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sickrick sickrick is offline
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Default Repairing vintage Philips 7871 receiver

In article m,
David Nebenzahl wrote:

On 4/3/2009 12:58 PM sickrick spake thus:

In article ,
"N_Cook" wrote:

A crystal earpiece is about the only piece of test equipment you need for
this sort or repair, in all probability. To check the central pins of the
treble control pot to start with.


Ok, I'll pick one up...but I have never used one before, can you point
me to some info on how to use one? I am assuming that i would not use
the jack plug, but would instead cut it off and ground the wire while
probing the treble control pins with the other wire?

Ugh I hope I don't have to replace the treble control pot, that would be
a pain with the way its layed out...


Forget the "crystal earpiece". It's an obsolete piece of hardware you'll
find very difficult to find, and not what's needed here anyhow.

You'll have to excuse "N_Cook", who is an inveterate bodger and tinker.

You need a multimeter (aka VOM); any kind will do, digital or analog.
(The digital ones sell for as little as $3 in the US.) Put it on one of
the resistance measuring scales and measure the resistance between the
wiper (center terminal) and one of the outer terminals as you turn the
control; the resistance should change smoothly between (X ohms) and 0
ohms. If it doesn't, the control is shot and needs to be replaced.

Surprised nobody has suggested the first thing to do, which is to squirt
some electronic cleaner into the pot and try to clean it. Often this is
all that's needed to fix a scratchy or non-working control. Be sure to
use something made for cleaning electronic components, not something
like WD-40.


i think the pot itself is fine: the same pot controls the right channel
which sounds fine...are you guys saying the pot itself is stereo? there
are 6 pins on the pot