[time-nuts] Lamp oven repair info for HP 5065A
cdelect at juno.com
cdelect at juno.com
Sun Aug 2 17:14:19 UTC 2015
Hi, Just thought I'd share some info on repairing a defective HP 5065A
lamp oven.
These ovens can fail either shorted to the oven cylinder
or have interwinding shorts.
I have repaired three optical units so far with this failure.
The original winding was insulated twisted pair wound
directly onto the Aluminum oven cylinder.
I used teflon insulated heater wire, Pelican P2332ADVFEP.009BL.
It is approx. 5 Ohms/ft. and I use a 50 Ohm length doubled and then
twisted tightly.
This is then wound onto the oven cylinder which is first covered with a
single layer of kapton
tape.
The original thermistor is replaced with a DigiKey 615-1007-ND.
The thermistor MUST be surrounded by heat sink compound.
I also install a digiKey TO220 100 degree thermal cutout switch for
future
protection. It is mounted to the top of the lamp assy. using one of
the 3 original mounting screws. The thermistor and heater wires are
brought out tie wrapped along the original cable and then soldered
to the appropriate pins on the db9 connector.
Cheers,
Corby
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