MV1FZ Hardware Test Failed (diagnostics help request)

[Kujako]

So taking another stab at fixing this MV1FZ that's been under my workbench for years. About 90% of the time, when powered on it presents the following less than helpful error.

With the UNIBOS, I can press <A> and from then on it works flawlessly. I've already replaced the RAM, but that seems to have had no effect. I've run the NeoDIAG BIOS and cart on it, and it passes every ttest.

So... what's wrong with this thing? Any ideas?

 

[stj]

make a fresh bios on a faster eprom and report the result.

 

[Hammy]

It could not be much clearer

Check the socket and lines too.

 

[Kujako]

make a fresh bios on a faster eprom and report the result.

With the original factory BIOS, it simply halts. The UniBIOS copy I'm running is one purchased from Razoola back in the day (has my name on it & everything). No issues there. This has been a head scratcher for years.

Check the socket and lines too.

Can't find any issues there. No bad traces etc. Looks like I replaced a NEC D7990A 9411F7(IC1) with a TI alternative and repaired a trace in the backup area.

But will re-check everything.

 

[stj]

that needs a clean in every sense.
when the original battery leaked i dont think it was vinegar-washed.

 

[Kujako]

that needs a clean in every sense.
when the original battery leaked i dont think it was vinegar-washed.

Yeah, looking at it now it does seem a little rough. I'm suspicious of the trace running up to the "R" in "area". Will get it under the inspection microscope and give it another look. May be that I was on the right path when I replaced the D7990A but didn't take it far enough.

 

[stj]

microscope is pointless, visuals can fool you.
check traces with your multimeter.
and remember that the through-hole plating can corrode as well as the traces.

 

[Kujako]

microscope is pointless, visuals can fool you.
check traces with your multimeter.
and remember that the through-hole plating can corrode as well as the traces.

Scope is just to help me make sure I'm on the right through hole. But everything checks out continuity wise.

 

[hatmoose]

Scope is just to help me make sure I'm on the right through hole. But everything checks out continuity wise.

Now that I’m over 40 this is the story of my life. I can’t even find the bloody trace without some kind of magnification any more…

 

[Kujako]

Now that I’m over 40 this is the story of my life. I can’t even find the bloody trace without some kind of magnification any more…

Yeah... same. One night this year I found I just couldn't read anymore. Never needed glasses previously.

 

[ack]

With the original factory BIOS, it simply halts.

You should check on the status/health of your hard dips. If the stock bios was really halting/crashing it would trigger watchdog and a reboot. If you are getting a video signal but its a black screen its an indication the bios is in a paused state because it thinks hard dip 8 is in an 'on' position.

 

[Kujako]

You should check on the status/health of your hard dips. If the stock bios was really halting/crashing it would trigger watchdog and a reboot. If you are getting a video signal but its a black screen its an indication the bios is in a paused state because it thinks hard dip 8 is in an 'on' position.

Interesting... will give the hardware switches a test and see what's what.

Edit: So what I see is that there is some connectivity when a dip is off, reading around 0.8. But that seems to be normal compared to other boards. So the dip switches look OK. In addition, if I do toggle switch 8 it halts as expected. I only get the BIOS error when it boots normally.

 

[stj]

switch all switches off - check the pins for relativly high resistance,
switch them all on and check they all show shorts.

i'v only seen bad dips a couple of times - excluding battery corroded ones though, but worth a look

 

[Kujako]

switch all switches off - check the pins for relativly high resistance,
switch them all on and check they all show shorts.

i'v only seen bad dips a couple of times - excluding battery corroded ones though, but worth a look

Dips seem OK, found some of my old notes....

When I jumper the watchdog disable (J2), I get color blocks etc expected on boot and can hear the game loading but then only see static. If I disable hardware check in the unibios, it kills the system (have to disconnect the battery and discharge the capacitor to clear the memory).

That's as far as I seem to have gotten in the past. Theory is that it's something to do with the watchdog timer state, but not sure.

 

[stj]

interesting.
so i'd be looking at the clock, the backup ram and the associated tracks.
does the clock work? maybe the crystal is dead.

 

[Kujako]

interesting.
so i'd be looking at the clock, the backup ram and the associated tracks.
does the clock work? maybe the crystal is dead.

Fair question... not sure. Will have to try and test that by setting the date/time and letting it idle for a day or so.

 

[stj]

is there a test-pin on the clock chip you can get 32KHz from?

 

[Kujako]

is there a test-pin on the clock chip you can get 32KHz from?

Will have to check. Set the calendar and it seems to track date and time without issue after 24 hours.

 

[frsj8112]

i have a fz1 that behaves the same way. if i push A to resume, the game boots up in arcade mode.
did you resolve the issue @Kujako ?

 

[Kujako]

i have a fz1 that behaves the same way. if i push A to resume, the game boots up in arcade mode.
did you resolve the issue @Kujako ?

Nope, so it went back under my workbench to be pulled out another day when I have more time to work on it.