Murphy's
Law as applied to Radio Servicing
Compiled by Tim Pullin. Additions gratefully
received.
Any of this sound familiar or am I just too cynical?
- Any faulty valve will either be
a. Not in your stock
b. Unobtainable
c. Horrendously expensive.
- Any component above suspicion will be proven to be faulty. Any components
unique to your set will be faulty. They will also be faulty in all other sets
of the same type you encounter.
- The most inaccessible components will always develop faults.
- Your test equipment will only mislead you when you believe it 100%.
- Intermittent faults will only manifest themselves when the chassis is in
the cabinet. When the chassis is out on the bench the fault will mysteriously
clear.
- The circuitry in your set will differ from your service data, especially
in the area of the fault. Any creases, smudges or staple holes in your diagram
will always obscure the area/component you are interested in. Any unreadable
component values will also be unreadable on the diagram.
- Only when you have cleared a simple fault will you realise it has a complex
cause.
- A complex fault will have a simple cause.
- Only after removing twenty screws and unsoldering ten terminations to access
a part, will you realise the part could be accessed by simply removing two
screws.
- The most difficult screw to access will always be the tightest.
- The replacement cost and rarity of a component will be directly proportional
to its likelihood of being faulty.
- Sets with awkward and complex tuning drive arrangements will always need
re-stringing.
Darren Stewart suggested another one, which he
calls "Engineers Syndrome":
When the engineer is present the item works;
when he's not it doesn't.
Henk added an extra one:
Intermittent faults will only manifest themselves
when the chassis is in the cabinet. When the chassis is out on the bench the
fault will mysteriously clear.
Ralph suggested:
The cost to repair an antique radio always exceeds the
fair market price of a fully functional radio of the same model.
John added:
When checking a series heater string, the faulty valve
will always be the last one you check.
Dan Robinson suggested:
After spending days fixing a problem and having taken
the radio apart 10 times, when you go to put it back together for the final
time, you will break something you can't replace or repair.
Any more?
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The types of equipment discussed on this
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Last updated 14th April 2006.