Good afternoon, or whatever time of day it is wherever you are! I'm working on an old Toshiba RT-7045 that has seen better days. I got it hoping I could fix it up for a friend. I can tell that someone else was in there before me, the radio works but when I turn on the cassette player, a motor runs briefly then immediately turns off. Upon closer inspection, there are two black plastic pieces that are broken and a third one that's missing. Due to the placement, it will not be possible to replace or repair the plastic parts. Additionally I only see one "for parts" RT-7045 on eBay that does not have a working cassette player. It might be repairable but I don't have any guarantee. Is there any hope of sourcing a similar/compatible cassette mechanism from a different model boombox that's easier to find? I looked through service manuals for other similar model boomboxes but none of them seemed to match. I know it's a long shot and won't be upset if the answer is "Sorry, no," but I figured I can't get a yes if I don't ask, right?
Update! I'm not entirely sure how but something I did fixed the cassette portion! I brought the main part with me but forgot to bring a cassette and worked at it between calls during work. Steps taken: - I took all three circuit boards out, reviewed them, comfirmed some old glue hasn't gone condictive as far as I can tell put everything back. - I noticed that the antenna cord came loose, not clear where it goes. Will reattach once I get the service manual in on Saturday - I also lifted the arms that interface with the cam gear, moved the cam gear, and put the arms back down. I suspect this might have been it because it was stuck in a weird position where the cam gear would only move about a third of a rotation and it just looked/felt off. The trouble is now volume is faint and one of the channels isn't putting out audio so I definitely have an electrical problem. I know it's not the power supply because I am using batteries. Once I get the schematics I plan to pull it open and see what I can figure out. I don't think anything fried because I was very careful to remove batteries while parts were out but it wouldn't surprise me if a wire or solder joint needed attention somewhere so that's where I plan to look next. Any advice would be appreciated in the meantime!
One good (and relatively low effort) avenue to explore early in the fixing process for just about any boombox is to "exercise" the control that switches between sources e.g. tape/radio/other, and the same with the REC control. On the radio side, the same might apply for the band control. The multi-contact slide switches that these controls operate inside the machine are notorious for getting contaminated and can present a variety of symptoms like losing audio from a source completely or just one channel. If simply exercising the controls doesn't bring any joy, further investigation may be helpful. Firstly operate the source switch with deliberate, controlled microscopic movements while listing carefully to see if it makes any channel or source work better or worse - and the symptoms can change during one operation! This might help with understanding the problem, but almost certainly you are going to need to spray the slide switches with a contact cleaner while exercising them gently but firmly. If you still suspect the slide switches, they can be unsoldered and disassembled; the major caveat being that you will almost certainly be unable to get new replacements if they are damaged - or if you damage them. One one occasion I had to hardwire a radio to FM only because the switch was, to put it bluntly, buggered from being forced to the point where its internal mech and contacts were unrecoverable.
Thank you so much for your input! It's good advice since I know switches and knobs can cause major headaches. I actually ended up hitting all the switches with contact cleaner, but I also discovered that a couple solder joints from a ribbon cable came loose. Thankfully they didn't take the pad with them. I reflowed all the joints which fixed the channel issues. I suspect that was the result of my tinkering. I think the cassette mechanism position was probably the original problem. I moved the cam gear till it matched what I assume is the home position shown in the service manual and that finally got it running again! I still need to do some creative soldering with some spare bits of plastic to see if I can keep the one piece in position but I might have it!
Final update: Got it all working! It's a little janky but the metal pieces I soldered/melted in to the plastic seem to be holding nicely. Thankfully it's going to a friend and if it breaks they won't be upset but I think it should hold pretty well. There isn't a lot of pressure on those pieces, they just hold down another piece so it doesn't go off track and the metal bits are accomplishing that goal. I am delighted to say we have reached a happy ending!
