Illinois brand capacitors still bad?

[Mark]

In the past I’ve seen quite a few fender amps with IC branded capacitors which are leaking, I dare say quite a techs made a good living replacing capacitors from Fender amps.

Have IC caps turned a corner and become reliable or do they still leak?

[Stevem]

Yes they are not at the bottom of the ladder any more.

[martin manning]

This problem was specific to Fender amps manufactured over some range of dates, and limited to IC electrolytics sold to Fender, IIRC.

[Mark]

This problem was specific to Fender amps manufactured over some range of dates, and limited to IC electrolytics sold to Fender, IIRC.

Great to hear from you as always Martin. I appreciate your input.

I must admit that I don’t know if the bad IC brand caps were limited to Fender. Perhaps if there was a large batch of caps that were bad and Fender bought all of them then it could be a problem exclusive to Fender. I don’t know if that would be the case. I imagine Fender are negotiating a price and they get the caps available.

What makes you think the problem is exclusive to the Hot Rod series Fender amps?

Thanks again for your input.

[Mark]

Yes they are not at the bottom of the ladder any more.

What makes you believe they are a good brand to use again?

What is on the bottom of the ladder these days?

I think F&T is my cap of preference, though if Nichicon had a product I would use that.

[martin manning]

What makes you think the problem is exclusive to the Hot Rod series Fender amps?

Something I recall reading about some time ago. May be just internet lore, but maybe Fender did end up with the bulk of the bad product from that era.

[Mark]

What makes you think the problem is exclusive to the Hot Rod series Fender amps?

Something I recall reading about some time ago. May be just internet lore, but maybe Fender did end up with the bulk of the bad product from that era.

Yeah, it’s hard know if they are still bad. I would rather have more options but I wouldn’t risk reliability. I had a similar experience with Carling DPDT switches. They were a disaster in wah pedals.

Thanks for your input Martin.

[Littlewyan]

Were the capacitors themselves bad? Or was it just that Fender used the lower temperature 85Degree ones?

[maxkracht]

I don't think I have seen 105c axial electrolytics from Illinois but I could be mistaken. Haven't worked on a fender with prematurely bad IC brand caps in the past year or so but I used to find them somewhat regularly and not just hotrod series. Guessing many of the premature failures end up being warranty repairs, which I don't see.

A handful of the more recent IC cap failures I have seen failed open without any visible sign of damage which could be a manufacturing error on fenders part. Maybe their reflow settings were off or something.

[GAStan]

Were the capacitors themselves bad? Or was it just that Fender used the lower temperature 85Degree ones?

Admittedly higher ratings are better, but Sprague Atoms are 85°C rated.

85°C = 185°F

[maxkracht]

I don't think temperature rating necessarily means anything in isolation, it's not a hard limit. It's that temperature at a specific ripple current and voltage for a certain amount of time. An 85c cap with otherwise better specs will probably outlast the 105c cap at 105c. No idea how much you need to derate to make things equal. I'm sure it depends on a lot of factors.

[Mark]

Oddly enough I had a friend get a Fender Blues Junior come in. It was built in 2019 and is a Mark 2 amp which uses cathode bias. The filter caps were the blues IC and they looked fine, no signs of spilling their guts.

[martin manning]

I don't think temperature rating necessarily means anything in isolation, it's not a hard limit. It's that temperature at a specific ripple current and voltage for a certain amount of time. An 85c cap with otherwise better specs will probably outlast the 105c cap at 105c. No idea how much you need to derate to make things equal. I'm sure it depends on a lot of factors.

Absolutely right. For 10C in ambient temperature, life will typically halve or double, so operating an 85C cap at 105C would reduce its life by a factor of four. I don't know what the temp is inside a tube amp that has been operating for a couple of hours. It'd be highly dependent on the configuration, of course. Anyone made measurements?