I just got this tape deck in today, the seller said it was untested, but I was hopeful. Upon turning it on, what appears to be the main motor starts up instantly and does not stop.

Every function works except for Recording. 

Does anyone know what I might be able to do to fix this? Any help is appreciated!

Edit: Actually, I've been having a similar problem with a Sanyo M-S300K mini boombox I bought, too. The issue there is that as soon as I turn it on, one of the belts starts spinning, much like this deck. However, the REC light is also stuck on, and that box will not play tapes or the radio whatsoever. I've made a more detailed post about this in the boombox section but it's been awaiting moderation for a few days so I figured I could add this here as well.  

Hi. It is often normal for the capstan motors on home cassette decks to run all the time. Most of mine do. The record malfunction may be down to a number of things; many decks have a large record / play switch on the main board that can be problematic.

Of course the motor in a boom box shouldn't run all the time; had this problem on an Aiwa CS-600. It was a sticky micro switch in the tape mechanism.

Cheers, Seb

Thanks for the tips! I opened up the little box today to have another look. I can't seem to locate any microswitches anywhere. What would they look like? Where should I be checking?

Sometimes they look like two small metal sprung fingers. I will take some pictures for you later. 

Here are a couple of examples of the type of switches you will commonly find in a tape transport mechanism. Hope this helps you find what you are looking for.

Hmm, I don't actually see anything of that sort in the tape mech. Having accidentally broken the motor off (which appears to have been glued on before) I can confirm that the fault doesn't appear to have anything to do with the tape mech. 

Also, if someone could track down a service manual for this model, that would be fantastic. I've been trying to track one down to no avail, and managed to remove the string that moves the tuner, without knowing how to get it back on properly, heh!

Sounds like it's turning into a bit of a mare! So the motor was glued in place?

Certainly! The break points were super clean and had glue residue on them. I've since glued it back and it seems to be fine. Not sure what else could be causing it to run! I tried desoldering and resoldering the connections on the board that ran to the motor in case one of them was loose, but no luck. 

Sorry to bang on about this but I still think that there may be a switch burried in that mechanism somewhere! Could you perhaps photograph the front an back of the mechanism? Cheers,

Seb

No need to apologize! I appreciate your help! 
Here's a couple of pictures, as best as I could get them, hopefully these are visible enough! (I'll post the URLs so they're full resolution)

http://i.imgur.com/SHnzIVu.jpg

http://i.imgur.com/qHE7RRA.jpg

Ah, sorry, this is the Sanyo boombox. Basically, as soon as the thing gets power, whether that be through batteries or a plug, the REC light comes on and the motor starts spinning. Pressing Play, FF or RW all work as they should, with the correct things spinning, but no sound is produced from a tape, nor from the radio. I've tried cleaning the record bar with some alcohol and working the switch, but to no avail. Do you think switch cleaner would fare any better at this? 

P.S. Sorry if I sound a bit dumb about this sort of thing, I'm kind of a newbie to audio hardware, video game stuff is more where I'm experienced.

Don't worry you are not dumb at all. These things can be tricky! From looking at your pictures of the tape transport I would say you are probably right, the switches aren’t mounted on the deck. I would guess they are mounted on the main PCB behind the deck, probably not too far away from the big record play switch. This is a mechanical push button transport so pushing any of the buttons (with the exception of stop and pause) should activate the switch for the motor. I would guess that someone has taken this apart before and not put it back together correctly. If you don't line the mechanism up with switches on the PCB correctly when putting the machine back together, these things can get stuck in all sorts of odd states! Sorry to be a pain but I would like to see a photo of the main board. (The section of it that sits behind the mechanism) Cheers mate.

Sure thing! Here's a couple so you can see the whole board.

http://i.imgur.com/03ZDhgO.jpg

http://i.imgur.com/SEc8cki.jpg

As far as I can tell, the only switches seem to be the record bar and that leaf switch next to it, though. 

Well; at a guess (and it is only a guess) the leaf switch is the motor on off switch. It is open and the motor is still running!  I think we need the service manual now!

Hm, well I have tried pushing it together by hand while it's on, and nothing happens. Unless the switch needs to be replaced? 

You could try measuring across the switch to see if it has gone short circuit (Do you have a meter?) But I think this is unlikely.

Unfortunately I don't have a meter! Hm, I guess tracking down a manual's going to be fairly essential. 

Yep, afraid so. You can get a multi-meter that does Volts, ohms and amps from Halfords or Maplin for about £20. A really good invetment if you are going in for d.i.y. repairs on audio gear!

Well, I just tried soldering the two points that the switch connects directly on the board, and that didn't switch the motor off either, so I suppose that's not what this switch does. 

We need the service manual!

Well, might as well move on to the deck, then! Here's a picture of the main board:

http://i.imgur.com/lFrqee7.jpg

The issue is that when I hit record, the mechanism doesn't move at all. The record light doesn't come on, and nothing turns. Every other function works fine. 

Edit: I do have a link for the service manual for this, but it's not really helping me very much as I don't really know what I'm looking at. http://elektrotanya.com/harman...sm.pdf/download.html