Repairing my Tek 4051

[MattisLind]

My Tektronix 4051 has been sitting on the shelf since the analog board blew several years ago. I think it is about time to get back to it and fix it. Back then the ceramic module with 8 laser trimmed resistors blew. For some unknown reason. Since then I built a replacement out of 40 pieces of precision 7.5 ohm resistors and also gotten a NOS original Tektronix module as well as a spare analog board (which has been sitting is the woods of Oregon for quite some time, though).

Now I have hooked up the PSU and the analog board on the bench with some wiring in between so that I can take measurements on it while it is running.

What would be great is to have dummy deflection coils consisting of resistors just to see if I can get it to operate properly. Unfortunately the 4051 itself is in storage quite far away so I cannot take any measurements on the coils myself.

Is there anyone that has their 4051 (or 4052 I guess) nearby and could measure the resistance of the deflection coils?

 

[nikola-wan]

My Tektronix 4051 has been sitting on the shelf since the analog board blew several years ago. I think it is about time to get back to it and fix it. Back then the ceramic module with 8 laser trimmed resistors blew. For some unknown reason. Since then I built a replacement out of 40 pieces of precision 7.5 ohm resistors and also gotten a NOS original Tektronix module as well as a spare analog board (which has been sitting is the woods of Oregon for quite some time, though).

Now I have hooked up the PSU and the analog board on the bench with some wiring in between so that I can take measurements on it while it is running.

What would be great is to have dummy deflection coils consisting of resistors just to see if I can get it to operate properly. Unfortunately the 4051 itself is in storage quite far away so I cannot take any measurements on the coils myself.

Is there anyone that has their 4051 (or 4052 I guess) nearby and could measure the resistance of the deflection coils?

Mattis,

I assume the "analog board" is your 4051 "Display Board"?

Looking at my 4052 Display Board schematics, the two big power resistors, R71 (390 ohm) and R75 (330 ohm) on each side of the custom ceramic resistor block are connected directly across the X and Y coils, respectively.

With my 4052 powered off, the in-circuit resistance across R71 with the coil plugged in measured 5.7 ohms for the X-coil.
The in-circuit resistance across R75 with the coil plugged in measured 4.8 ohms for the Y-coil.

Monty

 

[MattisLind]

Thanks a lot Monty!

Let's hope I now can get the board working.

/Mattis