Millipede voltage reading double

TriniTT

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Hey everyone, I'm new to the forum. I haven't been working on games for long, and I'm still trying to get the electrical down, so please go easy on me. I'm a quick learner, but sometimes things need to be spelled out for me :p

So my problem right now is I have a Millipede game that won't power on. When I plug it in, the screen pops up, but it's mostly blue with other random colors mixed around. I've read some threads on this forum with people having issues. I'm reading twice the voltage on the circuit board mounted on the right side (when facing the inside of the back of the cab, looking out the front). Where it should test 5v, I'm getting 9.8-10 (depending on how long it's been on). Everywhere else that has the intended voltage listed, I'm reading twice the voltage that's listed (i.e. it says 19, but I'm getting 28 on the readout).

Any suggestions would be amazing. Feel free to ask any questions. I'm read to get this game back in action! Thanks!

Jonnie B
 
Sounds like you have a defective A/R II. (the small board mounted on the side of the cab)

I only recall the power board, the long board on the right and a lower smaller one. Is the lower one the one? Can I trace it to a specific resistor or something on the board itself?
 
Yes, this can be easily tracked down to either the A/R II or the power brick. I am too tired from my trip today to type it all out for you. I have posted the info many times. Do a search for Dokert Atari power brick testing or Dokert Atari A/R II testing IIRC.
 
Ok, I tested everything per your outline. The power brick tested perfect according to your outline. The A/R board, however, is showing double the intended value.

A/R I
On the 9 pin connector P7

Set meter to 20vdc
Red lead to pins 5, 6
Black lead to pins 1, 4
Reading should be +5vdc (could be as high as 7 or 8 vdc because there is no load)

Mine is reading steady 10 volts. Any suggestions on where to go from here? I followed all the traces looking for burns, blown resistors, solder that could be toughing other leads it shouldn't, etc. and I found nothing visibly unusual.
 
Ignore me, I must have been on Crack. Was working on an Asteroids and got it stuck in my head.
 
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The 2N3055 at Q3 is bad (in the middle on the giant heat sink). Replace him, Q2, CR1 & 4. Check R29 and R30 for any signs of physical damage. If so, replace them as well with 100 Ohm 1/4W resistors. If the problem persists, replace the LM305 @ Q1.

I believe the rebuild kit comes with all those parts except the 100 Ohm resistors (both anyway) and the LM305.
 
The 2N3055 at Q3 is bad (in the middle on the giant heat sink). Replace him, Q2, CR1 & 4. Check R29 and R30 for any signs of physical damage. If so, replace them as well with 100 Ohm 1/4W resistors. If the problem persists, replace the LM305 @ Q1.

I believe the rebuild kit comes with all those parts except the 100 Ohm resistors (both anyway) and the LM305.

Thanks! I replaced the 2N3055 and that resolved the voltage issue. I'm not sure what the parts are for q2, cr1 or cr4. Can you shed some light on where I might find them (i.e. radio shack, online, etc.) and what the parts are called or a part #.

Just to clarify my issue, the screen comes up blue with letters and numbers randomly in 3 or 4 rows vertically.

Thanks again for your help guys!
 
Thanks! I replaced the 2N3055 and that resolved the voltage issue. I'm not sure what the parts are for q2, cr1 or cr4. Can you shed some light on where I might find them (i.e. radio shack, online, etc.) and what the parts are called or a part #.

Just to clarify my issue, the screen comes up blue with letters and numbers randomly in 3 or 4 rows vertically.

Thanks again for your help guys!

Q2 is a TIP32 power transistor. For CR1 and 4 you can use 1N4001's or beefier 1N5059's. Jameco, Mouser, Digikey, etc should have them - they're fairly common. Glad you got it working now! :cool:
 
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