Problem in Sony ICF-7600D
 

Hi,

I own a clean Sony ICF-7600D (ICF-2002), love the 80s boxy design, though it's not very sensitive compared to modern radio. The only thing annoys me is that while using MW & SW the frequency displayed on screen is off about 5kHz from the actual frequency. Of course I can use the +/- 5KHZ fine tuning to compensate the error but it kills off the fun. No problem in FM though.

Just wonder if there is anything I can do to 'align' the frequency display with the actual frequency? (Sorry I have little knowledge in SW and electronics). Thx

Problem in Sony ICF-7600D
 

On Wednesday, August 1, 2018 at 2:14:38 AM UTC-7, Fotopiggie wrote:
Hi,

I own a clean Sony ICF-7600D (ICF-2002)...The only thing annoys me is that
while using MW & SW the frequency displayed on screen is off about 5kHz from
the actual frequency.
It would help if you provided more information. Is it the same amount and in the same direction for all frequencies, or does it increase/decrease with frequency? The first would suggest an IF alignment error, while the second cold be due to an off-frequency oscillator crystal.

Problem in Sony ICF-7600D
 

On Wed, 01 Aug 2018 02:14:36 -0700, fotopiggie wrote:

+AD4 Hi,
+AD4
+AD4 I own a clean Sony ICF-7600D (ICF-2002), love the 80s boxy design,
+AD4 though it's not very sensitive compared to modern radio. The only thing
+AD4 annoys me is that while using MW +ACY SW the frequency displayed on screen
+AD4 is off about 5kHz from the actual frequency. Of course I can use the +-/-
+AD4 5KHZ fine tuning to compensate the error but it kills off the fun. No
+AD4 problem in FM though.
+AD4
+AD4 Just wonder if there is anything I can do to 'align' the frequency
+AD4 display with the actual frequency? (Sorry I have little knowledge in SW
+AD4 and electronics). Thx

Is this your service manual?

https://www.manualslib.com/manual/10...cf-Sw7600.html

Problem in Sony ICF-7600D
 

Thanks for the response. Yes it's consistently roughly 5 kHz below the designated frequency. For example if I want to tune in 11815 kHz I need to key in 11810 kHz to hear the signal (not perfect, still need tune up a bit with fine tuning dial) I don't know the exact amount of the frequency off as you may know the radio tuning is in a 5 kHz step.
So if IF alignment is the case I don't think I can handle the job. May need to find a technician to do the job...

Problem in Sony ICF-7600D
 

Thanks but that's Sw7600's manual. Mine is a ICF-7600D, an older model. I actually have got the service manual but I don't have the proper gears like a RF generator to do the job. Better find someone else to do it....


Frank於 2018年8月2日星期四 UTC+8上午5時53分01秒寫道：
On Wed, 01 Aug 2018 02:14:36 -0700, fotopiggie wrote:

Hi,

I own a clean Sony ICF-7600D (ICF-2002), love the 80s boxy design,
though it's not very sensitive compared to modern radio. The only thing
annoys me is that while using MW & SW the frequency displayed on screen
is off about 5kHz from the actual frequency. Of course I can use the +/-
5KHZ fine tuning to compensate the error but it kills off the fun. No
problem in FM though.

Just wonder if there is anything I can do to 'align' the frequency
display with the actual frequency? (Sorry I have little knowledge in SW
and electronics). Thx

Is this your service manual?

https://www.manualslib.com/manual/10...cf-Sw7600.html

Problem in Sony ICF-7600D
 

On Wednesday, August 1, 2018 at 10:21:54 PM UTC-7, Fotopiggie wrote:
Thanks for the response. Yes it's consistently roughly
5 kHz below the designated frequency. For example if I
want to tune in 11815 kHz I need to key in 11810 kHz to
hear the signal (not perfect, still need tune up a bit
with fine tuning dial) I don't know the exact amount of
the frequency off as you may know the radio tuning is
in a 5 kHz step.
So if IF alignment is the case I don't think I can
handle the job. May need to find a technician to do the
job...
Was it like then it was new? If so, it may be a manufacturing error. IF filtering is often done with ceramic resonators, and if they used 450 kHz instead of 455 kHz (or vice versa), that could explain it. It is unlikely that it would have spontaneously shifted frequency. I tried to look at the circuit diagram that Frank cited, but my eyes are too old and the my monitor resolution is too poor for me to read it.

Problem in Sony ICF-7600D
 

No idea if it's's like that while it was new. I got it from ebay some years ago but didn't play with it seriously until recently. FYI this is the correct manual:

http://diagramasde.com/diagramas/otr...e%20Manual.pdf

So is there a chance to fix it? Thanks



於 2018年8月2日星期四 UTC+8下午9時30分28秒寫道：
On Wednesday, August 1, 2018 at 10:21:54 PM UTC-7, Fotopiggie wrote:
Thanks for the response. Yes it's consistently roughly
5 kHz below the designated frequency. For example if I
want to tune in 11815 kHz I need to key in 11810 kHz to
hear the signal (not perfect, still need tune up a bit
with fine tuning dial) I don't know the exact amount of
the frequency off as you may know the radio tuning is
in a 5 kHz step.
So if IF alignment is the case I don't think I can
handle the job. May need to find a technician to do the
job...
Was it like then it was new? If so, it may be a manufacturing error. IF filtering is often done with ceramic resonators, and if they used 450 kHz instead of 455 kHz (or vice versa), that could explain it. It is unlikely that it would have spontaneously shifted frequency. I tried to look at the circuit diagram that Frank cited, but my eyes are too old and the my monitor resolution is too poor for me to read it.

Problem in Sony ICF-7600D
 

On Friday, August 3, 2018 at 12:55:02 AM UTC-7, Fotopiggie wrote:
So is there a chance to fix it? Thanks
Probably not economically, at least in the US.

The schematic shows a 450 kHz ceramic filter, so my hypothesis might be right. If it was made by Murata, it will have some indication of the IF frequency, and if it says 455, then this is probably the reason. Murata filters are cheap (under US$10 at Mouser), but I don't know if they are compatible with yours. Or, you could cannibalize one from another 7600D if you can find a bad one.

Even if you found the right part, in the US the labor charges would be more than the radio is worth. Maybe you could find a sympathetic hobbyist...

Problem in Sony ICF-7600D
 

On Wed, 01 Aug 2018 22:26:27 -0700, Fotopiggie wrote:

+AD4 Thanks but that's Sw7600's manual. Mine is a ICF-7600D, an older model.
I
+AD4 actually have got the service manual but I don't have the proper gears
+AD4 like a RF generator to do the job. Better find someone else to do it....

Or buy another one and keep your current one for parts. Or just live
with the error. The cost of getting a qualified tech to even diagnose
the radio might exceed the cost of a good used radio.

The only thing I can see that looks like a screwdriver adjustment to
change the radio's frequency is T 11, the AM 2nd IF VCXO adjustment.
It's a crystal oscillator at 55.395 Mhz. Could T11 pull the crystal
oscillator 5 MHz? That's more than I'd expect but I dunno. Anyway, why
would it be off? These things should hold their adjustment within a
small range indefinitely.

If you want to try your luck, try pressing around the circuit board with
the plastic part of a stick pen or some other nonconductor like that. If
the display corrects itself, you probably have found a bad solder
connection.

Otherwise, it's probably too much of a PITA to make it work perfectly
again.

Problem in Sony ICF-7600D
 

On Friday, August 3, 2018 at 8:40:09 AM UTC-7, Frank wrote:
Or buy another one and keep your current one for parts....
I had one, and in the 1980s, it was a technological marvel. One downside (also mentioned in a WRTH review) is that it is a terrible battery-eater. If you get a different radio, I would opt for one of the newer 7600 variants or something from Sangean or Grundig; they will have more memories and the batteries will last a little longer.