AIWA AD-6900 playback/channel issue - UK Vintage Radio Repair and Restoration Discussion Forum

4_track · 5th Jun 2022, 11:39 am

Hello.

I have posted same on Tapeheads forum but so far no response so thought I would try here too. Anyway, I picked up an Aiwa AD-6900 last week. It was sold as 'spares or repair' and looked like it may have been parked in a kitchen as it was covered in a layer of grease. Anyway, I gave it a deep clean with isopropyl, wd-40 and cocktail sticks and visually, to my eye, looks almost mint. Functionally, however, it does have a few issues. Wondering if I could get some help on this wonderful machine.

All buttons and levers are functional, FFWD and REW are a bit lazy to begin with but get better after a few stop/starts, play seems to hold speed ok. From switch on there is a brief squeal from either a belt or a motor and at idle one of the motors is continuously turning. I suspect this is normal but the motor itself is quite noisy/vibey. Playback generates mechanical noise and I think it is because of the vibrations this motor is causing. I have removed the front door and have traced the noise back to part of the mech which is vibrating during cassette play. What would cause a noisy/vibey motor and can it be corrected? I suspect a replacement motor would be near impossible at this age?

The major issue with the deck - and probably why it was consigned to 'spares or repair' is that there is no output on right channel during playback. The same symptom occurs either from RCA out or the internal headphone out socket. I have done recording tests with a MIC in the left and right MIC inputs and looks like record is ok on both channels (both left and right VU's register input) but playback is definitely only left channel. I have read about the rec/playback selector mechanism needing a clean to rectify this on other decks but not sure this machine uses that same mechanism.

I have, of course, lifted the lid and it is a complex setup. I would love to fix this myself so could anyone give me any pointers as to what to look for? My skill level is amateur really (although I did dissemble and sort out a stuck mech on my Sony WM-D6c yesterday) or maybe recommend a good tech in the SE London/Croydon/Kent area?

Thanks

paulsherwin · 5th Jun 2022, 11:49 am

The first thing to do is clean all switch contacts very thoroughly with proper contact cleaner such as Servisol (not WD40.)

It's very likely that a deck of this age will need new belts. Tired belts can produce all sorts of strange symptoms. The mech may also need a stripdown, clean and relube.

The fact that it was coated in grease is a bit concerning. It suggests it may have spent a long time in a restaurant or bar, and clocked up an awful lot of hours. There may be general wear throughout the mech.

This is a very nice deck if you can sort out the problems.

ben · 5th Jun 2022, 12:05 pm

This kind of high level deck is not really suitable for a novice, especially in view of the various different problems. I would consider looking for a local tech. There is just such a forum section here you could use.

Meanwhile, take Paul's advice and clean the contacts.
Re: sound fault. A loose or dirty internal connector on the preamp or a sub -pcb might need reconnecting. If it is three head, check source/tape selector. Also connector from PB head to pcb and cables at rear of head.

A tiny drop of light oil on motor shaft may ease the noise (bearing noise?). It could also be one of the spooling gears. Some photos and vids would likely help us to see what we're dealing with.

paulsherwin · 5th Jun 2022, 1:14 pm

I agree that restoring this deck will be challenging for a novice, but a professional refurbishment will be very expensive. It may be more cost effective to find a similar deck in better condition, though any high end deck of this age is likely to need work if unrestored.

4_track · 5th Jun 2022, 1:28 pm

It seems feasible/likely that it was stored in a cooking environment but that may have actually preserved its good looks/condition with a protective film. The logic controls are responsive and I get the impression it won’t take much to get this back to a fine working deck but from what I have read they are pretty difficult to work on given the busyness and complexity of the design. I will take some short videos and upload to YouTube and provide a link here, if that is within the forum rules?

I wouldn’t mind spending a few £ with a competent local tech so will also ask for a recommendation in the appropriate forum section.

5th Jun 2022, 11:39 am	#1
4_track Diode Join Date: Jun 2022 Location: London, UK. Posts: 2	AIWA AD-6900 playback/channel issue Hello. I have posted same on Tapeheads forum but so far no response so thought I would try here too. Anyway, I picked up an Aiwa AD-6900 last week. It was sold as 'spares or repair' and looked like it may have been parked in a kitchen as it was covered in a layer of grease. Anyway, I gave it a deep clean with isopropyl, wd-40 and cocktail sticks and visually, to my eye, looks almost mint. Functionally, however, it does have a few issues. Wondering if I could get some help on this wonderful machine. All buttons and levers are functional, FFWD and REW are a bit lazy to begin with but get better after a few stop/starts, play seems to hold speed ok. From switch on there is a brief squeal from either a belt or a motor and at idle one of the motors is continuously turning. I suspect this is normal but the motor itself is quite noisy/vibey. Playback generates mechanical noise and I think it is because of the vibrations this motor is causing. I have removed the front door and have traced the noise back to part of the mech which is vibrating during cassette play. What would cause a noisy/vibey motor and can it be corrected? I suspect a replacement motor would be near impossible at this age? The major issue with the deck - and probably why it was consigned to 'spares or repair' is that there is no output on right channel during playback. The same symptom occurs either from RCA out or the internal headphone out socket. I have done recording tests with a MIC in the left and right MIC inputs and looks like record is ok on both channels (both left and right VU's register input) but playback is definitely only left channel. I have read about the rec/playback selector mechanism needing a clean to rectify this on other decks but not sure this machine uses that same mechanism. I have, of course, lifted the lid and it is a complex setup. I would love to fix this myself so could anyone give me any pointers as to what to look for? My skill level is amateur really (although I did dissemble and sort out a stuck mech on my Sony WM-D6c yesterday) or maybe recommend a good tech in the SE London/Croydon/Kent area? Thanks

5th Jun 2022, 11:49 am	#2
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,970	Re: AIWA AD-6900 playback/channel issue The first thing to do is clean all switch contacts very thoroughly with proper contact cleaner such as Servisol (not WD40.) It's very likely that a deck of this age will need new belts. Tired belts can produce all sorts of strange symptoms. The mech may also need a stripdown, clean and relube. The fact that it was coated in grease is a bit concerning. It suggests it may have spent a long time in a restaurant or bar, and clocked up an awful lot of hours. There may be general wear throughout the mech. This is a very nice deck if you can sort out the problems.

5th Jun 2022, 12:05 pm	#3
ben Dekatron Join Date: Aug 2006 Location: Madrid, Spain / Wirral, UK Posts: 7,498	Re: AIWA AD-6900 playback/channel issue This kind of high level deck is not really suitable for a novice, especially in view of the various different problems. I would consider looking for a local tech. There is just such a forum section here you could use. Meanwhile, take Paul's advice and clean the contacts. Re: sound fault. A loose or dirty internal connector on the preamp or a sub -pcb might need reconnecting. If it is three head, check source/tape selector. Also connector from PB head to pcb and cables at rear of head. A tiny drop of light oil on motor shaft may ease the noise (bearing noise?). It could also be one of the spooling gears. Some photos and vids would likely help us to see what we're dealing with. __________________ Regards, Ben.

5th Jun 2022, 1:14 pm	#4
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,970	Re: AIWA AD-6900 playback/channel issue I agree that restoring this deck will be challenging for a novice, but a professional refurbishment will be very expensive. It may be more cost effective to find a similar deck in better condition, though any high end deck of this age is likely to need work if unrestored.

5th Jun 2022, 1:28 pm	#5
4_track Diode Join Date: Jun 2022 Location: London, UK. Posts: 2	Re: AIWA AD-6900 playback/channel issue It seems feasible/likely that it was stored in a cooking environment but that may have actually preserved its good looks/condition with a protective film. The logic controls are responsive and I get the impression it won’t take much to get this back to a fine working deck but from what I have read they are pretty difficult to work on given the busyness and complexity of the design. I will take some short videos and upload to YouTube and provide a link here, if that is within the forum rules? I wouldn’t mind spending a few £ with a competent local tech so will also ask for a recommendation in the appropriate forum section.