I have a few worn attenuators and one that I received that was fried by high voltage and I tried to swap the relays. Turns out it’s not really about swapping the coil, but a near impossible precision task if you want to swap the entire block without opening up the contacts and magnet gliders. If you desolder the coil pins, you can release them and expose the inner workings:
Usually the relay coil is not the problem. It’s either the magnetic shuttle (the black stuff between the two coils) that’s not moving smoothly or the contact metal spring does not naturally bend to make good contact anymore. I fixed the first one with WD-40 (the magnet glides on a custom plastic rail), so some vertical divisions that used to be capacitively coupled (i.e. there’s an air gap instead of good electrical contact) were fixed, but it still won’t pass calibration because of the worn metal spring. Here is what the spring(s) looks like:
To put the motor coils back, I slightly push it down to the board while guiding the shuttle (that has a tiny piece of magnet in it) with a strong magnet outside the coil housing. It will fall in place easily.
Given how reasonable watronics (Bill Watry) is charging for the attenuators, it’s not worth the time, effort, and uncertainty trying to perform the surgery. He basically serves any HP/Agilent instruments that uses this attenuator hybrid that looks like this. Bill Watry is a veteran of the 54500 series, which is the main consumer of this kind of hybrids. He’s the first person to talk to if you have any problem with HP 54500 series oscilloscopes. Please contact him directly rather than through eBay if you can, as eBay charges hefty fees (it eats up 13% of the transaction amount, not what he earned after costs).
54610B/54615B/54616B/54616C as well as first generation Infiniium uses this kind of attenuator too. I have everything needed to service 54615B/54616B/54616C except attenuators. If it boils down to attenuators, I don’t stock them and you’ll have to order it from Bill (I can do that on your behalf if I’m the one doing the repairs).
If you have an HP Infinium or Agilent Infiniium and your situation likely involves the computer section, I should be the first person to talk to, since I got nearly all the nasty quirks down over the last decade so you don’t have to spend months navigating through this minefield. The learning curve is really steep if anybody tries to figure it out on their own for the first time.
EDIT: Due to bloody competition amongst a few business un-savvy players that under-priced 500Mhz range scopes for the last few years, Bill Watry was squeezed out so bad that he closed his HP (Pre-Agilent) digital oscilloscopes sale/service business. I’m really sorry to see him go because I already moved out of it long ago and just passively selling the leftovers.
Despite I have the expertise, I’m reluctant to service these models given how little people are willing to pay. I actually passed a bunch of folk-knowledge about these scopes that I figured out to him hoping he’ll continue the legend and save the scopes from landfills. Too bad.
If you are desperate and are willing to pay at least $500, I can consider helping given that Bill Watry is no longer available. If it happens to be a tiny part that I have in the storage bin that doesn’t require work, you can have it for less. It might still be worthwhile to fix if you have 1Ghz or above (4835A/54845A/54846A), but not the 500Mhz models.
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