I have am going thru the process of reforming the PS caps in a ML-2500 amp.
I am using a Eico 950B resistance capacitance comparator bridge for a
variable PS and am measuring the ma by monitoring the voltage across a 20K
resistor in series with the cap. The general technique is to rise the
supply voltage until I see about 1 ma of current (20 volts across the 20K
resistor. . I let the voltage set until the indicated current quits
dropping and then rise the voltage until I see about 1 ma of current again
and then repeat the cycle.
This schematic on this amp shows 6 FP electrolytics 150 mf a @450 Vdc. The
amp has 3 spragues that match the skematic and 3 CD caps that are mutli
section that are hooked in parallel. So far I have reformed the 3 spragues
which had a leakage of about .5 ma at 450 Vdc. I will have to see how the
CDs look.
This subject has be covered before, but what is a good leakage limit guide
line for reuse or replace in this application and if replacement is
warranted, what is a good source for replacement caps?
The amp uses a 100K ohm carbon comp resistor across each cap. I plan to
replace these 3 watt MOF resistors.
73,
Jim Zellmer, KA0VSL
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