[TECH] Galaga Bootleg

[pobtastic]

[ukvac] [TECH] Galaga Bootleg
Hey all, me again....

The blue output on this Galaga bootleg seems a bit weak. The Galaga ship is
completely cyan instead of blue. Assuming (hoping!) that this is just a
resistor blown, does anyone else have this board?? It is marked DG-09-2 and
has a 22 way edge connector. I can see one suspect resistor at R48 which is
so bad it crumbles when I look at it... So much so, the colour bands are no
more, can anyone tell me the value of this resistor??

Thank you,

Pobster

PS. I am a newbie and without wanting to appear stoopid, I need to ask a
question..... When a resistor is blown, it stays 'open' right?? So, do I
just check every resistor to see which one returns a zero value?? Or am I
just assuming too much....? And BTW, I know it could be a number of things,
but I want to do this my way!!!!

 

[John Bennett]

RE: [ukvac] [TECH] Galaga Bootleg
Almost ... well you get 0 for a short circuit and infinity for an open
circuit. The analogue meters won't move at all if a resistor has gone open
circuit which means infinity and the digital ones will generally display
1/out of range. Both types will move to 0 if there is a short circuit (such
as touching the probes together).

Sorry, can't help with the resistor value but you might find that the
bootleg uses the same component numbers/locations as the orginal board.
From a quick glance, the galaxians bootleg cocktail board I got from Andy
has the same location markings as a Midway galaxian full size board so it's
probably worth a look at the schematics for the original.

Cheers,

Steve



DATA Imported from archives: originally posted by Steve Coule (steve@coule.freeserve.co.uk)

 

[pobtastic]

RE: [ukvac] [TECH] Galaga Bootleg
Thanks to everyone for all help and tips!!

I have found 8 resistors on the video board that should read 1K ohms and
give reading for between 450 and 700. I really didn't expect this many....
Should I replace them all?? Or is this telling me that something else is
amiss?? I thought with resistors because you can measure them while they
are connected on a PCB that nothing else would 'interfere' with the
measurements you get from them??

Sorry for all the questions....

Pobster

 

[John Bennett]

Re: [ukvac] [TECH] Galaga Bootleg

You can't measure them accurately in circuit because the rest of the circuit will drain some of the current supplied by your test meter and hence give a false reading.

If it reads open circuit when measuring an in circuit resistor then something is definitely bad but generally measuring resisitors in circuit will give a lower than actual reading.

You can get away with unsoldering one leg of each resisitor but I suspect the problem may lie elsewhere.

Steve



DATA Imported from archives: originally posted by Steve Coule (steve@coule.freeserve.co.uk)