Forums :: Resources :: Features :: Photo Gallery :: Vintage Radio Shows :: Archives :: Books
Support This Site: Contributors :: Advertise

It is currently Mar Wed 20, 2019 4:22 pm

All times are UTC [ DST ]

Post New Topic Post Reply  [ 13 posts ] 
Author Message
 Post subject: July 4th project-The Spirit of (Sony) 7600.......
PostPosted: Jul Mon 04, 2016 10:53 pm 
User avatar

Joined: Dec Sun 22, 2013 5:03 am
Posts: 2382
Location: Santa Cruz mountains
This story begins with me answering an ad in the ARF classifieds for a dead Sony ICF-SW7600
shortwave radio:


This radio has some "history", so to speak:


When I got the radio in the mail, it was pretty much as described. A very sad case indeed. all in
pieces, but everything was there. It appears that the radio had developed a problem and a previous
owner had opened it up intending to troubleshoot it, had torn an unobtainable ribbon cable and
then things went downhill from there. The ribbon cable between the keyboard and main board had
been torn up and the connector was damaged beyond repair. At least two previous ARFers had given
the radio up for dead. The original speaker was trashed and a substitute of the same size but not
as robust was included.

I have an SW7600 that has worked well for years. Its only problem was that some sort of plastic
attacking chemical had been spilled on it by a previous owner. The radio above was the perfect
solution to that, being a parts radio and all, so I didn't really care that it didn't work. I
would just rob the good case from the parts radio and put it on my working radio, and all would be
good. I'd even get a US-spec'ed wall wart for it as part of the beans

So, I got out my "working" SW7600 in preparation to make the case swap, plugged it in to the new
wall wart, and discovered that it wasn't working anymore. Weird, machine-gun like noises came out
of the speaker and what little the radio could receive was off-frequency.

These SW7600 radios are known to have a problem with surface mount electrolytic caps going bad and
leaking all over the board. My SW7600 had been working perfectly for years, so I assumed that it
had magically escaped the "bad caps" problem......I guess not!

The only way out of this was to replace the caps. I don't have any surface mount equipment in my
shop and I didn't want to use new but possibly failure-prone electrolytics anyway, so I decided to
use tantalum caps instead. The size is similar and they would seem a better choice for long term

If you are in the same boat as me and want to re-cap your own SW7600 without specialized
equipment, here is what you need to do:
First of all, you need one of these:

0.JPG [ 155.85 KiB | Viewed 2803 times ]

A termperature controlled soldering station is a must. Don't even THINK of trying this with a
regular old-school plug-in iron; you'll simply burn up the traces on the board. The tip you'll
need is very narrow. I used an extremely narrow screwdriver tip for this and it works wonderfully.

You'll also need fine diameter solder to mete out the solder in fine quantities in the right

Now, it's time to disassemble the radio. To do that, take the four screws off the back.

1.JPG [ 114.6 KiB | Viewed 2803 times ]

you can now pull the case halves apart like a clamshell. take the back off first. There is a fifth
screw that you'll need to remove in the center of the PC board.

2.JPG [ 155.19 KiB | Viewed 2803 times ]

Now, take off the front to expose the keyboard and speaker. from this point on everything is held
in place by little plastic tabs. Take care not to break or deform these tabs

3.JPG [ 144.54 KiB | Viewed 2803 times ]

Carefully lift the tabs holding the speaker in place to free it, then disconnect the speaker and
set it aside.
4.JPG [ 126.51 KiB | Viewed 2803 times ]

5.JPG [ 146.06 KiB | Viewed 2803 times ]

6.JPG [ 97.19 KiB | Viewed 2803 times ]

Remove the snap-on control cover cover on the right side.

7.JPG [ 140.67 KiB | Viewed 2803 times ]

Now it is time to remove the keyboard/display board assembly. BE CAREFUL HERE. The cable is
fragile and brittle. I was very gentle and I still came within an angel's breath of tearing the
cable. Fail to heed the warning on the board at your peril!

8.JPG [ 160.49 KiB | Viewed 2803 times ]

Looking at the cable from this angle, you'll see that the cable edge connection is partially
exposed. This is normal for a properly seated cable.

9.JPG [ 140.87 KiB | Viewed 2803 times ]

 Post subject: Re: July 4th project-The Spirit of (Sony) 7600.......
PostPosted: Jul Mon 04, 2016 11:01 pm 
User avatar

Joined: Dec Sun 22, 2013 5:03 am
Posts: 2382
Location: Santa Cruz mountains
There is a black connector on the board that cinches the cable in order to secure it. It order to
remove the cable, you will have to very gently pry on the edges of the black connector to lift it
up until the cable edge connection is no longer exposed

10.JPG [ 142.96 KiB | Viewed 2799 times ]

Very gently pull the connector straight out. Notice how i'm doing this with both thumbs and
forefingers for more support and a straighter pulling action. This is to ensure that the cable
doesn't tear when it's pulled on.

11.JPG [ 120.52 KiB | Viewed 2799 times ]

Once the connector is free, pull the keyboard off and set it aside.
Next, unsolder the leads for the LW/BC loop antenna. There are four of them and three of the color
coded connections are marked on the board, but I would still make a note of where they go.

12.JPG [ 141.7 KiB | Viewed 2799 times ]

You can now remove the main board from its plastic framework by gently lifting the plastic tabs.
This what you'll wind up with before you start replacing caps:

13.JPG [ 139.92 KiB | Viewed 2799 times ]

Now, here is the evil that you are dealing with:

14.JPG [ 114.69 KiB | Viewed 2799 times ]

See that green crusty stuff migrating on the solder pad? when the cap is removed, this is what
you'll likely find underneath:

14-2.JPG [ 152.15 KiB | Viewed 2799 times ]

It goes without saying that all of these surface mount electrolytic caps will need replacement.
Do not try to unsolder these caps. That crusty crap resists heat, so you'll probably start burning
up the pads if you use a soldering iron on them at this stage. Instead, use a small jeweler's
screwdriver to gently pry up the center of the cap so it will pivot, and then use a pair of long
nose pliers to rock the cap back and forth to break it free. It usually doesn't take much force. I
found that this was the least destructive method of getting these caps out.

15.JPG [ 159.32 KiB | Viewed 2799 times ]

Once the cap is removed, clean as much of the crusty stuff off as possible using alcohol

16.JPG [ 186.07 KiB | Viewed 2799 times ]

Now, put fresh solder on the pads with your iron. Once that is done, Use a solder sucker to suck
the solder off the pads and then put more fresh solder on the pads. The reason for this is to take
off as much of the leaked electrolyte as possible to avoid contaminating the connection on the new
cap that is about to be installed. You'll want to put enough solder on so that it forms a little
mound on each pad.

17.JPG [ 174.22 KiB | Viewed 2799 times ]

Now apply a dab of solder flux to the pads. This will ensure proper wetting and a clean joint when
the cap is installed.

18.JPG [ 123.07 KiB | Viewed 2799 times ]

 Post subject: Re: July 4th project-The Spirit of (Sony) 7600.......
PostPosted: Jul Mon 04, 2016 11:11 pm 
User avatar

Joined: Dec Sun 22, 2013 5:03 am
Posts: 2382
Location: Santa Cruz mountains
19.JPG [ 159.63 KiB | Viewed 2798 times ]

Cut the leads of the tantalum capacitor very short and tin the shortened leads with solder.

20.JPG [ 111.76 KiB | Viewed 2798 times ]

Grab the tantalum with long nos pliers and put one lead on the most robust of the pads and then
apply heat to the pad and the lead with your iron. hold the cap very still while the solder
hardens and then solder the other lead to the other pad the same way. Be sure to observe proper polarity.

21.JPG [ 167.02 KiB | Viewed 2798 times ]

22.JPG [ 132.96 KiB | Viewed 2798 times ]

And there you have it, one cap replaced. The other surface-mount caps can be replaced in the same
way. I didn't have any problems with burned up traces using this method.

Please note that there is a shielded section next to the volume control that contains the Dc/DC
converter circuitry. You MUST remove this shield and replace the 22uF cap underneath. This cap is
crucial to the proper operation of the whole radio so it ABSOLUTELY MUST be replaced.

23.JPG [ 139.86 KiB | Viewed 2798 times ]

All done with this one....Here is what the board looks like with the replacement tanatalums:

24.JPG [ 158.83 KiB | Viewed 2798 times ]

And here are all the dead caps I pulled out:

25.JPG [ 66.53 KiB | Viewed 2798 times ]

There is one more cap on the Keyboard/Display board assembly. That cap controls the time constant
for the LED backlight when the button is pressed. The larger the cap value, the longer the LED
will stay lit on a single button pressing. You can experiment with this if you wish. I changed the
stock 22uf cap to a 47uf cap and found that the increased illumination time was much more
convenient in a darkened room.

Assembly of the radio is exactly the opposite of disassembly. Once I got the radio assembled, it
fired right up and worked perfectly. It seems a bit stronger now that it was before. I'm a happy

.....Which leads me to radio #2, the radio that was sold (twice!) on this very forum. Suddenly,
after doing my SW7600, this basket-case parts radio didn't look that bad. Yeah, it had the bad
connector on it, but I had all the pieces, and all the tools were still out and the techniques
that I used on the first SW7600 were still fresh in my mind so I decided to take a stab at
repairing this poor, sad little set and make it happy again.

Replacing the caps was basically the same as with the first radio, so I won't repeat that here.
There were a couple of challenges like this:

26.JPG [ 133.68 KiB | Viewed 2798 times ]

This is why you don't want to try to unsolder the caps. There were a couple of pads that were
wiped out like this by a previous repair attempt. I fixed this by scraping off enamel adjacent to
the pad and creating a new grounding pad for one of the leads. The other lead was soldered
directly to one end of the surface mount resistor you see in the photo.

You'll also note that the keyboard connector on the bottom right of the photo has been removed by
a previous owner. That was done because the original connector was unrepairably broken.

So, that leaves the question of what to do about the broken cable and connector. The cable is
ordinarily welded onto the keyboard using tools I don't have, even if I got another cable, I
couldn't reliably attach it. The connector is broken and probably unobtainable also. The only way
out was to hard-wire the keyboard to the main board.

Fortunately, the seller included the now useless cable and connector in the package:

27.JPG [ 68.6 KiB | Viewed 2798 times ]

I was able to insert the torn cable into the broken connector just good enough to do continuity
checks on it to see how it all connected the keyboard to the main board. From that information, I
drew a connection diagram.

28.JPG [ 123.85 KiB | Viewed 2798 times ]

 Post subject: Re: July 4th project-The Spirit of (Sony) 7600.......
PostPosted: Jul Mon 04, 2016 11:22 pm 
User avatar

Joined: Dec Sun 22, 2013 5:03 am
Posts: 2382
Location: Santa Cruz mountains
The guy who broke this radio initially had attached wires to the keyboard in hopes of repairing
the radio but gave up and sold it to the guy I bought it from. He removed those same wires in the
hopes of attaching a much neater ribbon cable but abandoned that idea when the capacitor leakage
inside the set came to light and sold it to me instead. He included the disconnected wires in the
package along with everything else so I decided to use them. Here is the board with the wires I
attached to it:

30.JPG [ 163.43 KiB | Viewed 2798 times ]

Attaching these wires to the keyboard is not for the faint of heart. Take a gander at this:

31.JPG [ 177.42 KiB | Viewed 2798 times ]

Steady nerves and patience are a must with something like this.
Believe it or not, I actually got this perfect the first time-not a single wire you see there is
touching any other wire!
I connected these wires to the main board according to the connection diagram I made earlier,
reattached the speaker, crossed my fingers and applied power. I got a time clock on the display,
which is a good sign:

32.JPG [ 161.83 KiB | Viewed 2798 times ]

(Note the red clip lead up top. The reason that is there is so the alligator clip can press down
on the "lock" switch to allow the radio to be powered on.)
I held my breath, pressed the power button and started hearing all the right noises. I set the
radio to 810 (KGO radio) and heard normal reception. Tuning up and down the AM dial revealed
normal reception on other stations. SUCCESS!

33.JPG [ 159.89 KiB | Viewed 2798 times ]

I then tried shortwave and it works, fine, too.

Alas, there is a problem with FM. It's very insensitive. I'm not going to try to fix that right
away. I almost never use these radios on FM anyway, and I can use my other SW7600 on FM if need
be. The fact that I got this far with this thing with all its problems is pretty incredible.

...Which leads me to this:

I also have a third non-working Sony digital radio, an ICF-SW7600GR. This radio is way cooler than
the two above. It has Sync detection, one Khz step tuning and true seperate upper / lower sideband
tuning capabilities. It is the latest and greatest (and possibly last) version of the 7600-series
Sony radios. I bought it for pocket change at a CHRS flea market last July because it didn't work.

when I got it home, I tried powering it up and this is what I got:

36.JPG [ 145.68 KiB | Viewed 2798 times ]

That is a low battery indicator on the display, when the radio is being powered from a wall wart.
This is not normal. Attempting to turn the radio on resulted in power up for a fraction of a
second and then immediate power-down again.

I have a working SW7600GR, so I did some board swapping and determined that the problem was
somewhere in the keyboard / display assembly. At that time, I saw evidence that some beverage
(probably coke) had been spilled inside:

35.JPG [ 130.59 KiB | Viewed 2798 times ]

 Post subject: Re: July 4th project-The Spirit of (Sony) 7600.......
PostPosted: Jul Mon 04, 2016 11:28 pm 
User avatar

Joined: Dec Sun 22, 2013 5:03 am
Posts: 2382
Location: Santa Cruz mountains
At that point, I just assumed that the spilled beverage had fried the CPU, which is also on that
board, and posted a WTB in the ARF classifieds looking for another board. I got no replies which
was not surprising for something of recent vintage.

So there it stood until this weekend. Encouraged by my success with the first two radios I decided
to take another look at this one, with schematic in hand to see if could decipher what the
symptoms were trying to tell me. The constant low battery warning was a tell-tale sign that
something was amiss in the power circuitry.

It turns out that this radio has two small comparator chips that are specifically designed to shut
the CPU down if they detect a low-battery situation. This is done so that the CPU always shuts
down in a clean and orderly fashion, and memory doesn't get corrupted. I thought for sure that
this circuitry would have something wrong with it, but when I checked all the voltages they were
all right on the money. I did notice that the outputs of these chips would drop during the very
brief time the radio would try to power up, but I didn't know if that was normal or not.

I checked some other pins on the CPU but found nothing conclusive.
At this point I decided to give the failed board a chemical bath in 91% alcohol. I figured that
this would be the surest way of removing any remaining contamination caused by the soft-drink
spill I noted earlier. I removed the LCD display and submerged the rest of the assembly in the
alcohol for a good long time, more than an hour. I then dried it off with a hair dryer until it
was bone dry and then installed it back into the radio. This time, the radio was dead-really dead.

No clock, No low-battery, No nothing. Seemingly the chemical bath made things worse.

I got curious and decided to check the voltages I had checked earlier. voltage. all of
the voltages that I had noted as being normal before the alcohol bath were now gone. This was
weird because nothing I did should have affected anything there.

Checking further, I saw that the voltage coming directly from the battery to the keyboard assembly
was still there. I traced that to a point where it fed power to the other side of the board
through a plated-thru hole. There was no voltage on the other side. WHAT??

I decided to solder a jumper wire between the point where I knew I had voltage to its plated-thru
mating point on the other side.

37.JPG [ 193.44 KiB | Viewed 2796 times ]

I then applied power to the radio. The clock immediately came up on the display. No low-battery
indication this time either. I pressed the power button and the radio came alive!
I tuned to a station and left things on for about an hour to confirm that nothing was
intermittent, then I buttoned it up. It's playing as good as new now.

Apparently that plated-thru hole was defective in some manner. I'm at a bit of a loss as to why I
was getting normal readings and and some semblance of power up originally though. I'm guessing that
there was just a tiny bit of conduction in that junction, just enough to supply a zombie-state
amount of current to the radio. The alcohol somehow killed that, and made the problem a lot more
obvious and easy to diagnose. I'll probably never know for sure.....ah well, I got a working
radio, so I'm happy.

Here are the three finished radios on my bench, all tuned to RHC:

38.JPG [ 178.49 KiB | Viewed 2796 times ]

And here is a YouTube video: ...

 Post subject: Re: July 4th project-The Spirit of (Sony) 7600.......
PostPosted: Jul Tue 05, 2016 2:09 am 
User avatar

Joined: Jan Thu 01, 1970 1:00 am
Posts: 30474
Location: SoCal, 91387
Remind me to send you all the dead Sony ICF-SW7600's I run into! :wink:

Seriously, great illustrated tutorial!

\\\\\\\\\\\\\\\\\\\\\\\\He Who Dies With The Most Radios Wins//////////////////

 Post subject: Re: July 4th project-The Spirit of (Sony) 7600.......
PostPosted: Jul Tue 05, 2016 2:40 am 

Joined: Jan Thu 01, 1970 1:00 am
Posts: 1831
Location: Monroe, NC 28112 USA
Very entertaining narrative! Sometimes I find myself digging into new'ish electronic gadgets presumed dead just to see if I can get them going again. There is no economic justification, it is just fun :D

I have a SONY CD boom box purchased new some 15 years ago. Ticked me off when only a month out of warranty the LCD display started loosing segments. I presumed it was the driver chip but at the time, there did not appear to be a source for the chip. Within a week or so the LCD was completely unreadable. A bad run of chips??? I have not been happy with Sony since...


 Post subject: Re: July 4th project-The Spirit of (Sony) 7600.......
PostPosted: Jul Fri 08, 2016 9:37 pm 
User avatar

Joined: Jan Tue 31, 2012 1:55 am
Posts: 7278
Location: Mountains of Mourne. Ireland.
Excellent post.

Come on baby let's do the twist!
Here is a short video extract from norcal715 showing how he removes surface mounted capacitors.
norcal715 aka Steve has a shop up in Chico Ca. His youtube channel is packed full of good info regarding the repair of modern day TV's.
Video clip→ Mitsubishi DLP Electrical Chassis Rebuild.

Replacing C69 on pin 23 of CX20111 is a known fix for no FM
The correct value is 220Mfd 4V not 22Mfd as shown on the schematic.
oh... C69 is not the easiest cap to get to, but I guess you already knew that.

Mods, repairs, errors + corrections.

Thanks for taking the time to document your repair :)


Edit: image updated.

Last edited by egg on Nov Thu 22, 2018 4:59 am, edited 1 time in total.

 Post subject: Re: July 4th project-The Spirit of (Sony) 7600.......
PostPosted: Feb Sun 11, 2018 10:41 pm 

Joined: Jan Tue 01, 2013 3:53 am
Posts: 141
Location: Mar del Plata - ARGENTINA
The C126 (Memory Backup) not changed it...?

 Post subject: Re: July 4th project-The Spirit of (Sony) 7600.......
PostPosted: Feb Sun 11, 2018 11:55 pm 
User avatar

Joined: Jan Tue 31, 2012 1:55 am
Posts: 7278
Location: Mountains of Mourne. Ireland.
Hola henrypal,

tristemente, Scott Harvey tambien conocido como Primitiveradiogod muerto en un accidente de bicicleta 1 Febrero 2018

Noticias tristes acerca de Miembro Primitiveradiogod

Scott's obituario... ... tent-start


 Post subject: Re: July 4th project-The Spirit of (Sony) 7600.......
PostPosted: Feb Mon 19, 2018 5:09 pm 

Joined: Jan Thu 01, 1970 1:00 am
Posts: 689
Location: dayton oh usa
be sure to remove the tan/brown glue while you are in there.
it turns conductive and corrosive.
as for trace damage desoldering caps i have never had that problem.
i use 2 fine tip irons and heat both sides at once lifting the cap when free like using chopsticks 2 handed.
technique developed servicing sony ccd-f series camcorders and standard c5900 transceivers.
i keep 2 isotips in my road case for use onsite with industrial stuff.
i can change a smd lytic in about 30 seconds replacing with a smd tantalum.

 Post subject: Re: July 4th project-The Spirit of (Sony) 7600.......
PostPosted: Dec Mon 10, 2018 9:57 pm 
User avatar

Joined: May Fri 25, 2018 1:50 am
Posts: 361
Location: Petaluma, California
Here is a thread one should read if you are going to redo these capacitors, notes that the black mark on the original caps are the negative (cathode) end, and you could, like me, end up with them reversed if you don't know and are not smart enough to do research before diving in :!: ...

The Green Man says: He who has smelled the smoke is never again free.

 Post subject: Re: July 4th project-The Spirit of (Sony) 7600.......
PostPosted: Dec Tue 11, 2018 12:10 am 
User avatar

Joined: Feb Mon 21, 2011 4:19 pm
Posts: 177
Location: San Marcos, CA 92069
Impressive work. I was quite surprised by your method of removing the surface mount capacitors. I've an old Sony 7600A that still works. It is the old analog version of the 7600.

Post New Topic Post Reply  [ 13 posts ]  Moderator: Dave Doughty

All times are UTC [ DST ]

Who is online

Users browsing this forum: No registered users and 9 guests

Search for:
Jump to:  

Privacy Policy :: Powered by phpBB