Point Blank - Working perfectly one day, dead the next

[HolySNES]

Ok, I know VERY little about what could go wrong with an arcade PCB and even less repairing then

Here's my situation...
I have a Point Blank PCB. The board is very clean, in great condition and it was working flawlessly.
I took the board out of one cab and chucked it in another cab and was still perfect. No graphical glitches and played it for months.
One day I decided to take it out of that cab. Had it sitting on the bench for a few more weeks and then popped it back in the same cab.
Plugged it in and nothing.

I checked over the board and there's nothing damaged. No traces look damaged (there's so damn many of them), caps look fine.. Everything looks like it was the day I took it out.
All that shows is a black screen with a 2mm white line running down the right side of the screen, about 20mm from the edge.

I have no idea where to start to diagnose this. Is it something I've knocked? Has something shorted? It might be just a tiny little fix but I have no clue where to start looking.
I've tried it without the guns and without the 24v (used to power the guns) and it's like it just died.

I can post a pic of what it shows on screen and also a pic of the PCB but my camera battery has died so will try and get one in the morning.

Any help would be greatly appreciated.

[Asayuki]

That is not surprising. Electronic components die sooner or later; and they typically do so when you apply power, because that is a stressful moment for them.

The photos and videos you offered would allow our trained eyes to see if anything looks wrong; but in the end, whatever the problem might be, there's a high chance you will have to try replacing some of the components. Would you feel comfortable doing so?

[HolySNES]

I can get why applying power to something old can just kill something. When older components haven't been used in some time, plug them in and poof, they blow. It's just strange because I've had it for ages and have been using it a lot. The kids would play it every day and it wasn't out of the cabinet for too long before I plugged it in again.

And yes, I'd be happy to replace components if I need to. I have a fine iron but don't have a ROM reader or anything too technical.

Oh and also, I read that the first thing one should test is the TTL chips for voltage. I think I tested the correct chips (the chips with Toshiba TC51832A on them).
They're all showing a solid 4.9V, same as what the the JAMMA connection is showing.



This is a pic of what comes up on screen. Just a solid whitish/greenish line, slightly curved...





Board pics...

[Asayuki]

It's not a matter of how much time you leave it off, but rather how many times you turn it off and on. There's no use worrying or being sorry about this, because it's gonna happen sooner or later.
Thanks for the photos by the way; at a first glance everything looks fine...
I assume the multimeter is your only weapon, so I am limited in the amount of things to make you try.

- First of all you can try pulling and reseating everything that has a socket; including the rom extension board for the sprites (the small daughtercard) and the light gun board (to the side of the main PCB). If you see dirt, you can scrub the pins with one of those fiber glass pens you find in every electronics store.
- You can flip the dip switches one at a time and power the board hoping that it boots into the service menu which might tell you which component is broken by running the self test.
- You can carefully inspect all the pins of 17C (the CPU), in the hope that one of the pins is loose out of aging (try gently moving them with a toothpick; well soldered pins won't budge).
- You also might want to power the board, let it sit for some minutes and finger-check the temperature of every IC. Chances are one of them will be scorching hot, which would indicate the part to replace.

Be careful not to bend any pin or cause any damage to the board.
I hope this helps.

[HolySNES]

Thanks for the advice.
Unfortunately I tried all of that

- Pulled out every chip and reseated them.
- Took the extension board off and checked underneath.
- Tried the dip switches (4 possible combinations). No service menu.
- Checked every pin on 17C with a multimeter and all connected to it's trace point.
- Inspected very closely, every leg of every chip to see if any had come loose. Checked pretty much all the traces closely for well over an hour.

I even tried cleaning the entire board with a fine toothbrush and iso. I thought perhaps there's some gunk that's bridging some of the pins somewhere.
Oh and I have tried disconnecting the JAMMA adaptor and even the I/O board (and that green pin connector) and running just the bare PCB. Same screen shows.
I guess the only thing I haven't tried is powering it on and checking to see if any of the IC's get hot. I did leave it on for a while and noticed it did get slightly warm, but I figured this was normal.
And yeah, at this stage a multimeter is the only tool I have. I guess I can get a logic probe, but I wouldn't have a clue where to start.
I watched this video the other day (https://www.youtube.com/watch?v=7l039y8dX5A) but I'm questioning whether this board is even worth the 20,000 hours it would take me to learn all this, read the schematics (if I can find them) and test everything. Was hoping it was just a capacitor I had to replace or something as simple as that hehe

[Asayuki]

Meh :/ Lucky shot didn't work. Too bad.
The next things you might want to try are:

- Check voltage of pin5 (clock) at 17C (CPU). You should measure around mid voltage.
- Check voltage of pin6 (reset) at 17C (CPU). That should measure the same voltage as pin7 (vcc).

Be careful with the above, as the pins are tiny and very close to one another. You don't want to short two pins together while power is applied!

Two more questions:
1) is that white line on screen visible even if you disconnect the board entirely and power up just the rest of the cabinet?
2) what's written on IC 20J (probably the reset controller)?

[HolySNES]

Ok left it on for a while and none of the chips got hot at all. I mean, they were semi warm but nothing that seemed alarming.

Pin5 at 17C = 1.84V
Pin 6 at 17C = 4.96V

I took the reading from the end trace point rather than directly on the chip leg.

1) the white/green line is from this board. Without anything connected my cabinet just gives a black screen.
2) 20J reads ...

3771
9516
M54

[bagheera369]

Just wanted to chime in here for a sec.
I know its a long way to ship, but if you actually wind up needing repairs on this, my shop sends everything Namco related out to Speedy's One stop. They are in the states, and have an excellent track record for us.

I hope it's something you can solve yourself, but if not, maybe Speedy's can help.

I have two Point Blank boardsets, so I definitely have a vested interest in seeing you get it running, and finding out what went wrong. Best of luck!!!

[Asayuki]

Ok left it on for a while and none of the chips got hot at all. I mean, they were semi warm but nothing that seemed alarming.

Meh :/

Pin5 at 17C = 1.84V
Pin 6 at 17C = 4.96V

Clock is likely present, reset is high. Meh :/

2) 20J reads ...

3771
9516
M54

Yep, that's the reset controller.
You can try replacing C40, if you feel like being able to handle SMD stuff.

Next I would try and dump/check the EPROMs at 13B and 15B, as well as the RAMs at 20M and 21M, but as you can see we are quickly shifting into the realm of "beyond the tools you have".

One other thing that comes to mind, is that the board might just be working but not displaying. What happens if you try to coin up? Do you hear anything from the speaker?

[HolySNES]

Bagheera thanks for the advice. I think sending this abroad is going to cost a little more than it's worth though.
Shipping international from Australia is pretty expensive because we're so far out. I definitely post back when/if I get this working though.

Asayuki thank you also for spening time to help me get through this. I do appreciate it

I never actually tried coining it up. Just tried it then and no sound

I'm just posting to let you know that I'm getting my mates logic probe tomorrow so going to have a probe around at it and see if I can find anything.
I know that there's more to it then just probing at this and that, so anywhere can you recommend for me to start?
I'm a fast learner but completely new to this. I have been reading up on logic gates (how they work and what they do) and it's not something too complex for me to dive into.

Also, is there somewhere I could get the schematics for this board?

One last thing, I have a mate in another state who has a eprom programmer (he used to dev dreamcast and V.Boy back in the days heh) so I'm asking him about buying one. Might borrow his for the time being.
When I get one then I'll definitely be dumping these ROMs.

[Asayuki]

Bagheera thanks for the advice. I think sending this abroad is going to cost a little more than it's worth though.
Shipping international from Australia is pretty expensive because we're so far out. I definitely post back when/if I get this working though.

Well, the Guru is in Australia as well. And he sure does fix boards. http://members.iinet.net.au/~lantra9jp1_nbn/gurudumps/

Asayuki thank you also for spening time to help me get through this. I do appreciate it

You're welcome.

I never actually tried coining it up. Just tried it then and no sound

Meh :/

I know that there's more to it then just probing at this and that, so anywhere can you recommend for me to start?

Sure thing. You can start around the 68020 (17C) and try and understand if it's running or not.

Also, is there somewhere I could get the schematics for this board?

I've had a brief look around on google but couldn't find anything interesting. When I desperately need schematics I typically do an extended search by using all titles that run on the same board (see here: http://system16.com/hardware.php?id=529) and try several search engines; expecially japanese ones. The common places where to find schematics (or upload them in case you find something new) are listed here: http://wiki.arcadeotaku.com/w/Arcade_Schematics I doubt yours is to be found at one of these links, but it's worth a try.

One last thing, I have a mate in another state who has a eprom programmer (he used to dev dreamcast and V.Boy back in the days heh) so I'm asking him about buying one. Might borrow his for the time being.
When I get one then I'll definitely be dumping these ROMs.

Cool. If you want one for yourself, the Wellon ones are very cheap compared to a mainstream programmer but still do cut the mustard. eBay has them.

[caius]

Most of times this issue on Namco NB-1 boards is caused by the SMD electrolytic capacitor @C40, this is part of the reset circuit along with the 3771 voltage monitor.Try to replace it also with a thru-hole electrolytic capacitor.