Author Topic: Tek Power Supply Capacitor Q...  (Read 215 times)

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Tek Power Supply Capacitor Q...
« on: August 13, 2019, 12:40:27 am »
Hey Folks! 

First post and I'm just a tinkerer....

So I'm replacing the PS Caps on my Tek 475A....
I cannot find the same capacitance ratings for replacements.

I've read Ron Childress' Tek 465 PDF and it was VERY helpful but as a noob I question the selection of replacement capacitor ratings....

Part                  Purpose              Original                 Replacement
C1512   +110 VDC Filter Cap      550 uFd, 100V      560 uFd, 160V
C1513    +55  VDC Filter Cap    1200 uFd, 100V    1200 uFd, 160V
C1542    +15  VDC Filter Cap    5500 uFd,  30V     5600 uFd,  35V
C1552     +5   VDC Filter Cap    5000 uFd,  25V     5600 uFd,  35V
C1562      -8   VDC Filter Cap    3000 uFd,  35V     5600 uFd,  35V

I don't question Ron of course...esp because his scope works now....But I just cant get around choosing a 5600uFd cap in place of a 3000uFd one (C1562)

I have more than these caps to replace and I really need to understand the logic behind it!!!!   |O

PLEASE educate me!  :o


Online jdragoset

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Re: Tek Power Supply Capacitor Q...
« Reply #1 on: August 13, 2019, 01:13:34 am »
In general, PS caps can be replaced with a larger capacitance value and voltage rating, provided the package fits in the location.
This will work within at least a 100% increase of capacitance and likely not cause a fuse or diode overload.
This philosophy also works for in-circuit decoupling across resistor networks, etc.
Looking at the tolerance spec', e.g. "+50,-10% or +100%" is also a good indication that substitutions can be increased in capacitance value without ill effect.
This helps with limiting the number of values that must be purchased for such replacements.

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