Advise for Sony ICF-7600W
 

Hi you all,

I need an advice, as I try to repair my (old) Sony ICF-6800W...(Sony, of
course, refuse to do the job)

a) AM & FM are ok
b) No sound on SW bands... Digital led readout indicate wrong values. Drum &
preselector are ok.

If someone got the same problem... any advise welcome!

Jean

Jean, very common problem with the 6800W. I have four of them, which all
had the same problem. Problem is caused by corrosion on the 0 - 10 - 20 MHz
slide-switch inside the radio. This corrosion causes the PLL circuit to
fail. The only way to get at the switch is to completely disassemble the
radio. If you're lucky, you can simply clean it with a spray electronics
cleaner such as De-Oxit. If it does work, it will only be a temporary fix.

The correct fix is to remove the switch (S6) from the main board. This will
require the removal of several other components just to get at the switch.
Once removed, you'll need to carefully dissasemble the switch and clean the
contacts with very fine emory paper... or something like it. There is no
available replacement for the switch, so be very careful.

You absolutely need a service manual to perform this task and need
technician-level soldering skills. Even with that, plan on the entire
operation taking four to six hours... if you're careful. The service manual
doesn't talk about disassembling the switch itself.... but it can be done.

Good luck!
Craig

"jb.pinelli" wrote in message
...
Hi you all,

I need an advice, as I try to repair my (old) Sony ICF-6800W...(Sony, of
course, refuse to do the job)

a) AM & FM are ok
b) No sound on SW bands... Digital led readout indicate wrong values. Drum
&
preselector are ok.

If someone got the same problem... any advise welcome!

Jean

Craig!

Ok & tks for advise.

I spend some hours today in order to remove S6... (main board removal is a
nightmare!) Inside S6 was a kind of green jelly and corrosion on the silver
contacts. After cleaning (ultrasound + polishing) I put into S6 a silicon
paste normally used in high tension transformers (radiology) in order to
avoid corrosion on the bushes. I have also removed and cleaned 2 others
switches (S1 & S2)

After re-assembling the set, a great improvement: readout on digital meter
is now in accordance with position of SW band selector. I have now to
adjust VCO1 & VCO2 (and probably whole set adjustment) as frequency dont
change yet when I turn tuning dial knob....

I keep you informed! Again thank you!

Jean

"jb.pinelli" a écrit dans le message de news:
...
Hi you all,

I need an advice, as I try to repair my (old) Sony ICF-6800W...(Sony, of
course, refuse to do the job)

a) AM & FM are ok
b) No sound on SW bands... Digital led readout indicate wrong values. Drum
&
preselector are ok.

If someone got the same problem... any advise welcome!

Jean

Great news on cleaning the switch. What you found sounds about right.
Alignment should help with the frequency adjustment problem. I've also had
to replace transistors in the buffer stages between VCO circuits after I've
fixed the switch. For some reason, they failed... most likely from the
switch failure. This was the case in two of the 6800W's that I repaired.
The good news is that you can get replacement substitution transistors.

Regards,
Craig

"Jean Bernard Pinelli" wrote in message
...
Craig!

Ok & tks for advise.

I spend some hours today in order to remove S6... (main board removal is a
nightmare!) Inside S6 was a kind of green jelly and corrosion on the
silver
contacts. After cleaning (ultrasound + polishing) I put into S6 a silicon
paste normally used in high tension transformers (radiology) in order to
avoid corrosion on the bushes. I have also removed and cleaned 2 others
switches (S1 & S2)

After re-assembling the set, a great improvement: readout on digital meter
is now in accordance with position of SW band selector. I have now to
adjust VCO1 & VCO2 (and probably whole set adjustment) as frequency dont
change yet when I turn tuning dial knob....

I keep you informed! Again thank you!

Jean

"jb.pinelli" a écrit dans le message de news:
...
Hi you all,

I need an advice, as I try to repair my (old) Sony ICF-6800W...(Sony, of
course, refuse to do the job)

a) AM & FM are ok
b) No sound on SW bands... Digital led readout indicate wrong values.
Drum
&
preselector are ok.

If someone got the same problem... any advise welcome!

Jean