This is the Equipment
Archive Section of
The Broadcast Archive
Barry Mishkind - The Eclectic Engineer
Last Update 3/12/01
Need to stock up on parts?
From John Stortz ... here are some always timely tips!
--------- Stortz's Top Ten Rules of Parts
Stortz's rule of parts #1: If you have a part fail once, it is likely
to fail again, so order an extra one whenever possible. Next time, you will be
the hero for getting the thing back on the air fast.
Stortz's rule of parts #2: Keep all unique spare parts for a specific
unit in a larger box, clearly labeled as to what equipment they belong.
Stortz's rule of parts #3: Label all used parts to indicate if they
were working when removed, or if something is defective, or if pieces have been
removed. If a component is being saved to take pieces to repair another unit,
mark it on the label.
Stortz's rule of parts #4: Each critical fuse should have a box of
small fuses [of the correct size] right next to the fuse holder, attached by
Velcro, for quick access. This makes them easy to locate in an emergency.
Stortz's rule of parts #5: If you can, buy generic. [ A warning,
though: all parts are not equal in quality or tolerance. Be especially careful
about generic substitutions in critical, close-tolerance or matched-pair
Stortz's rule of parts #6: When ordering generic parts, try to replace
components with ones that have higher voltage ratings [capacitors, lamps, diode
PRV], higher current ratings [diodes, relays, wires, switches ...], higher
wattage rating [resistors, potentiometers, zeners, transistors, SCRs,
Stortz's rule of parts #7: If you must replace the same soldered-in
component more than once, think about installing a socket, next time.
Stortz's rule of parts #8: If an EXACT part is not available, do you
have something close in value? If so, but you are not sure how it will affect
the performance, call the tek-support people. "Hey, your model xxxx
normally has a 9.2V zener diode for component ZD-3. Ours is shorted and we are
off the air. However, I found an 8.4V zener on my shelf. Do you think I might be
able to use this until you can send me the correct part, if I reduce power a
Stortz's rule of parts #9: If no part is available and you are off the
air, try something way out: would the equipment work without the defective part?
Can the failed area be bypassed? Can you think of a temporary repair? From what
available material could a repair be made?
One of my first transmitter repairs was for a failed screen capacitor, that
was built into the base of an IPA tube socket. It was a weekend, of course, and
nobody returned my call from the manufacturer. To get back on the air, I rebuilt
the capacitor with about 3 sheets of plastic, cut out of a transparent notebook
cover. I had no idea what the melting-point of the plastic would be, not how hot
the socket became while operating, or the effective capacitance, or voltage
break-down rating, so I sandwiched in some silicone RTV for good measure. The
socket held, at half-power. The next day, I went up to about 3/4 power. After
the new part arrived, I moved the power back up to 91%, and eventually to 100%.
We ended up running that way until the next regularly-scheduled maintenance
shut-down. Then I kept that old tube socket for future emergency use [it was
better than nothing and was working when removed].
Stortz's rule of parts #10: After the panic, and you are back on the
air, consider if you might be able to salvage the old part. For example, many
plate blockers tube sockets [also, tubes] and blowers can be rebuilt. This can
provide a spare at a fraction of the cost of a new unit.
WKES and WKZM
"Moody Broadcasting for Central Florida"
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