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Having verified this one filter cap in the power supply of the Tektronix R7623A is indeed bad, it's ALSO the tallest one of the assortment of caps. Four ground terminals, one Positive terminal, and it's nearly touching the bottom of the subassembly chassis. There's a flange that's bent upwards and the end of the power supply assembly, and the terminals of the can are long enough that there's no way to get that cap out without lifting the PCB assembly off of the power supply assembly chassis.
After studying this Rube Goldberg assembly to realize this is the one part in the entire assembly....if it goes bad, and you called Tektronix Service Dept during the period these were in production, the peels of laughter you'd hear while the service tech on the phone stopped to put you on speaker phone for the rest of the staff to hear your question again.....I need to remove C811 to replace it.....would definitely dampen your day. The only other part in that assembly that would be worse would be having the power transformer fail.
As I kept removing more and more parts to try and find a way to lift up that PCB so I could extract that now-desoldered capacitor, since it's too tall to just swing it out from underneath the PCB like all the rest of those caps can do.....this part had me in stitches laughing as I got further and further into disassembly to keep finding more and more obstacles preventing the elevation of that main PCB. I thought at one point, I'd need to unsolder the power transformer header....which would be another potential disaster if the PCB pads & traces firmly object to such an effort....I then found there's no header. You're looking at discrete tinned magnet wire formed upwards to poke thru the PCB. So, building this assembly was certainly a fixed procedure. No workarounds or it wouldn't go together.
So, another afternoon spent finding obstacle after obstacle in trying to get this assembly apart. The rear fan/BNC Output PCB assembly housing had to come off, all of it tethered to points yet to be found and such....and still no closer to a solution to lift that PCB up. It appeared I'd have to unmount the power transformer from the chassis. Only access to it requires further panel removal, to which the fan has to be removed, then another cluster of parts that indirectly mount to an upper transformer core screw, of all things. WHO thinks these things up at Tektronix???!! No wonder they're so bloody expensive when new. Date codes indicate the caps were produced in 1984 I found an Avery label stating NEW #933110 5/3/85.
After removing the fan, that gave me access to more panel screws, and got that subpanel off. Then found a wire from the top of the Filter PCB down to a Thermal Switch on the bottom of this pwoer supply chassis was taut, so it had to be unsoldered too. Finally:............
All that work to get a simple filter capacitor off of the PCB. I did find that I can install a 35mm dia 10mm-L/S Snap-In Cap onto that PCB, though the neg lead would be fitting into that LARGE hole near the edge of the board, where the original cap has the one wide solder tab. I'll work that out when I get the replacement cap. I looked at this using that short Black 15,000uF/50V cap, and for a brief moment thought maybe I'd just solder that in. NAW! Leads are already too short, and don't want to have to do all this over again. I can wait a few days for a new part to arrive.
And, it looks like I won't have to install any jumpers to restore circuits that the ground leads of this bad cap were needed for.
I haven't yet pulled my Tek 7633 apart. THAT is the instrument that has failed, no longer having any trace image, nor any indication of the Storage System working. Figuring it's a power supply problem, I brought this instrument in to educate myself in how to extract the power supply.
I just looked at the back of the 7633 scope, NOT a rack-mount R7633, and see it's NOT really built this way. Though uses the same power supply assembly, but totally different mechanics with a different fan, so this might have been an exercise in futility. Hope not. More reading to do, but I now know how to replace this stupid cap!!
https://music-electronics-forum.com/...lloscoe-failed
This is the rest of the ordeal in trying to learn how to fix that Tek 7633 scope thus far.
After studying this Rube Goldberg assembly to realize this is the one part in the entire assembly....if it goes bad, and you called Tektronix Service Dept during the period these were in production, the peels of laughter you'd hear while the service tech on the phone stopped to put you on speaker phone for the rest of the staff to hear your question again.....I need to remove C811 to replace it.....would definitely dampen your day. The only other part in that assembly that would be worse would be having the power transformer fail.
As I kept removing more and more parts to try and find a way to lift up that PCB so I could extract that now-desoldered capacitor, since it's too tall to just swing it out from underneath the PCB like all the rest of those caps can do.....this part had me in stitches laughing as I got further and further into disassembly to keep finding more and more obstacles preventing the elevation of that main PCB. I thought at one point, I'd need to unsolder the power transformer header....which would be another potential disaster if the PCB pads & traces firmly object to such an effort....I then found there's no header. You're looking at discrete tinned magnet wire formed upwards to poke thru the PCB. So, building this assembly was certainly a fixed procedure. No workarounds or it wouldn't go together.
So, another afternoon spent finding obstacle after obstacle in trying to get this assembly apart. The rear fan/BNC Output PCB assembly housing had to come off, all of it tethered to points yet to be found and such....and still no closer to a solution to lift that PCB up. It appeared I'd have to unmount the power transformer from the chassis. Only access to it requires further panel removal, to which the fan has to be removed, then another cluster of parts that indirectly mount to an upper transformer core screw, of all things. WHO thinks these things up at Tektronix???!! No wonder they're so bloody expensive when new. Date codes indicate the caps were produced in 1984 I found an Avery label stating NEW #933110 5/3/85.
After removing the fan, that gave me access to more panel screws, and got that subpanel off. Then found a wire from the top of the Filter PCB down to a Thermal Switch on the bottom of this pwoer supply chassis was taut, so it had to be unsoldered too. Finally:............
All that work to get a simple filter capacitor off of the PCB. I did find that I can install a 35mm dia 10mm-L/S Snap-In Cap onto that PCB, though the neg lead would be fitting into that LARGE hole near the edge of the board, where the original cap has the one wide solder tab. I'll work that out when I get the replacement cap. I looked at this using that short Black 15,000uF/50V cap, and for a brief moment thought maybe I'd just solder that in. NAW! Leads are already too short, and don't want to have to do all this over again. I can wait a few days for a new part to arrive.
And, it looks like I won't have to install any jumpers to restore circuits that the ground leads of this bad cap were needed for.
I haven't yet pulled my Tek 7633 apart. THAT is the instrument that has failed, no longer having any trace image, nor any indication of the Storage System working. Figuring it's a power supply problem, I brought this instrument in to educate myself in how to extract the power supply.
I just looked at the back of the 7633 scope, NOT a rack-mount R7633, and see it's NOT really built this way. Though uses the same power supply assembly, but totally different mechanics with a different fan, so this might have been an exercise in futility. Hope not. More reading to do, but I now know how to replace this stupid cap!!
https://music-electronics-forum.com/...lloscoe-failed
This is the rest of the ordeal in trying to learn how to fix that Tek 7633 scope thus far.
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