I won a NIB J707 off ebay, took a chance on a whim. This is the one with the front face speaker on Aiwa's long-running chassis and design. The unit is brand new as described, can still feel the surface textures when holding it, and I actually needed a little muscle to snap on the two battery cases. The tape section seems ok mechanically but the output I get from both on the speaker and through the headphone jack is a loud screeching noise that sounds like massive signal interference. I'm far from a repair expert, but it reeks of failing caps? The radio tuner is also unable to pick up stations on both AM and FM modes. Weird, because the preset, tuning, clock (and backup memory) and other electronics seem fine. I didn't really expect the thing to work after lying dormant for 25+ years. I nabbed it because it brings back memories of the one I had in the 90s. But would be nice to repair it. It looks the part, literally brand new.
While it's probably the unit, it can also be the tape, make sure it does the same with a known good tape. Here's some diagnostic info on another thread. https://stereo2go.com/forums/thread...decks-articles-from-around-the-internet.4777/ I'd clean it good and check over the headphone jack wiring to make sure everything is still attached. AIWA's are known for having capacitor issues, here's one of Plop's Old Threads that might help. Plop knows a ton about these but hasn't been around lately, this forum has been around since 2002 but a ton of it was lost or archived in the "Old_forum" button at the top. You might find more information in there. https://www.stereo2go.com/topic/ind...7178235650847317&board_oid=522740502721869426 Another new thread https://stereo2go.com/forums/threads/aiwa-hs-j880-repair.9262/ I know they're different but they tended to use the same suppliers for parts.
I took it apart recently, and yeah the capacitors had leaked pretty badly. I removed them all but a good thing they didn't destroy any traces. Took pictures and ordered tantalum caps to replace them with.
Something worth checking is all the contacts on both ends of the ribbon cable between the main board and the cassette bay lid.
Update- put the new caps in, it works better at playing tapes, but the new caps get SUPER hot. And the volume doesn't get very loud. I triple checked if they were installed right and they were. Should have I got electrolytic capacitors instead?
Yep. Oddly enough it works without the caps? Only the 7 4v 220uf caps I removed because I noticed an issue with those
Do keep in mind the dot on the PCB silkscreen is the + not the - side on AIWAs. Not familiar with this particular model, but another thing to note is on SMD tantalums the marking is the + not the - as it is on electrolytics. Best thing to do is take pictures of before and install the new capacitors as before, as there can also be errors on the silkscreen. Fact you installed tantalums instead of electrolytics is not the reason they get hot (assuming the caps themselves don't have a problem).
I took a picture of the old caps and triple checked before I powered it on, all were in the right place.
Assuming they're installed correctly can only assume the caps themselves are faulty based on the information provided so far. You can check with a multimeter the DC voltage across them and see if it matches the marked polarity. As a sidenote, you don't need to quote previous posts, unless you quote just a part of the post. Instead of using "Reply" button (which quotes automatically), you can type in box below the post and press "Post Reply" instead.
Key point in valentin's post above: Electrolytic caps always have a polarity identification stripe on the negative terminal; Tantalum caps always have the stripe on the positive terminal. (Don't ask me why!!) So the new caps need to be installed with the stripe pointing the opposite way to the originals!
Maybe it's just me, but every time I've tried to sub in tantalums for electrolytics in my experience it never goes well. I always have followed the the reverse polarity rules too, but I still end up with strange symptoms which went away when the proper electrolytic caps were installed. Due to this (and the fact I think they look odd and not factory), I'm still using good ol SMD electro caps.
