[Coco] Weird CoCo3 problem...

[RJRTTY at aol.com]

In a message dated 1/5/2010 11:57:18 A.M.  Eastern Standard Time, 
gene.heskett at verizon.net writes:
>And historically,  teks attenuator pads attached to the 1-2-5 range 
switches 
>have NOT been  stable with time.  Seen this many times, and no amount of 
>fiddling  with the probe compensator will alleviate it.  Tek of course 
will  
>laugh at you when you query them for parts that old.  I can  remember 
when, 
>back in the 60's, tek had a lifetime warranty on some of  that stuff, and 
>honored it, NQA.  Now its ebay material.  



Thanks for the tip Gene.   I have an old BK Precision 20mhz
I need to replace.    Its attenuators have noisey  selectors
and have to be "jiggled" into good contacted.   Most of the
time you can tell when that is the problem tho.
 
So now I know not to buy Tek.
 
>No high frequency stuff there unless the boards bypass caps have all  
>developed 100 ohms of ESR, each.  Not impossible at these things  ages 
though.
 
>Individual caps could be due, but the tool to find those is about $225  
these 
>days, called a "Capacitor Wizard".  Nothing else like  it.  It measures 
ESR at 
>100khz, a characteristic of paramount  importance in digital circuitry.  
Its 
>the ONLY thing that allowed  me to keep 2 dozen Panasonic dvc-pro 
recorders 
>going most of the time  the last 4 years I worked sorta full time.  But 
the 
>coco is slow  enough its not nearly as critical as that stuff with 100+ 
mhz 
>clocking.  ;)
 
I can vouch for that.  I got mine last week and it performs
as advertised.   Saves a ton of labor and guess work.
 
Roy