Build Your Own Arcade Controls Forum
Arcade Collecting => Miscellaneous Arcade Talk => Topic started by: harveybirdman on September 25, 2015, 09:43:00 am
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Finally sourced a Fighting Hawk PCB and it has what I understand to be a common problem with these particular Taito boards. Basically some sound effects are still present (shot, explosions, missiles) but the music and coin up sounds are missing.
In reviewing some repair logs it seems that the culprit can be the dual operational amplifier, NEC part number c4556c.
I can get what I think is a valid replacement for about 5 bucks shipped, however the second series of numbers on the replacement chip don't match the second series of numbers on the board chip. This might be a problem, or it might mean nothing.... I was hoping someone with more experience with this sort of thing could enlighten me.
If it helps the second series of numbers on what's on my board is 8809e and on the replacement they are k91025. Thoughts anyone?
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From what I'm reading the second set up numbers could possibly be date and production run information. Certainly would make sense since the first number on the second line of the existing chip is 88 and the game was released that year.
Pulling the trigger on the replacement, gonna have a solder party soon between this and my switcher mods...
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I would be quite interested in the results, A scope might be a fun test for perimeters.
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Pops has an oscilloscope in his shop, though it might as well be a magic wand in my inexperienced hands. One day I'll invest in a JAMMA test rig workbench for proper troubleshooting, but until then it's a large helping of Google with a side of trial and error.
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DO NOT WAIT! .... A small analog dual trace (25Mhz, or so) can be had very reasonably on the Epay, Phillips made a nice one with a floating ground, and a battery pack option. (My first ::)) .... They are the cats meow for fun projects like this.
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Pops has an oscilloscope in his shop, though it might as well be a magic wand in my inexperienced hands.
Pfft. If you know how to use a voltmeter and do simple multiplication and division, you can use an O'scope.
Center pin of the probe is the red lead, shield/ground clip is the black lead.
The controls are divided into voltage, time and trigger sections.
On the screen: Y-axis is voltage, X-axis is time.
Volts/div = how many volts it takes to move the trace one square (a division) vertically on the display.
-- Signal is 5 divisions high, voltage knob is set to 1v/div ==> (5 divisions) * (1v/div) = 5v signal
Sec/div = how many seconds it takes to move the trace one square horizontally on the display.
-- Signal takes 5 divisions to complete cycle, time knob is set to .5ms ==> time per cycle = 2.5ms (.0025 seconds per cycle)
-- Frequency (cycles per second) is the inverse of time (seconds per cycle), so the frequency = 1/.0025 = 400 cycles per second. (400 Hz)
The trigger section tells the scope when to start drawing from the left of the screen.
-- When the last trace has finished drawing and the level = 0v (level knob setting shown in pic), start drawing again
--External Input is when you use another signal to determine when to start drawing (like the starter's gun in a race)
That covers most of the ways you'll use an oscilloscope. Now go play and learn. ;D
(https://upload.wikimedia.org/wikipedia/en/f/f2/WTPC_Oscilloscope-1.jpg)
Scott
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When did Jen stop using the 3rd person?
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When did Jen stop using the 3rd person?
Jennifer?....Jennifers not here Mrs. Torrence.
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When did Jen stop using the 3rd person?
Jennifer?....Jennifers not here Mrs. Torrence.
Not a particular fav of mine though Jack was quite good.
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Redrum.............Redrum!!!!!!!!!!!
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Please just spend the $5 and slap a new chip in there. Nobody wanted oscilloscope lessons.
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Way ahead of you Jim, it's in the mail.
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Please just spend the $5 and slap a new chip in there. Nobody wanted oscilloscope lessons.
HAHAHAHAHAHAHAHAHA! I know sometimes that Jim Gotta Jim, but often there are some gems that come out when he does.
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Its not lessons, Its the difference between a crutch, or finding out why it gave out in the first place a fixing it correctly, Not to mention running a test like that requires a breadboard, (confirms pinouts), And if that op/amp was actually was problem in the first place.... But its your project, slap some random chip in there if you want.
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Its not lessons, Its the difference between a crutch, or finding out why it gave out in the first place a fixing it correctly, Not to mention running a test like that requires a breadboard, (confirms pinouts), And if that op/amp was actually was problem in the first place.... But its your project, slap some random chip in there if you want.
Just putting this out there, I do appreciate your feedback as well as Scott's.... I was just egging PBJ on, he's by far the most entertaining controversial poster.
In this case this issue is relatively well documented with this board. Yes I want the knowledge that many of you have on original hardware. Yes I want all the tools to diagnose and fix without trial and error. However I also wan this PCB fixed before either one of those things is possible, and I'll chalk this all up to experience.