Level42
New member
I am trying to run an original Atari Asteroids PCB in my Asterock cab.
Now, it runs, but only for a short while after I turn it on. I measured the +5V and sure enough it was very low (about 3,7V, I was amazed that it ran at all for a while). When things start heating up after let's say a minute or so, the board obviously crashes).
Now, I tried to up the +5V adjusting the pot but I can only reach +4V.
Note that the power supply works fine at +5.1 Volts with the original Asterock PCB. However, the Asterock PCB uses different type of EPROMs which require +12V and -5V which are supplied separatly.
So, the larger "power hunger" of the Asteroids probably lies in the extra power the EPROMs take.
Anyway....I wonder why the power supply can't get up any more after I have fully turned up the +5V pot.
The Asterock machine uses a similur set-up as Atari (power-brick, and a neat "AR-2" board but the +5V regulation is different. It uses an LM723 as regulator.
Here's the schematic:
Note that the sense inputs are NOT used.
I was thinking maybe the regulation is (too) limited because of the used resistor values around the pot ?
Now, it runs, but only for a short while after I turn it on. I measured the +5V and sure enough it was very low (about 3,7V, I was amazed that it ran at all for a while). When things start heating up after let's say a minute or so, the board obviously crashes).
Now, I tried to up the +5V adjusting the pot but I can only reach +4V.
Note that the power supply works fine at +5.1 Volts with the original Asterock PCB. However, the Asterock PCB uses different type of EPROMs which require +12V and -5V which are supplied separatly.
So, the larger "power hunger" of the Asteroids probably lies in the extra power the EPROMs take.
Anyway....I wonder why the power supply can't get up any more after I have fully turned up the +5V pot.
The Asterock machine uses a similur set-up as Atari (power-brick, and a neat "AR-2" board but the +5V regulation is different. It uses an LM723 as regulator.
Here's the schematic:
Note that the sense inputs are NOT used.
I was thinking maybe the regulation is (too) limited because of the used resistor values around the pot ?
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