not the circuit on the back? :(

I'd sooner make new lights using LEDs and a little fiber optics.

No audio out = time to recap the audio section. I sell kits on my site if you don't want to dig all the caps up yourself.

That's what I figured. I had a gander at the audio section while I was ripping out the battery -- that's a LOT of caps :(

On the monitor, it's VERY easy to rejuvenate a CRT. If you were closer to me I'd say bring it over and I'd show you how.

I don't have a rejuvenator though. If I have to go that route that means either a) ripping the tube out of the cabinet and making a day trip to Chad's or b) somehow convincing Chad to come here. Either way it'll cost enough money to definitely not happen anytime soon.

What do you think the odds are of it being a tube problem vs. a chassis issue? Chassis problems I can fix myself... probably.
 
Yup... the panels themselves are bad. They do that... it's a downside of using EL panels.

Yup... it's a shitload of caps to replace, but once done the audio will be good for years to come.

And from your description, I'm 95% sure it's the tube.
 
And from your description, I'm 95% sure it's the tube.

Sigh :( In that case it's gonna sit in the corner for a few months until I have some spending money, upon which it'll probably get some better carts and a CP rebuild first. Monitor is good enough to play, just hard to see.
 
I shot the tube, and I won! At least, that's what the meters on my 5230 tell me. I'm letting it cool off before I fire it up on the chassis. Adjusting the color bias/gain is gonna be a bitch.

-E- Yep, I have red and green now, and they look pretty strong! Blue is a mite stronger but I think I can adjust that out with the gain/bias pots. Speaking of, I think I'm gonna put the factory chassis back in just to not have to readjust both flybacks. I don't know if one of them might have a pinhole...
 
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Glad to hear the rejuvinator won :D

Let us know if you plan on tackling the audio caps. I have an odd audio problem on my Big Red myself, but it isn't that the audio is weak or anything.

I just get a very loud clicking occassionally when hitting loud notes (not all the time, but fairly often). This happens even if I have the speaker volume all the way down, no sound then suddenly the loud clicking.

I have the same work around at the moment. Took an external speaker, put it on top and hooked it to the headphone jacks and it sounds beautiful :D
 
Sounds like the amp chip is oscillating. You'll find some mylar caps on the outputs... follow the traces back from the JAMMA edge connector, past the 470uf caps, and back to the mylar caps.

Remove them.

I've seen that before and removing those caps from the outputs takes care of it.
 
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