nightcustard

I was asked a few days ago to help a prospective buyer by suggesting a few questions to ask sellers of the ADF770. Here's my response, which will hopefully be of interest:Questions and considerationsI suppose it's stating the obvious but the big issues with the 770 are its age and lack of spares. I bought mine over 42 years ago and it staggers me it's still playable. I only have the one deck so I can only advise regarding what's gone wrong with mine. The drive belts needed replacing, the bearings of the capstan rollers needed cleaning and lubricating and the tape FF/REW idler wheel tyre had hardened and needed fettling. The tape transport path needed cleaning and I also realigned the tape heads. I considered demagnetising the rec/replay head but decided against it as it sounded OK (I did…

I was asked a few days ago to help a prospective buyer by suggesting a few questions to ask sellers of the ADF770. Here's my response, which will hopefully be of interest:Questions and considerationsI suppose it's stating the obvious but the big issues with the 770 are its age and lack of spares. I bought mine over 42 years ago and it staggers me it's still playable. I only have the one deck so I can only advise regarding what's gone wrong with mine. The drive belts needed replacing, the bearings of the capstan rollers needed cleaning and lubricating and the tape FF/REW idler wheel tyre had hardened and needed fettling. The tape transport path needed cleaning and I also realigned the tape heads. I considered demagnetising the rec/replay head but decided against it as it sounded OK (I didn't want to disconnect the heads electrically which is normally required when demagnetising). I also checked the capstan motor speed. I don't have any test equipment for measuring wow & flutter, so I had to rely on my hearing but thankfully it sounds good in that regard.Electronically, I haven't had a failure, other than a burnt-out fuse resistor I caused myself when being sloppy with my test leads(!) and I've not seen any issues with dry electrolytic capacitors. That's for a deck which has not been abused and stored in a reasonably dry, benign environment.Considering a deck with unknown history, you can reasonably expect to have to do the above as a minimum. Mechanically, you could also be faced with electrically noisy switches, broken push buttons, worn tape heads, seized motors, eccentric capstan rollers, stiff bearings etc. Electrically, as the internal wiring resembles an explosion in a spaghetti factory, I imagine there's the possibility of snapped or trapped wires caused by previous repair attempts as well as circuit failures caused by damp and/or old age etc.I think your options are limited when it comes to what you could reasonably do when faced with combinations of the above. The big issue is the lack of any spares. Even if you're lucky and acquire another 770 as a sacrificial spare, it's likely most of the rubber parts you'll need are unusable on both decks, due to age. Fortunately you can still source the drive belts. I've not (as yet) found a source for capstan roller tyres. The new idler wheel tyre I bought (advertised for the 770) was larger than the original and jammed the mechanism. I ended up treating the original tyre with platen cleaner and weakening a spring on the one of the spools (the feed spool, I think). This has worked to date. My takeaway experience is definitely 'caveat emptor' and be prepared for disappointment!Electronically, there are no surface mount components (of course), so all the discrete parts, such as transistors, diodes, resistors etc. are probably replaceable with modern parts. The display and ICs are a different matter - they appear to be custom parts for ADF decks and I think the only spares these days would be ones you can salvage from another deck.In the light of the above, what questions should you be asking a seller? Well, you can probably formulate your own after reading the above but I would definitely want to know: How many owners has the deck had? How's it been stored? When was it last used? Did it work fully on that occasion and if not, in detail what didn't work? What hasn't been tested? Is the deck a 110v or 240v ac version? Has it ever been repaired? If so, is there any accompanying paperwork? Is there more than one deck on offer?I'd be very wary about paying top dollar for a deck that hadn't been fully tested and available with a warranty, although I'd be very surprised if such a deck existed!If you're keen on tape decks, please don't let me put you off - I've focussed on the negatives for obvious reasons. I still occasionally listen to some of my old recordings and it's always a joy*!* tempered by having to keep half an eye on the take up spool function to avoid tape jams!!

Thank you!

Hi It's actually 7 screws you'll have to undo to remove that access panel. That will only give you access to the underside of the switch board but hopefully you'll see how to access the top part from there (I've not disassembled that part, so I can't advise from experience). With a bit of luck, you'll find some debris is fouling the switches. If you're unlucky (and more likely), the lack of movement will be because the switch underneath the button is jammed. They look like fairly common switches though and if you've got an old VCR or similar up in an attic, you should have some to harvest and reuse as replacements. I haven't opened the .mov file as I'm a bit paranoid about downloads - is there a YouTube link or similar?.

Good to see you found the reason the Monitor button doesn't work as it should. I'm not sure what adhesive to use as I think it's a type of plastic hard to glue. In your shoes, I'd probably try epoxy and maybe use a small metal dowel drilled longitudinally to give it some strength.Can you describe the sticky 'Play' button issue? Is it hard to press? Does it stick down after you've pressed it?The cassette drawer eject is damped with a small friction mechanism near the hinge (see photo). It's very likely the cause of the sticking drawer is due to the damper being dirty/misaligned or damaged. Either that of there's something fouling the hinges. I would suggest ignoring the first part of my Instructable and follow the second part, where I remove the transport assembly from the case. You'll…

Good to see you found the reason the Monitor button doesn't work as it should. I'm not sure what adhesive to use as I think it's a type of plastic hard to glue. In your shoes, I'd probably try epoxy and maybe use a small metal dowel drilled longitudinally to give it some strength.Can you describe the sticky 'Play' button issue? Is it hard to press? Does it stick down after you've pressed it?The cassette drawer eject is damped with a small friction mechanism near the hinge (see photo). It's very likely the cause of the sticking drawer is due to the damper being dirty/misaligned or damaged. Either that of there's something fouling the hinges. I would suggest ignoring the first part of my Instructable and follow the second part, where I remove the transport assembly from the case. You'll then have access to all the moving parts. Just be very careful not to break or trap any wires when reassembling (it's easily done) and don't use force - the mechanism will go back in without difficulty when offered correctly!Most faults you'll find with a machine this old will be mechanical. I've been lucky (so far) that I've not had any circuitry to fix (apart from a resistor I burned out through sloppiness on my part). All the electrolytic caps on mine appear to be OK (which are the most likely components to suffer through old age) and I'm glad to hear yours too appear OK.

Hi Ed! I'll help if I can. Best to sort out the belts first, then see what else doesn't work. Like I said before, I'd be surprised if the belt repair fixes the non-working tape counter display. I'll be happy to take some photos for you of mine - looking at the wiring you mention, for example. Cheers and good luck! Mike

Hi Ed! I should have read your original post more carefully! I didn't notice the tape counter wasn't illuminated on my deck when the belts were broken, but that doesn't mean it wasn't. I think the most likely cause though is a fault in the circuitry driving that part of the display, which could be simple to fix or in the worst case, irreparable due to the lack of spares. It's possible, however, the display doesn't illuminate because the reel movement sensor isn't providing pulses to the display driver circuit on power-up (I don't think this is very likely though). I suppose the usual process applies - fix the faults you know about (ie) the belts and then see what's left. I'll help if I can!

Hi Ed - good luck with the investigation. Maybe it's a language thing and I misunderstood what you originally said but if the counter section isn't illuminated, that won't be fixed by a change of belts. An illuminated but stuck at 0000 counter would be (most likely).

I've not played with the counter part of the 770 but I'm pretty sure the counter is fed from pulses output from the take-up reel, so if the belts are inoperative, the counter would definitely not increment.Good luck!

Thanks Steve - 3-12 possibly? 3-13 is the cassette sensor lever. I've checked the 3-12 steel balls - they're 2mm diameter and in place. The ball I found is more like 1mm diameter. I can't find it in the parts listing though. It could of course be part of a smaller sub-assembly that's not broken down any further in the parts listing. However, knowing my 'workshop', it possibly could have migrated from outside, so I won't lose any sleep over it unless something starts misbehaving.The good news is I've found the circuit board issue - one of the fused resistors - R913 - supplying -16v to the -5v regulator transistor - had gone open circuit. No -5v supply, no response to the cassette sensor switch. I haven't done a proper check yet that nothing else has been affected but it's looking goo…

Thanks Steve - 3-12 possibly? 3-13 is the cassette sensor lever. I've checked the 3-12 steel balls - they're 2mm diameter and in place. The ball I found is more like 1mm diameter. I can't find it in the parts listing though. It could of course be part of a smaller sub-assembly that's not broken down any further in the parts listing. However, knowing my 'workshop', it possibly could have migrated from outside, so I won't lose any sleep over it unless something starts misbehaving.The good news is I've found the circuit board issue - one of the fused resistors - R913 - supplying -16v to the -5v regulator transistor - had gone open circuit. No -5v supply, no response to the cassette sensor switch. I haven't done a proper check yet that nothing else has been affected but it's looking good at the moment :-)) Many thanks again for your invaluable help (and the photo booth is again open for business)!

Was the video any use? I noticed that with power removed, you can push the head assembly to its engaged position with your fingers. A spring returns it to its rest position. It may help your troubleshooting the presumed foul.

It's my Instructables username at a well-known search engine provider and Android purveyor beginning with a 'G'. I will delete this comment shortly(!) Grateful thanks.

Right - my 770 is in bits again(!). Here is a vid of the mechanism moving up and down when hitting play and stop. I've bridged the 'tape present' microswitch in case you're wondering....Hopefully something will suggest itself!Please let me know if you want any particular views. Incidentally, and rather worryingly, I found a small ball bearing underneath the tape drive when I removed it. I've no idea where it has come from - the two ball bearings on the capstan flywheels are bigger and still in place, so I'm going to have to have a good look around. Does your exploded parts diagram show many ball bearings? I can measure this one but off hand it looks to be about 1mm diameter. Is there a ball bearing in the door damper mechanism?

Disaster! Sorry to report Steve that while testing a thin plume of smoke emerged from the power supply area of the board and now the logic controlling the tape mechanism no longer functions. So, I can no longer be of much help regarding practical demonstrations and I have need of a circuit diagram!Where did you get your manual from and does it include a circuit diagram and component placement diagram? Of course, the circuit board layout and wiring is a complete mess and none of the components are marked on the boards, so working out what does what is doubly difficult. I'm really annoyed with myself for being so sloppy and rushing the job :-((

Disaster! Sorry to report Steve that while testing a thin plume of smoke emerged from the power supply area of the board and now the logic controlling the tape mechanism no longer functions. So, I can no longer be of much help regarding practical demonstrations and I have need of a circuit diagram!Where did you get your manual from and does it include a circuit diagram and component placement diagram?Of course, the circuit board layout and wiring is a complete mess and none of the components are marked on the boards, so working out what does what is doubly difficult. I'm really annoyed with myself for being so sloppy and rushing the job :-((

Hi Steve, thanks for the video. I would focus on the feed pinch roller. It should engage with the feed capstan and it looks like it's trying to (it appears to move slowly towards the capstan before the auto stop kicks in). The take up sprocket (near your thumb) should also start turning. I would look for a foul or an incorrectly positioned spring on or near the feed capstan roller assembly. If I can find some quiet time, I'll take my machine apart and we can compare photos. I'll keep you posted. Good luck! Mike

The LED flash is normal - mine does that. When I press 'play', both pinch rollers engage and the heads pop up and stay that way until 'stop' is pressed. The behaviour you're getting looks like a mechanical issue (a foul) as the electrical side sounds like it's responding as it should. You could look at the pinch wheels/head engage mechanism to see how the pinch wheels can engage but not the heads - I can't remember how these parts are coupled to the actuator, so I can't be much help currently. However, I'm due to strip mine down again to fit a new idler wheel tyre I bought recently on eBay and I'll have a look at the mechanism then to see if anything suggests itself. Please let me know how you get on.

That should be the feed spool tensioning. I presume with the contact still pressed, pressing 'play' doesn't do anything. Any clicks etc?

What happens when you power the machine up without a tape in and you press the microswitch in the top right hand corner? The feed spool should rotate clockwise for 1 second or so and the Tape Type light should illuminate.

I presume you saw my last post with a photo of where the spring end goes? You might well be able to nudge it into position from the outside but if I were doing the job, I'd accept my lot and strip the mechanism down - there are too many bits of irreplaceable hardware nearby just awaiting a loose jab with a pair of pliers or screwdriver!

It's not an easy view to get with the mechanism in place but I hope you can see the end of the spring in your photo should be as shown in this one.

It's not been easy to get a good view of the spring in-situ without stripping the mechanism out and it's defeated my photographic skills! However, the end of the spring that's sticking up in yours should be tucked behind the pinch wheel shaft, as shown in this photo.

That's your foul - I'll send a pic of mine this afternoon 😁

That's your foul :-). Here's what mine looks like.

You're no doubt correct - I started the job anticipating only having to change the belts and wanted to disrupt as little as I could in the process. As it turned out, it probably would have been better doing what you did. Good for future reference!

I haven't experienced what you describe. Does the door close properly without a tape in? From the way you've worded your question, I suppose it does. That would eliminate a simple mechanical misalignment. There's a little lever at the top right hand (as you look at the deck - see photo) which if gently pushed upward simulates a tape in position. With the deck powered, push the lever up and keep it there. You should hear a click from the mechanism and you can now select play, rewind etc. so you can confirm it's not in any odd 'mode'. If you're able to confirm that, then it's mark one eyeball time - looking for anything which might be fouling the door mechanism. Good luck!

The left hand pinch roller was pretty easy to remove (it's documented in the Instructable) and it certainly wasn't riveted in place - I suppose the other one will be similar. Mine were in reasonably good shape so didn't need replacing - hopefully yours will be likewise. The black goop is not nice stuff to get on your hands or anywhere else for that matter - be careful! As for the idler wheel, I think I'll have to investigate rubber reconditioning.... Good Luck with your deck!

Hi! Thanks for your comments and glad to hear another couple of these lovely machines might have a few more years of life. Since I wrote the tutorial, the idler wheel on my machine has started to play up again - it looks like a replacement is needed. Either that (which is probably a forlorn hope) or some way of rejuvenating the rubber is needed - any thoughts?

Hi Penolopy - thanks for your nice comment. I'll take some more photos and add them to the Instructable. Please let me know if you need anything else 😁

Yes, UK 😁. The speed change may be belt related so give them some use before making adjustments. More likely is speed control circuit component ageing though bearing lubrication loss may also be a factor given the motor was manufactured around 35 years ago. The latter would probably show up as wow or flutter. Good luck!

Hi! Thanks for your nice comment - it's always pleasant to get positive feedback :-)Unfortunately I can't answer your question directly as I don't have a copy of the service manual (and - horrors of horrors!) I didn't check/adjust the speed post repair other than doing a listening test. However, I believe a free copy can be had here: http://www.hifi-manuals.com/Aiwa/ADF-770/downloads but as this requires a sign-up I haven't done it myself (and I can't confirm or not whether you get bombarded with spam as a result). Alternatively, at least one of the comments below mentions adjusting the speed, so you might like to try asking the author. That said, it's almost certain the speed adjustment is built in to the motor - tape decks of this vintage often used motors with a small speed adjustme…

Hi! Thanks for your nice comment - it's always pleasant to get positive feedback :-)Unfortunately I can't answer your question directly as I don't have a copy of the service manual (and - horrors of horrors!) I didn't check/adjust the speed post repair other than doing a listening test. However, I believe a free copy can be had here: http://www.hifi-manuals.com/Aiwa/ADF-770/downloads but as this requires a sign-up I haven't done it myself (and I can't confirm or not whether you get bombarded with spam as a result). Alternatively, at least one of the comments below mentions adjusting the speed, so you might like to try asking the author. That said, it's almost certain the speed adjustment is built in to the motor - tape decks of this vintage often used motors with a small speed adjustment pot accessible at the rear of the motor (in fact, I've just checked the photos of my repair and there is a hole at the rear of the motor opposite the connections). Please proceed with caution though, and make sure any adjustment you make is reversible!

Hi - here's the photo of the back of my motor showing the hole. Hope it's of use. Regards Mike

Thanks Dave - ...and I've only just seen your comment! Glad you liked the design and I'm pleased to be able to say it's still in operation and has worked flawlessly from day one. Unfortunately, the lockdown has so far this year curtailed my car use (as has the new dog but that's another story!). Cheers :-))

Thanks Dave! I'm really pleased with it myself - one of my better efforts! Good luck with yours :-))

The Steampunked result looks really good and is food for thought....many thanks for presenting this 😁

Hi BJ and thanks for your comment - it's always pleasant to hear from a fellow enthusiast and it's very rewarding to hear one of my Instructables (which, if truth be told, can often take just as long if not longer to put together than the task it's describing!) is appreciated. Since I wrote the 770 piece we acquired ourselves a lovely* but time-consuming border terrier - I consequently have a number of unfinished or even unstarted Instructables awaiting a possible future time when the BT is able to entertain himself without getting himself into trouble ;-) Cheers, Mike* except when he's not.

Hi DimitriThanks for your kind comment - thankfully I didn't have to replace the pinch rollers but just cleaned them. I haven't researched where you could buy replacements so can't help with any first hand knowledge - sorry!Mike

Hi Steve - thanks for your comment.In comparison with modern electronics those Aiwa decks are a real rat's nest but it's good to hear there are easier ones to work on.There are a few websites where I found the belt dimensions but I've struggled to find them again - however, my Instructable has a link to where I got my belts from (a quick check today shows the belts are still available). The deck has been working fine since I fitted them. Incidentally, I found a website with the service manual and specs for the AD-F810 if you're interested - https://www.hifiengine.com/manual_library/aiwa/ad-... and here's a discussion about AD-F770 idler wheels - http://www.tapeheads.net/showthread.php?s=54c64ac7...Best of luck!Mike

You're welcome and thanks for the feedback. I hadn't considered the non-scratch 'feature' but I can see its merits!I guess if you were keen, you could make one with a small magnet in the base to keep the bit more securely in place but in this particular application of mine magnets are not a good thing...Cheers, Mike

I've started research into how to drive a 4" Bourdon gauge, application TBD - this looks a much more promising approach than ones I'd been considering (eg) direct drive of the spindle via a servo. Space will be the issue but your design definitely gives me food for thought. Thanks!

Oh I wish I had a 3D printer! Thanks for the link.

Thanks - I do feel a lot better about being underneath the thing since I added the restraint, although I always have to remember to duck!