Re: 475 questions


Hi Graham,

No need to apologize for "bad" jokes. That kind of humor is okay with me, as it's less likely to go "over my head." If the cap fits...get it? ;-)

Sorry, tested in place. I'll yank them and try again, since I believe them to be bad, anyway. However, if I replace them, I'll never know what fault they introduced, if any! Too bad.

Two photos posted at,,,20,2,0,0!


On Tue, May 26, 2020 at 06:30 PM, VK1GVC wrote:

Bruce, I wouldn't be concerned about tolerances on the 2.2uF filter caps
on a power rail - to some extent the more uF the better, within reason. 
Some capacitors for this purpose have tolerances of -20% and +100%
indicating just that.  Anyway others have tracked down better info on
C1091 and C1093 and tantalum makes sense.  For an 8V rail anything over
about 12V rating is fine so 20V or 25V is more than OK, or even more if
you happen to find a 2.2uF cap which fits the space on the PCB.  (If the
cap fits?  Sorry ... bad joke)  BTW did you test these 2 caps out of the
circuit or in place?

I can see that your component knowledge is growing fast with the help of
ppl here and, fortunately, the low voltage DC part of a complex piece of
test eqpt is the easiest place to start fault finding.  The sheer
complexity and design cunning by Tek engineers which went into these
units is amazing and I'm dreading fault-finding in the really tricky
parts of my 2465 if I ever have to do it.

Re pins 14 and 16 of the transformer, if you've tested CR1412 rectifier
out of circuit (good) and the adjacent two capacitors (bad) then there
is no reason to try to disconnect the transformer at this stage. 
Disconnection was only so that you could test CR1412 and as you tested
it by removing it from the PCB then you've got it covered.

If you wish to share photos I understand that the TekScopes photo place
can do it altho' I haven't tried it yet myself.


On 27/05/2020 10:33 am, ciclista41 via wrote:

Ok, Tektronix Common Parts Catalog. Got it!


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