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Thanks Sirius for the info. I think is has to do with one of the circuits also (reset, watchdog, etc) and will get into it with a logic probe on Monday afternoon. Tried pushing in all chips with no changes. Also not seeing anything on the blue screen even though it only comes up for a split...

It has something to do with the CPU/Video board. When I switch out the CPU/Video Board with a good one, everything works fine. I switched out the MPU 40 pin chip (chip 2I), the 7474 chips (at 6R AND 7J)the Video Decoder ROM 2, (3E) and the Video Decoder ROM 3 (3K), one at a time, all with the...

So I just got a Switching Power Supply from Bob Roberts and hooked it up. And we are progressing, ever so slowly. I have 5.04 Volts at Pin 9 of all the 24 RAM chips. This is what I get now when I turn on the machine: - I get the initial startup sound (yaay). - The Monitor comes on but it...

Thanks for all the good information. I will be cleaning and checking the output voltages of the Power Supply and hopefully make it more reliable. As much as I am trying to keep these Defender machines original, I thought I would order a switching Power Supply that has a variable adjustment on...

While I haven't dealt with the Power Supply problems yet, I did do the following while waiting for my Logic Probe to show up: 1) I tested the Power to the RAMs in my working cocktail game table. They all have RAM chips that are upgraded to 41256 chips, and pins 1, 8 and 9 are all at 4.04...

OK, so I tested the voltages in all the 24 RAM chips and got the following: Pin 1: - 5.49 Volts Pin 8: 12.16 Volts Pin 9: 4.79 Volts These all seem to be in the acceptable range as far as the power for these chips go.

You're right. There are actually 5 of the 4116 chips. Across the top they read MCM4116BP25 and on the bottom they read QC8109. I guess that means they are 4116 chips made in the 9th week of 1981. The other 19 chip across the top read AM9016DPC and on the bottom they read 8119 WP. I am...

Defender Upright Not Starting Up - CPU/Video Board Problem I am a newbie on this site and also a novice when it comes to electronics. I have a soldering station but am not too good at soldering (beginner with shaky hands, lol). Am pretty good with trouble-shooting and dealing with schematics...

Jehuie, the following parts were used from your Cocktail Table: - Both Control Panels - Transformer and Power Supply (But not the White wood Mount) - Wiring Harness - 1 Speaker - Coin door Mechanics (not the wood door or faceplate) - All of the other PCBs - And the Monitor/PCB and its...

Thanks Broodwich. I think I learned how to post the images now!!! <br> <br> <br> <br> <br> <br> <br>

This is my 1st post and I want to thank jehuie for recommending me on this site. OK, so I am really a Defender Arcade Game addict. I now have 2 Cocktail Tables and 1 Upright Arcade. After buying my latest Cocktail Table from jehuie, 4 days later I was able to take the best part from the 2...