On 08/29/14 22:10, John Miles wrote:
Looks like a really nice piece of hardware, well worth fixing up. You might
check the hot-wire ionizer filament on the Cs tube for continuity, as a failure
there may not show up in a meter indication.
Apart from that, the detailed troubleshooting steps in the contemporary HP Cs
service manuals (5061A/5061B generation) would be very much applicable to this
one. The block diagram will be similar. You could try measuring the beam
current and SNR manually if all else fails; one approach that I used is
detailed at http://www.ke5fx.com/cs.htm .
-- john, KE5FX
Miles Design LLC
Hi John,
Nice piece of kit and it will be fixed, one way or another. Neat setup
you have there and could probably do something similar, other than for
the hv psu's. Can take decades to build up a good lab. Cheap test gear
bought broken and fixed + the occasional real bargain from Ebay etc, but
there are still quite a few gaps to fill in here. I restore old test
gear as a hobby and for some items, you really need a very well equipped
lab if you are following the book calibration procedures. While you can
often find workarounds, it's so much easier and faster if you have the
right kit in place.
Had a look at the manual for the FTS4060 to get some background, but
will have a good read of the 5061 manual as well As mentioned. one of
the boards has an sma jack input from what looks like a coax lead to the
tube area. It's terminated on the board in a 1meg (misread that earlier
as a 100K) to ground and straight into an op amp. There's a test point
at the output of the op amp and hung a scope on that earlier today.
Reads ~80mV p-p, noisy sine wave and guess what ? - around 138Hz and
verified using the scope fft function. No idea if this is enough, but
the signal is definately there, so looks like the tube hv, ioniser and
cesium heater is at least functional. Can't really determine the op amp
gain without feeding in an external signal in, as it has a trimpot in
the feedback loop, but suspect either unity or a few X, as it's primary
function will be as a high Z input buffer for the tube signal.
It's been in the bench for a week now and will have to put it to one
side soon for a few days to get some work done. Will give me some time
to do more background reading / manual hunting...
Regards,
Chris
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