Ronan:
There is a great amount of satisfaction in successfully repairing high-tech
instrumentation. Some of my old equipment out-performs the latest
offerings. Often it is worth the trouble to do the repairs. Try not to
think of the disappointments.
Gary
On Dec 1, 2014 6:31 PM, "dudelucky583@... [TekScopes]" <
TekScopes@...> wrote:
Hello!
I've troubleshot my beloved 485, to the point I have to just let go -- I
must send it to my scrap heap (spare parts shed) -- with the help of the
service manual, I traced the problem to the -3KV cathode supply; once I got
into it and tore the scope apart to get to the "transformer board" (whoa
what a mess) -- I realized I might not have the time/patience to get it
back together, even if I could test the HV diodes, multiplier (for anode)
etc, "pot" my own multiplier, find a replacement, etc....
How much time should a person spend reviving a 485 when you can find them
on craigslist for $400 "calibrated"?
I used a digital scope (Rigol 50mhz) to easily capture that 485 startup
"balancing node" thingy, where actually the Rigol proved it's $300 value by
saving me a lot of headaches to capture that 20ms period after power up and
after the 6ms initial delay. It asked that I bend a pin on one of those
"comb" connectors, and if the scope powered up (sans HV), it was the
cathode supply short circuit (then I didn't find any obvious problem in the
HV in continuity checks I assume my DVM doesn't put enough volts out to
cause forward conduction).
So, if anyone has any "encouragement" on what I should / can do with the
485, that's appeareciated but by default I am "beyond mourning" -- I'll
just leave it for another day or when I need to steal parts to make a Ham
radio.
Yesterday I acquired a 454; it actually has one trace working (rough test)
and the other trace doesn't appear. Anyone know if this is a "known or
common issue"? SN 60101XX series, if that helps. I hope to avoid another
half day wasted ending in frustration as I don't have the parts nor
experience to know what parts to substitute, where to get oddities that
won't break my bank, etc.
I've not mustered the courage to crack the 454 open, I bought it from a
fellow HAM who knows what he's doing, I don't think repair attempts have
been like made.
I have one thread of me wanting a Tek analog scope back on my bench, I
know the Rigol has it's own plusses/minuses, but I have only so many years
to spin away on fixing stuff so I can do what I want to do ultimately
(building ham equipment and actually using it).
Thank you kindly!!!!!!!
Ronan/KB6NHQ
Meadow Vista, CA
[Non-text portions of this message have been removed]
Gary Robert Bosworth