Egnator rebel 30 no sound

[The Dude]

The Atlas ESR meter is still a valuable tool for testing ESR. You just have to know its limitations. ESR meters are quite good for finding dried out or high ESR caps- just not meant for finding shorted/leaky caps.

[Helmholtz]

The leakage should show on an Ohmmeter (red meter lead to positive cap terminal) at least with cap installed.
If the cap leaked conductive electrolyte, there might be a conductive path on the board between the terminals

[Chuck H]

Still sort of on topic for the repair... I notice discoloration of R55 in three of the four photos posted. I wonder if that's a result of bad paint for the band colors or actual heat damage to the resistor. I'm used to seeing more acute damage to the resistor before the banding changes color.

[nosaj]

Still sort of on topic for the repair... I notice discoloration of R55 in three of the four photos posted. I wonder if that's a result of bad paint for the band colors or actual heat damage to the resistor. I'm used to seeing more acute damage to the resistor before the banding changes color.

And I still don't know what value it was supposed to be .....it measure 4.3k or 4.7k Don't remember at the moment.
nosaj

[The Dude]

I think that would depend on how much leakage the cap has and therefore how much current through the resistor. A direct short might incinerate the resistor. Some extra current might change color bands. And then, there's everything in between.

[g1]

I notice discoloration of R55 in three of the four photos posted.

I noticed that too. My impression is that the one that is not discoloured is fairly new and will get there eventually. That resistor must be running hotter than the others around it. If they are not failing, I don't think going to a higher wattage is really necessary.

[g1]

And I still don't know what value it was supposed to be .....it measure 4.3k or 4.7k Don't remember at the moment.
nosaj

It should be 4K7 and that's what you measured.

[Helmholtz]

It should be 4K7 and that's what you measured.

So the cap drew a bit less than 30mA, corresponding to a leakage resistance around 250R.

[nosaj]

Based on what i am seeing one leg of the cap was bleeding voltage to the ground plane which is where i witness the embers wen i powered it up.
I used a fiberglass brush to remove any char. What would you suggest to seal it ? Superglue, nail polish, or?
Thanks,
nosaj

4.7k is a long ways from the colors i read for orange black brown.

[The Dude]

As long as you have all the charring removed, I don't think you need to seal it with anything.

[Chuck H]

What would you suggest to seal it ? Superglue, nail polish, or?

Since that resistor seems to demonstrate discoloration commonly in all photos I think you need something at least a little heat stable. Neither CA or nail polish fit the bill. What does? Not sure. Maybe a little smear of high temp gasket sealant if you have any on hand.

4.7k is a long ways from the colors i read for orange black brown.

Looking at your photo and considering the utter lack of any color in some others, and this with no clear signs of resistor failure, I'm going to speculate that the resistor does get hot but is probably still suitable for the spec and the paint used for the banding is shit for temperature stability. I think you should ignore the percieved colors as it is and go with the 4.7k measurement. This would be the value clearly shown in the only photo that doesn't demonstrate degredation and it's also the value for the most common circuit in the "20". So the yellow turned orange, the purple turned black and the red turned brown because of heat and shitty paint. This is the most logical conclusion at this time. Not enough evidence to confirm it but this is what I would use as information if it was on my own bench.