Asterock your baby !

[gyruss]

Noob question: How do you know which wire is what?

[level42]

By comparing the pin-outs on both schematics.
The schematics (or pin out tables) list which pin carries which signal.
F.i. you look up the "fire" input on one board and then on the other and you will know between which pins you need to make a connection. You do that for everything, +5V, Ground, video signals ( in this case X,Y and Z and their grounds), buttons and sound.

In simple terms you are simple re-routing the signal from one pin to another.
I always create a table (see above) which shows which pin needs to be connect to which pin on the other side.

The Asterock has two "weird' things though. Those have been discussed earlier. (a "common" plus (instead of a minus) going to all buttons and the sound output stage is different, hence the suggested cap by Speleo....

 
The thing looks basically like this (except that I used two separate finger-boards):

[gyruss]

okay, cool. I'll have to do the same with my cosmic zero, i'm sure i'll ask you some more questions.

[level42]

@Speleo_De: gonna sound like dumb but should I put that cap between the audio signal and GND or in series ?
Please explain what we're trying to do, I guess "decoupling" the circuits ?

I meant it in series, any 10uF to 100uf/25 V, plus to Asterock output. This is to keep DC out.

BUT ... this seems to be redundant then, as the Asterock Amplifier PCB has a Cap already, just looked at it.

I guess you mean C16 at the Amplifier on the " AR " board right ?

[speleo_de]

I guess you mean C16 at the Amplifier on the " AR " board right ?

Yes.

[level42]

Mmmm, hooked everything up except for the sound (to eliminate that if it would give a problem), double checked the connections. fired the machine up with the adapter and Asteroids board and I see a flash near the fuses of the power supply. Both 23V fuses blown.
Houston, we've got a problem...

Gotta figure out what is wrong in the connections....tomorrow......

[level42]

Even though I had to work late today I managed to do some investigating.

I figured I'd better go back to the initial working set-up before doing anything else, so back to the Asterock board.
First checked all the fuses on the power supply and replaced both the 23V fuses that had blown.
Power up, not working.
I have neckglow, no deflection chatter, the board's not running.

Checked all votages, +12V is missing on the extra connector (so ROM's not working). No voltage on the input of the 7812 on the "AR2" board.
Measure voltages across all the big caps on the Power Supply, one doesn't have any voltage across it.
Measured all diodes and found a short across two diodes in the diode bridge of the 23V section.
I need 1A 100V diodes, got some 1N4007 which should work fine. Heading to bed now though...more tomorrow....ah, just 2 more days to work and then a LOOOOOONG weekend with excellent weather up ahead. Not sure about the wife's plans, but I'm planning at least 1 day for working on the games. If anyone is in the area and wants to join the fun, let me know

[level42]

Desoldered both diodes and both were blown (full short). Soldered new one's in and powered up. Still nothing....WTF ?!?!

Ahh, but of course ! Because of the shorted diodes, the fuses that I had replaced had blown again ! Replaced and yes, we are back in business. Asterock is back.

Now.....what can have caused the short. Seeing that the problems were in the +23V section, the issue has to be there....will need to investigate further....

[Etienne MacGyver]

Glad that its working again, would be a shame to miss asterock on eurocade, you know euro bootleg - eurocade   

maybe better continue after Eurocade ? 

[level42]

Believe me, you do NOT want to hear that fire sound of the Asterock all day....

I'll have a look if I can find it easily. The 23V must be shorted in one kind of way...else I may ask for some support from 'around town"

[Etienne MacGyver]

Believe me, you do NOT want to hear that fire sound of the Asterock all day....

I'll have a look if I can find it easily. The 23V must be shorted in one kind of way...else I may ask for some support from 'around town"

Thats actually not too dificult....



See those wires? just disconnect one of them  

seriously, i think that the guy around town can help you out, and i think he likes that too  

[level42]

I desoldered 3 wires from the adapter, one of them the "common" wire for the buttons, which should be GND for the Atari board and +23V for the Asterock. Maybe there's the problem somewhere...

Anyway with those 3 wires loose I got the Asteroids PCB running again. Well. Somewhat running. The astroids and everything is pretty dim, except for the saucers and their firing. It also is "blinking" a little bit.

After some time, I heard that the deflection chatter stopped, looked at the screen, blank.
Powered off, on again, works again.....for a while...

Measured the +5V, only 3,7 Volts !!!! Some kind of miracle that it actually DID some running sometimes at all !!!
Fully adjusted the pot for the +5V on the "AR" board but I can't get it higher than 4.2 Volts.

It's probably that the Asteroids board is "eating" more power from the +5V, f.i. the EPROMS used on Asterocks use +5V, on the Asterock there EPROMS that are fed by the +12V and -5V.

Now....both the Atari and Sidam boards feature "power sense". Sometimes this feature has been cursed by people, blaiming it for burning parts. Often people "solve" the problem by modding the AR-2 so that the sense circuit no longer works.

Now.....the AR-2 and the Sidam "AR-2" boards are different. They use different regulators. However, I would figure that any sense level is simply still a (somewhat) +5V level, so am I right that I can hook it up just like that ? I know the Atari board also uses a -sense (not only +sense).

Any help here would be appreciated !

[level42]

Mehhh, checked it and there are no wires connected to the "sense" inputs of the Sidam. So, the Sidam doesn't actually use the sense inputs on this game.

So why can I only get like 4 volts from it while the pot is ALL the way up. The 2N3055 should be able to deliver loads of power....

By the way, I had a good non flickering screen for a while after I fully turned up the pot, so I have good hopes that when the +5V is OK it will run fine.

Of course I could put a switcher PSU in there, but that's not like we do it right ?  

[Etienne MacGyver]

you could test it with a switcher to determine of it is indeerd a power issue (which probably is)

i remember my CK board in comparation with your CK board that one i could not get the power high enough eather, while the other board went over the 5 volt, so i think some board just draw more power than others..

[level42]

Yes absolutely, the Asteroids draws more power. One of the simple reasons is that it has a couple more chips on board (sound !) but the main difference is that the ROMs are also powered from the +5V on the Asteroids while the Asterock has separate +12V and -5V for them (different kind of ROMs).

However, the PSU should be able to easily provide enough current. The set-up with the 2N3055 transistor should be able to provide 10A easily, and there's really no board that draws that amount of current....

I am thinking of either that the set-up of the regulation may have resistors that simply limit the range of adjustment or there might simply be a defect somewhere ....

Here's the schematic: