The spacing of the leads can be different on different capacitors. If all the other dimensions are the same, they might match up just dandy, but you never know. Just like 'standard' capacitance values, the standards have changed over time.
Please take a look at this capacitor
- Thread starter Brian302
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Hopefully those caps are discharged pretty quickly after shut down through design in the circuit (bleeder resistors), you can check them with a digital multi meter (DMM) to see if they are retaining a charge before doing the replacement, if they are carrying a charge you can take something like a 2 watt resistor of a value of something like 170 kohms and place across the positive and negative terminals of the capacitor for a few minuets to discharge what remains, then do the same with the second capacitor.
cpt_paranoia
Addicted Member
Capacitors that have an electrolyte between the plates, rather than a simple insulator. That makes them a bit like a battery; an electrochemical device, so they are polarised.
A capacitor with a simple insulator between the plates can be connected either way; it's a purely physical/electrical device.
Bruno Primas
Super Member
A Realistic STA-2080 I worked on had a fubber/foam spacer glued to the top of one of the caps to keep the top cover from hitting the cap directly. Could it be remnants of this?
Nope, but I admire your detective work!
Thanks. I'll do that.
Not sure how much you know and you may already be aware, but I'll mention that you will have to set the meter to read DC when checking the caps for charge.
Worth looking over all the other electrolytic caps for signs of bulging or leaking while you are at it.
Hope it goes well for you.
Thank you. I know a little bit and I'm still learning. I did know to set it for DC. When testing the caps, is it possible to test from them from the bottom of the board? There's very little room to get the DMM probes in there.
Test with probes placed on the positive and negative terminals of each cap, so that would be on the underside of the circuit board?
I was thinking I could test the connections on the underside of the board where the terminals are soldered? Unless I'm misunderstanding, I can't get to the terminals while the caps are still on the board.
I'm a little confused, if you can test on the underside where the terminals poke through the board and are soldered, that is fine.
northpaw
Super Member
I don't know the details of the HK unit, but if there is not a removable bottom panel to provide access to the underside of the board, you will have to remove the board in order to service the caps. That is, to remove and/or install the caps, you will have to desolder them from the underside, so you must have access to the underside of the board.
The reason I asked about the bottom is that the caps have some sort of sealant at the bottom so there's nowhere for me to access the terminals.
DaveVoorhis
Addicted Member
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DaveVoorhis
Addicted Member
That's assembly glue, used to hold the cap in place during assembly at the factory. It also makes it less likely to vibrate/rip out of the circuit board if it's shaken violently during shipping.
The terminals you need to access and unsolder are on the underside of the circuit board. On some units, there will be a bottom panel you can unscrew to expose the underside of the circuit board. On other units, you'll need to remove screws (and occasionally plastic snap fasteners) or nuts to lift the circuit board off the chassis so you can access the underside.
The terminals you need to access and unsolder are on the underside of the circuit board. On some units, there will be a bottom panel you can unscrew to expose the underside of the circuit board. On other units, you'll need to remove screws (and occasionally plastic snap fasteners) or nuts to lift the circuit board off the chassis so you can access the underside.
DaveVoorhis
Addicted Member
You're going to have to access the underside no matter what. That rusty capacitor, whatever the cause of the rust, needs replaced.