Restoration
of the Sony ICF-6700W - nr 1 (1978)
1. OLD
I bought this ICF-6700W out of nostalgia on a Dutch 2nd hand site. It
was not in great shape when it arrived:
- AFC switch lever broken off and the hole filled with glue (yuck)
- glue smeared all over front in the process
- some dirt
- antenna mod to accept external FM
- no receive on narrowband AM, USB, LSB/CW
- no receive on AM >750 kHz
- preselector knob not original
2. NEW
a. Clean with water and soap
b. Remove glue (mechanically and solvents - unfortunately took some
lettering as well, but the glue was very thick, and had eaten into the
glossy finish)
c. Put in new AFC switch, run wiring to lamp board
d. Contact clean all switches
e. Remove new antenna wiring, restore the old as per service manual
f. AM rx problem - align as per service manual
g. AM narrowband, USB, LSB very low audio - since wide AM was fine this
problem had to be in the switching or the AF filter. I took the
shielding of this area on the main board, the switching and DC measured
ok, I touched up the transistors Q15, Q46 and Q47 and this solved the
problem.
h. Alignment of SW1-2-3 as per service manual
3. OPEN ISSUES
If I knew the exact font and size I could go look for some stick-on to
repair text - if available.
A good match for the original switches and knobs would be great.
DigiKey, RS, Farnell - anyone?
4. SUMMARY
It
was not as difficult as
expected - a lot of horror stories are found on the web, but
this radio is very
servicable. One absolutely needs a good RF generator (I use
an HP
8662A) and a decent AF Voltmeter (here HP 3478A). An RF spectrum
analyzer
and an LF scope are helpful but not really needed.
Fun to work on, about 8 hours work, technically runs perfect now, some
cosmetics to be improved. I did pay too much for the condition it was
in I think.
At work, many foreigners are struggling to get good BBC World
Service and locals are struggling getting good FM... not a
problem with this
one (although FM is not its forte)... so decent performance is obtained
once the radio is recalibrated
- even by todays standard!
5. DOCUMENTATION
Good documentation is hard to find. BAMA scans are low quality. Here
are good scans of schematic and components:
schematic
diagram Sony ICF-6700L
component
placement Sony ICF-6700L
For the 6700W everything is the same except that the LW parts
don't exist,
and the MW/LW switch is now AFC to ground/VCO. All numbering and
placement is the same. Note that the documentation (service manual)
contains some errors.
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