Tektronix cam switch PCB contact repair -- Solved? - Page 1
Forum section: electronics / repair

author: rodd
author_rank: Regular Contributor
timestamp: May 19, 2022, 07:25:08 pm
content: Since I was unable to calibrate this unit and it was showing erratic behavior, I removed the main board for a closer inspection.After removing the cam of the Step/Offset switch to clean the contacts with Deoxit I discovered that the pcb contact of one position was damaged and the PCB metal contact is almost gone.The finger is intact.I have posted a photo on the forum on the Tek 577 Main board repair albumThis is a gold plated contact and I have no idea of how to repair it.Any suggestions?Thank you

author: wraper
author_rank: Unknown
timestamp: May 19, 2022, 07:31:33 pm
content: IMHO you could do a hack. Alter shape of the wiper (bend it) so it lands on undamaged part of the pad. Repairing the pad itself is not trivial.

author: CaptDon
author_rank: Super Contributor
timestamp: May 19, 2022, 08:30:39 pm
content: Old tek gear was indestructable. I think they realized the market was flooding with their used stuff being so reliable and passed down from lab to experimenter to hobbyist and so on. So they had to build in a bunch of nearly un-repairable flaws to get more of their gear into the landfills more quickly. And it doesn't help that many companies like GE have no idea how to market used lab gear so they generally crush it or in some way destroy it often getting tax benefits when they do!!! Also, in many (most) cases Tek charges more than the used market price of the gear for repairs thereby making in impractical to repair their very overpriced gear. Tek has differential signal probes that cost more than a very nice used car. Some of their scopes cost as much as a mini-mansion!!!

author: coppercone2
author_rank: Super Contributor
timestamp: May 19, 2022, 08:37:44 pm
content: Are those basically remanents of torn spot welds?You use rubberized abrasive to grind that down to flat metal very carefully and then replate with a plating pen, I think. Or you need to replace the pad if you are worried about thermal damage underneath what looks to be a torn spot weld ? (the finger weld itself to card and when ripped out that got left behind?You probobly need to polish the wiper too.

author: rodd
author_rank: Regular Contributor
timestamp: May 21, 2022, 12:54:37 pm
content: Dear all,I decide to use a gold plated finger contact from a PCB "donor" and solder it on the top of the arched contact.The finger plating was gone but since I have no replacement for it I have just polished it and soldered it in place.I have posted photos of the repair in the " Tek 577 Main Board Repair" album for reference.I checked continuity with a DMM and it seems to be working fine.When the board is in place and tested I will come back and confirm that this repair works "in real life".Roger

author: rodd
author_rank: Regular Contributor
timestamp: May 21, 2022, 01:03:52 pm
content: I used the gold plated edge connector contact from a "donnor PCB" in the repair.The contacts were pulled off after baking the pcb in a oven to delaminate.After polishing the contact, I applied solder to the copper side.The contact was positioned in place and heated with an air heat gun to solder it in place.

author: coppercone2
author_rank: Super Contributor
timestamp: May 21, 2022, 04:56:06 pm
content: yeah thats a fine repair, some people I think would prefer to remove the old contact (not sure if you did) because there might be thermal damage to the glue underneath the pad that might effect future reliability but that is if you need to re certify it for NASA or something. I don't think the pad looked that bad, not prolonged overheating that ruin the substrate.