|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
63.246.183.22
In Reply to: RE: Hickok 6000a test slide switch repair? posted by fredtr on July 01, 2017 at 16:11:55
Here are the answers I received recently on this same subject...
--------------------------
Buy Chinese. Bury freedom.
Follow Ups:
Looking at the picture you posted, yours is the same as mine. I'm going to see what other responses I receive before disassembling and attempting to resurface the contacts.
I don't think the contacts can be resurfaced. The need for frequent cleaning is an indication that the original plating has worn off. The base metal doesn't conduct as well, and it oxidizes quickly. Unless you want to drill out the rivets and have the contacts re-plated, I think new switches will be required. It's just one of the things that wear out in old gear.
--------------------------
Buy Chinese. Bury freedom.
This is what the slides look like after ultrasonic cleaning. I'm thinking about having just the slides plated and see how much it helps. What do you think Triode?
I'm hesitant to offer advice past this point, other than what simply seems logical for the situation. Bear in mind, I haven't ever been involved in refurbishing a switch at this level.
My overriding concern is that all the surfaces should be plated at the same time, otherwise the harder one (probably the base metal) will quickly wear away the softer one. A second issue has to do with the metallurgy of the plating. It's not clear to me which metal - or metal alloy - offers an optimum combination of conductivity, wear resistance, tarnish resistance, etc. Similarly, I don't know if the most appropriate material is readily available for plating a small job like this.
At some point, I might look for a more modern replacement for the Hickok switch bank. I do have a CNC mill and small lathe, so constructing a custom mounting bracket is possible. Whether I can locate new push switches with the same contact patterns is another matter.
Good luck with the project. Please post results, even if things don't work out. This is bound to become a more common problem as these testers age.
--------------------------
Buy Chinese. Bury freedom.
The ultrasonic cleaning didn't do much to improve the appearance. And I tried three different brands (DeOxit, CRC, Nutrol) of contact cleaner scrubbing with a brush. That also didn't do much. The last thing I tried, an eraser, made the slides look pretty much brand new and it doesn't look like the material was worn. One thing that was interesting is that the last set of contacts on each slide were the most discolored before cleaning, maybe cathode and anode? I should trace it to the schematic. I thought about using emery cloth on the pincer contacts, which is the only thing I could think of that would slide between them. Instead, I just sprayed them with contact cleaner.
The result is that the test button now works well. Time will tell if it hold up.
Those are gold plated, right? Do you mean that the plating looks uniform all along the contact after using the eraser? That would imply that the discoloration isn't an area where the gold is worn away, but rather a deposit of some sort on top. I wonder if the mating contacts are tinned (or other silver-colored alloy), and that's what gets deposited on top of the gold. Just trying to understand the situation you're describing...
--------------------------
Buy Chinese. Bury freedom.
I can't tell if they are gold plated. It did look like the eraser removed whatever was deposited. And yes after eraser the color was uniform. The pincer contacts that they slide through, appear to be copper.
That's interesting, I hadn't paid that much attention when I was in there. Would be great if you could post about this in a few months and let us know how they're holding up. I'll take mine apart soon as I can find time.
--------------------------
Buy Chinese. Bury freedom.
No problem, I will do that. Although I can't predict how much I will use the tester. If fix/mod equipment mainly for myself and occasionally a friend. So I use the tester only intermittently.
Thank-you, that's helpful. I can remove the contacts, ultrasonic clean them and see what they look like, have them plated if necessary.
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: