Hello guys,
I’ve got a 1970s Sony CF-320 portable radio on my bench for repair. So far, I’ve replaced two of the three rubber belts and about five electrolytic capacitors. One was a 2200µF at 10 volts, but it only measured around 110 pF—definitely done for—so I swapped it with a 2200µF at 16 volts. There was some foam padding taped over the wires that had deteriorated, and I’ll post photos of it. I’m curious what others have used as a replacement. One thing I could really use is the service manual, as this is the one model missing from my Sony documentation. Here’s a photo showing the radio and its condition.
Also couple of the other capacitors that were bad were a couple of .47 ufd electrolytics I replaced with some film capacitors instead . they were basically a 15 ohm resistor they were so leaky .
Rich,
So electrotanya didn't have anything? I found one for my Roberts 8 track player on there, I just hope that the early Op Amp ICs are still good, they look like a large transistor with many more legs. This Sony probably has a more modern one, if it has any at all.
Regards
Arran
Hello Arran ,
Greg, aka Egg, found one for me and posted it on the ARF forum. This unit is being restored for a client, and I have an AM/FM Sony radio from the same era that I restored a few years ago, which still works great. Back when this unit was new, my repair shop was an authorized dealer and service center for Sony, so I still have many factory manuals and technical information, but I was missing this particular manual. I stopped being a dealer in the ’90s.
Anyway, my Mouser order just arrived, so the Pioneer amplifier will go back on the bench. Since I now have the new 4.7µF electrolytics and 1µF film capacitors, and only had two 4.7µF capacitors left in stock, I went ahead and ordered 100 more.
Rich;
I was thinking of doing something similar with the smaller value electrolytics in some of my transistor radios, there is a newer type of ceramic cap that can replace things like 4.7 uf electrolytic caps, this may be a good idea because sometimes the polarity isn't as obvious on a small cap.
Regards
Arran
Hello Arran,
I bought some new ceramic capacitors from Mouser, along with small pre-made circuit boards that let me replace PC mount capacitors with surface-mount ones. Small value capacitors are getting harder to find as companies stop making them. For example, the amplifier I’m repairing had a couple of 0.22 uF electrolytic capacitors on the phono preamp that had basically turned into 20-ohm resistors.
Hello Guys,
Thanks to Egg from ARF forum he posted a download for the factory sony manual.
Here is the current state of that radio on my workbench .
I had to strip down to service the tape deck and clean the cabinet .
Hello guys,
Here’s what I’ve done so far and still need to finish today: replaced seven electrolytic capacitors, resoldered cold solder joints, removed that nasty glue and latex foam, and cleaned and lubricated everything.
Sincerely Richard
Hello Paul,
I’ve mostly put the radio back together but forgot to install the new counter belt, and I still need to clean the tone control and AM/FM switch. The tape player will need one of the idler tires replaced, so I’ll check if I have the right size—this radio has about three idler tires. Back in the day, I worked on a lot of Sony equipment, since up until the ’90s I was a Sony authorized dealer and service shop. The business I bought had been carrying Sony products since they first started selling in the U.S.
You want to hear something funny? I was looking for my bag of used parts from this set to put the tape counter belt in. I must have looked for 15 minutes before putting some parts in its shipping box, where I found the rest of the parts. But then I lost the belt and spent another 15 minutes searching, only to find it stuck to my elbow.
Hello Guys,
I ran into an issue where, for no apparent reason, the motor stopped running. When I checked the 6-volt supply across it, it measured about 0.5 volts DC. After lifting the positive motor power wire, the supply was restored. My next step was to use my bench supply, and the motor worked perfectly. The screenshot shows that section of the motor and power, with a 2200 μF and a 470 μF electrolytic capacitor—both brand new—and the motor power switch has been cleaned.
Hello Guys,
I think it might be one of the recifier diodes because when I first replaced C41 the original capacitor was open .
I have some 1N4007 I think I will go ahead and replace them .
Because for a test I just put my fluke across C41 and when the motor is hooked up the voltage goes down to 1/2 a volt .
Sincerely Richard
Hello guys, I went ahead and replaced the diodes with some 1N4007, but it still didn’t change anything. For testing, I hooked up the meter to the AC coming off the transformer into the rectifiers, and no matter what happens, it never loses AC. So, I think that rules out a bad power transformer.
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