Space Invaders keeps blowing fuses

Mr.Smiley

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Hi,

i have a Taito Space Invaders Part 2 Table with a Moon Cresta PCB. Now i replaced the Moon Cresta PCB with a Space Invaders PCB 3 stack from Taito.

As soon as i power it up, i see some lines on the white monitor and hear a whistling sound. Then the 1A and 6A fuses blow and the lines and the whistling are gone, monitor is still white.

I double checked my pinout and adapter, I am using this one:

http://arcarc.xmission.com/PDF_Dip_Switches_and_Pinouts/taitoinvaderpinout.pdf

Currently Coin and Power on Reset is not connected.

Can anybody help me, I am really running out of ideas :(

Thank you!
 
Hi,

i have a Taito Space Invaders Part 2 Table with a Moon Cresta PCB. Now i replaced the Moon Cresta PCB with a Space Invaders PCB 3 stack from Taito.

As soon as i power it up, i see some lines on the white monitor and hear a whistling sound. Then the 1A and 6A fuses blow and the lines and the whistling are gone, monitor is still white.

I double checked my pinout and adapter, I am using this one:

http://arcarc.xmission.com/PDF_Dip_Switches_and_Pinouts/taitoinvaderpinout.pdf

Currently Coin and Power on Reset is not connected.

Can anybody help me, I am really running out of ideas :(

Thank you!
Hi.

I'm going to assume this PCA and Monitor was 100% functional before you converted it?

If yes, I hate to sound like Captain Obvious, but it sounds like you have something shorted on the the +5 or +12 to ground. The whistling sound you hear might be an unhappy cap, and it stops whistling when the fuse(s) blow because the power is removed.

Double check the voltage inputs and grounds on what you rewired to make sure it's correct. If that checks out, replace the two fuses, and with power OFF, take resistance readings across +5 and Ground, then +12 and Ground to check for a short.

If you don't find a short, disconnect the harness from the games Logic Board and turn it on. Did the fuse(s) blow? If no, the short is in the harness, because the fuses blow when the harness is connected to the Logic Board.

Remember, if that whistling sound was an unhappy Cap, be sure to replace it.

Hope that helped!

Thom The Tech
http://www.thomthetech.com
San Jose, CA.
 
Thanks!

Yes the monitor worked before but I dont know of the PCB. I cant read any resistance between 5V/12V and ground, does that mean i have a short somewhere in the table?

The fuses only blow when i connect the harness to the pcb, without is works.
 
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When I am connecting the harness to the lower board only, it blows fuse F2 1A and the 12V drops down to 3.8V.

Cant find whats wrong :(
Hi.

If the 12vdc is dropping to 3.8 vdc, there is your short.

kb0jjn nailed it. Track the wiring down and you should find the problem.

Hope that helps!

Thom The Tech
http://www.thomthetech.com
San Jose, CA.
 
Thanks for your help, i tracked 12/5V and GND to the power supply but everything seems fine. Whats strange, when i unplug the top board and connect only the lower and center board to the 2nd harness the fuse doesnt blow. Could it be that there is no problem with a short but maybe a broken capacitor on the top board?

When i plug in the top board again, the 12V fuse blows right away but the 5V fuse takes some time before it blows. It seems something is charging? and then he fuse blows and the voltage goes down to 0.85 V. What i dont get why there is still voltage when the fuse is blown.

Table worked before but with a Mon Cresta PCB instead of the Space Invaders.
 
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Just checked the PCB and noticed on the top board the 12V on Pin 7 is scratched out but just on the top, bottom looks ok. Could this cause any problems and how can i fix it?
 

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Doh thats was my fault, Pin 7 top isnt even connected to anything on the pinout. Pin 7 bottom is connected to 12V as well as both Pin 5. So the scratches cause nothing.

I still think its a faulty cap somewhere on the sound board.
 
Doh thats was my fault, Pin 7 top isnt even connected to anything on the pinout. Pin 7 bottom is connected to 12V as well as both Pin 5. So the scratches cause nothing.

I still think its a faulty cap somewhere on the sound board.

Before you go replacing caps you might get an esr meter to test them.

http://www.ebay.com/sch/i.html?_fro...1313&_nkw=esr+meter&_sacat=See-All-Categories

I would first disconnect the 12 volt wire from the supply and ohm it out (the wire coming from the pcb board) and ground; with power off. I will bet it is going to be very low. If it is good you should have about 100-200 ohms if I remember right. If it is bad you will probably have much less then you can remove a leg on one cap at a time till you find the bad guy. If the meter changes while you ohm it, it is just a cap charging and is normal. I really don't know that board very well and this it general info but Space Invaders is in my want list.

usually the +12 volts is for audio amps for sound but not Always.
 
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