Pimp my arcade machine - Enigma II

[Russ]

Yeah AC, I tested the feed for the power supply board from the transformer, which says 14v. It was 14.4 with no load so that's ok so I went on to test the transistor (the bit on the metal heatsink you mentioned previously).

At the moment the second i plug the power supply board in it takes the fuse out for the 14v feed, so I'll probably try replacing the transistor first and see if that stops eating fuses ? Once I can plug it back in (I shoulda bought the one you sent a link for!) I can test the reset voltage

Cheers

 

[twoforty]

Once you get it out measure across the case of the transistor (collector) and pin 2 (emitter) you will probably find its a short if its bad. If it checks outok unplug the edge connector from the game board and try to power it up again. Do you have 2 edge connectors on your game? one on the top board and one to the lower board? make sure you unplug both when you try the power supply again. Could be an easy fix , it gets addictive once you've fixed a couple... I have about 10 sets of star wars boards to fix right now...the mathbox section that calculates the 3D effect is amazing for its day, you could probably do the whole thing on a couple of small chips today.

 

[Russ]

wicked, thanks, can't wait to get home. I've learnt a fair bit already from this.

You're right, I did computer graphics as part of my degree and one of my final year projects was a (rubbish) computer game engine. I'm sure the math is very similar, I was doing it programmatically and in the past it was hardware based

Cheers

 

[Russ]

Ok, well I tested the transistor and it doesn't appear to have a short, but at the same time I couldn't measure the ohms on it now either? Weird. Anyway put the power supply board in and didn't connect anything to it and it ate the fuse and this time a tiny puff of smoke came from it or something around there I'll get there though one day, shoulda bought that board! lol

 

[twoforty]

you need to have your meter on diode setting to check the transistor, It could be one of the other transistors on the board, I expect the smoke was a resistor burning up from having too much load on it.

 

[Russ]

Yeah I had it on that, err turns out I had the probes the wrong way around testing the diode lol

This time between emitter and collector I get 501 and base and collector 478...

 

[twoforty]

Probably need to remove it to test it, you should get around 0.500 ish with one lead on the base and the other on the emitter or collector...if you don't see anything use the other lead on the base and try again. You shouldn't get anything between the emitter and collector.