@Fulltimehuman thanks very much for the tips here, I’ll definitely get on the SMDs and see how I go. I’m kind of hoping the traces aren’t toast to help eliminate that. There must be a fix! But yes I’ve followed how much work you’ve done so I’m under no illusions that it’s a tricky one!
Hi @nutronic amazing work on reading the schematics! That all makes perfect sense. I’ll start by getting the caps and resistors changed and see what that returns. I too have a few scrapped units that should yield some parts. Does your f707 totally work now?
Thanks @Seb, yes my F707 is working perfectly now. It needed a mechanical overhaul as well (mostly routine stuff, cleaning and lubrication), and some careful bending / twisting of the head armature to get good azimuth alignment. The more time spent on a restoration, the more satisfying it is to listen to when it’s complete, that’s what I enjoy about this hobby. I’ve certainly had my money’s worth out of these two units (F707 and F701C) - still yet to open up my R707, I wonder what challenges that will have in store for me!
@nutronic I've started the repairs and decided on bridging R719 and R720 and now all the buttons work!! Definitely wouldn't have got here without your help so I'm SUPER grateful! I also realised that the band change and stop/radio off button require a longer press than the others so that did have me stumped at first.. The radio comes through loud and clear (sounds great through the 742's) I will need to set up the EU/UK freq setting as it's defaulted to 76-90MHZ funnily enough TV band preset one picks up Capital 95.8..I saw a write up on how to change the area setting so i'll give it a go. The tape sound very good mechanically, low W&F new belt from Deck Tech cleaned up pinch and head. But it's very quiet and thin/distorted so obviously that must be the caps that @Fulltimehuman describes in his very good tutorial. Did you change all the caps? the blue and black as well as the silver ones? I'm just wondering which ones would cause the audio issues on the tape. I'm guessing the problem is from tape head to amp as the radio sounds fine? I enjoy doing these restos too very therapeutic (and occasionally frustrating!) I must admit you both really made this an easy one for me though.... I've mainly been doing the 100 series, a few Wm-30's and 20's and a Wm-75 so it's fun to do something new.
@Seb that's fantastic! When I discovered this issue it seemed so obscure - I'm amazed it has turned out to affect more than one unit. Still not exactly sure which component has drifted with age to cause these units to stop working - although as I say, it looks like the design was very marginal even when new. The sound quality issues will be the 47uF SMD caps (C106/206), the electrolyte will have dried up (or leaked) causing them to go high-ESR. The through-hole electrolytics should be fine, they at least they measured ok on my unit. One day I will get around to sharing my DIY method for testing electrolytic caps in-situ...
@nutronic yes especially as the resistors show as on spec when tested. I think your posts are going to save a lot of 70x’s! Going to order the C106/C206 SMDs probably try and use two soldering irons to get them out.. I tested C407 as it was easy to get out and it showed 167uf should be 220 so I might change that too.. Definitely interested in your in-circuit method..keep us posted! Huge thanks again for now⭐️
@nutronic, it's been a while, but I have only now been able to revisit the old F707 project again. I just wanted to report back that I did reconstruct the entire group of vias you mentioned in an earlier post. The effect was zero. The behavior is exactly as before, the device is dead, that is. While I am unsure if this issue existed before, I noticed that I am also seeing exactly the same problem with the tuner buttons you also described earlier. If I manage to turn on the tuner, pressing any other button on the device will make the static noise cut out briefly, thus confirming that the other buttons are working. This problem seems unrelated to the no power-issue, though. For the moment, I have decided to shelve this project for as long as I do not discover any new leads. I am considering refurbishing a second, spare F707 PCB that I still have lying around and that might yield better results. That might be a sensible way to go. Anyway, thanks very much for your help and enjoy the holidays!
Quick update: I had some time last night to fully restore a spare F707 PCB. I did the usual stuff, as reported above. Well, it did "something", as it seems. There's apparently life in this thing at last, but it's very erratic. The solenoid will click on button press, the motor will at least attempt to run (but seize up frequently) and the mechanism, again, does "something" making a clicking noise. There's not much else to report. It seems to me that, aside from the PCB, the whole thing is also mechanically gunked-up badly and needs a complete cleaning and regrease, including the motor. Let's see when I find time for that. ;-)
@Fulltimehuman, sorry to hear the via repairs didn't solve the problem. Did you also reduce or bridge R719 and R720 as discussed in the later posts above? On the mechanical side, this thread might be relevant: https://stereo2go.com/forums/threads/sony-wm-701c-703c-wm-ex80-solenoid-spring-problem.5446/ Also the 4th photo in this thread (idler gear similarly gummed up with dried grease): https://stereo2go.com/forums/threads/sony-wm-f701c-back-to-life.10155/
Hi all, I'm Dan. found this forum and was very happy! My situation: I have a 701C 10th anniversary addition, love it! Got it out of the loft, it was trying to function but spools not rotating, motors running. Opened it, chore! Belt disintegrated. Bought belt. Cleaned goo off belt cogs etc. with Isoproponol 99%. Mistake: decided to clean everything inside with it! Was sparing. Put it back together, no power. SO ANNOYED! Fixed one thing, broke a bigger thing!!! So my Qs are if anyone can shed light please: Do I, 1. Buy a 701 on Ebay, cheapest found £200 and swap internal. However, this one is the 701 with radio function in lid. Would anyone know whether interchangeable? I can see that technically it's the same, but it has a ribbon from chassis to lid for radio. If said ribbon goes no where as mine is not the radio version, do we think that would stop the chassis functioning. i.e. a ribbon required for radio function would be left flapping as no radio to connect it to?! 2. Are any of you chaps willing to take it on and investigate and repair, please?! Thank you very much. Dan
Hi Dan, the 701c is a lovely walkman but they are fiddly to work on. The fact that you did have power to begin with is good news- in the sense that it's unlikely you have corroded traces etc. 1.Have you tried both battery options-the gum stick in cassette compartment and the AA battery holder? 2.There are very thin wires going from the battery terminals to the main board-have you checked that they haven't come off as you opened it/closed it back up? 3.Do you have, and have you tried the inline remote to power up? try holding the play button for 5-6 seconds-mine would start after that-which points to the point below. 4.In this thread you'll find a few reasons why you might not be getting the unit to start-the one that worked for me was the bridging of the tiny resistors explained in nutronic 's detailed operational breakdown of the 700 series. 5.Fulltimehuman has been dealing with the DC converter issue, but so far this appears unresolved. 6.I would imagine all 700's would now need to have their capacitors replaced as per nutronic 's explanation- bear this in mind if you're buying a donor unit.. 7.I think you might be able to put the 701 radio version board in yours, the ribbon cable can be unsoldered from the main board. I hope something helps you identify the issue Good Luck, Seb
Hiya Seb, that's so nice of you to reply with such helpful info, thank you! Yes, it was all fine, then it wasn't! I was gentle with it and I have inspected it closely throughout, I see nothing broken or disconnected. I cannot believe that a little bit of Isoproponol might have killed it! 1. I bought a new gum stick and yes tried the external battery. 2. Will check 3. No! will try! 4/5/6/7. Thank you, will investigate further and consider the 701 radio version option too! Will feedback. Best wishes and thanks again. Dan
