Replacement High Temperature/Long Life or Horizontal Deflection Capacitors

[kozard]

In a search for particularly long-life capacitors someone suggested that I look at capacitors that have a proven track record in horizontal deflection circuits. They said that horizontal deflections circuits are very tough on capacitors.

Can anyone suggest a brand and series which have a solidly proven long-life in horizontal deflection circuits?



The actual application is in the SMPS of a Tektronix oscilloscope (they call it an inverter). I was looking at UCC KY, Nichicon UPW and Panasonic FM-A series. All are 105C and low ESR. (I was looking at 10mm to 12.5mm diameter for 1000uF and 50V or 63V to get lifetime ratings of 4,000 (FM) to 10,000 hours (KY).) The originals are Mallory of which a number have leaked.

I would like to pick a very reliable capacitor that will never need to be changed again. (Outlive the rest of the instrument.)

 

[Johno]

Horizontal deflection manufactur is extinct and has been for a decade or two. So I think that what you have found is it and will certainly outlast the screen phosphors and probably you too!

 

[NareshBrd]

The ambient temperature in the circuit has an effect on the capacitor life.
See if you can find 125 degree or mil grade caps, and put ones with a higher voltage rating, space permitting.

Pay attention to ventilation, if needed and space permitting, install a fan.

 

[kozard]

For the UCC KY, Nichicon UPW and Panasonic FM-A I did pick a higher voltage and case size so that the ESR is lower and the heating from the ripple current is reduced. The optimum seems to be around 50V or 63V. I also suspect the larger case size helps with heat dissipation (when the heat is generated from the SMPS ripple currents in the capacitors.) I will also search for 125C (such as the newer automotive capacitors) and see what I find.

I did already replace the oscilloscope fan (it arrived with the fan motor but no impeller...)

It is possible that the capacitors will outlive me but I like to do repairs that last. And they are not making any more analog oscilloscopes.



For the lower voltage SMPS capacitors I read that solid polymer is much better than the electrolytics since the lifetime apparently decreases less rapidly as the temperature increases. Also the ultra low ESR should further reduce the heating from the ripple current.

There are likely better references but I read:

In terms of performance, solid capacitors generally last longer than electrolytic ones, especially at lower working temperatures. At 65 degrees Celsius, for instance, the average lifespan for a solid capacitor is more than six times greater than an electrolytic capacitor.

Solid capacitors also last longer with an average lifetime of 23 years compared to only three for electrolytic capacitors, according to Gigabyte.

Additionally, solid capacitors have a higher tolerance for higher temperatures and they also perform better with higher frequencies and higher current than electrolytic capacitors. The superior heat resistance and better electric conductivity will allow PC enthusiasts to tweak the highest levels of performance from their system without fear of excessive capacitor wear or exploding capacitors, said Gigabyte.

https://www.extremetech.com/extreme/50450-gigabyte-launches-solidcapacitor-motherboard-line

 

[NareshBrd]

I see solid capacitors in motherboards, no idea where else they are used.

Put the biggest AC fan that will fit, from a good brand.
Sleeve bearings are quieter than ball bearings, however failure results in short circuit on sleeve types sometimes. Risky for the rest of the circuit, put a fuse there as well.
A hack is to use the circulation fan from a frost free refrigerator....Quiet.

AC fan has no circuit to make AC from DC, which is how DC fans work, and where they fail.
Have fun.

 

[kozard]

Yes, I first saw the solid capacitors on motherboards. The higher quality and more durable motherboards used them first and they are found in the SMPS/step down converters for the CPU, memory, GPU, etc. I have occasionally seen them in other SMPS also.