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The big smoothing capacitor is put back into the set. A new mains-rated block shaped capacitor replaces the original waxed tubular next to it.
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All the control potentiometers
in this set are now opened and waxoyl applied to their tracks. This
is done to make for more reliable operation in the long term. Here,
a cotton bud is being used to anoint the track of one of the frame
linearity pots.
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The remains of the
old broken mains inlet has been removed and a large washer drilled
with mounting holes, to act as a bearing plate for the large sleeved
grommet. This grommet has to be made up from various grommet parts
and rubber rings to hand.
The HT metal rectifier
can be seen beneath. This will be left alone - for now. I'll see
how it performs in the finished, working set before deciding whether
replacement is necessary.
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A start is made on
replacing and/or reforming the main run of capacitors.
It proved possible
to reform both of thses electrolytics rather than replace them,
so this aspect will continue to look original. One of these is dated
1959, matching the year of the set.
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Here's the underneath of the I.F. chassis. All the waxed tubulars and black Hunts capacitors here were replaced with new. Then the resistors' values were checked.
There will now be
a break for the weekend, while I switch to Detinnitiser development
work.
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Come Monday, I work
through replacing the waxed tubular capacitors atop the IF panel,
and, after turning the chassis over, the tubular capacitors the
other side - shown here.
Some have slightly
awkward values...
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... like this monster
here. This, designated C96 in the service sheet, couples the live
end of the heater chain to the high tension rail. A similar capacitor
is seen in other Bushes - for example the TV22.
Its function is somewhat
mysterious, but presumably it is intended to provide hum neutralisation
by one way or another.
The necessary replacement
capacitors are ordered from RS, and should arrive tomorrow.
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Here is C96 on the
circuit diagram, circled in red. What do you think?
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Across
my well-worn workbench are strewn the valves. All these will now be
tested and, if they pass, will be cleaned up to look like the new
ones fitted alongside them. |
In the event, several
are revealed as faulty. The EY86 EHT rectifier has an open-circuit
heater, and one of the PCF80s (now getting rare) is low, as is one
of the PCL82 output valves. All are replaced.
Here we see the EBF89
(sound IF amp) under test, which it passes with flying colours.
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The new complete set
of good valves are now all plugged in to the cleaned-up chassis.
In this view, we
can see into the line output transformer's box (to the right). A
cover plate will hide this.
Tomorrow, reassembly
and fitment of the tube will be undertaken and it'll start to look
like a television chassis again!
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