I purchased a Tektronix 571 curve tracer off Ebay awhile back. It was listed as working but it actually did not. The current drive was out so I would see the voltage rise when testing components but no current. I finally got around to fixing that part of the unit. I tested a DUT with it and all was good. The monitor that was in the unit (a 9" CRT monochrome green) had issues at the very top of the tube and had burn in artifacts as well. After getting the unit working I wanted to swap the monitor with another unit I had. I discharged the tube's anode using a screwdriver against chassis. Installed new CRT and now I am only seeing green lines horizontally filling the screen?
What did I do??
This curve tracer uses 8032 Intel processor and a NS405 chip that does the video.
There is 2 EEproms that store firmware for the curve tracer function and 1 for NS405 video. I read the BINs and compared to the other unit I have and they were identical. I can not figure out what the heck is going on. The service manual discusses connecting the unit to a Centronics j625 port IEEE 1284 port I believe? That's to use a VT100 terminal. I have ordered a IEEE 1284/centronics cable to USB with the plans to see if I can use my PC and emulate a terminal as thr service manual states. This is supposedly how I can see if the issue is monitor or program issue. This is over my head and any guesses would be a HUGE help. I was SO happy when it worked and was fixed then SO bummed when monitor did this and nothing else. I swapped out the monitor driver board AND the main PCB from curve tracer and it was doing the same thing?
Where are all the extremely smart individuals around here?
Thanks in advance.
BTW- firmware that was downloaded from Tek wiki website for the 571 is different than what my unit has. I have ordered UV programmable 27C256 eeproms so that I could write their firmware versions and try it. Testing the firmware was my thought and could be the absolute wrong way to go. I was just thinking when I discharged the crt maybe it did something to cmos.