Re: Is my Tek 468 beyond repair?


John
 

Bit more progress today!. The replacement CPU arrived and has been installed. I am now getting all of the correct signals on the CPU board as per the service manual and comparable with Tony's "quick once around the processor" report. I have re-installed the two ICs that were removed and the display came to life on the next power up. It initially shows [ . . . .] then [8.8.8.8] then all of the digits flicker with 0's for a while until it settles to [ 0. 0.]. I am getting no display on the CRT at the moment although I do see a trace when I hit the beamfinder button.

So it seems that the computer is now working. Since the "Lamp Test" is ocurring as shown by the [8.8.8.8.], it seems that the ROM Checksum Test and the Lamp Test have passed. Next comes the "RAM Verificaton Test" and I am unclear as to whether this is succeeding or failing. I have so far been unable to find what [ 0. 0.] means although the manual does suggests that a RAM check will return a zero for "No error". It does also say that the display should blank and the scope should start operating which does not appear to be happening.

I will wiggle the chips on the RAM board, but if anyone has seen [ 0. 0.] and can tell me what it meas that would be appreciated.

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