Pinx's Atari Asteroids Restoration...

As it came in.
Front view.
Left side .
Right side.
Start to clean.

Monitor (no screen burn).
Back door.

Audio Reg (AR1).

With this restoration, i decided to start here, mainly because this is my first vector cab and other than the power brick, it was the only thing in it that i had worked on before.

Replacing components.

So i order'd a Bob Roberts rebuild kit and replaced all the caps and the TIP32 transistor at Q2 and the 2N3055 in the black heatsink.
By replacing all these components, i new that what ever other faults i might find with the game, they wouldnt be down to bad voltages.

Deflection pcb.

The Deflection pcb was supplied as working, but as i want the game to be reliable, i decided to re-cap it anyway, bearing in mind that this game was made in 1979! it pays to replace as many parts as you can obtain, rather than just replace the parts that go, as you normally find that putting in a new part, puts more of a strain on the old parts still being used.
Before removing this pcb from the cab make sure all power to the cab is removed and remove the signal input from the game pcb. Otherwise possible permanant damage, could be done to your tube !

Replacing components.

There are 2 capacitors at locations C804 and C806 they are 470uf 50V caps. Rather than shop around for these caps i order'd a Electrohome GO5/801rebuild kit
from Bob Roberts as it also supplies parts for the HV section and the monitor regulator pcb.

Monitor Regulator pcb.

This pcb, has the job of smoothing out the voltages supplied to the monitor, hence the two large blue filter caps. Just in front of these but behind the large heatsinks are 2 small capacitors that are prone to failure.

Monitor Regulator pcb cont...

These small caps are located at C102 and C103 they are 1.0uf 50v capacitors and come supplied in the rebuild kit. When working on this pcb, you must pay very special attention not to accidentally short between the connections on the large blue caps at C100 and C101 as these store alot of residual current.


Deflection Transistors Heatsink.

These are the main "X" & "Y" transistors, that give the monitor its amplification. The "X" axis has a 2N3792 at Q707 and a 2N3716 at Q708. The "Y" axis has a 2N3792 at Q607 and a 2N3716 at Q608.
These are another component, that are prone to failure due to old age. In between the transistor and the heatsink is a insulating mica, these break down with age and can then cause a short in the amplification circuit. When replacing the transistors as well as using heatsink compound ALWAYS replace the mica's with new ones. And once you have fitted the new transistors, meter each transistor from the base to the monitor chasis with a digital mutlimeter, to be sure there is no continuity.
Pic on left shows the old rusty transistors. Pic on right shows new ones fitted.

Big Blue.

The large blue capacitor in the middle of the power brick is a logic filter capacitor and due to the age of this component, it is probably no longer doing its job properly. It's job is to smooth out the 5+ volts, going to the logic pcb in the game. It is a 27000uf 16V capacitor. These can be obtained from Bob Roberts in the U.S.
Dead Atari video game cabs are more likely to be faulty by this cap being duff than any other fault.

After only 2 weeks of work its alive already !!

But then...

After only a week of playing it decided to die... and all that could be seen on the screen was a thin horizontal line. This meant that somehow the monitor had lost its "Y" axis. So the first thing i did was meter the transistors in the "Y" section. The large ones on the big heatsink were o.k. but a TIS98 transistor on the Deflection pcb located at Q601 meter'd duff.

TIS98 transistors.

Not exactly easy to source, as they are pretty much obsolete now, but after asking on the Vector mailing list and snooping around on the net, i managed to get some from Dial Electronics. So rather than just replace the one that had died, i shot gunned the whole deflection pcb and replaced them all...

F600 axial lead fuse.

After replacing all the TIS98's i put the deflection pcb back in the cab and tried it, but still just a flat line. Which had me really baffled, as i had replaced all the transisors in the "Y" section (and the "X" section too) and so i had to remove the deflection board again and start metering other components and found the 2 amp axial lead fuse at F600 was metering open. I had never seen one these before and didnt have any, so i solder'd a couple of legs cut off a spare capacitor onto the old one and then solder'd a 2A fast blow fuse across them (see arrows in pic) and this did the trick.

Axial lead fuses.

When looking at the schematics for the deflection pcb, it listed F600 as a fast blow 2 amp Pico fuse.
After much discussion in the
#Jamma+ forums and on the Vector list, it was decided that these were the same as"Wickman" or "Busman" fuses and Farnell do these. Though a mate from #Jamma+ donated me some
(cheers Julian "dreamdvd")

Axial lead (Pico) fuses cont...

These type of fuses have a very low tolerance for heat and so fitting them is a bit of a delicate task. In order for me to solder it to the pcb i used a heatshunt (in this case a pair insulated tweezers) and left some length on the leads, so i could hold it in place with
the tweezer (arrow'd in pic). I dressed the tip of my soldering iron with a medium blob of solder and then with the tweezers holding one lead close to the pcb, i solder'd it on. I then gave this a few minutes to cool before soldering the other lead.

Axial lead (Pico) fuses cont...

Once it was safetly in place, i then checked it for continuity with a multimeter, to make sure it had'nt blown during soldering. It was then just a case of re-installing the pcb back in the cab.

(pic shows new Pico fuse fitted, not a great photo but you get the idea)