I got lucky with the meter, but not with the S-Meter pot on the side of the
rig: it's fried.
I've always been somewhat troubled by that screw moving around when I loosen
the nut - from now on, the wires will be desoldered instead. Thanks for
that recommendation, guys!
BTW, I just read these emails after posing the question on the 7236 Sunday
net and the guys there said the same thing.
Anyone have a source for one of those 500-ohm pots for the S-meter
adjustment? I'm about to go on to Mouser's website, but if anyone knows an
exact part number, I'd be much obliged...
73,
Steve Wedge, W1ES/4
Live free or die: Death is not the worst of evils.
John Stark.
All my computers have my signature with various pearls of wisdom appended
thereto.
--------------------------------------------------
From: "Garey Barrell" <[email protected]>
Sent: Sunday, January 01, 2012 1:13 PM
To: "John Meyer" <[email protected]>
Cc: <[email protected]>; <[email protected]>
Subject: Re: [Drakelist] S-meter shorted to case.
John -
Beat me to it!! :-) Been lots of meters destroyed by loosening those
nuts. Key to watch for is only ONE. Expensive meters have two, one to
hold the terminal in place, the other to tighten over the solder lug.
Those two extra brass nuts would have seriously affected the slightly less
than $1 production cost of those meters.
They do seem to break at the coil rather than at the bolt terminal.
Hopefully Steve will get lucky! If not, they're ALL the same meter, from
to 2-A to the R-4B so donor units not that hard to find.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
John Meyer wrote:
Steve,
If you have to work on the meter don't remove the nut on the back,
unsolder the wire. Go into the meter from the front. When you do you will
see why. I made the mistake and loosened the nut which broke a very fine
wire close to the coil body.
John Meyer K8IHY
----------------------------------------------------------------------------------------------------
From: [email protected]
To: [email protected]
Date: Sun, 1 Jan 2012 11:04:13 -0500
Subject: [Drakelist] S-meter shorted to case.
I'm working on an R-4B and fried a resistor in the metering circuit. The
560-ohm resistor is now measuring about 80 ohms. I thought, perhaps, the
resistor had simply failed, but decided to sniff around the circuit some
more before subjecting this no-longer-obtainable meter to any more stress
(it is still indicating when I put an ohmmeter across its terminals).
Whilst metering the meter (don't you love it?), I discovered that the
right-hand terminal (when facing the back of it), was shorting to the
metal case! Arrrggggghhh. I played around some more with the insulator
and torque upon the nut and have it so it's no longer shorting to the
case. When I lifted that oblong insulator to peek at the screw and where
it comes through the back of the case, it appears that it is supposed to
be isolated from the case - as I would expect.
What could have caused this short? I'm very much suspecting that this
could have fried that resistor. I've eliminated the short but am uneasy
because I didn't see anything that fixed it other than re-torqueing the
nut.
Anyone ever have one of these puppies apart?
73,
Steve Wedge, W1ES/4
Live free or die: Death is not the worst of evils.
John Stark.
All my computers have my signature with various pearls of wisdom appended
thereto.
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