Let's start with some pictures Front Top Nothing on this end But on the other end we got a lot of stuff going on and some very basic instructions On the bottom there's a sticker That says: licensed by Thomas international corporation, USA Let's got a close-up of the battery compartment And now the other side of the back close up That should do it. The next grouping will be opening this up. Edit. Try taking the screws out and only one came out. One pylon is broken and one is missing in the battery compartment and I think that the power supply is plugged in by two wires and then there's two wires for the antenna. Let's get some pictures The gray and red wires coming from the power supply go to a plug that's near the center of this picture An antenna wires plug in here Inside the back cover Now we have a broken pylon and the screwdriver is pointing to the missing pylon for where the battery screw would go if it had one which it didn't.
The top picture here is the m7850k the one I'm taking apart. The one underneath where you can see the front speakers and then the chassis is the Sanyo m7900k as I'm using it for reference So what I'm learning is by having the other model to release the chassis from the front of the radio after removing all the knobs on the front. If I unscrew these three screws that I'm using the magic magnetic wands to point to the three screws that I need to remove I've got a close up As I said in my video, this definitely needs belts so here's a picture before I take it out of the chassis Another thing I'm learning is. While I think it's possible to remove the cassette deck from the front without removing the radio back after I had a chassis out, I still need to remove one screw from the circuit board near the motor on the back chassis and it is here. Let me get a close up 1 screw you'll need to remove is underneath all those wires that I'm pointing to with the magic magnetic wand. Again, it is helpful to have the 7900k already apart to understand how to take apart the 7850 Well, I took out those three screws but that didn't release the chassis from the front of the radio. And as I'm poking around I'm seeing two more screws that look like they have arrows pointing to them. Whereas the rest of the screws on the circuit board do not have arrows on them. So I'm guessing as I'm using my little magic magnetic pointers do, but those are the ones that will help to release the chassis from the front to the radio now that I've removed all the knobs and hopefully these two more screws Hopefully if I unscrew these two screws and unplug the microphones and the speakers from The left side or the where they're at and then I should be able to release the front of the unit from the chassis. Well, I just took out the two screws that I mentioned with the arrows to them and earlier I mentioned about a screw near the motor. Well now it seems that that has an arrow to it as well, but it was hidden behind all kinds of wires going to everywhere and unplugged three plugs including the microphones and speakers and move them out of the way and then finally got down to where this little white arrow is near the motor which is seemingly the only thing holding the chassis still to the front of the radio. So let's get a picture of that I took this picture three times and it kept rotating to the right. I don't understand but that's what I'm pointing to is the hopefully the last screw or to unscrew to release the chassis from the front of the radio and. Here we go. Almost once I unscrewed that screw but now I have to unclip these wires and then somehow give it some more length to the wires so I can somehow release the connection to the amss which is the music search function switch from the inside and let me point you those wires And once releasing all that and untangling some of it I was able to release it and now have it precariously standing. So I should be able to undo the two screws That is holding a switch to the front of the radio and then remove the chassis. Yay Let's do that now Finally, geez. Now we got to clear all the tools put away all these screws and take these two screws for the switch and put them back in the original hose that came out of because they're different so I don't lose them and then clear off my area. Get rid of the front cover and then put the chassis down. Let's start working on removing the old tarry belts from the cassette deck cuz I've been getting black all over my fingers and having to wipe that off every few seconds.
So I removed four screws from the tape deck and three screws from the potentiometer board and fluffed it over and then it was able to flop over the cassette deck Now let's look at the tape deck Well I'm going to have to remove the flywheel to see how many levels of belts there are Just two screws holding the flywheel on Okay, two screws The first screw was on really tight but I didn't strip it, but this screw must have been put on with impact because I could not get it off using My JIS screwdrivers, it would not come off until I finally nearly rounded off the head of this tiny little screw and finally had to use vice grips to finally finally get it to unscrew. Unbelievable. I couldn't believe I had to stand up and exert an incredible amount of force and it still wouldn't budge until I finally used those grips and then it came loose. I finally got the flywheel off More idler tires I Hope I do not need to replace them cuz I don't think I have any of that size maybe. But it's too much work to get to this point to know if I need them.
Well I got the flywheel out and now I'm cleaning the tar off of it and I'm not spinning it but I'm holding it with this and just so you know, I have a fan blowing on me that's why the paper is holding up like that Yes I got to stay cool Edit now a little bit later I'm cleaning the motor and to remove the motor. It's held on by two bolts and those are 5.5 mm head nuts so you'll need that wrench or something very small to take those off with. Here's a picture Always best to use the right tool. That little drawer in front of me is the small dipping container of denatured alcohol. For my q-tips to dip into to clean with.
Well the motor and flywheeler now finally clean again. Next thing you go do is find what size belts this thing takes. Going to replace three the motor belt. The the rewind belt which is operated by an idler tire and then a belt and then the counter belt which was driven by well. I don't know what it's drivin by, but I'll show you a picture Cleaned finally and now the rewind and counter belt are driven by or on this same shaft Yes that's the rewind now. The fast forward is this other idler tire which is driven off of the flywheel and then touches on the white wheel, which is also the take-up reel. Here's a picture Now the thing that I like about this particular cassette deck is that the take-up reel is gear driven and uses a cloth clutch. So it goes from the belt driven from the motor to the flywheel and then underneath the flywheel is a little tiny gear which then drives a larger white gear underneath which then directly drives the take-up reel which is the larger white gear. I like this arrangement because it's positive that the take-up reel is always going to run because it's gear dripping through a cloth clutch. Here's a picture This is like an underside view. If the parts were in place, it wouldn't look like this and you wouldn't be able to see this little gear under the flywheel that turns the well. Let me flip the phone around and take a picture from the other direction. Maybe it looks better and you can see where the motor mounts cuz I'm not mounting the motor right this minute But I need to mount the motor back so I can measure what size belt this thing takes. And also the other very tiny little belts which goes underneath the idler tire. Well you can see that maybe
Okay I mounted the motor and I put some lube on the capstan flywheel now I'm measuring for belts so I put a 105 mm or close to 4 in is the main belt and the secondary belt is about a 40 mm belt. Here's a picture The secondary belts is this tiny little thing for the rewind I almost forgot the counter belt. It's about 70 mm Got belts Now I just got to find that 70 mm counter belt and put it on first and then put on the rewind 40 mm belt or 38 mm.
And of course the rewind idler tire is broken. I didn't break it. It was already broken. It was just sitting there dried up. It broken two places Once again I got out all my belts and in this package of an assortment that I bought from somebody off of eBay a long time ago I got one item that will fit. Yay! The package I'm pointing to but I hope he still sells this has. It's helped me out three times now.
This is rewind mode with the button depressed on the front without the tire in place. Just to show you how close it needs to be the tire that is Now let me put the tire on. Okay tire is on. All the belts are on and now we got to go and start putting this back together. Probably finish this Monday. This is a tedious little Sanyo like most sanyo's are tedious.
Okay, now I'm installing new belts in the m7900k and the m7850k is in the background for reference and here's a picture. If you've taken apart the radio this way you're doing it wrong because you don't need to take apart the radio this way. But since I'm already here, I might as well change the belts out rather than taking the cassette deck off the front and leaving the radio connected or the main boards which are two pieces and connect together with straight pins. So I'm going to have to find a bunch of screws install the radio onto the black chassis after I get the belts put back in new approximately 105 mm for the main belt and I think 40 mm for the secondary belt and 65 or 70 mm for the counter belt
Finally had time to get back to this to replace motor which has a dead spot as it does work but it won't start on its own. Once again I have to. Thank Nick Eccles for sending me these motors well over 10 years ago. I don't know if he remembers doing that for me. Thanks very much. I'm just now getting to it. Now I've made two solder connections using my helping hands. Here's a picture Now I just got to slide those shrink tubing over that and shrink them and then put this all back together.
Well I've already cleaned one set of speakers and now I'm cleaning the other set of speakers. I just hope I don't get these mixed up because the guts are similar but the outsides are different as far as the model number to go, but here's a picture Yesterday I went looking for screws and that took a long time because these screws are very specific as to their pitch and length. They're basically 1 in but have a different pitch as opposed to wood screws or metal screws or any other screws that are common present day. They just different And then my last little problem will be finding all of the knobs that go to the front of the 7900 because they were not kept together.
