Sony CF-550A complete and original

Hi everyone, was looking for a simple radio boombox to use while finishing a new detached garage for our house. Saw this on Facebook Marketplace for 45 dollars and decided to take a chance. It appears as though it’s pretty complete, including the seemingly hard to find 4 prong AC power cord. There is also a 1972 rechargeable battery pack that hopefully I can modify with some new cells. The radio itself charges the battery pack if cord is plugged in. I don’t think any work has been done on this for a long time, or possibly even ever. All of the functions work that I tested but I haven’t tried the built in stereo mics yet. The 27” antenna is broken in two places so hopefully I can find a near original looking replacement. It works even with the stub portion but I’m sure will work better with the full length antenna. The volume pot is super scratchy and some of the toggle switches are touchy as well so at absolute minimum it needs a good deoxit servicing. Parts units are pretty cheap on eBay but I’ll want to avoid that if I can help it. The aluminum faceplate has basically no scratches on it and the plastic case is dirty/grimey but my guess is this will clean up really nicely. Although everything seems to work, the audio is pretty flat and thin so my guess is there are plenty of out of spec caps. I know I don’t want to mess with anything with the tuner as I’m not an FM alignment kind of guy. Definitely looking forward to learning more about these. People call them the “first boombox” and also point out that famously Tom Petty used one of these to record his band practice in the early days. Any thoughts or opinions greatly appreciated. I post on the Walkman forums occasionally but this is my first boombox post

 

It's a nice compact style / look and that is why I tracked one down a couple of years ago

Deoxit and enjoy! FM radio at close proximity should sound impressive with the "Matrix Stereo Sound". As in right in front of the listener on a table or sat on their knees. Really cool early "Surround Sound" effect.

Mine has the old NiCd battery pack too. It crossed my mind to change the cells inside, but, hmmm, to pop that battery case open without damaging looks tricky. I have yet to try. For the radio and cassette itself I spent way too much time and effort in re-capping. And changing a dozen or so transistors to track down a crackling left channel. You have probably already seen my discussion thread on the Sony CF-550 already. (But here is a link for future readers who maybe have not seen it yet.)

(Gawd. Never. Again. No more vintage Boomboxes for me. The stress was too much in my obsessive need to obtain perfection and get everything working. My personality type is not good for this type of work. Too destructive in terms of stress.)

 

Ha! thanks for the comments and yes I did see your thread. Have to admit your concept of "first I did this, and then it sounded better, and then I did that, and it sounded better yet" was certainly inspirational but given your comments, maybe I'll back off on targeting "as good as it can be" to more of "good enough". I may start a different thread if I go beyond DeOxit in pursuit of good enough. I thought I was close to getting a Sony FH-215R here in the Minneapolis area but seller pulled it down. That's more of an ideal "all in one" for me. I'll keep looking. Other issue with this CF-550A is any work I do detracts from my real passion which is collecting and restoring Sony (and other) Walkmans. End of the day, it's all good. Gotta have a hobby. I just have too many of them... Cheers

 

I'm glad I got the CF-550 sounding great again though (and the CF-490 (CF-1990 in Japan) and CF-480 (CF-1980 in Japan) and CF-470 and CF-160. Had my fill of the old Sony's and got some indigestion

Check out the "modern" early 1990's Panasonic Cobra boomboxes for much better sound. I picked up a DX-R707 on local e-bay for $65US that was fully working. Amazing sound! A must buy in my opinion just to experience what an ugly plastic boomer can do. I have a thread on it here.

Panasonic RX-DT75 is another one. But be aware they would need an electrical engineer to repair if they break down as such complex electronics. And a bit ugly overall too. But they can be cheap if you are patient and are persistent in searching.

 

Hyperscope, wondering if you remember how you were able to remove the cassette circuit board so that just one large bundle pig tail holds back. I went back and looked at your pictures and all of the cable ties are in tact so I must be missing something. I’ll keep looking. Don’t want to disturb the beautiful cable bundles. I’m just being slow and cautious. Thx! Mark

 

Yep I can definitely post a pic in the Battery thread! Mister X are you in the Twin Cities? I don't think it was on Marketplace very long before I saw it...

 

Yes I left all cables alone. The cassette board opens like a page with the cables as the hinge. Then prop up with a stick.
Make sure to get the service manual with instructions on how to disassemble.

 

Thanks. I have the free service manual but it’s for the CF-550. Not the A version. Not exactly the same. Didn’t think to look and see if the 550A manual also out there. I’m at the point of opening the page and it definitely is 45 degrees out but binding somewhere with the wire bundles. My pic is about as far as I could get it.

 

Just a quick pic to show where I’m getting held back. The grey wire goes to a reed switch by the transformer. That was looped around the main bundle in a way that I could barely get the board pivoting much. Unsoldered that, and now the main culprits are the red and black wires that go to the 4prong power plug. Black pointer for visual aid. They went into the socket from behind and there were 4 screws holding the clear plastic insulator housing that surrounds the socket in place so I removed them thinking I could free up the socket and red/black wires but no go. I can’t see but assume the 120V wires head straight back out of that socket so it’s not going to come out. I really don’t want to keep unsoldering the constraining wires from the circuit board but I can. I’ll go back and look at your pics again.
Thanks!

 

OK I can see from your recap thread photos that you clearly removed the 4 pin socket but it looks like your wires all go in to a clear plastic sleeve where mine definitely do not as far as I can see. I’ll keep digging. I don’t want to post your picture in this thread as it may be confusing.

 

Just quick update I begrudgingly did clip one of the vintage cable ties as I saw no options to go further and, alas, there was another cable tie immediately below it that didn’t capture the offending black and red wires so I’m all good now…. Moving on to remove the super stretched belt…

 

Thanks for the link. I saw that one and downloaded but the copy is a bit fuzzy to interpret the schematic and mechanically looks similar the CF-550 manual. I did a mild disassembly and cleaning of what I had access to, including DeOxit on the volume pot and everything is working OK+. Weirdly with the stretched belt the W+F is still not so bad that I can’t play it for casual listening. Audio Fidelity on FM is what I would call “Fair”. I just don’t know how to compare it to anything. I need to go back inside and lube all of the switches and the other two pots. I expect some fidelity will come back. FYI new antenna from Amazon retrofitted perfectly. Longer term project will be replacing caps in the Audio Path…. As mentioned before, don’t know how to align FM so likely I’ll avoid the multiplexer…

Mark

 

One thing kind of interesting is with the UK Manual you can see some of the changes made in the later units. Newer models have a pull feature on the volume pot that is a Mains On Off feature. Other notable difference is newer models have a separate Mains in plug and the 4 pin dual purpose plug is gone. Would explain partly why the 4 pin cords are very difficult to find. They were discontinued at some point in the product run.

 

If you compare an FM station on the 550 to another stereo radio / boombox there should be a difference due to the "Stereo Matrix sound". I used Rock 101 here locally. For some reason this station really "pops". With the 550 sat right in front of the listener I was hearing this really pronounced w-i-d-e stereo separation and cool effects in the music. Listening to another FM stereo radio (Hitachi 3D5) it sounds kinda flat and dull / lifeless. Again... I suppose I just got lucky with the radio in that it still works fully.

In my CF-550 I noticed later on / recently that there is a bit of ghosting on the FM band, at the start at 88Mhz, some of the end 107Mhz stations appear duplicated down on the lowest end of the band. The FM section adjustments covered in one of the service manuals are very thorough / rigorous. I skimmed through them with some amazement at the work involved. Yikes.

I also missed the earlier posts here on how to open out the main circuit board. Sorry about that. It seems you have it sorted out all right anyway.