Chris,
Yeah, yours (the yellow one?) doesn't have a polarity marking on it, but Bruce's does appear to...
That being said, if it's not necessary, I'd probably pick the non-polar one with the higher working voltage. Much less likely to blow up...
Something in my Olympus BHB exploded...
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Hi everyone. Just uncovered two old Olympus CH-A microscopes which at first appeared to be in working condition. However, after a very brief time using both of them, the same thing as described by the OP occurred, a loud popping sound followed by foul-smelling smoke. Opening up the board I found the same problem in both (and the same as the OP): the .1uF, 500v capacitors had both blown their innards all over the chamber.
I'd really like to find some replacement capacitors but have had no luck as of yet. It seems like this capacitor was a nonpolarized metallized film capacitor with a single wire coming out one side and was connected as follows:
AC power source -> On/Off switch -> Fuse -> Small exploded capacitor.
The other wires off the fuse immediately connected to the larger gray capacitor pictured earlier in the thread.
So, can I just rig up any old .1uF >500v radial capacitor? What would I do with the second, seemingly unused lead on it?
Here's a pic from one of the scopes. You can clearly see the blown capacitor at the bottom.
I'd really like to find some replacement capacitors but have had no luck as of yet. It seems like this capacitor was a nonpolarized metallized film capacitor with a single wire coming out one side and was connected as follows:
AC power source -> On/Off switch -> Fuse -> Small exploded capacitor.
The other wires off the fuse immediately connected to the larger gray capacitor pictured earlier in the thread.
So, can I just rig up any old .1uF >500v radial capacitor? What would I do with the second, seemingly unused lead on it?
Here's a pic from one of the scopes. You can clearly see the blown capacitor at the bottom.
I would suggest that it had two connections before the traumatic incident occurred!
Obviously you can't put a replacement in unless you can work out where it was connected. A single lead doesn't do anything.
Its function is probably to either stop radio interference when the switch is operated, or to help protect the switch contacts, or be part of a high-frequency filter but I can't see that anything in the microscope would be sensitive to that. Hard to guess without a full circuit diagram.
"M" may just mean "20%" tolerance. The part is unpolarised. I have a dim recollection that the bar indicated which end is connected to the case, or another construction detail. It may indicate which should ideally be the "earthy" end.
If the thing still works, I'd make records, remove the remains, and secure uninsulated wiring, and carry on until you find out more.
Obviously you can't put a replacement in unless you can work out where it was connected. A single lead doesn't do anything.
Its function is probably to either stop radio interference when the switch is operated, or to help protect the switch contacts, or be part of a high-frequency filter but I can't see that anything in the microscope would be sensitive to that. Hard to guess without a full circuit diagram.
"M" may just mean "20%" tolerance. The part is unpolarised. I have a dim recollection that the bar indicated which end is connected to the case, or another construction detail. It may indicate which should ideally be the "earthy" end.
If the thing still works, I'd make records, remove the remains, and secure uninsulated wiring, and carry on until you find out more.