Nolannniah
Active Member
I currently have some high voltage issues, which I am working through with some other members.
I've read some other posts about recapping their units, and was wondering if it would be advisable. I know the original owner of my 780 had work done to it 25+ years ago. A lot of the caps look different and newer than what they should be (basing on other post and pictures from the before pics). With this being said, all of the ones in question are rated at 85C vs. 105C, which seems to be the standard here at AK. Should this be a concern? Do caps go bad from non use?
I have had it 25 some odd years, and it has set in a closet for a good while. I have used it from time to time, but it has not been put into regular use (which is what I plan on doing after repairs are done). I found these issues I'm having now after I pulled it out of storage.
I plan on repairing the high voltage issue first, but from what I read about ESR values and ripple current (see below); could the caps cause some voltage issues and trip my relay?
"Aluminum and tantalum electrolytic capacitors with non solid electrolyte have much higher ESR values, up to several ohms, and ESR tends to increase with frequency due to effects of the electrolyte. A very serious problem, particularly with aluminum electrolytics, is that ESR increases over time with use; ESR can increase enough to cause circuit malfunction and even component damage, [1] although measured capacitance may remain within tolerance. While this happens with normal aging, high temperatures and large ripple current exacerbate the problem. In a circuit with significant ripple current, an increase in ESR will increase heat dissipation, thus accelerating aging.
Electrolytic capacitors rated for high-temperature operation and of higher quality than basic consumer-grade parts are less susceptible to become prematurely unusable due to ESR increase. A cheap electrolytic capacitor may be rated for a life of less than 1000 hours at 85°C (a year is about 9000 hours). Higher-grade parts are typically rated at a few thousand hours at maximum rated temperature, as can be seen from manufacturers' datasheets. Electrolytics of higher capacitance have lower ESR; if ESR is critical, specification of a part of larger capacitance than is otherwise required may be advantageous."
So, if you have some input and experience in my re-cap dilemma, please let me know-:scratch2:
Thanks
I've read some other posts about recapping their units, and was wondering if it would be advisable. I know the original owner of my 780 had work done to it 25+ years ago. A lot of the caps look different and newer than what they should be (basing on other post and pictures from the before pics). With this being said, all of the ones in question are rated at 85C vs. 105C, which seems to be the standard here at AK. Should this be a concern? Do caps go bad from non use?
I have had it 25 some odd years, and it has set in a closet for a good while. I have used it from time to time, but it has not been put into regular use (which is what I plan on doing after repairs are done). I found these issues I'm having now after I pulled it out of storage.
I plan on repairing the high voltage issue first, but from what I read about ESR values and ripple current (see below); could the caps cause some voltage issues and trip my relay?
"Aluminum and tantalum electrolytic capacitors with non solid electrolyte have much higher ESR values, up to several ohms, and ESR tends to increase with frequency due to effects of the electrolyte. A very serious problem, particularly with aluminum electrolytics, is that ESR increases over time with use; ESR can increase enough to cause circuit malfunction and even component damage, [1] although measured capacitance may remain within tolerance. While this happens with normal aging, high temperatures and large ripple current exacerbate the problem. In a circuit with significant ripple current, an increase in ESR will increase heat dissipation, thus accelerating aging.
Electrolytic capacitors rated for high-temperature operation and of higher quality than basic consumer-grade parts are less susceptible to become prematurely unusable due to ESR increase. A cheap electrolytic capacitor may be rated for a life of less than 1000 hours at 85°C (a year is about 9000 hours). Higher-grade parts are typically rated at a few thousand hours at maximum rated temperature, as can be seen from manufacturers' datasheets. Electrolytics of higher capacitance have lower ESR; if ESR is critical, specification of a part of larger capacitance than is otherwise required may be advantageous."
So, if you have some input and experience in my re-cap dilemma, please let me know-:scratch2:
Thanks