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Post by tonup69 on Sept 17, 2020 15:39:22 GMT
Hello all - new to this forum and to jukeboxes in general - although I have experience with fixing pinball machines, vintage radios, vintage phonos and old British motorcycles. I just picked up this BEAUTIFUL AMI B series jukebox and even freed up the stuck changing mechanism. I was told that it came with the parts to convert it back to 78RPM, but I think I am missing some things. I have the 78 tone arm and a brass piece that I don't recognize. Picked up a new cartridge for the tone arm. I think I am missing the snail cam for the tone arm that puts the needle down in the right position for 78s. Also, how do you change the motor speed to 78RPM? Any advice, parts, hints welcome.
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Post by gazzy58 on Sept 17, 2020 23:25:15 GMT
Hi, its been some years since I had my AMI model B, but will try and help as best I can. First things first, (and I am sure Ron Rich and others would agree) if you haven't already got one, buy yourself a service manual. In order for myself and other members to be in a better position to help, may I suggest you send some more close up pics of the mechanism so we may be able to identify what parts are missing. For your machine to be in 78 mode, I think the tone arm should be a one piece casting (mine was gold in colour) and not like the modern looking version for 45s. I think from memory the 78 version used an Astatic 51 cartridge with a "bent pin" type stylus. If your cartridge is dead or missing, unfortunately they are no longer available, but I believe Pfansteil make a good equivalent. In terms of record speed, I am not sure if there are two different types of turntable motor for this model ie one for 45s and one for 78s. If your machine is currently in 45 mode, then it should have the blue plastic inserts to accommodate a 7" record, which would have to be removed for 78 play. I may have some spares for sale as I bought a spare mech years ago, then sold the machine. Its buried away in the loft, but will try and dig it out. Please let us know what stage you are at with this restoration and what parts you need etc. Having a manual will make things easier for yourself and other members in terms of being able to communicate better by identifying parts using the correct terminology. My memories of this machine are good. My machine, although more or less complete, needed the amp rebuilt and there was only a small non original speaker which was replaced by a new 15" "Big Cat" speaker and it delivered a glorious sound. Once set up properly this machine proved to be a good reliable machine. Crucial to the operation of this machine is the correct set up of the cam microswitch (among other things). There is section in the manual which relates to this. This is an oddball switch which was apparently only made for AMI. Finding a new equivalent will not be possible. The good thing with these switches is that they can come apart and most of the problems associated with this switch are dirty contacts. A word of caution though, if you have to take this switch apart for cleaning, be very careful as there is a tiny spring inside which has a nasty habit of firing out across the room. Not much fun trying to find it scrambling around on your carpet. If I remember correctly, the transfer motor and carriage motor are essentially the same but with different gear ends. Again, these motors are fairly easy to take apart and clean. Replacement carbon brushes are also fairly easy to get. Good luck with your project and keep us up to date with your progress. Gary
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Post by tonup69 on Sept 18, 2020 1:10:42 GMT
Thanks, Gary! I am just starting the project but will get you up to speed on some things so we are on the same page:
1) I have a PDF copy of the manual, which is not that helpful, but does have schematics and some part names.
2) The amp and speaker work great! I played a 45 record and it sounds fantastic.
3) I have the 78RPM tone arm and just picked up another (more complete) 78 tone arm. Ordered a new cartridge - ruby needle.
4) I have the mechanism free for changing the records and oiled it - it now works, but I broke a switch by accident - my friend who fixes jukeboxes is scouting me a replacement.
5) I do not have a 78RPM motor, I have a 45 motor - is that the only way to change the speed?
6) I believe, but am not sure, that the snail gear which raises the tone arm must be replaced with a 78 snail gear - true?
Once I get it mechanically working, change the tubes and the volume pot, clean it up and replace one of the lights I will be ready to strip down and clean it. I am also going to re-upholster the inside and get rid of the nasty gold curtain like material - and nasty green material a previous own used on the sides of the box (inside).
That's the plan - main issue now is getting it to play 78s.
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Post by jukenorman on Sept 18, 2020 9:11:19 GMT
Hi Tonup,
As far as I'm aware, these conversion kits were produced by more than one after-market company so it depends on what you have! Having said that, AMi made changeover kits for the C, which I suspect would fit a B OK.
If the turntable is a simple idler wheel arrangement, then increasing the motor spindle diameter in the ratio of 78/45 will increase the speed to 78rpm (ie fit an interference fit sleeve). If the motor spindle already has a spring fitted for 50/60 Hz conversion, it makes your calculation slightly more complicated because the spring should be removed IMO.
I'm not familiar with the term "snail gear".
Norman.
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Post by gazzy58 on Sept 18, 2020 10:51:35 GMT
Hi Tonup (you haven't given us your real name), I would go with Norman's suggestion of re-sleeving the spindle to make the correct speed. I got a friend with a lathe to turn me one to the correct diameter. you have to be careful not to make it to high otherwise it will fowl the turntable. If you are going for originality, the gold and green materials are, as far as I know the original material. I personally would not change it out, only if it is really badly worn or damaged. I am not familiar with the term "snail cam" either. Perhaps you could send a picture. Which switch did you break? I might be able to help. Gary
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Post by tonup69 on Sept 19, 2020 22:32:25 GMT
This is what I call a snail cam - some people may call it a sling blade, but I call it a snail cam.
I got pretty far today - even played a 78, but as you can see, the needle is wrong and it also starts midway through the record - I have the cam and the tone arm assembly on order - should be fixed soon.
I'm sure there will be many more questions - and my real name is Larry, but you can call me TONUP if you like.
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Post by tonup69 on Sept 19, 2020 22:35:59 GMT
P.S. I was able to solder the switch I broke - now it works fine.
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Post by tonup69 on Sept 19, 2020 23:13:05 GMT
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Post by jukenorman on Sept 20, 2020 15:19:05 GMT
Hi Larry,
That looks like the 45rpm tone arm from a C - the original tone arm should sort you out.
Norman.
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Post by robbytherobot on Sept 20, 2020 16:08:00 GMT
 Hello, You need to double check which Tonearm Cam you got.
From your photo, looks like 78 version.
Compare like this :
Tonearm is from the 45 conversion, you need a shorter one. Or you can enlarge holes to move it to outer edge of 78 rpm. I know someone one who did that.
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Post by robbytherobot on Sept 20, 2020 16:11:26 GMT
I looked at the video, your turntable only start when needle is already dropped on shellac.
Mine spin way sooner, before shellac is on it !
Any idea why ?
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Post by robbytherobot on Sept 20, 2020 16:17:19 GMT
I am also going to re-upholster the inside and get rid of the nasty gold curtain like material - and nasty green material a previous own used on the sides of the box (inside). Original curtain is like a towel, and it's yellow, not gold  Original green material should also look like a towel, it's original. |
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Post by robbytherobot on Sept 20, 2020 16:20:25 GMT
That's the original tonearm for 78 rpm  |
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Post by Ron Rich on Sept 20, 2020 16:43:41 GMT
Hi Robby,
The turn table (TT) motor on these AMi's, I THINK, should be powered when any of the "bail switches" have been closed? If my great, but not too long memory is correct, the bail switch closes a relay that starts both the search, and the TT motors --
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Post by robbytherobot on Sept 20, 2020 16:55:30 GMT
Yes, that's what happen on my B, as soon as Search start, TT too.
But not on the youtube video from tonup69 youtu.be/sZT6l5gWxBU
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