Title change:now gunfight and cosmic invaders fix

[Lurch666]

Cosmic invader now working except for missing UFO sound.Am awaiting a replacement 76477 to fix it.

After I got it working but with the bottom of the invaders missing the board died again.Took me ages but tracked it down to pin 12 of A3 not providing a strong enough signal-it was going between 0V and 1V so not triggering the logic.

Replacing this got the board running again.

As part of the troubleshooting the previous problem I removed all the chips on the sound section that were connected to the data bus to see if it was any of them stopping the board from working.Also was in the process of replacing E3 when the board went down again.

After getting it running for the second time I replaced all the chips I had removed with new ones and the invaders were correct.

This left me with two problems.Some sound FX were missing and the invaders bombs has lines on the top and bottom.I used the 1.2 test rom to test the shifter and found a bad chip.

On this board the shifting is done by a matrix of eight 74LS151s and it was one of those causing the problem.

replacing some of the LM3900 amps fixed most of the sounds.A new 4030 in the noise generator helped (actually used a 4070 as it's compatible).

A new 556 at H4 fixed the missing extra base sound so now it's just the UFO.

Moving onto the gunfight now as with what I've learned should let me fix this on as well.

Also here is the cosmic invader with the space invader schematic chip positions marked in case anyone else is trying to fix one.

NOTE:might be mistakes and sometimes different pins are used so use this as a guide but check yourself to verify the info.

The white numbers are the motherboard chips and the red are daughterboard chips.

ALSO:I marked the E3 chip in red incorrectly as B3.

(Right click on picture and "VIEW IMAGE" to see it full size)

Lurch6662019-03-09 19:49:27

 

[Lurch666]

oops double post
Lurch6662019-03-09 19:49:12

 

[Ace`]

Good job, some times you question was it worth it when you get ones that need a lot of work like this. It usually is worth the effort.

 

[Lurch666]

Gunfight nearly working now.

I've got it through a ram test but when I put the gunfight roms in I'm getting garbage.

I have the board strapped for standard 2716s and since the gunfight roms are 4x1024 I put the H and G on one rom then F and E on another but just got a blank screen.

then I tried 4 eproms with a double image and now get random gargabe after a reset-sometimes it moves and sometimes it doesn't.

Here is how it's strapped:

Have checked E2 and am getting output from pins 1-4 so I'm thinking either I have the roms set wrong or maybe there's another fault.

@ace:It's always worth fixing things.It's when they are working that I lose interest

Lurch6662019-03-21 13:22:53

 

[Lurch666]

Got this running at last.

After trying quite a few variations with the eproms I ended up modifying the pcb so I could just use a single 2732 by sending A11 to pin 21 and connecting pin 18 to 20 to ground the chip selects so this eprom is always active.

Now it's working I think it maybe the 74LS42 at E2 was faulty even though it was showing data since this mod bypasses it completely.

Anyway game is running but can't coin up and no sound since the daughterboard is missing the amp chips so more work but it good to finally get something on the screen.

 

[Lurch666]

Thanks to ace for providing an adaptor so I could fit the smaller replacement 76477and now the saucer sound is back so my space (cosmic) invaders is fully working.Dead chuffed.

Found the input problem with my gunfight is with he opto isolators used on all the inputs.Just going to replace them all.

Also waiting for the sound amp chips to replace the missing ones and see where it goes from there.

 

[Ace`]

Good job mate.

 

[Lurch666]

I have had a request for info about the pinout of my cosmic invaders board so I thought I would post it here for everyone who needs it.

If the 10 pin connector is not present the board does not reset.

Also on the 10 pin connector where I have put the ? is a wire I have not connected but assume is the player2 start.

 

[mhaaland]

Thank you for posting the pinouts. I have a stack of these I'd like to get going. (8 to be exact)

 

[galaga1982]

Hi Lurch666,

I also own this pcb, but I couldn't find any information such as pinout or schematics before that.

Recently, I got to know that ukvac's repair post and hope that i can fix it.

I made a jamma adaptor with the pinout you suggested, but I could not see it except for the garbage screen.

It is beleved that one of the 16 rams is fault, or that the POR circuit is not working properly and thus does not pass over to the title screen.

There are something I don't understand in the last post.

1. How is the POR circuit configured and where does it connect, 36 pin or 20 pin edge connector?

2. Is the sound wire connected to 10 pin of 36 pin edge SPK+? if so, where does the SPK- (ground) connect to?

3. Your pcb has jump wire which connect to 10 pin and resistors in pcb. Mine is not like that.

Does this need to be connected for operation?

Unlike yours, my romset has six configurations and is marked 'a/w'. Maybe it is not a cosmic invaders.

Luckily, after several on and off attempts, I was able to see the alphabet...

Once again, I would appreciate it if you could show me the detailed photo of each pinout.

Thanks!

galaga19822021-05-19 08:58:23

 

[Lurch666]

IMPORTANT:Verify you have -5V to this boardset. The ram and CPU both need -5V and can be damaged if they don't have it.

1)I never looked at the POR circuit it just worked as long as the small edge connector (the one on the right in your picture) was fitted and the pins 4 and D were both connected to GND.

I think reset is pin 12 of the 8080 so check that.

2)I just connected the other Speaker wire to GND.

3)That wire is for sound so your board should work without but obviously no sound.

You can worry about that once the board is up and running.

Looking at your picture you are missing a ram chip-there should be 16 of them.

The boardset can be configured for a wide variety of eproms so the number and type of eprom can vary.

Someone will have to verify but it looks to me like you have standard 2716 eproms in there so should be easy to check.

Don't see how any more pictures of the edge connectors could help but if you want a picture of the smaller one I can dig my boardset out and take one for you.

 

[galaga1982]

Hi Lurch666,

Thank you for your quick reply.

+5V, -5V, +12V for the board has already been properly connected.

I agree with your opinion as well. The lack of ram could be a problem.

Ram for empty socket is on the way. The mm5280 ram is not easy to get.

I'm sorry, but I'd appreciate it if you could send me detailed pictures of each connector and jumpwire for the sound section as a confirmation. I can't see the connection on the other side, solder side.

I'll try it again and let you know the change.

Regards,

 

[Lurch666]

 

[galaga1982]

Hi Lurch666,

Thank you very much. The picture helped me a lot.

The resistance of the sound jump wire seems to have been added. May I know the capacity of the resistance? and I'm curious about the purpose of the small daughter board equipped with a capacitor, and where is it connected to?

Dozens of attempts to install and remove rams have barely succeeded in driving, proving the contents of the rom set.

The game turned out to be 'Ozma Wars', but due to faulty mm5280 drams, the normal screen is currently not visible. Additionally, I am planning to purchase mm5280 drams.

I will post changes after purchasing and fitting them.

Please look forward to it.

Regards,

 

[Lurch666]

I put the resistor on the wire that connects the sound because there is no volume control and it was too loud in my cab. Can check the value for you but I just tried different resistors until the sound was at an acceptable level.

The other small PCB is a cheap ebay single channel sound amp connected to the sound output as there isn't any amplification on the PCB.

I took the sync and video signals before they were joined into the composite signal that is available on the edge connector so I could convert it into jamma output.

 

[galaga1982]

Thank you always. That's what I'm curious about.

 

[galaga1982]

Hi Lurch666,

I want to ask you a question first.

From set of cosmic invaders is wondering if you used mame file penrhos uploaded at mame team. In my case, whether this is a set, test rom (test.h), invaders.zip, it didn't boot. If you have your own rom set, I would appreciate it if you could send me a rom file.

For some reason, test rom files, invaders, and ozma wars roms did not work at all, except for the originally equipped roms. I tried alternating roms in the E/F/G/H position of pcb, but I couldn't boot them.

The jump wires on the back of the board and the broken traces around 74151 may have something to do with not working. Has your board been modified?

Aren't space invaders, space invaders deluxe, ozma wars all in the same architecture using 8080cpu, sn76477 psg? Oh, there's a little bit of a difference. Maybe because other boards use separate por circuits.

Let's get back to the point and talk about the repair process of cosmic invaders.

1)ram issue

I ordered the mm5280 ram from China, but it came into my hands in two months. It took too long even if it was a Pandemic situation. In addition, 40% of the orders were defective. I didn't know it was a defect, so I put it on and took it off many times. Because of this, it has wasted a considerable amount of time.

2) replacing ram socket

Only one side of the socket was in contact, and the spring tension was eliminated, so there was a high probability of poor contact. This is also replaced with a 11 pin round hole socket that is now discontinued.

3)game screen

Rams work properly, a little contaminated, but the game is ozma wars.

4)control

The credits went up, and the start and shoot buttons worked. However, there was no control at all. I put it on and took it off because I didn't know if there was still a faulty ram left. After a considerable amount of time, the edge contacts and connectors were loose and could not be reached. I put a piece of wood into the loose connector to make it tight, so I could control it normally.

5)sound

What fun would a game be without sound? Based on your picture, I connected the resistance to the 10th pin of the large connector, but I heard only a very, very faint noise. Normal invader shooting and ufo noise were not heard.

Is there a problem with the amp? When I touched the sn76477 and lm3900, I couldn't feel any warmth. One of the ways to check the condition of pcb that has been acquired for a long time is to touch the ic and check whether it operates according to the presence or absence of warmth. It was quite effective for me.

Once again, looking at midway and taito's invaders schematics, all sound is supposed to occur through lm377 amp. There is definitely lm377 on the chipboard, +12v supply and output contact. It was strange why other people didn't connect it.

Connect +12v, spk+, spk- to the small connector. As soon as I turned on the power, a very welcome noise welcomed me. Both lm377 and sn76477 are warm to the touch. At times like this, the board is like a human being. Everything connects, so the blood works normally as if circulating in the human body. Like a dead body when blood doesn't flow. At times like this, I have the illusion of being a doctor, and I feel joy.

6)correct rom set

There is the last question. It works, but there are still errors on the screen.

I decided to investigate one of the mounted roms. When I read into the programmer and uploaded it to the "rom identification" of the Arcade restoration site, I found that it was a bootleg of ozma wars called "solar fight". I thought there was little information because it was an old and unpopular game, but it was an unexpected result. Of the six roms, five matched and one did not. By matching it, graphic errors disappeared and normal play was possible.

Replacing all six roms with ozma wars (set 1) of mame does not work. The reason remains to be questioned now. Even a modified or hacked board would have been for ozma wars.

Thank you!

 

[Lurch666]

My board doesn't have the modifications yours does but it does run the test rom,space invaders (standard tatio set) and lunar rescue.

Puzzled by the incompatibility especially with the test rom. Did you try it in all the sockets?

That's great info about the amp-it never occurred to me to see if it was connected.

 

[galaga1982]

Hi Lurch666,

Sorry for the delayed reply. I have another layout board like space invaders of taito, it's logitec space invaders. I posted here on ukvac forum. If you search for my old post, you can see the picture. A few days ago, an unknown boot error suddenly appeared and I've been having a hard time solving it.

It was judged that it was a problem with cpu because it was not able to boot, so I used a heating gun during the replacement process. By the way, the heat seems to have caused problems in the 10v 22uf tantalum capacitor next to the cpu. It showed severe short-circuit symptoms with voltage of 0V without a screen. After a long time of trouble shooting, I just heard the screen and the booting ufo noise.

However, there is no further progress on the bar screen. The cpu and ram do not seem to be a problem, but I cannot see any garbage on the screen even if I replace the other romset. It cannot be checked with the latest programmer due to using 2708 eprom.

Do you know any idea? Is it possible that the screen cannot be changed due to a problem with the logic IC other than Rom?

Perhaps, when testing the cosmic invaders pcb, this romset was used, and the problem was that 2708 eprom was installed in the 2716 socket for a moment.

Of course, my cosmic invaders board works well with solar fights (ozma wars bootleg). Unfortunately, testing other space invaders roms on all sockets did not allow booting.

Regards,

 

[Lurch666]

So is the screen blank?

I presume you have checked the clock and reset for the CPU?

If this boardset is a copy of a standard one then you might be able to change the strapping so it takes standard 2716.