Grandstand Astro Wars Game (Faulty) - help with component identification

Thread Starter

bobmoo79

Joined Jan 25, 2019
2
Hello all, new member here!

when I was a child I owned a game released by Grandstand in the UK called 'Astro Wars' (also known as 'Galaxy II' and released by Epoch in other countries).
It was awesome, at least that's my recollection of it, but unfortunately the unit I have no longer works and so I have been trying to repair it, and I was wondering whether any of the kind folk on this board would be interested in helping...

This is what I'm talking about!


After spending quite a bit of time on this I have narrowed down the faulty component but I have been unable to identify exactly what it is, so I'd appreciate some advice.

With no circuit diagram available I had a go at creating one (see attached) but I can't guarantee it is correct, although maybe it'll help see what the component might be doing. I'll add some description below.

The faulty component is S06 (bottom centre of the schematic), and I have confirmed this by obtaining a working game and taking the S06 from that unit to repair the faulty unit. With that good S06 in place the broken unit works perfectly. Obviously to get the faulty unit working I need to find a new S06 for it.
You can see the component below (this was taken during testing, which is why one leg is detached).



The circuit takes a 6v input and produces a -10v supply for the microcontroller and -39v to drive the VFD display.
Pink voltage values in circuit have been measured in the working unit.

With the broken S06 in circuit I noticed that the Transistor (S02 - a D882 npn transistor) gets very hot very quickly when power is applied. When switched on the voltage (when measured at the supply) drops to around 2.5v and the current is high - 1.5A(!). The game does nothing - appears dead.

When S06 is removed from the circuit, all voltages on the board are as expected (except -39v VFD voltage is not present), and the microcontroller is working. I provide a separate dedicated supply to the VFD I can see the game is functioning correctly.

I have checked all caps, confirmed operation of all transistors, confirmed all resistors. S06 is definitely the problem.

The component looks (to me) like a diode (see picture above) but when removed from circuit the faulty S06 measures 20ohms in either direction when measured with a DVM - not typical diode behaviour. The working S06 acts like a typical diode when tested in the same way.

I first though this component was a 39v zener diode based on my observations below:

The cathode of the S06 (assumed 'diode') connects to pin1 on the transformer.
I disconnected the other end of the diode from the circuit to see what's going on here.

I was surprised, but I'll report what I saw. Keep in mind I have only a basic handheld scope and it may not be correct.

The Transformer is providing an ac signal, 200v pk-pk, period 10us, -140vdc offset to the cathode.
At the anode, which is disconnected I see a -39v dc signal with only minor ripple of 1v pk-pk.


I ordered a 39v zener and installed it but the game still did not work, the D882 transistor got very hot, very fast. Unit is dead. Hmmm.

Next I connected five 9v batteries in series with a resistor as a simple circuit to test the known working S06 component to confirm the zener voltage but that appeared to confirm this is NOT a 39v zener diode after all. The component did not clamp the voltage when measured across it with a DVM...

Can anybody add any insight into this problem??

I'm quite determined to get to the bottom of this but have run out of ideas....
 

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Thread Starter

bobmoo79

Joined Jan 25, 2019
2
Update: I even contacted Epoch (the Japanese manufacturer) but they don't appear to have any useful information. Shame. I had hoped they'd keep an archive somewhere.

A closer look at the component in case anybody can help.

Orange glass body, two bands. Reed at the end, then Brown.
20190216_133657.jpg
https://ibb.co/xqdtCQL




Sorry should have said red and brown.
 

BulletMag

Joined Aug 4, 2019
2
Looks like a schottky diode to me (I’m guessing that would fit with the S06 label,

What value though I have no idea sorry.

Please update if you have any luck
 

BulletMag

Joined Aug 4, 2019
2
Managed to grab myself a non working one too from a car boot,
S06 on mine has just the red band.
I get exactly the same symptoms as you describe, I have replaced the D882 with no change.
I’m hoping to get this fixed as if I recall correctly this was the first video game I ever completed
 

panic mode

Joined Oct 10, 2011
2,814
yes the component looks like a diode but what kind of diode it is hard to tell. since there is no RF etc present, most likely it is just a regular signal diode or maybe a zener or maybe a shottky. you already ruled out zener so most likely it is either regular signal diode or schottky. since you have a working unit, this is easily confirmed since shottky has low forward voltage.

next, where did you get that schematic? it does not look right... and could you put more pics of the PCB?
 

Retroid

Joined Nov 18, 2019
2
*Bump*

Got the same game right here & trying to find a replacement for the S06 diode. A lot of Googling seems to suggest it's a Germanium(?) BA2 diode but I have no idea what a modern equivalent would be.
 

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cilaos14

Joined Oct 25, 2020
1
hello Bobmoo79, BulletMag, Retroid,

I'm facing the same issue with my Astro Wars game.
I have replaced the S02 transistor D882 , bu it's getting very hot when I switch on the game, and the game still does not run.

Did you manage to repair your game ?
Did you replace the S06 component ?

thanks for your feedback
Cilaos
 
hello Bobmoo79, BulletMag, Retroid,

I'm facing the same issue with my Astro Wars game.
I have replaced the S02 transistor D882 , bu it's getting very hot when I switch on the game, and the game still does not run.

Did you manage to repair your game ?
Did you replace the S06 component ?

thanks for your feedback
Cilaos
For what it's worth, I fixed one of these with the exact same issue by replacing S06. I used a 1N5275B though.
 
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