Advice for mono cassette recorder restoration?

[gfuller]

Hello, everyone. I recently scored a vintage Rheem Califone AV80 mono cassette recorder on eBay, which I figured may make a good project if I can ever build up my confidence to actually restore it. I somehow lost my Sony pocket cassette recorder (not a Walkman, also just a cheap mono deck) a few years back, and I haven't had a functioning cassette recorder/player since. (As I mentioned in the "introductory" post about this machine on my blog, Rheem — who once owned Califone and actually had a much more diverse history than I was previously aware of — also manufactures HVAC equipment, one of my other "interests.")

After the deck arrived I bought some D cell batteries, popped them in and tried none other than the "A Guided Tour of Macintosh" cassette that accompanied the guide software for the early Macs. As the seller mentioned, the player started right up (despite some mechanical sounds) and played fine. However, fast forward and rewind don't work. There's also some rubbing sounds, although the tape seems to be running at approximately the right speed.

I've never (successfully) worked on a cassette player, but I'd like to restore this machine — clean and lubricate the parts to get it working like new, and getting fast forward and rewind working again. I'd also like to make sure it's electrically fine and safe. It also likely needs new belts, maybe a recap (?), and a good cleaning on the outside.

Opening the machine revealed a daunting amount of wires, belts and other parts. However, it seems more serviceable than my grandparent's Emerson boombox I attempted to fix once. (Cassette player had issues in it, opened it and got quickly overwhelmed and decided to call it quits before I messed anything up worse. I'm also worried about that in this case.) Plus, a quick google search yielded an electrical schematic and exploded parts diagram for the AV80.

If I can successfully restore this, I'd like to try to fix a family relic I received a few years back — another "worthless" mono cassette recorder/dictation machine, a Soundesign 7621. Although the Soundesign is in better cosmetic shape (outside of its deteriorated "leather" case), it doesn't work at all. It just destructively ate the tape I put in.

Any tips for properly fixing these old tape recorders without making a mess/making anything worse? Any advice would be greatly appreciated. I hope I'm not in over my head, as I'm racking my brain as to what some of these parts even are. (I see the AC transformer, which is actually on the opposite side from the AC line connector up in the top right on the first photo. I believe the main drive motor is to its right, with a pulley going straight to the capstan? I'm curious as to how fast forward and rewind work mechanically. So many questions.)

Photos of the AV80:

 

[lauland]

In my experience most issues are mechanical, since the electronics are analog, very simple, and were well made back in the day:
Clean pinch roller. Junk on it can cause it to not grab well enough. Rubber on roller can also deteriorate. (I've even seen melted ones).
Capstan pulley belt almost ALWAYS stretches with age and doesn't stick well enough to motor/capstan and needs replacing. Test with a good rubber band. (Not TOO tight, but really tight).

If it ffwd's and rewinds but doesn't play or plays wobbly it'd be one of the above.

The speed the tape goes past the head doesn't have to be regular/smooth, except during playback, so the motor always runs at "full speed". The capstan grabs the tape and regulates it.

If it plays but doesn't ffwd/rewind, it could be too much friction and need lube somewhere. While playing, pull the capstan roller back from the tape carefully, and see if the takeup reel is strong enough to still pull the tape. It might be only strong enough at the slower playback speed (where the capstan is doing most of the work). Depending on how the reel is connected to the motor, likely another belt, deteriorated rubber, or sticky wheel.

----

I used to make good money on the side during high school in another life, fixing people's walkmen. I found a good supply of high quality rubberbands/belts as 90% had just broken!

Most of the challenge was, of course, taking them apart, keeping track of all the screws/pieces, and getting them back together safely!

When everyone started going to CD I was NOT able to transfer a lot of my skills since things were so much tinier and the tolerance for mechanical things being not-quite-there were so much tighter...and of course the electronics being digital and surface mounted...although I did re-solder a ton of headphone jacks.

 

[gfuller]

Looking at the schematic, this thing is very basic — eight transistors in the entire thing. I wish I knew what year the AV80 was from, hopefully a date code or two can provide some clues. I don't even know if I'm the first person in this thing, as there's some electric tape around the wiring harness running throughout. The components are definitely from the '60s or '70s... I'm still trying to figure out what some things are. (For instance, the component marked "2L8K" near the volume potentiometer in the fourth-from-top image, and the round part with two wires marked "018" in the third-from-top image. I think the latter might be a diode since another one near it has a diode symbol, but I've never seen a diode look like that. I initially thought the former might be a resistor, but I don't even know if it has any electrical connections.)

Play works fine. I tested a music cassette today and it played real good, and a rough audio recording I took (placing my phone next to the speaker) revealed it seems to truly be playing at approximately the right speed.

The issue is there's no rewind or fast forward. I assume lubrication or some other mechanical issue (caused by time getting even with everything) was the culprit. As for the test to see if the takeup reel is strong enough, pull the capstan (right) side of the tape out as it's playing?

I'd like to flip out the circuit board but I'm worried a wire or something else might break off.

 

[lauland]

Yes, if you pull roller back from the capstan, it should continue playing, but the speed will be unregulated. It will be faster than normal, and wobbly. It has to be faster as it is taking up the tape, but not TOO fast or it'd put too much tension on the tape. It isn't a perfect test, because it isn't using the same mechanical config/path as ffwd/rwd, but it takes the strength of the capstan out of the equation.

Really stupid question I should've asked first: What does it do with no tape in it when you try ffwd/rwd? It's a different problem if the spindle/hubs don't spin at all, vs they seem to spin fine, but just aren't strong enough to pull the tape. If they aren't spinning, the two things I'd look for are a stuck gear, or a loose belt.

A loose belt is easy to find: While it is running, look at all the belts and the wheels at each end...if you find a wheel is spinning, but the belt isn't moving, you've got it. The opposite is when the belt moves, but a wheel it is connected to doesn't spin. Not enough friction.

If a belt is too tight (which almost never happens), while running, you should carefully stretch the belts, pulling them just off the wheels, on both ends, so they aren't touching them, one at a time. If you find a wheel that then starts spinning once the belt isn't touching it, it is very likely it should be able to pull the belt and spin the wheel on the other end when working normally. Too much friction. (I say "very likely" because sometimes things "just spin" for no reason, due to the way a design works, etc).

Looking again at the belt/wheel configuration, the capstan is two level, and the motor drives it at the top level (so you'll see the capstan still spins when ffwd/rwd'ing). The bottom level is smooth on the sides, and touches a smaller two level plastic wheel, which has rubber AROUND THE EDGE on the bottom. If that rubber shrank or lost it's stickiness, so the wheel doesn't spin, that may be your problem right there. That rubber will be harder to replace than a belt, as it has to be the exact size of the wheel unfortunately.

I wouldn't worry too much about solder joints failing, they were pretty solid/big in those days, and if a wire disconnects, easily fixed with an iron if you're inclined. Gently pulling the board up might reveal something obviously off, maybe even something touching something it shouldn't (ie it might work with the board unscrewed). Although it doesn't look like there's too much mechanical under the board from what I can see.

 

[gfuller]

Let me apologize: I had the capstan confused with the take-up reel. Now that I have a better idea of what everything is (at least in the tape deck mechanism itself), I think I see what you're saying. I'm guessing after pressing play with the tape door open I can just push the roller aside?

When I engage FF/rewind with no tape in, the spindles/take up reels don't rotate at all. I'll check the capstan, but I don't think it's moving either. The motor, however, is running when engaged. I haven't had a chance to test the machine with the cover removed. I tried to last night but the batteries won't stay in place without it removed so I might have to hack something together for testing.

It might very well be that the capstan lost that rubber. (Speaking of which, is the item circled in red in the photo below the inside of the capstan?) I know there was pieces of rubber and old tape just floating around inside.

Speaking of which, something (a small piece of tape perhaps, though it wasn't sticky?) may have came out of the machine after ejecting a tape earlier today. Afterward the audio became more muffled. I'll try to record it later (machine is at work again). Adjusting the tone control helps very briefly, but that control crackles a lot. (I'm guessing I'll need to give it a shot of DeoxIT later to hopefully clean it up.)

I'm almost certain now that I'm not the first person to be inside this machine. In addition to the electrical tape that I was unsure was 50-year-old factory original, I happened to find a bread tie that I believe is used to hold the wiring harness close to the circuit board. With that mentioned, I removed the three screws holding the board in and gently tried rocking out but had no luck... it didn't want to budge. I'm pretty sure those are the only screws holding it in place, but I didn't want to force anything and risk breaking something.

After replacing the screws and covers, I reinserted the four screws holding the back cover in place. Three of the four went in just fine, but for some odd reason the fourth keeps only going in crooked and sticking out.

I'm still trying to figure out what SW-05 is. There's clearly a diode icon on the component, but SW usually refers to a switch? I don't see a SW-05 on the schematic, but I see two diodes in the schematic on the secondary of that transformer. (The main AC line transformer.)

Lastly, another potential issue: The record button doesn't engage, or at least not without a tape in. Is that normal? Maybe my memory is fuzzy (haven't used a tape recorder in years) but the record button should engage the mechanism like it would in play, or am I missing something? lol

Thanks for the help. I wish there was someone local who could help me tackle this among other electronics projects, especially something fairly simple like this project.

 

[lauland]

The capstan is the large metal wheel, which has a tiny almost always pointy axel. They are "precision engineered", at least compared to the rest of the mechanics, to ensure smooth regulated speed. The pinch roller and heads move forwards on playback. The roller presses against the capstan axel. It looks like in your machine the capstan is driven directly from the motor and everything else is pulleys/wheels off of it. We know it is working (spinning correctly), since playback works.

I don't know the correct term for the wheel you circled in the picture, but I'd definitely check it. Doubly so since it has rubber along the edge, which is a worse case scenario for aging and hard to replace. I can't tell if/how it is involved in playback. But just by looking at it, I am suspicious of it.

I forgot to mention about belts/rubber: Before you replace them, you can just clean them, even just soapy water. Sometimes the tension is fine, but the rubber just has enough built up dirt/dust that they can't stick well enough. For that particular wheel that's the first thing I'd try since, unlike the belts, it has a small surface of contact.

If the audio is muffled, I'd check the play head is touching the tape enough. I can't imagine what might've fallen out that'd affect it and hopefully you figure it out!

For crackling knobs, you'll want to use "graphite cleaner". Just a tiny amount. Alternately sometimes if you just spin them all the way back and forth enough any built up cruft will get loose. This is if the crackling is due to oxidation which is very common. If, instead, it is because the knob was overused and wore a groove inside it, you'd need to replace it.

It looks like the board is tied down in addition to the screws from the 2nd picture. If you determine those really are just ties, you can probably cut or remove them to get the board loose.

It is extremely common when tinkering to not have a screw or two go back. Especially with old plastic, sometimes the screw hole/peg will deteriorate and give up the ghost as a screw is removed, friction and/or dust being the only thing that was holding it in.

My guess with the "diodes" is that they're really ancient tech...I've never seen any circular like that either, but the symbol is clear. They might've been a late addition to the design to stop current flowing back somewhere somehow and that's why they aren't on the schematic.

It is completely normal for the record button to not engage with no tape. The reason is how the "write protect" mechanism on tapes works. Because you poke that little bit of plastic out, there's a "sensor" finger switch that can't tell the difference between there being no tape vs one that is write protected.

 

[gfuller]

Today I did a little more disassembly. The circuit board finally came out. I don't see any date codes on components (haven't looked real close either) but they certainly look 50 years old. The circuit board traces were definitely laid out by hand. The caps don't look too bad, although that doesn't mean much.

I wonder what the switch in the middle of the circuit board does, as it's positioned under the tape deck. I see it on the board layout diagram in the schematic document, but I can't find the same component in the electrical schematic? I think it could be "SW1" with 10 connections (SW1-1 thru SW1-10 on the electrical schematic and S1-1 thru S1-10 on the board layout diagram), which looks correct on the solder mask side of the board.

I shot some video of it running in play, fast forward and rewind, with a tape in and without a tape. Removing the cover revealed that the belt spins normally in play, as to be expected. In fast forward, the belt spins a little but the pulleys seemed stiff. In rewind, the motor spins but the belt doesn't spin and nothing happens. (It also seems like the belt loosens when in rewind.) You can see that footage around the 5 minute (without a tape in) and 8 minute, 40 second (with a tape) marks in the following video:

I tried the pinch roller test you mentioned twice. The first, not recorded and using a music cassette tape, actually worked — using a pen cap I gently depressed the roller, and the tape started playing faster and at an uncontrolled rate. (On the Sony pocket player I had, it resembled the "effect" you'd get if you only partially engaged the mechanism.) I tried it a second time, while recording video and with the other/"Guided Tour of Macintosh" tape, and every time I pressed the roller the tape would completely stop. After a couple attempts, I started smelling a strong "mechanical" odor coming from the player. Then, I noticed a small puff of smoke coming from the rear of the tape compartment, which is approximately where the motor and most of the mechanical components are. hmm... I immediately shut the recorder off, pulled the batteries and opened it up. After making sure nothing looked out of place, I reinstalled the batteries — keeping the cover off — and pressed play with the tape still in. It played fine. Fast forward and rewind still don't work, but at least that faint, brief (thankfully) smoke show wasn't a magic smoke show.

Before I go much further I'd like to take some time and document the circuit board, see where all the wires and components go just in case I need to further disassemble the machine. There's a lot of wires, many more than the electrical schematic would lead you to believe. The electrical schematic doesn't have any wire colors listed, nor does the part diagram have a list of parts or tell you what anything is.

I also "fixed" the problematic screw, or at least I think I did. I just screwed it directly into the piece of chassis it mates up with, just without the cover on. Went in fine when after placing the cover on.

 

[lauland]

I've seen things like sw1 on tape recorders. It usually is what is used to switch between playback and record modes, hence it needs to swap several parts of the circuit around. If that's what it is, you'll want to be sure the switch gets in just the right place when you put the board back. You could verify that is what it does by trying to record something, while the board is loose so the switch isn't moved...it'll end up erasing the tape since the erase head is engaged, but not record anything (since the circuit is trying to play!)

Oh man! The dreaded puff of smoke! I'm SO glad it survived! (Though probably took a few years off its very long life!). I should have warned you first thing, if something is "stuck", NEVER leave it running more than the minimum you need to for testing! The capstan is (was) doing the lion's share, and when disengaged via the pinch roller, the take up reel mechanism is far too weak/sticky to consistently pull the tape, causing a jam.

Your main belt looks BAD in the video, it is far too loose, it should be butter smooth and never flop around or shudder. The end around the motor visibly bows to one side (or the other) at times, showing it is pulling as hard as it can on the belt, causing slack to one side and tension on the other. It should never be slack, as smooth as the other belt(s), and both sides always have the very close tension. Probably so tight you can tweak it like a guitar string (although that can vary on different recorders...not ludicrously tight!)

So you need to replace the main belt, but that might not necessarily fix everything. It's possible a jam/sticking elsewhere caused it to put too much tension on the belt and it stretched to try and compensate. So it may be effect and not cause.

At around 6:17ish you can see one of the wheels spin a little and then stop. A definite clue. If something spins, it should always spin.

I cringed when I saw the belt flip at 6:38ish!

If you replace the belt, be extra super careful testing further if it doesn't "just fix everything". With a tighter belt you'll have a LOT more tension on everything, and much more potential for smoke! When you do, if ffwd/rwd still don't work, never EVER leave them depressed more than a few seconds at a time.

You can try different various rubber bands and might be able to get away with being "too tight", which, if everything was working, is far better than too loose. This is NOT a long term fix, as rubber bands will deteriorate relatively quickly under then kind of strain the motor will put on it...but will give you an idea. (Obviously they also stretch which a real belt will only do a bit) If it's just the belt you can probably salvage one from some other equipment you'd sacrifice, but it may be tricky finding the right size. Again, tight is better than loose.

 

[gfuller]

I shut the player off as soon as I saw the smoke. It was in play mode, but I was pushing down on the pinch roller when it started smelling funny and the smoke puffed up. As mentioned, I tried the same test with a different cassette and it did what you described.

I was suspicious of the belt since it was real loose. I didn't notice it flip, but I did notice it lagging. I'll try replacing with a rubber band.

Is it possible to spin the pulleys with the play mode engaged without the batteries installed, just to see if anything is obviously stuck or needs lubrication?

What lubricant(s) should I use?

 

[lauland]

You can definitely spin things while it is off (and play engaged) with your fingers, but, unless you know what should and shouldn't be moving, and how, it won't tell you TOO much. That said, you can definitely try and reproduce what the motor does while running, ie make it "go through the motions". One issue with that is you can never reproduce the speed the motor runs with fingers, so everything will be moving much slower than normal, and thus harder to see.

As far as lubes, WD40 is only good for initial and temporarily checking if something else would help (as it isn't really a lube). I'm hoping your issue may just be the belt. If you end up needing to lube something, I don't know any specific brands, but pretty much anything will do.

 

[gfuller]

I haven't had the machine open since last Wednesday, but looking at the pictures has me wondering: How do I even remove the belt? I thought there might be a screw on top to remove the metal bracket, allowing me to replace the belt, but it's not?

Unfortunately the electrical schematic and exploded parts diagram (without the legend/index to tell you what everything is) is all I've found on this model. Are there any cassette player forums out there that might be able to guide me in the right direction for figuring out how to properly replace the belt. Next time I open the machine I plan to start diagraming where everything goes to the best of my ability, especially with the various wires going everywhere on the circuit board. (Everything is soldered, so hopefully nothing electrical needs attention... though I wouldn't mind getting some soldering experience.)

I have some lubricant from a few years back when I intended to clean/lube the 800k drive in my SuperSE. I wonder if the "SuperLube" would be good for this application.

 

[lauland]

Isn't that a screw on top of the capstan bracket? I'm hoping so. It looks like it might not let you remove the capstan or the bracket, but might allow a gap to slip the belt off.

If not, chances are the bracket'd need to be removed to get it out...and that'd probably need semi-major disassembly...

One semi-crazy idea you might try, because I really do think the belt is the problem, is to very gently see if a hair dryer could tighten up the belt with some careful application. This probably'd be only a temporary solution as it'd likely go back to being too slack when it cooled down, but you never know. I think without replacing the belt, you'll be stuck so it's worth a try?

 

[gfuller]

Removed that teeny, tiny screw on top of the capstan bracket but didn't have enough clearance to slide the old belt out. So it looks like I'll probably need further disassembly, which might've been necessary anyways. On the plus side, I didn't manage to lose that tiny screw, which I'll take as a win. (Usually stuff like that slips through my fat fingers at the first chance it gets. lol)

Problem now is I don't know how to properly further disassemble this thing without damaging anything.

Unfortunately I don't have a hair dryer here. But I agree, that belt is likely a big part of the problems here. It's very loose, and even seemed to flip around in play (despite still seeming to play at a somewhat normal speed.)

 

[gfuller]

I've continued the discussion on Reddit: https://www.reddit.com/r/cassetteculture/comments/1barvk3
Today I removed the cover yet again and tried removing the belt. After removing the screw again, I found a way to get the existing belt out. I replaced it with a rubber band I found. It still played with the rubber band, although a lot slower. (The only bands I could find were smaller than the belt.) Fast forward and rewind still don't work. I reinstalled the existing belt, since it still plays with it. (After reinstalling that tiny capstan screw, it started not playing unless I manually spun the capstan enough to get it going. However, I believe I overtightened that screw since it played fine after loosening it a little bit.)

I still need to find a belt for this thing, along with figuring out what is going on with FF/rewind.

 

[lauland]

Dang! I was REALLY hoping a rubber band would help more. I've had a lot of luck with them in the past. It's possible a different size will work better...but I'm having my doubts.

One reason it'd play slower may be the rubber band is too tight...but I'm really only guessing...you might as well try different sizes and see if there's any difference...even if you don't find just the right one you'll have more data points, right?

The fact that the rubber band didn't help at all with ffwd/rwd is a real puzzle...because my theory, obviously, of what was going wrong was just (or very primarily) the belt. So, either there's something ELSE additional going on...or, just maybe, a different rubber band...maybe?

FYI Rubber bands are MEANT to stretch, and the kind of belt you need is definitely not supposed to, so it was going to be a poor replacement at best anyway. But it's not going to be easy to find anything better.

 

[gfuller]

Next time I have the belt removed I'll try to measure it. Unfortunately there are no parts lists or specs that would tell me what size of belt I'd need to replace it with.

With the cover removed recently, I did a little work on tracing wires to see which is which, and labeling the wiring diagram accordingly. (The diagram has no wire colors listed.) It's a little difficult since the density of components on the circuit board make it difficult to see where the wire connects, and find the correct lead on the solder mask side of the board. I've been using the continuity feature on the multimeter to ensure I have the correct wire, although some connect. (Electrically, it seems this player is fine, but figured it wouldn't hurt to label the wire colors on the schematic for future reference.) While inside I also learned more about how the mechanism works electrically.

I recently got a SoundBlaster PLAY! 3 sound card to record audio from the AV80. It doesn't sound bad, and playback sounds far better than the cheap Sony pocket recorder I had a while back. I went ahead and digitized my "A Guide to Macintosh" tape using the AV80 and PLAY! ADC.

Unfortunately still no insight into what might be causing fast forward/rewind to not work.

 

[lauland]

Hey, completely unrelated, but your signature mentions you have an accelerated Mac SE. I ported a game just for machines like that and was wondering if you'd be willing to test it. I'm 99% sure it'll run:

https://macintoshgarden.org/games/arashi

Grab "arashi_110_bw.img" and look in "arashi source"/"Game Source". There are 4 apps. I think the only one that'll run without color quickdraw in rom is "Arashi 1.1.0bw_nocqd". I've tested it on my Amiga with AMax (which emulates a MacPlus), with an '020, an '030 and no accelerator.

If you get a chance...let me know if it runs, and if so, how playable it is...if you don't have time, no worries!

 

[gfuller]

Just tried Arashi, using the "Arashi 1.1.0bw_nocqd" file. The setup menu and instructions worked, but when I tried to start the game it immediately crashed, forcing a manual reset. This particular machine does this quite often with software, often first launching programs. I'm assuming it probably has to do with software not liking the Mobius accelerator(?) It can be real finicky, and doesn't like System 7.

As for the Califone, I discovered (and digitized) another tape in my grandfather's basement. This tape had a lot of blank space for me to experiment with, so I connected the Rheem 3818 microphone I got to pair with it and inserted Side B of the tape, which was completely blank.

Pressed record and nothing happened. The motor didn't even run, unlike with FF/rewind. That'd odd, since I'd think it'd be like play but the switch on the circuit board would be flipped, just reversing its circuitry to activate the erase head and write to the tape instead of read. It's kind of a bummer, but at least I can still listen to tapes. :/

While inside the player last time, I noticed the contacts for play(? - not listed on electrical schematic)/fast forward/rewind. I wonder if I should shoot them with DeoxIT. Obviously still need to find a belt. Hopefully next time I have the cover off I can remove the belt and use a ruler to measure its diameter to help track down a replacement.

Wish I was more knowledgeable, since it'd probably be best to disassemble this player for a proper cleaning and lubrication after 50+ years. (Though I know most wouldn't bother wasting time or money on it.) Problem is reassembling it and making sure it not only still works, but FF/rewind/play work. I'm still curious about some components, such as this coil that I don't see referenced on the circuit board schematic. Because it's outside my limited scope of electronics knowledge, I'm also curious of the thermistor's (I believe the small white part to the left of the bottom transistor) purpose in these old tape players. I noticed the Soundesign (which oddly lists all of its components on its rear cover) also contains a thermistor. What does it do? I'm also curious of these old players have an "auto-stop" I don't know about, or if it'd just continue to run regardless. (Don't have a tape willing to ruin to test with, and don't want to potentially further damage the player.)

Thanks for all your help so far, and sorry about the bad news regarding the game. :/