BBH 2 - LED Sign not working

[Rocketeer2001]

Hey, wondering if I could get some insight on troubleshooting my Big Buck Hunter II: Sportsman's Paradise?

It has a red LED dot-matrix style sign up in the marquee and it doesn't work. I initially thought it wasn't working because it needed the online tournament servers to work, and those haven't been active in a decade. But then I found this bit in the manual that states if the machine is unregistered, it will display generic game features.

There's only two connections to this sign: 12v power wires, and a phone jack which is really just a data line to connect to the game board.

I've spoken to other people online and some of them don't even have a BBH arcade board in their machine and are simply using the cabinet for a custom build, yet their LED sign works. It just needs power to play some default messages that are saved to the memory in the microprocessors on the sign board.

I've checked voltages in numerous places on the board and I am getting 12v and 5v in the right places, yet all I get is a lit Power LED indicator, and a flashing Status LED indicator. I don't know what the flashes mean.

I contacted Incredible Technologies customer service support to see if they could tell me what these LED indicator flashes mean, and they of course told me "this product is no longer supported", but they did give me a trouble shooting document. It offers limited assistance because it tells you to check some things, but then doesn't tell you what your results mean. I've attached the pdf for anyone else that might find it useful.

I thought maybe my machine was registered to the IT Net and it wouldn't display anything because it couldn't connect to the network, but I went into the service menu and this machine has never been registered. I tried to set up the registration to see if that would make a difference, but since it can't connect to the servers it just gives up and I can't continue.

Any ideas? Should I just take a hot-air reflow solder station to it and see if that does anything?

[lilshawn]

man, the number of these signs i've thrown away over the years.

Any ideas? Should I just take a hot-air reflow solder station to it and see if that does anything?

honestly, this is probably the best start. reflow the ROM RAM and CPU and see where that takes you.

also check out U25... see if you can lift up pin 7, to keep it from being reset... see if for some reason the IC (LT699 microprocessor watchdog) is holding the sign in reset. you could also test this pin/line to see if it's being forced low (reset) or if it's high (ok to run). gonna need a logic probe or something similar to really get more into this.

[Rocketeer2001]

Thrown away because they never worked or because you had a stock-pile that never got used?

I should mention that I have two of these boards. I've labeled them "Original" (the one that came with my machine) and "New" (the one that came with the parts machine).

On the Original board I get the Power LED and flashing Status LED, but on the New board I only get a Power LED.

I checked pin 7 at U25 on both boards, and this is where it gets interesting:
Original = has 5v and holds it steady
New = has 5v but it pulses every second to zero. Does this mean it's stuck in a reset loop?

On that same LT699 chip, I also checked pins 1 and 2 for their supply voltages:
Original = 5.85v
New = 4.98v

Visually, I also noticed that both boards are a bit discolored around voltage regulators U31 (8M05A CQY147, should output 5v) and U32 (78M09 RC925, should output 9v), as well as their large yellow diodes beside them. Those same diodes run along the bottom of the board (there's about 10 of them) and they're all about the same color of yellow, except for the ones beside U31 and U32.
Maybe I just need to replace some voltage regulators and diodes? I should probably pull one of those diodes off the board, test it, then compare it to one of the good looking ones.

[lilshawn]

those yellow "diodes" are capacitors. in particular, tantalum capacitors. they can have a tendency to fail shorted and cause power supplies to go into an overload condition.

as for the reset line, i suspect if it's pulsing low every so often, the watchdog is trying to reset the CPU to get it going again. the watchdog chip looks at the power and if it's within spec, it pulses the reset line... as having dirty, not-ready power can cause a cpu or microcontroller to lock up or not startup properly. resetting things after the power has stabilized, ensures the CPU has a good startup from fresh with nice stable power.

[Rocketeer2001]

Gah! Yes of course they are capacitors. I'm not sure why I thought they were diodes. Their labels even start with a 'C'  Thank you for pointing that out Shawn.

That cap is used all along the board, so I used my ESR meter to test them. The ones furthest from the voltage regulator (actually almost all of them) had an ESR of around 0.06 to 0.045 ohms. The two caps beside those regulators where 0.07 (for C40) and 0.23 (for C44). I got similar results when testing my 'new' board. Now, this could just be an false-negative result because those caps are still on the board and could be compounding some readings from nearby resistors, so I'll remove them tomorrow and test them away from the board.

Currently it's looking like maybe the C44 caps are out of spec. Possibly why that watchdog chip is resetting on the one board?
If I do need to replace, can I just use an electrolytic or ceramic capacitor? I have a small pile of old electronics I rob parts off of, so the availability of the exact part may be limited and I was hoping I could use a different type if I have the same cap size.

The cap part markings say 226, 25k, 121. I believe that's a 22uf @ 25v.