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-5v= -5.08v +5= 5.12v 12v regulated= 11.66v 12 volt unregulated=12.85v

I Think, I'll send it to be repaired. the power supply does function, but the machine says initial tests indicate ram failure. the cpu board has been tested successfully working in another machine. I think its the 12v line. 12v regulated reads 11.66v at the chips. so what would be a reasonabe price?

who's Bob Roberts? and, or how can I contact him.

I need to rebuild my defender ps, I've search around, but where can I get a rebuild kit? and also the 2 transistors both say 8126 on them but have differing part numbers in the schematic are they the same type of transistor or are they 2 different ones?

6R pin 11 is OF(over frequency)/6R pin 8 is 4mHz/the E and Q are 1mHz. and you said that 6R pin 8 is the 4mHz clock and the 6mHz.???

ok, I've probed the board. 2I pin 37 low plused for 1 sec then high like it should. but 6R pin 6,8,9 dont pulse. I replaced the chip again. 7J pin5 and 7L pin 9 dont pulse. and 5P pin 6 doesn't pulse. 4C pin 8 does. and so does 1F PIN 3,5,9,11,13 as defined in the video recap flowchart. ??

ok, just trying to rule any possible causes of the problem. EDIT: I ordered a logic probe, I'll do a run through of the troubleshooting guide when it arrives.

just a quick thought. after inspecting the board closer, I realized the 7474 chips I removed were SN 7474N and the new ones I used are just 7474 is there a difference??

well..... now what. I'm out of ideas of what the problem could be.

6R pin8 reads 4.000mHz, chip 2I pin34 reads 1.000mHz. the others read OF witch is over frequency.(meter can only read up to 4mHz) here is a video of the testing. http://www.youtube.com/watch?v=6njMXe-BFsk

I bought a new meter so I could check the Hz,kHz,MHz output. (see video) I only checked the 7J chip that andykmv mentioned . I couldn't locate the others on the schematic. I probably missed them, I searched and didn't see them. http://www.youtube.com/watch?v=g5FSRQxYX_w I was using these...

I checked the voltage at the ram. -5v=-5.22v/12v=11.66v/5v=5.12v after re seating the ram and fixing a few solder points. all I get is a black screen now. It still plays the start up sound, but still cannot blind play. I think it might be the 12mhz crystal it looked pretty bad when I got it. I...

no I don't. This is my first machine so I don't have any kind of spare parts laying around. here is a new video if it helps, I remove the signal cable from the cpu board to see if the monitor still has lines on it. it doesn't. and I can't blind play it. http://www.youtube.com/watch?v=lPhem6F_Jos

no its not the brightness. I've already tried adjusting that.

now it just has a white screen with a slow moving black bar. no message. but an occasional fleck of pink or some other color. the rom chip with the pins broke off is working the pins were still in the socket so I just reinserted it and they made contact. I need to replace it but for now it...

no I don't have an eeprom reader. I'll try to remove them clean the pins and reset the chips. most of the chips I have tried to remove wont come out there stuck in there pretty good.edit I used an IC puller to remove the chips the first chip I tried snapped off 2 pins these are so corroded.

they just blink once, all on for a few seconds and then off. and sometimes all four stay lit

I bought a defender from a friend a few days ago. It didn't work the 4700mfd cap on the PS was loose from the board. I replace it and the 5 other ones in front. as well as the 3 radial ones on the cpu board. I still wasn't getting anything so I removed the cpu board and examined the chips. the...