Space Invaders power supply

[P-feif]

Any one know of a good place to get a rebuild kit for an original Space Invaders power supply. Need to rebuild mine and I can't find a rebuild kit. Maybe someone that can put a kit together for me?

[CLHelms]

Try Ian Kellogg he is on here constantly..very good tech and parts supplier . Give him a shout in the shoutbox

[P-feif]

I did but haven't gotten a reply back from him and I didn't want to bug him to death.

I remember John mentioning in one if his vids that someone else put together a kit for the computer space. Wasn't sure who might reply to this...

[CLHelms]

Tothwolf , went back and looked ...

[P-feif]

O.k. got a kit from Bob Roberts, however the two big filter caps are the wrong uf value. I sent a note to Mr. Roberts and he replied that they are modern equivalents and are o.k. to use. I always thought that you can increase the volt value but the uf had to stay the same. Thoughts??? Ian I'd love to hear what you have to say.

Old caps
20000 uf, 16 v
6000 uf, 35 v

New caps from Bob
22000 uf, 35 v
68000 uf, 35 v

I'm guessing that the higher uf may do nothing more than act like a better filter but I'm really not sure.

[iankellogg]

it will act like a better filter and slightly increase inrush current but that isn't a very high difference.

[P-feif]

Thanks Ian.

I've been sending e-mails back and forth with Bob and he sort of said the same thing. Thanks for you input as it makes me comfortable enough to install them now. I don't minds mods as long as I know they will work.

[P-feif]

O.k. installed all new caps in the power supply and still have the same problem. With the -5 pot turned all the way I can only get to -5.2 and with the +5 pot turned all the way I can only get to 4.9 volts, with the mother board plugged into the harness. If I unplug the harness from the mother board then I can set -5 and +5 perfectly.

Here's what I have done...

The game had stopped working, it had lines under the alien ships that you couldn't shoot through. I had this problem before and resetting the voltages is what fixed it so when it happened this time the first thing I did was to check voltages. They were not set right so I tried to reset them but could not get to -5 or +5 so I ordered a rebuild kit from Bob Roberts. I can with caps only. I installed the caps. While I was at it I also pulled the mother board and installed a cap kit on it too. I separated the daughter board from the mother board and cleaned the connections, I removed all socketed chips cleaned the legs and re installed/reseated the chips, I went over both boards and touched up any solder that I thought looked crummy and reflowed all header pins and made a small repair to the board edge (the harness connector looks fine). Then I reinstalled the daughter board on the mother board. I then put the power supply back in the game and set the voltages with the harness not connected to the mother board, then plugged in the harness to the mother board and rechecked the voltages. They were way off, the -5 was around -5.45 and the +5 was around 4.65. I tried to reset them but got the results listed above, however the game works now even with the voltages sort of wrong. I feel that over time this can only cause problems with the mother board so I would like to get the power supply sorted so that I can actually supply the correct -5 and +5 to the mother board. I have no problems setting the +12 volts, I can get it set to 12 volts on the nose.

Idea's???
Any ideas what I should look at next, I'm sure it's something with the power supply and not the mother board and harness.

I hope this link works.
https://www.facebook.com/thomas.f.pfeiffer/videos/10206045396310997/?l=7952607930697282068

[P-feif]

So today I had a little time to fool with this thing. I found in the schematic that there are four diodes that sort of tie the -5 and +5 circuits together. I removed them and tested them. All were good however I found one of them was loose, it had one leg that I could remove without desoldering it. I resoldered all four diodes back into the board and made sure they were in there real good. Still got the same problem. With the pots cranked all the way I just can't get -5 or +5 volts. I guess next up is to check the transistors that are mounted in the heat sink? Maybe the resistors that are inline with these two circuits? I don't know what's left?

[P-feif]

Alright haven't fooled with this thing since the last time I posted about it. Weeks have gone by but I've been thinking, it just might be something on the mother board and not a power supply problem. Thoughts???

[iankellogg]

I have been pretty slow to respond here lately but reading through this. 4.9V is more than good enough. I would move on from there. What issue are you having?

[P-feif]

I can only get 4.9 volts if I crank the pot all the way. Same with the -5, I can get to about -5.1 if I crank the pot all the way. This is with the board plugged in. If I unplug the board I can get 5 volts and -5 volts with the pots centered. Something has got to be pulling the power supply down. I'm guessing that if I just ran it the way it is it would work for awhile but sooner or later something is going to let the smoke out. Maybe I'm wrong and being too picky but I just want to make sure it's right before I push it against the wall where it's hard to get into the back to work on it.

[iankellogg]

that sounds fine to me.

[P-feif]

So give it a go with the pots cranks all the way huh?

[iankellogg]

there is probably something going on making it need to be cranked all the way but 4.9V is more than fine and I would move on to something else. I still haven't see anything about what the game is actually doing to help you out.