Frogger Rehab (1st project ever)

ElectronWrangler

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I have just recently joined this site so I apologize in advance if many of these questions are really basic.

As part of a new years resolution promise to my son Luke (6yrs old) I told him we would either fix or trash a Frogger arcade game I picked up for cheap from my aunt in law when they were doing an estate sale for a friend who passed away.

Anyways this is what I can figure out. Please correct anything I may have wrong.

1) The case is a Stern Electronics, but Stern Electronics never made a frogger game.
2) When I figured out how to take it apart I found info and tags for a game called "Super Cobra" which Stern did make so I'm assuming it was a retrofit.

Issues I have:

1) I have no idea what boards or parts were used in this unit.
2) The case had sound for about the first 5 minutes it was powered up. Then nothing. I
measured the speaker and it came in at 6 ohms (correct) and when I measured RMS AC voltage it seem to go up down like there was something there. When I looked at the speaker it looked okay.
3) The color on the screen is not black and I think some of the other colors are wrong.
4) After the screen is on for awhile it gets lines and sometimes the screen flashes intermittently.

Anything anyone can help me and my son work on this would be a great help! Thanks!
 

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Please correct anything I may have wrong.

1) The case is a Stern Electronics, but Stern Electronics never made a frogger game.
2) When I figured out how to take it apart I found info and tags for a game called "Super Cobra" which Stern did make so I'm assuming it was a retrofit.

Issues I have:

1) I have no idea what boards or parts were used in this unit.
2) The case had sound for about the first 5 minutes it was powered up. Then nothing. I
measured the speaker and it came in at 6 ohms (correct) and when I measured RMS AC voltage it seem to go up down like there was something there. When I looked at the speaker it looked okay.
3) The color on the screen is not black and I think some of the other colors are wrong.
4) After the screen is on for awhile it gets lines and sometimes the screen flashes intermittently.

Anything anyone can help me and my son work on this would be a great help! Thanks!

You are correct; your frogger is a conversion.

If you're technically inclined, I'd think I'd suggest looking at the Stern Super Cobra manual for things like cabinet wiring and power supply schematics: http://arcarc.xmission.com/PDF_Arcade_Manuals_and_Schematics/Super Cobra.pdf And for the Frogger schematics: http://arcarc.xmission.com/PDF_Arcade_Manuals_and_Schematics/Frogger Schematics.pdf

As far as the black being dark gray, try turning down the brightness (aka contrast, screen, or black level). It'll be the little knob on the flyback transformer that isn't focus. Can't really make out the pic too well, but it may be that the red and green signal wires are mixed up, too(?)
 
Your converting this frogger back to a stern super cobra.

Rolls up your selves, This might not be so easy as you think.

I don't want to scare you but I am not going to lie to you.
You might need to learn how to solder wires.
You might need to know how to read a digital volt meter.
You might need to know how to put on connectors.

Do you know if your parts work?

How far do you want to restore the stern cab to a Super cobra? There is control panels, Side artwork. monitor shrouds and Marquees you might have to deal with.

You know that your dealing with old electronics and rarely can you find New stuff just to plug it in to make it work .

I hope I have not scared you. It like eating and elephant. Just one bite at a time and sooner or later. you get it done.

In simple terms your arcade is power supply, wires, Game board,controls, speakers, coin door,lights and a monitor.
 
Great Info Thanks!

I appreciate all the help.

Its going to take me a while to look over all these schematics and wiring diagrams to get a good feel for what exactly is in my conversion machine, but I think it shouldn't be too much of a problem.

My degree is in electrical engineering and I've spent about 5 years designing electronics controls, 2 years doing systems engineering and the last two years designing harnesses and wiring diagrams for appliances.... I will say these schematics are pretty complicated but I'm up for a challenge.

Thanks for the ideas about adjusting the contrast and looking at the flyback controller. I'll be messing with it right after I get figured out why the sound isn't working.

Thanks again!
 
My degree is in electrical engineering and I've spent about 5 years designing electronics controls, 2 years doing systems engineering and the last two years designing harnesses and wiring diagrams for appliances.... I will say these schematics are pretty complicated but I'm up for a challenge.

Ah hah - a degree in electrical engineering! You should have no problem fixing something as simple as a little video game then! :)

Yeah, I know, some of this stuff seems complicated, but it really isn't - just break it down logically.

At the moment, the game works, but you have no sound. First thing is to check the power supply - look at the pinout of the game board and measure the voltages at the edge connector on the PCB. If, for instance, you lost the 12v, then the sound probably won't work. Generally speaking, the 5v runs all the digital logic, and the 12v runs things like the sound amplifier. I don't remember exactly if Frogger only uses the 12v only for the sound, but it's likely. Some games will work perfectly on only 5v, since the only place 12v is used is sound.

On Frogger, the top board is your sound board. It contains the sound chip, an I/O chip to communicate with the processor, the sound EPROMs which store sound data, and the analog components and audio amplifier IC to amplify the sound. If the interconnect ribbon cable has developed dirty contacts, then you can also have sound issues, if it affects the communication between the processor and the sound chips. Verify that. Do the cursory first-pass stuff, like ensuring all the chips on the sound board are seated properly and making good contact with their sockets. Dirty/poor quality sockets are a very common problem on these games - they didn't exactly use the highest quality parts to build them... Similarly, a bad volume pot is another common failure point. Press on it and wiggle it. Can you hear static on the speaker? If you do, then the sound amplifier chip is working.

If you have good power and everything is connecting properly to everything else, then you can start checking things like the audio amplifier IC - look at the schematic and find the input and output pins, obviously you're not getting any output, but is there input? If so, then the amp chip is bad. If you don't get any input, then follow that back to the rest of the circuit and figure out why. Do you have an oscilloscope? This is where that tool comes in handy - tracing audio sections. Doesn't have to be a good one, even an ancient tube type scope will do - you just want to see where there is signal.

If you're not getting any sound, then start suspecting things like the sound I/O chip, the sound chip itself, etc. Checking the digital section is where a logic probe comes in handy. You can use a scope, but a logic probe is a lot faster. Again, check inputs, check outputs. When you find something that has input signals but no output, then you've found a problem.

But, like I said, start with the simple stuff first. Most of the time, that's the problem. Check your power supply voltages and interconnect cable/chip sockets and the volume pot.

-Ian
 
I kinda figured you knew an electron from a hole when you specified your AC voltage as RMS :)

About your Frogger game PCB: I'm no expert on Froggers PCBs, but it looks to be different from the ones shown here on this high-score save kit page: http://www.brasington.org/arcade/products/hs/frogger/boards.shtml Yours does appear to have a 36-pin edge connector, but the rest of it is different from the 834-0069 or -0075 boards pictured. Does your game PCB have ANY markings (brand labels, part numbers, insignia, etc?? It's possible that it's what's known as a "bootleg" version of Frogger, or a "hack" (originally the PCB of another game which has been modified to run Frogger). Just mentioning this before you get too far into studying the Frogger schematics. There are at least two different version of "legitimate" Frogger PCBs, and who knows how many bootleg varieties... and there's almost never schematics to for bootlegs.

I'd expect that much of the rest of the cabinet wiring (transformer, power supply, coin door, marquee, speakers, etc) should match the Super Cobra documentation. It doesn't look to have have the wiring too badly hacked in the conversion. This is likely because both Frogger and Super Cobra were actually designed by Konami around the same time, so they both have what's known today as "Konami classic pinout" (http://www.arcade-museum.com/pinouts-class/Konami_Classic.html) This meant that the Frogger PCB was more-or-less a plug-n-play swap for the original Super Cobra PCB... which meant that your wiring harness was spared the horrors often inflicted upon conversions.
 
Could his reconversion be as simple a s a ROM swap and cosmetics?
 
Next Steps

Thanks for the links and insight. The info about the layout of the boards is very helpful. I wasn't able to see any markings on the boards when I took the pictures (and I did look) but with it inside the machine I couldn't get a good look at everything. Tonight I've got volleyball, tomorrow night I have company, and Friday night is "date night" so I don't think I'm going to really be able to dig into it till the weekend.

Right now I'm just looking at getting the Frogger fully working, no rush to convert it back into super cobra or anything. I have the world record scores from twingalaxy posted near it and my kids are excited to try and beat them.... I don't think they realize how hard that would be.

About the sound -
- I noticed that in the schematics there is a pot so I was going to check that for the sound since it was strange that it worked and then just quit after about 5 minutes. Pots are notorious for failing.
- The speaker does have static.

About the toolset -
- I do have an scope. It is a very very old tube type one from like the 1970's but for tracing audio signals it might work. I hardly ever use it since it weighs like 100 lbs it seems. Time to lug it out.
- I also have a multimeter and nice soldering iron (Weller) and workstation (Christmas present) to lay everything out. So far from what you are saying I should have what I need. And of course I have a credit card and accounts at digikey and newark... and of course there's always ebay.
 
Yeah, try checking the pot. I can see it on your PCB, it's an off-white plastic knob a couple inches from the heat sink. On many PCBs the audio amp is the only thing with a heat sink on it... and any volume pot (and other audio circuitry) is sure to be nearby. Other things to check before breaking out a soldering iron: the PCB edge connector, the wiring harness including any free-hanging connectors that might be between the PCB and the speakers, the connections at the speaker, and the speaker itself (I just had one a few weeks ago where the wire going from the terminal to the coil was hanging on by a thread, causing static and intermittent audio...)

If you can demonstrate that everything in the cabinet is OK (by, for example, connecting an amplified audio source to the audio pins in the edge connector housing and getting good sound), and ensure that your 12VDC power is good (most audio amps run off of the 12V supply) then it's time to consider the PCB. Common issues there a bad electrolytic output coupling cap, PCB damage, or a bad amp IC (the on connected to the heat sink).
 
Weekend Findings....

It was a mixed bag this weekend, but overall pretty good.

1) I was able to confirm the power supply board was the stern
one from the schematics for super cobra. I was also able to check
the power rails (12V, 5V, -5V to Ground) and confirmed at least
from a DC multimeter (not saying anything about how clean they
are) that at least they were close to what they should be.

2) I disconnected the main connector from the control board and
then measured the wires called out going to the speaker from the
main harness connection point. Measure 6 ohms for the 6 ohm
speak so the harness to the speakers looked good. I noticed
Cu traces looked pitted so I cleaned off some of the corrosion
with an pencil eraser.

3) When I reconnected the board I turned the pot up and down, it
did have a large impact on the sound output volume but it was
still mostly just static.

4) I took the board out and looked it over. I replaced all the
electrolytic caps in the area of the audio amp and the mylar cap
across the output. (Luckily I had stock of all the right values
in my parts bin.)

5) I took some pictures then put it back together. When I powered
it back up the screen looked alot better. If you look at screen image
before (attached) it was almost like the CRT wasn't getting some of
the color channels. Now it looks more like a frogger game should I
think which is great. The color issue was the second thing I was
going to fix but I seemed to have stumbled onto making it work.
Sometimes it seems it is better to be lucky than smart. :) But
the sound was still not working.

One thing that seem strange is according the schematic I had the
IC driving the audio amp was labeled 3A and should be a 741 opamp,
but when I looked at the board the part is a sn74ls367an which is a
digital Buffer/Line Driver, Non-Inverting IC. That has me a bit baffled.
I took pictures of the board and found in the copper etch that it
was called GHC-03B, besides that no markings to figure out what it
is.

I hesitant to replace an IC since it seem surprising to me that it
would be wrongly populated. An op-amp does seem like the right
thing to have there because the input has many resistors going to
it so it is setup as a summing amplifier (I think taking many multiple
digital type signals and summing them together so that in the
summed version you get different sounds depending on which
mix of input digital sounds are put into the chip.)

As a side note I noticed the that marquee (is that what it is called)
on the top wasn't lit but it was unplugged. I plugged it in and
it lighted up but the conversion frogger marquee put up in that
area doesn't let any light through it so you can't see its lit up.
Happy the light works, bummer you can't see it from the front.

The board did have large ICs with silver numbered stickers on them. That
might be the conversion chips to go from super cobra to frogger. Or maybe
they are original?

I'll attach some more pictures. Any ideas you have on the
sound and other items are appreciated. Thanks!

Dave
 

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A few more pics related to the previous post

See attached pics related to previous post.
 

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wasn't the audio pot on a frogger was 200 ohms?

I should hunt down that link

found it

http://www.arcadecollecting.com/info/FroggerSound.txt

That information is relavent to legitimate Sega/Gremlin Frogger PCBs. However, the OP doesn't appear to have such a PCB (see his pics & post #7... and the fact the he has a pot on the PCB). He appears to have a bootleg of some sort. My guess is the so-called "Falcon" bootleg. One way to be sure would be to pull a couple of EPROMs, read them, and check them to a romident database. Take a close look at the title screen... does it say (C) KONAMI? or SEGA? or something else? Does it say "FROGGER" or "FROG"?

Anyway, looking at the Sega/Konami schematics isn't going to show how a bootleg is built... There usually aren't any schematics for bootlegs. Look around the amplifier IC, for any type of op-amp (look up anything that isn't obviously just a 74xx-type IC). Make yourself an audio probe or use a scope to trace the audio signals from the AY-3-8910 to the amp.

[Here's how I made a dirt-cheap simple audio probe: http://forums.arcade-museum.com/showthread.php?t=202473]
 
Last edited:
hum....

They all seem to be 74LS styles parts from looking at the picture I have. (I'm traveling for work now so that is all I have to go from.) It looks like they've got R4 going to the pot then
R5,R6,R7,R8,R9 and R10 all going to the otherside of R4. Then all the resistors go to (4C)
which is the M5L8255AP-5 which is a PROGRAMMABLE PERIPHERAL INTERFACE to pins which are specified on the datasheet to be "Bi-directional data bus" which seems strange. Its hard to tell looking at the pictures took though.
 

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They all seem to be 74LS styles parts from looking at the picture I have. (I'm traveling for work now so that is all I have to go from.) It looks like they've got R4 going to the pot then
R5,R6,R7,R8,R9 and R10 all going to the otherside of R4. Then all the resistors go to (4C)
which is the M5L8255AP-5 which is a PROGRAMMABLE PERIPHERAL INTERFACE to pins which are specified on the datasheet to be "Bi-directional data bus" which seems strange. Its hard to tell looking at the pictures took though.

Be careful trying to trace lines visually from a photo... it's difficult enough to do visually IN PERSON. Those lines could very well go between the pins, and off to somewhere else. I rely on DMM continuity, combined with VERY careful visual inspection, to trace lines. Also, don't forget that the board is double-sided... and watch out for vias under ICs.

An 8255 is a fairly common I/O interface device. You can read about it here: http://en.wikipedia.org/wiki/Intel_8255 (the Mitsubiti is just a clone of the original Intel device). The one is your photo is probably the interface between a CPU and the AY-3-8910.

The sound will be generated by the AY-3-8910. It can generate 3 different voices (A, B & C), which will be on pins 4, 3 & 38. That's the beginning of the analog audio section. I'd try to audio probe those pins to see (hear) if anything is being generated. If it is, you'll need to trace where it goes. Not sure how this clone works, but on original Froggers the three channels were connected (thru resistors) to 4066s (bilateral switches), which allowed control signals to turn on/off each individual voice. They were then mixed (tied together thru resistors). At that point, one design had the op-amp you posted a pic of (the 0069 sound board); however the other type of original Frogger sound board (the 0074) does not have an op-amp. This difference is presumably due to the different audio power amps used in the two different designs (M51516 vs MB3712). After the op-amp (or mixing), it's through the volume pot (voltage divider) then to the amp, and finally out to the speaker.
 
Your right it's not a frogger nor is it a bullfrog (Frogger clone).
There was some talk about a conversion of a super cobra to a frogger back in 2005 but after looking at super cobra boards it is not even close.

Since it is a clone board. You might want to consider converting the cab to 1 n 60. Just as a back up plan if you can not get this clone board to work.

I wonder if that is the Audio amp that is clamped to the Heat sink? It was a common to do that in the early days..
 
Little Progress

To answer a few questions. Yes the power amplifier is tied to the heat sink.

I haven't been able to get at this machine much, my daughter has a party on Sunday and she has requested that it be put in place and working by then. So work is in a holding pattern.

Thanks for the info on the AY-3-8910 and which pins the sound comes out of. This will be a great help to probing back the sound to the source.

What exactly is a 1 n 60? Since this machine is a conversion there isn't much in making it authentic if I can't get what I have to work.... (Although I haven't given up yet!)

Thanks!
 
1 n 60 is a jamma board system that will give you 60 games in one cab.
They go for 75 to 100.
The reason why I suggested it. It would bring you closer to a working game. Something a little less frustrating to work on than a clone frogger with no docs.

You can disable some of the games so that you don't have to add more controls on your Control panel. I am just thinking it might be more fun for you and your son.
 
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