| Products > Test Equipment |
| HP 3466A restoration - DPDT switches |
| (1/3) > >> |
| calin:
I got an old HP 3466A (with battery option) of Craigslist ...40$. Pretty nice find; and now I am working to bring it back to life. I have to say these things are pieces of art - I posted just for "porn" a photo of the gold plated PCB of the battery charger. However, i dug (first day only) and I think I found the issue. Meter powers up, all nice, display etc but looks like the function and range switches are all over the place. I tested everything else and is in the parameters given in the service manual (7 volt logic circuits :) and an micro working at a smashing 200kHz) . So I got to the stage in which I believe the old switches are the culprit - actually i can see they literally cause buzzing and flickering when I push them. Parts are listed in the manual .. but fat chance finding something with that part number. Google blah blah ... nothing. I recon I am compete noob - how the heck these "selector switches" are actually called. they are simply listed as DPDT switch in the manual - how the heck are they called. And even more, does anyone have any idea where i can find something like this. Attached are a few photos; any help is welcome :) |
| robrenz:
If at all possible remove switches and dissemble. Thorough wash in your fave solvent. Sparingly lube all the mechanical aspects of the switch with your favorite non silicone grease. Use Caig Deoxit D100L on all the contact areas. If any of the contacts are gold clean off the D100L and apply Caig G100L. Thoroughly cycle the switch and then test the contacts with meter or scope. I suggest taking pictures at every stage of diss-assembly and be very carefull opening the switch so you can see how it works and not lose any flying springs or contacts. A container for all the parts helps also because many of these unobtainium parts will run away from home all by themselves if not constrained. :palm: EDIT: If the switch has any crevices that you could spray cleaner and deoxit into then blow out with compressed air it would be worth a shot before doing the autopsy method above. |
| calin:
He he ... I was thinking to do that but before performing the "surgery" I was hopping there is some pill I can take to fix the thing :) I think I can pop just the hood open - I mean the top cap of the switch - and clean them that way without de-soldering. The darn things are also in an assembly that makes them work toghether - u know push one the other pops out like in the old channel selectors in TV-s. Oh man remember those :) . The thing is that switches not only select the digital part of the function or scaling (for dsplay) the also select the input circuitry V, amps etc and the input gain. Have these shorted and meter measures nada :( . I will start with the function ones .. wish me luck. %-B As for configuration the things are really simple - each group of 3 has a dumb slider - for exaple de-pressed u have 1&2 shorted and pressed 2&3. No link between sides --- Code: ---+-------+ | 6 7| | 5 8| | 4 9| +------+ | 3 10| | 2 11| | 1 13| +------+ --- End code --- |
| robrenz:
I have some Tek 7000 series stuff with that same type of switch gang. Same thing here, way to much disruption to remove so I used my edit version 2 method above with great success. IMO the high pressure compressed air blasting is key to having the stuff get thru the switch assy. |
| calin:
I tried .. no luck. These things are press fit forget about opening them, you just break them. So ... I will apply the cleaner then blow the heck out of them strategy. They have some small openings at the end facing the control panel and some on top. |
| Navigation |
| Message Index |
| Next page |