Hello everyone, So it's finally time to register on this forum that has helped me multiple times before. So before I proceed, my sincere thank you. I'm not a collector, but I do like putting a nice unit in good shape to use when one comes my way. Thanks to this nice but demanding hobby I was "forced" to learn how to solder along with other requirements, many defeats but also some nice triumphs, and the sweet taste of the latter and that feeling of accomplishment by my own hands is what keeps me going sitting in my basic stool and my professional workbench, aka my folding table, when my vision is getting tired and my back is begging me to walk away. So here's my current predicament: I recently stumbled upon a nice Panasonic RQ-SJ1 that was clearly well loved, and with quite a lot of charm. I was told that it made some brief noise when clicking on the playback functions, power light turns on, but that it all stops a split second later. They weren't sure if it was some kind of protection / detection as they didn't have a cassette to test, so I got it under that context. It had clear signs of battery spillage on the outside shell and it got to the board and the horizontal barrel of the motor itself on the batteries' side. I removed all solder points for the batteries, screws and wires, took the motor out with its capstan feeling somewhat stuck and erratic, ran it with a simple battery for an hour lubing it, cleaned everything, swapped the belt which was deformed but still in one piece, and put everything back together making sure the leaf switches were correctly mounted. It had the exact same behavior: Play, FF, REW all start, light is very briefly on, and stops after a small split second. Then I noticed that some caps were leaking, recapped everything... still the same behavior. The corrosion that had gotten in the board membrane was visible in many places, so in the first disassembly I tested continuity for the most critical spots after cleaning, and they all came back fine... The mechanism side has absolutely no traces of corrosion of any kind... If I desolder the motor wires and attach a battery the mech starts running smoothly in a continuous fashion... So I'm kind of stuck at this point. Do you guys know what might be happening here? What am I missing? I thought that being a simple model with no auto-reverse to give me grief I'd be in the clear but guess not... Still, I can't be that far from getting there surely? Thank you everyone for your time and replies
I did see this problem once or twice when restoring these models, but just can't remember what I did to fix it as too much time has passed. One thing I can tell is it's a simple fix and likely related to the switches. What likely happens is Q11 turns on briefly then turns off. Check around that area of the circuit. If I remember what the fix was I'll post. If you find it yourself, please update the thread for reference.
Hello Valentin, thank you for your kind reply. I've read threads / posts from you along these years that have helped me tremendously, thank you so much for that. As soon as I have some time I will check that, but do you remember if it was an electrical fix or a mechanical one? I know that people point out the need to make sure the switches are well seated using the guide posts, as described/shown here: https://stereo2go.com/forums/thread...-wj1-rq-kj1-rq-sj1-belt-change-tutorial.3705/ (Image credit to user "stuck-in-time") Mine are well seated in place like the picture and actuate correctly, leafs look clean... maybe resolder those points in the board membrane?...
Glad to hear you found my posts useful. Can't remember for sure if problem was mechanical or electronic, although incline towards being mechanical. What I do remember though is this problem appeared after I recapped the unit and re-assembled the PCB, don't remember it being there to begin with. As for soldering don't think it's a soldering problem. Capacitors leakeage mostly cause problems with the audio: no sound on one channel, amplifier osillation etc.
I see, for me it arrived already with that issue, before and after maintenance. The mech turns smoothly with a battery attached directly to the motor wires, but I'll check that as well as the Q11 section you mentioned when I can. In any case Valentin if you remember the actual fix I'll be most grateful, it's such a pretty and compact unit it's a true shame to be this close to fixing it. I don't know if you keep some sort of log of your repairs or pictures, if you need some pics from me I'll happily upload them, maybe it'll jog your memory?...
Hey Valentin, so I think I may have found the fix. The fact that you said you remembered it was an "easy fix" kept lingering, so I tried something on a hunch... and oh it was "simple" alright... For reference: ***THESE SPECIFIC PANASONIC WAY MODELS SHUT DOWN A SPLIT SECOND LATER WHEN HEADPHONES ARE NOT INSERTED*** Simply put, what constitutes a feature in the 80s, is an absolute nightmare in 2026. Anyway, it played some music on one side only, probably something related with caps or corrosion, and after another pass with the iron now it won't even turn on at all, so I'll keep at it again later and see if I'm able to save it or if it's done for good. But at least there's a reference here for others. Thank you as always
Indeed this explains why I didn't document the "fix" because there wasn't anything in particular that I've done. Even forgot these units don't work without a jack plugged in as I always used them with headphones plugged in. Looking at the schematic I do indeed see a switch in the jacks that goes to the Q11 circuit. Regarding no sound on one channel, check the feedback capacitors in the power amp, found many issues in that area: C22, C24, C18, etc. Not the caps themselves (as they're new), but the connections to the rest of the circuit. On these units replacing the PCB is also a viable option (new ones are available in China) as there can be quite a few vias corroded which takes time to identify. As a sidenote, there's no need to quote previous messages. Instead of using "Reply" button (which quotes automatically) you can type in the box below and press "Post Reply" instead.
