Robotron Power Issues

jgeiger

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My Robotron (that I got for $30!) had been working just fine until recently. It stays on for about 10 minutes or so then the game goes out. If I let it sit for a few hours it starts and eventually fails again. One other detail is that the game wont work at all if the coin door power is connected.

Monitor and marquee lamp still have power. The +5vdc LED (LED 1) on the power supply board goes out. I need to re-check the voltage coming out to the board but it looked like the -5 and +5's were all fine. The +12 seemed to be really low, closer to 5. I checked the fuses and they seemed to be fine. Im going to check the power again after a couple hours to see what it looks like before it starts failing.

Any suggestions? What are some good ways to test the power supply out? Would this be a candidate for Bob Roberts repair kit?

Thanks for any help.
 
At a minimum, the power supply board needs to be rebuilt. Based on your symptoms, the BR cap kit may not be enough to get it stable. Once the power is fixed you will be able to determine if there are any other issues. Always fix the power first. Bad power can cause a lot of other things to look like they are bad.

ken
 
also, as a diagnostic aid, grab your schematics and measure the voltages of all output AC windings, and, the voltages at all the test points indicated on the schematics - do that before and after the shutdown

that will help to determine if:
1. the transformer is working fine
2. whether the components before the 5v regulator are fine
3. whether the 5v reg (the IC) is dud
4. whether the transistors on the heatsink are duds

then pull the board and
- cleanup all ground points on the pcb and mounting plate
- rework/reflow the solder on all header pins, caps and the 5v reg ic
- reflow solder on the diodes and diode bridge(s)

after that retest to see if that improves things

as yellowdog alludes to (as well as cap kit) prob need to replace the 5v reg ic (put it in a socket too if there isnt one), poss the transistors on the heatsink so a full repair kit from bob roberts
 
Btw: Great buy at $30. Did you need to use a gun? ;)

ken

PS: For those who apparently have very thin skins around here, I was just kidding about the gun.
 
Thanks for all the help guys. Ill keep testing out the power and see what I come up with.

Getting the game for $30 bucks is both a happy and sad story. Found it on a Craigslist posted and figured it was junk based on the price. The woman said she wouldnt hold anything and I was in the middle of brewing a batch of beer so had to wait until the next day. When I got there the cabinet was in really good shape. Marquee and bezel were both in great shape and the control panel in good enough shape. I didnt bother even plugging it in, just loaded it up and gave them 30 bucks. Took it home, plugged it in, and it plaid just fine. Had to recap the sound board but other than that worked great.

Now, the sad part. Right when I got there someone was walking away with a Dragons Lair that they paid the same price for and the night before someone made off with a Galaga cabaret for $30 too.

Thanks again.
 
I dropped a power supply conversion kit from Bob Roberts in to the cabinet and the game powered up and played just fine. Im definitely going to use the info that everyone game me to rebuild and get the original ps working to keep the game in original condition. Nice to be able to play it while I take the time to do the repairs.

Thanks again for the help.
 
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