(Topic ID: 300405)

Fixed - Bally Mata Hari - 5vdc low - Need some help.

By barakawins

12 days ago



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  • 7 posts
  • 5 Pinsiders participating
  • Latest reply 10 days ago by barakawins
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#1 12 days ago

Hi all,

I'm working on a Mata Hari. TP5 on the mpu should be 5vdc. But, I'm only getting 4vdc. On the rectifier board, I re- pinned all connectors and get the same result. TP3 on the rectifier board should give me 12vdc but I'm only seeing 10.5vdc. Removing JP3 from the mpu should give me a higher voltage reading but I'm not seeing the same 10.5vdc reading. I thought maybe BR2 was giving me the lower voltage so I changed it. Again, same reading, 10.5vdc on the rectifier board at TP3. This is low. I then thought it may be the fuse holder in line with TP3 on the rectifier. I changed this too. I'm still getting the same result. Anyone have any ideas? On the mpu the red LED is stuck on. No flash or flicker because It's not getting 5vdc.

#2 12 days ago

Same advice I always give…..start at the wall. Follow the power all the way into the machine and fix as you go. Does the service outlet match the power at the wall? Is you filter or varistor pulling the power down. Is you wiring to the transformer good? Are the windings at the transformer the correct power? What does the wiring from the transformer to the rectifier board look like? Have you rebuilt the rectifier? Have you repined the connectors and replaced the headers? What are your voltage reading with only the rectifier board hooked up?

#3 12 days ago

Follow pinwiki. Disconnect all boards except rectifier board. Verify your voltages are good there on the test points. Add the SDB, check all voltages again. You have to get the voltages right at this point before going any further.

#4 12 days ago

Could be a bad filter capacitor. If the large filter caps have not been replaced now is a good time to replace them. While waiting on the new caps, unplug the SD board and measure the test point voltages on the rectifier.

#5 12 days ago

Ok.. I started with voltages at TP3 first once I removed connectors from all boards. I was getting the required 12vdc which is used to generator the +5vdc
on the put. So, now I knew the transformer and bridge rectifier board are working correctly. I plugged in the connectors on the mpu next and all was well. I was getting 16vdc at the bridge rectifier TP3 which is still good and getting 7 flashes now where before I just had a locked on led. When I plugged in J3
on the driver board is where it all went down hill. This connector, when plugged in locked on the led on the mpu. So, I unplugged and replugged and was
now getting proper voltages on the driver board and correct flashes. All is good now. I'll need to re pin J3 on the driver board. Seems those pins caused my havoc.

#6 11 days ago
Quoted from barakawins:

Ok.. I started with voltages at TP3 first once I removed connectors from all boards. I was getting the required 12vdc which is used to generator the +5vdc
on the put. So, now I knew the transformer and bridge rectifier board are working correctly. I plugged in the connectors on the mpu next and all was well. I was getting 16vdc at the bridge rectifier TP3 which is still good and getting 7 flashes now where before I just had a locked on led. When I plugged in J3
on the driver board is where it all went down hill. This connector, when plugged in locked on the led on the mpu. So, I unplugged and replugged and was
now getting proper voltages on the driver board and correct flashes. All is good now. I'll need to re pin J3 on the driver board. Seems those pins caused my havoc.

The 12v unregulated return, orange wire, is the typical problem. Definitely repin but consider doing the 'ground mods' while you have the board out. That takes stress off of that orange wire that likes to burn.

#7 10 days ago
Quoted from barakandl:

The 12v unregulated return, orange wire, is the typical problem. Definitely repin but consider doing the 'ground mods' while you have the board out. That takes stress off of that orange wire that likes to burn.

Thanks!

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