MVS MVH-MV4 Board Issues A Plenty

[Nerdygrrl]

Use just the bottom board and try tapping the chips and see if anything happens on screen. Also did you check the battery if there is leakage?

I did not see any leakage. There 'may' be trace damage from a battery before, but it is hard to say. I don't know if I am seeing actual damage or if my mind just wants to find the cause.

I powered up the bottom board, got the cross hatch and tapped all of the chips. Nothing happened. I put the board back together, fired up wind jammers in slot 3 and played for 1 minute before it cut to black.

I give up, I need another tested and working board or I need to bring this board to someone's place that has a cab.

 

[Nerdygrrl]

I am starting to wonder if this issue is unrelated to the previous owner's black screen and if the monitor is going into hv shutdown.

 

[Alpha Skyhawk]

There 'may' be trace damage from a battery before, but it is hard to say.

Multimeter.

Continuity test.

That chart (if applicable).

*Beep* *Beep*

You now know if there is any trace damage.

 

[Nerdygrrl]

I will check the traces tomorrow. I think I am having two separate issues.

Issue 1: No sound slot 1. I am guessing this is the board and the trace.

Issue 2: Blacking out a minute or so in and restarting in 20+ minutes. I am guessing it is going into HV shut down. I pulled the monitor out and made sure everything was plugged in and tight. So far I have played 30+ minutes with no issues. I took the rear door of so if I can get it to blackout again I can verify the shutdown.

This was supposed to be my easy fix today. Over 5 hours in and I still haven't looked st my Joust boards.

 

[Nerdygrrl]

Update while the PCB has issues with slot 1 with no sound. I believe the blacking out is a problem with the monitor. I feel like I just got hosed big time.

Yesterday I fired up the cab a few times, got the screen image only to have it black out after a minute. You could still hear everything playing but the monitor was black. After getting paranoid that it was going into HV shutdown I removed the monitor, reseated everything and all was well again. I played for a good hour plus. Fast forward to today, swapping carts I get the black screen take the back door off to check for shutdown, but I have neck glow and I can hear the monitor running.

Get cranky, kick a puppy or two, and head to my office to grab an LCD to test it to see once and for all if this is a board or a monitor issue. Get home, remove the RGB harness from the chassis only to find the pins on the molex and the LCD are different sizes, cuss and scream and kick more puppies, reinstall the RGB fire up the cab and I have a picture. WTH?! Not only do I have a picture, but I played through 5 levels of spinmaster.

I don't know if I am grasping at straws, desperate to find out what is going on, but this is the third time that I have regained the screen image by taking off and reseating the RGB. The cabinet has not moved, there is no pressure on the harnesses so it's not like the harness has moved.

 

[Xian Xi]

What brand and model is the monitor? It could be the PSU for the monitor, usually they have regulated power supplies. If the PSU is getting wonky it could do just that. It could also be a diode going bad or even a resistor going bad. If those points are fine then it could just need a cap kit.

 

[Nerdygrrl]

It's a Toei TC-RM251S with a Toshiba tube. I am hoping to pull the chassis on Sunday to check the caps and the B+ (just in case)

These monitors are very new to me. I have owned a plenty of US woody cabs, but this is my first candy. There is another guy on AO that is going through the same thing with his Astro. I am hoping between the two of us we can figure this out.

 

[Xian Xi]

Try searching online for a flowchart for your monitor, those help out a ton.

 

[Tyranix95]

Now is the time when known good parts would come in really handy.

(A second board, a backup PSU, an extra harness, or a spare monitor.)

You really need to know what parts in that cab work, Ok, and what parts are not.

IMHO, I'd start with the baord.

 

[Nerdygrrl]

Now is the time when known good parts would come in really handy.

(A second board, a backup PSU, an extra harness, or a spare monitor.)

You really need to know what parts in that cab work, Ok, and what parts are not.


IMHO, I'd start with the baord.

I am trying to source a local board or a MVS to Jamma Adapter (oh why can't this be Jamma)

I am also going to try and fashion a monitor harness so I can hook up the LCD. It looks like the same sized pins as a Sanyo EZ20. I may sacrifice a video cable from one of our Nintendos and splice in a WG style monitor adapter so I can hook up the LCD.

 

[Tyranix95]

DIS-Connect the Speaker(s) from the JAMMA Harness (in the JAMMA cab). IMHO, it may be easier if you disconnect the speaker wire(s) on the speaker side (instead of the harness side). And remember how to re-connect the speaker wire so you can put 'em back when you're done testing.

Now, you can run the MVS board in the JAMMA cab withOUT any speaker(s) connected to an MVS board. In theory, the MVS baord ought to work OK with the speakers DIS-connected from the MVS board. You just will NOT hear any game sounds. (IIRC, the 4 Slots have two headphone jacks built on to the side of the board. You may be able to test game souds through these ports.) If the MVS board problems persist, the you have a board problem.

 

[Nerdygrrl]

DIS-Connect the Speaker(s) from the JAMMA Harness (in the JAMMA cab). IMHO, it may be easier if you disconnect the speaker wire(s) on the speaker side (instead of the harness side). And remember how to re-connect the speaker wire so you can put 'em back when you're done testing.

Now, you can run the MVS board in the JAMMA cab withOUT any speaker(s) connected to an MVS board. In theory, the MVS baord ought to work OK with the speakers DIS-connected from the MVS board. You just will NOT hear any game sounds. (IIRC, the 4 Slots have two headphone jacks built on to the side of the board. You may be able to test game souds through these ports.) If the MVS board problems persist, the you have a board problem.

Thank you so much! This will help a ton.

 

[mjs256]

(IIRC, the 4 Slots have two headphone jacks built on to the side of the board. You may be able to test game souds through these ports.) If the MVS board problems persist, the you have a board problem.

MV4 boards have headphone-like jacks that are indeed connected to the sound circuit, but they are NOT headphone jacks. The jacks do carry the sound signal but you will hear very little (if anything) from them if you connect headphones to them because headphones have much too low impedance. However, you might be able to use it as in input to a high-impedance amplifier and get sound from them that way.

 

[Nerdygrrl]

A major thank you to everyone who helped out so far. Thanks to Tyranix95's chart I modified the cab's harness to allow me to install a Jamma board in the cab. Within five minutes the screen cut to black. I tested the PS and I am getting normal readings leaving me to believe this is for the most part monitor oriented.

The 4 slot is missing sound on slot 1, but that appears to be all.

 

[Tyranix95]

So far, it looks like you have two problems: (1) No Sound On Slot 1, which is an MVS board problem; and, (2) Monitor Blacking Out, which is a monitor issue.

Need to see your parts: Post a good pic of the PARTS side of the top MVS board and the bottom MVS board--Post a good pic of the SOLDER side of the top MVS board and the bottom MVS board. Post a few of good pics of the BACK of the monitor. Try and get a good shot of any boards, caps., and connectors.

 

[channelmaniac]

The way the slots work on the 4/6 slot boards is this: They have interfacing TTL chips then the far side (from the slot) of the chips for each slot tie together and go to the bottom board.

In other words... Data bus 0 connects from a slot (any slot... pick one) through a 74LS245 bi-directional latch to the bottom board. Where it goes to connect to the bottom board you'll have the other slots' data bus 0 connection too.

If you have a sound problem on one slot it's either a dirty slot, bent slot contact, or a gouged/corroded trace. It's RARELY the TTL chips as since they are tied together on the far side one bad chip tends to cause problems on all slots for that particular line's signal. Since you have the problem on one slot this leads me to lean towards a dirty slot, bent slot contact, or a gouged/corroded trace.

RJ

RJ

 

[Tyranix95]

Thanks CM.

@ NG, DID you clean the cart & slot contacts real well--like XX told you?

 

[Nerdygrrl]

I have that Hasa D5S stuff on order from Amazon. I took a tooth brush and some high concentrate rubbing alcohol to it and contemplated Simple Green.

Right now I am going to focus on finding the source of the black out. The previous owner mentioned that the RGB cable would come off whenever it was moved and it would play blind which is essentially what it is doing now on and off. When I picked up the cab we rolled it down the dway and into the car where it sat for an hour plus ride and the RGB harness never came off. I have also found it to be fastened quite well when I have gone to remove it to look at the monitor. I doubt it would fall off from being moved. I am thinking he assumed the lost picture was a result of a loose RGB and reset it and voila picture. This has happened to me on three occassions.

My guess is there may be a short somewhere or possibly a broken solder joint that has gotten worse with time. Since narrowing down the problem to the monitor I noted two things:

1. When I touched the screen to see if the monitor was still on I got the static surge which briefly brought the image back-like split second.

2. When closing the CP the 'force' also brought the screen image back

I am going to check the continuity in the RGB harness and then start looking over the chassis tomorrow starting at the RGB pins for cold solder/bad solder joints.

I can live for a week or so with now sound in slot one. No picture is another story. I can't thank everyone enough for helping me narrow this down. It was tough when I was told both the board and the monitor at one time or another would black out.

 

[Tyranix95]

Forget Simple Green. Instead use Rubbing Alcohol, WinDex, or DeoxIT DN5 and Q-Tips & Paper Towels and a Club-Card. Also, use uncented Dish Sopa, a Toothbrush, and Warm Water if you need to clean the PCBs.

Also, spot check the board for broken traces and corrosion.

-----

As for the monitor, do the same: Spot check the boards for broken traces, corrosion, swolen caps, and loose headers.

Good luck.

 

[Nerdygrrl]

The previous owner noted that the lack of image/sound in slot 1 was still present when he tried a different top board. I am guessing there is a bad trace somewhere on the bottom board.

 

[channelmaniac]

Nope... Not a bad trace on the bottom board. It doesn't work that way. All the slots share the same lines for data coming down to the bottom board from the top board.

 

[Nerdygrrl]

OK, cleaned the hell out of the board, but still no sound in slot 1. No bigs. I'll either send this board out to be fixed or buy a new board.

Traced the monitor issue to the RGB board/harness. I am going to reflow the solder to the pins on the RGB board and then fashion a new harness for the RGB cable.

Word!