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Detailed view of the instrument
while scoping. The input signal is a 100Khz - 4Vpp sine wave and
you can see the good geometry of the instrument. The squares scale
has been adjusted too to obtain an accetable resolution. |
Internal right view of the instrument after the covers removal.
You can easly see on the bottom the power supply board with the
high voltage capacitors battery (the red ones) and all around the
CRT the magnetic shield. This cover avoid that external noise can
deflect the electron beam introducing deformations on the displayed
image. There are 10 tubes plus the CRT and 2 of these in the power
supply section. The others are small power triodes or pentodes used
in the horizontal, vertical sections and triggering circuitry.
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The enlarged view here is the high voltage rectifier, a tube type
EY86, a single wave rectifier. Note that the CRT works with
a nominal voltages about of +1,200V, with this diode the
voltage from the transfomer is rectified and sent to the cathode.
It's a negative voltage, so it will be easier to obtain 1,200V
just putting the last acceleration grid to a voltage of + 300V.
This trick avoid dangerous voltages all around the instruments too
This tube was often used in the horizontal section fo many TV receivers.
Its low heather voltage was obtained with only 1 (one!) coil around
the horyzontal trasformer (flyback trasformer).
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Another view of the instrument
taken from the left side, this time with the magnetic shield all
around the CRT removed. You can see the BIG power supply trasformer.
This was the only component I had repaired. The rest of the scope
has worked fine at the first time after applyng power. |
On the left is the detailed
view of the damaged power supply trasformer before its restoration.
All the output wires and many coils unfortunatly was in short circuit.The
component was completly dissassembled (!), repaired with new wires
and closed again. |
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After a black hand painted and
... looks new again :) |
View of the instrument during its restoration. As you can see
has been complelty disassembled. The time required to make this
work, with the trasformer repairing was about one week
Important tip:
While disassemblig/reassembling instruments like this or more
generally receivers it's VERY important to write down very
accuratly each cable, socket, switch BEFORE its removal.
This because after days in the reverse operation it is very easy
to forget the right routing... Believe me !
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Panoramic view of the components
after ... washing :) These components, tubes, CRT and platics was
whashed with... water and soap. Naturally was left two days without
reassembling in order to obtain a PERFET drying. |
Another picture taken during
the restoration work. It was an hard operation due to the big quantity
of wires all around the instrument. Note the long.. very long colored
cable with the potentiometers and switches just removed.. |
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