All but one IC is replaced and the potentiometer is repaired on the VBA Curve Tracer

INTEGRATED CIRCUITS AND DIODES REPLACED, ONE TO GO

My shipment from Digikey arrived early and since I had lots of frustration working on the computer typewriter, I was able to relax by replacing everything I had onto the front board. The only part that was not in stock at Digikey was a surface mount timer (LM555) which is coming early next week from Mouser. 

POTENTIOMETER ON FRONT PANEL HAD LEADS TORN OFF

One weakness of the design for this curve tracer is that one of the potentiometers on the front panel, for sweep offset, is not soldered onto a PCB but instead mounted on the front panel and connected with discrete wires. However, to fit the space available the part chosen and listed in the bill of materials is a PCB part, not panel mount. 

Thus the part has small fragile leads which tore off as I opened and closed the sandwich of front panel and front board in order to test, debug and replace parts. The broke off right at the base of the part. 

REPAIR OF POT AND REPLACEMENT ON THE PANEL

Although I did purchase a new pot of the same type, it won't arrive for a few days. Thus, I decided to rescue the current part if possible. I dug out the plastic potting around the broken leads using an Xacto knife, until enough metal was exposed to solder onto. 

I chose to use soft ribbon cable for the wiring, rather than stiffer individual wires as I had before, so that there is less risk of damaging this part again. I was able to get the wires onto the leads and put this part back into service. 


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