Fustrated Robotron issue...last chance before I JROK it

MonsterBash

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Fustrated Robotron issue...last chance before I JROK it

I simply can out figure out this Robotron sound issue I'm having. I thought I finally got it yesterday then blame...gone again. I've spent sooo much time on this I could have easy wired in the JROK board a lot faster..sold my chit load of robo backup boards..and been way a head in both time and money. Here's the story...I've probably done more than list here to


The machine has a Bob Roberts switcher in it.

Yesterday I recapped and replaced the CPU (6208 i think) in 2 sound boards.

I stuck it in the machine and presto...sound..yaahhh. The next day..nothing. I just installed the second sound board..nothing. Board boards give me sound when I press the test sound button.

I've tried 3 different ROM boards (all had the pins re flowed). All 3 ROM boards play fine with no sound..all 3 used their own ribbon cable..thus 3 different ones

I tried 3 different CPU boards..again..all 3 play fine with no sound.

I have 5.05 volts at the sound board.

I've replaced the compete hardness (and tested it while it was out of the machine) minus the interface boards.

I tried another switcher (I have no idea why...just cuz I was out of ideas)

after every test and part swap I have sound VIA the test switch on the sound board...however..pressing the reset switch on the CPU resets the game but the sounds continues to play.

When the game boots on the ROM board the LED goes to 0...then will 'flick' to 3 (when the sound it suppose to fire I think) then back to 0

HELP!
 
Well I don't want to jinx myself here but I 'think' I can chalk this up to a rookie mistake.

So I took one of the 3 CPU board I had and reflowed the pins as yet another attempt at fixing this thing. (can ya tell I'm stubborn =0))

I reflowed the pins..stuck it back in the machine and the game play (with no Audio). I started feeling around the back of the board where the pins were freshly reflowed and felt a REAL hot pin.

I shut the game off (obviously) and removed the board. Now here's the rookie mistake

When I reflowed the pins I (I've done a few in the past..not many) I always used a bit of paste flux to aid in the melting of the old solder...then add some rosin core over the top. Well I never cleaned the flux off ( after reading a bunch of post here..it's my understanding that this isn't the best practice to use flux because of it's corrosion properties).

SO I cleaned the piss out of the CPU board and the heat thing went away

Fast fwd to the 2 sounds cards that were capped and reflowed. I did clean up the 'cap' part of the board but didn't pay much attention to the flowed pin. After cleaning both boards completely...BOTH worked and both had sound during game play.

I played a few game last night and checked again this morning and still had sound

After this little fiasco I did read here about using flux...I'm guessing it 's a no-no with electrical components?

Here's to hoping I have sound when I get home from work!
 
That depends on the flux. There are two basic kinds, one is a rosin based (similar to what is used in the rosin core solders). That one is fine. The other is an acid based flux commonly used for stained glass and copper tube plumbing soldering. That one is not good for electrical work as it will eventually eat away the traces, wires and components. Depending on the brand, it can also have some traces of metal in it, which can cause shorts.

I normally just use the rosin core solder, I don't add additional flux. When I am done soldering, I clean the residual flux with 91% isopropyl alcohol on a clean rag. That makes sure that there isn't any left to be sticky and pick up extraneous particles that might cause a short.

ken
 
Yeah, no extra flux.

And clean it up after soldering with as close to 100% alcohol as you can find.

I also use flux when soldering wires together, or something was not intended for solder, but now I'm using it with solder, such as two pieces of metal.

Glad you figured it out!
 
Well...
Game was on all day and I just played a game with 100% sound!

Think I'm gonna tear the boards out of it one more time and really make sure they are clean

The flux was definitely not a rosin base flux.

The next move it to rebuilt the William PS and get rid of the switcher..but first I gotta enjoy a few games!
 
Also, one thing to keep in mind about those Williams sound boards is that just like the pinball games, Williams did a great thing and made the PCB traces thick and also used plated through holes for the molex edge connectors. However, what can happen is that the plate through 'tube' can break loose from the actual PCB traces and cause an intermittent connection. Now, as you mentioned, reflowing is a terrific idea, however if the trace is cracked on the component side of the PCB, reflowing won't necessarily fix it as the fresh solder can't get up there, especially under those flat bottomed Molex connectors that mount flush to the PCB. So, in all my years of dealing with *really* frustrating intermittent connections on Williams PCB's from the early 80's... I just do this...

1. Unsolder the connector completely and take it off the board.
2. Inspect the plate through's and make sure they are not cracked on the top of the PCB.
3. If the thrus are cracked, reflow them on the top and get them solid.
4. Replace the molex connector (this is a good time to get all the pins even too) and then resolder with fresh rosin core solder (don't use extra paste).
5. Viola.... good for another 10-20 years.

Of particular 'finickyness' on those boards are the two 4-pin molex to the speaker and volume control, do both. Also, spray out your volume pot with tuner cleaner, spin it back and forth about 25 times (game off) and it should be nice and clean. Those pots get flaky too if they sit dry too long.

jess
 
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