Are there any Gottlieb System 3 guru's lurking in the tech forum???

I've got a Street Fighter 2 that I'm rebuilding, had to piece together a board set. I purchased an untested Audio Board (from another SF2), an AUX Audio Board (from rescue 911) and two AUX Power Supply (both NOS from PBR).

The first AUX power board that I installed was accidently smoked (like a dummy I plugged the DMD power plug into the AUX power board header and POOF the board needs a rebuild, magic smoke and all). So while that one is on the backburner for repair, I purchased another NOS Aux power board from PBR.

When I install the trio of boards, and power the game up, there is no "screech", amp pop, nothing. Sometimes the LED's come on the Audio boards (and stay on), other times they don't come on at all. The new AUX power board has a questionable odor as if it burned up as well, however I can't find any bad components on it.

Where should I be looking? What do these boards do when they boot properly? From what I understand, they screech on startup, and then the LED's blink on/off to signify they are working.

Thanks for any help

THANK YOU for this information, very helpful.

In short, after reading the posts quickly, sounds like I need to verify all of my voltages FIRST. I was having a DMD problem until I rebuilt the board, and recall messing w/ the 5v trimpot. I want to say I'm at 5.25v right now, but need to verify. Also, didn't realize the aux power board only outputs +12v and -12v, should be easy to weed out if its a power or logic problem.

The Aux Audio (speech board) roms are brand new, burned em myself. The sound board roms came with the board, and verify in my burner. Don't believe its a rom issue.

I'm leaning towards the LM340T or MC3403 being blown on my board. The one board that I accidently smoked most certainly has a blown LM340T (its charred), and I suspect the other one I have has a bad MC3404 (he's the stinky guy I was talkin about before). Assuming my voltages aren't in range, it'll probably be one of those three IC's. Maybe if I'm lucky I can rob some parts from the smoked board tongiht and save a trip to the parts store.

I'll post back when I get more info... thanks!

I should also mention- BEFORE smoking my Aux Power board, I did get a "screech" on power up. After smoking it, screech went away (with the new AUX Power board). I'm guessing the 12v -> 5v regulator on the Aux Audio board was fried during the harness mix-up... still just speculating.

I took another look at my SF2 last night. The Aux Power Board that I tested with instantly pops Fuses F10 and F11. Any tips on where to start looking on the Aux Power? I'm suspecting I'll want to get that board working before I troubleshoot the other sound boards.

Can I boot the Sound and Aux Sound boards without the Aux Power supply? I measured 5v on the boards, and was getting 5.1v, but the LED's do not blink, they're fixed on.

Nice- i'll test the diodes and let you know how that works out. I have two of these boards on hand, so if I'm lucky I can get a working set of 4 out of the pair!

Any idea what could have fried them to begin with? I know how one of the Aux Power boards died (I plugged in DMD power by accident). No clue what happened to the other board, they were both NOS.

I tested all of the diodes, and they're all fine. The one thing I did notice when comparing my two boards, D3 (nearest to the cap) was installed the opposite direction of the other diodes. I desoldered and flipped it around and I get the same result. I'm guessing its one of the IC's on the board causing the fuses to pop. Since its only about 5 parts per board, I think I'm going to just shotgun both of them.

Dumb question, but do you have recommended points to test 12.6vac from? I recall it being within range, but its worth double checking and verifying the best spot to test.

Thanks!

Just changed out the known burned components on my Aux Power supply (LM7912, LM340T and MC3403). Sounds like the fix took on the PCB (can hear a hum on the speakers when I power the game up), however I'm still blowing fuses. F12 gets visibly red and blows within 10 seconds.

I measured pins 3 and 8 and I'm getting 25vac!!! WTF! If I understand the transformer correctly, it is simply transformer windings to get 120vac down to 12.6vac. If its coming out of the source double-voltage, does that mean my transformer is bad? I tried other region's jumper plugs just to see if I could get the voltage down, but best I could get it was 25vac on the 120v jumper plug (orange).

Should I start swapping in my other transformer next? I believe there's a bridge rectifier issue, so I'm going to have to mix and match parts to get a good one I'm thinking...

Thanks for all the help so far, getting close I can feel it

Well that sucks. I took my spare transformer assembly, pulled the transformer and installed it on my other (mostly working) transformer assy (left the known working fuse panel and bridge/cap in place). Fired up the game... ALL of the DMD related fuses burned up instantly. The game still booted (sans DMD)... the damn 12.6vac is STILL reading 25vac.

I've come to the conclusion that BOTH of my transformers are faulty, please correct me if I'm wrong here. In the 20-some-odd games I've owned (and I've had some REAL junky machines that I saved) I have never encountered a bad transformer... let alone two.

All this sound about right before I go ahead and track down another one?

Hmm now I'm starting to scratch my head. My readings were as follows:

P1-2 to P1-3 12.6vac
P1-2 to P1-8 25.8vac
P1-4 to P1-3 12.6vac
P1-2 to P1-8 12.6vac
P1-7 to P1-3 26.3vac
P1-7 to P1-8 12.6vac

I double checked pins 2-8 and 7-3, and they consistently read just about double what it should be. Is this potentially a ground issue? I have not done the recommended upgrades yet, I'm thinking that might be next.

Thanks for your input

Yeah totally was measuring it wrong before like a dummy. I was going pin 3 to pin 8 (that explains double the voltage).

I'm going to switch the Diode's direction and see where that gets me. All of the pictures I've seen online (pinwiki, ebay, pbr) have the diodes going the same direction... mine has D3 reversed. While I'm at it I'm going to do the ground modifications and see if that helps get more consistent voltage readings.

Well would ya look at that! Signs of life!

I swapped the diode around and the board came to life, didn't pop any fuses and it is outputting the correct voltages! When I did the initial rebuild, I changed VR1 and VR2. Neither have shorts at the moment (phew!). Mind you this running is with the transformer that keeps popping the 3/8a display fuse for the DMD. The other transformer doesn't pop this fuse, but kept popping the 12.6vac fuse, maybe that issue is gone now?

I think there's something faulty on my sound board, aux sound board seems OK. While fiddling with the 5v line, I got both board's LED's to blink at the same time, and heard the awful squeel. During a few of my tests, I got the aux sound board play about three different samples (can't get them to fire consistently). I suspect the roms on the sound pcb itself might be a problem... firing up my rom burning station now to verify that.

Roms are OK...

Making some progress...

I brought over the other transformer block, and both the audio and display fuses stopped blowing! DMD is back on, and audio is still sort of working. While I was in there, I performed all of the ground mods, nothing is better/worse related to my audio problems.

I am convinced my Aux Sound board is OK and my Main Sound board has a fault. Here's what I've found:

*YM2151 chip at U9 Aux Sound Board is good, tested in a another game
*Audio roms AROM1 and AROM2 and U1 digital audio processor on Aux Sound Board are good, some samples play intermittently
*5v present on Pin1 U10 (dac) aux sound board
*Ribbon cable is NOS, passes continuity test between boards
*Only one deep/squeal present on bootup, and that isn't doesn't happen every time (I understand there should be two)
*DROM and YROM from Main Sound board verify against pin mame binaries
*Sound Board attempts to play what sounds like a looping synthesized symbol. It does about 20 or so repetitions before cutting out completely. No other midi-style music is played.
*Sound test results in the same looping symbol (like above) for every location.

I've concluded there's an issue with the data bus going from Main Sound Board to Aux Sound Board. I am suspecting bad ram(s) sending the data bus garbage, but I suppose it could be one of the TTL's or even one of the CPU's. Next step is to look for activity with my Oscilliscope on the data bus, and hopefully figure out where the issue is. If I find either of the ram chips suspect I'm going to pull them and hope my rom burner can verify them (it can do a lot of rams, but not all).

Has anyone done component level repairs on these boards before? Fortunately I have a similar era gottlieb audio board from another game that: looks identical, is populated with twice as many components and shares the same CPU/Ram/TTL set.

Thanks again!

Yes- when I perform the sound test, all audio locations result in the same looping symbol noise.

The Aux Audio board LED rarely comes on, and the Main Sound LED usually stays fully lit. Occasionally the pair will blink at the same time, but that rarely happens. The voltage on both of the boards is 5.20v.

Regarding the sound board being a black box- I don't buy it There's <20 IC's on the entire thing, can't be that hard to weed through it.

Yes, when it reboots, the LED on the Main Sound board stays lit, the Aux Sound board LED doesn't light up. It generally plays the same looping audio, however not always.

I will look into this tonight and report back. I might just change out A3 and see if that helps.

All of them are the same looping "symbol" noise.

Identical result as my current Aux Sound board. Since the result is the same, I am assuming both Aux Sound boards are good and Main sound board has the fault.

It is also worth mentioning that two sound effects play consistently during the game, the torpedo jackpot audio effect and the regular jackpot audio effect (both are generated audio). The rest of the time, there is no generated music, and IF an audio sample plays, it either plays a portion of the sample, gives up and tries again, or it plays the sample at inconsistent speeds (sometimes slow voice, sometimes correct speed/pitch). Its a grab-bag for the audio samples.

Also worth noting that sometimes the boards LED's will randomly start blinking at the same time, at a random time. Unfortunately no audio plays when this happens. I have tried rebooting the board when they are blinking at the same time, but that just goes back to the same results I have above.

Thanks for all the input!

Thanks for the suggestions guys. I will investigate A3 and the 6522 PIA tonight and see what I can find. I'm pretty much a n00b with my silly-scope, but I can at least hook it up properly and identify high/low signals

The GOOD news is I have a faulty control board on hand, if I'm lucky the PIA isn't cooked. I guess its worth mentioning my working control board was from a lower-ram game. I upgraded the ram chip and adjusted the jumpers to accept the larger ram type. I suppose its possible the board has a fault I haven't realized yet, everything else appears to function correctly.

Thanks for your input Jeff! This really strikes me as a data bus OR ram problem. Since I have parts on hand, I'm going to swap A3 and both H2/H3 rams and see where that gets me.

I haven't actually fired up my other sound board as its from another game (presumably a jamma), however its the same PCB, same components, only fully populated (the system 3 one is only 1/2 populated). I actually considered removing the extra components from my spare board and making it identical to the System 3 board, however I don't feel like tracing the entire thing out incase they revised the PCB!

Exactly my train of thought my friend. Looks like I'm leaning towards RAM(s) as my first area to check, followed by A3, followed by 6522 (ugh so many pins...) Hopefully my snazzy desolder vacuum can make short work of these!!

PROBLEM RESOLVED!!!

I swapped out both the H2 and H3 rams from my other board and all of the audio came to life! Speech, music, everything! Thanks for all the help guys, case closed!

Unfortunately I do not know exactly which ram was bad. The PCB's are a nightmare to work with because they are so delicate. I snipped out the original rams with angle cutters, then desoldered the pins one at a time. From there I cleared the through holes with my solder vacuum. That went super smooth with zero damage. The working pulls however were not so smooth. I was able to get both chips pulled without damaging them, but I damaged the donor board's traces in about 5 spots. Not a huge deal however as I'm not even convinced the donor board was a pinball PCB! Pretty sure it was used in a gottlieb video game, it had programmable sound generator chips present (weird!).

Anyways, thanks for all the help guys! The game has been playing flawlessly since the weekend going 50-75 plays strong! I'm calling this case closed