Hey guys I recently picked up this recording Aiwa model HS-JX609 and it’s a nice model in really good condition. I’ve just replaced the belt as the old one has dissolved into tar, cleaned it all up, and it is now working great with the new belt. it sounds really nice (and I was surprised that it didn’t have a Dolby control!), but two minor questions I have are: 1. it has an OSC switch on the rear. Am I right that this is for filtering interference or suchlike when recording? 2. as soon as I remove the twin AA battery pack it loses radio presets and clock settings etc. Is it meant to have some sort of internal battery or way of storing all the settings when batteries are removed to swap out for new ones? It’d be a real pain to reprogram it every time you change the batteries so I assume there must be something but I didn’t see it. other than that, it’s really nice machine and working great although not tried recording at all yet, won’t really use it anyway. Actually I just thought of one other thing, would this model ever have used a rechargeable pack? It only says AAA or UM4 on the back and they’re the same thing I think, but assume if it even did it would have been one of those lead acid types that can’t be used now anyway? Thanks!
Congratulations for the repair ! Glad to hear the device is working so good ! 1. Don't know what the OSC switch does. Never seen such a switch before and I don't have user or service manual for this particular device. But it is likely other members will tell us what it is. 2. In regard to the radio presets and clock settings, there should be either a coin-type battery or a supercapacitor. The battery is long dead if it has one, but supercapacitors can also fail. The supercapacitor is usually of large diameter and the height is very small (<5mm) and it is of very high capacity (in the Farad range). Without a service manual I can't tell for sure if it has a battery or supercap, but if you put a picture with the unit disassembled (with both sides of the PCB) I can tell if there is one or not.
Thanks Valentin I googled about an osc switch and didn’t see anything re’ having it on a Walkman but the explanations I found for full size systems were that it was related to interference in recordings so I guess it must be that since this is a recording model. No pics I’ve already taken of the board sadly, so I’ll have unsolder it all again to check that, although I think I saw a service manual online so will try that first (as a couple of tracks on the board were getting a bit loose and if I can avoid unsoldering all again it’d be better I guess).
Apologies, it was oscillator actually now I’ve checked. Afraid I was paraphrasing incorrectly! https://www.vintage-radio.net/forum/showthread.php?t=60815
Ok, thanks for sharing ! Now it makes sense, it's clear what it does. It's there to avoid intermodulation between the bias and the relatively low carrier frequency of MW and LW radio stations. What that switch does is changes the frequency of the AC bias so the AM radio frequency isn't a harmonic of the bias frequency. It's explained in this video: www.youtube.com/watch?v=gm0dT-vi0XU
You probably already know this... I recently learned that desoldering is vastly easier if you coat some flux on the braided desoldering wire before you apply the heat through it. If you wreck a terminal pad a jumper wire will have to be installed as per a wiring diagram. The rule is to not apply heat to traces for more than 2 seconds.
