diameter shaft turntable motor AMI Continental2

Hello,

My Conti 2 is equipped with the AMI intermix system (singles at 45rpm, ep's automatically at 33rpm) . Normally on top of the shaft there should be a spring to give 45 rpm, and lower there should only be the shaft to give 33rpm. In my case on top I have a smaller spring, that gives a speed that is too low (for 45rpm), and the lower part is bigger(?) spring (never tried the 33rpm, for me only 45rpm is important). Because of this setup I start doubting that the rubber drive wheel is the original size as well. Is there somebody who knows the following parameters:diameter of turntable motor shaft, outer diameter of drive spring (for 45rpm), outer diameter of rubber drive wheel, rpm of turntable motor? If i have these parameters I can start calculating and check out where my system is wrong.
Thanks,




1 mal bearbeitet. Zuletzt am 11.04.07 09:23.

Hello Michel,
The diameter of the rubber idlerwheel have no effect on the speed of the turntable. The top of the shaft is normally for 33 RPM and the lower (and bigger) part is for 45RPM. I think that you must check the idlerwheel position. I'm not so familiar with AMI juke boxes but that must be not so difficult. Maybe somebody else can explain that.Good Luck
Piet

Hello Piet,
thanks for your answer, but my manual says otherwise: The top of the shaft should have a spring (bigger diameter) to drive the 45rpm. The lower part is just the shaft diameter (smaller diameter) to drive 33rpm. The higher-lower position of the idlerwheel is commanded by a solenoid. Only my situation is different, as described in my first "eintrag". So I'm a bit confused. According the diameter of the idler wheel you're completely right! It's an itermediate wheel and does not affect the ratio between motor shaft and turntable inside diameter.
So does anybody know the standard diameters for the motor shaft, the spring outer diameter and the rotational speed of the turntable motor?
Thanks again, Piet. By the way, are you Belgian or Dutch, because your name sounds like that. I'm Belgian

Hello Michel,
I'm Dutch, living and working in Belgium and not familiar with AMI juke boxes as you can see.
Kind regards Piet

Hello Michel,
I think Piet is right! The upper (small diameter) part of the shaft is for 33RPM and the lower part (bigger diameter) is for 45RPM. In USA, the motor runs with 60Hz 20% faster than in Europe with 50Hz. The two springs are needed for the conversion 60Hz to 50Hz. Maybe the service manual is some confusing, but is is written in and for the USA, where the two springs are not needed.
The idler wheel must run in the middle of the lower (bigger) spring and must stay in this position while playing a 45RPM - single with big centerhole. It will only be pushed in the upper position, if a 33RPM - EP with small centerhole is put on the turntable.
You can find further information in the "archiv" on the top of this page. Archiv - > AMI - > FAQ - > ???
I hope this is helpful for you
Greetings from Austria
charly49

Hello Charly,

Thanks very much for your reply. If I take a look in the archive you describe above, I find a topic on the intermix system with pictures. If you look on the second picture with the turntable motor, you can see a spring on top (bigger diameter for 45rpm), and underneath only the shaft (smaller diameter for 33rpm). This means that the idler wheel is commanded to the smaller (lower) diameter of the shaft by a solenoid if 33rpm is needed. For 45rpm the solenoid is not activated and the idler wheel stays on the spring. This is exactly the situation as described in my manual.
I got my conti 2 out of the Netherlands a few weeks ago in good playing condition, though the turntable speed was to low. My system looked different to the one described in the manual. I have a smaller spring on top of the shaft, and a bigger spring lower on the shaft. The soleniod to command the idler wheel is not connected or broken because my idler wheel is always turning on the top spring (for a big as well as for a small hole). So I tought i could solve my low speed problem by ordering a new 50Hz spring to go on top of the shaft? When I got the spring it didn't fit over the old top one so I took the old one of. Now I end up with a bare shaft top of about 2.7mm (where the old smaller spring is taken of) and a 50Hz spring with an inner diameter that is too big, and falls over it. I tried to put some tape on the shaft before mounting, but this gives vibrations in the music , probably because of small diameter variations. Does anybody now a good way to fill the "gap" between shaft and 50Hz spring?
This way i can keep my box running as it did before, with a normal turntable speed.
Regards,

Hello Michel,

it seems, there are some different versions of the automix. Obviously Your system is like I described and remember (I have worked on this machines in the sixties and seventies), with the smaller diameter of the shaft on the top, but with reversed function. Probably the solenoid must be activated to push the idler wheel in the lower position for 45RPM. The function will be activated by the small microswitch with the wirearm. Is it correct adjusted and in a good condition?

Another cause could be the second (bigger) microswitch. All switches (not only microswitches) are inclined to get problems, if they are not activated for a long time.

Have You tried, to push the idler wheel in the lower position by hand, while playing a record? Perhaps You can also try to fix the solenoid - plunger in the activated (down) position with a tape for testing the turntable speed. I think, the speed must be correct.


I hope this is helpful for You. Good Luck.

Charly

Hello Charly,

Thanks very much for your reply. I did some testing tonight and it seems that the automix system is still functioning! With a big hole record the center pin is not pushed, the NC contact in the microswitch stays closed, and the solenoid is pushing the idler wheel up to the top of the turntable motor shaft. With a small hole record the center pin is pushed, opening the NC contact on the microswitch, and the solenoid is disactivated. Normally the solenoid plunger with the idler wheel should turn to it's lower position through it's weight or maybe a permanent magnet, I'm not sure. So the whole system is comlpetely operative. Only on my system a spring is placed externally between the solenoid and the plunger shaft, forcing the plunger always in upper 45rpm position. Probably this has been done to play 45rpm records with a small hole. This indicates to me that this box has been restored with care (the guy I bought it from claimed he got it from someone else, who bought it on his turn from Jolina some years ago, a well known jukebox company in the Netherlands?).
The only part that doesn't fit in the picture is the turntable motor shaft, that has a top diameter of about 2.7mm, and an old bigger spring on the lower end (it seems that the shaft diameter is bigger underneath the spring, but I'm not sure). My goal is to restore the box as close to original as possible (with functional automix), so this means I have to find a way to fit a 50HZ spring on my 2.7mm shaft. Is there somebody who can tell me what is the diameter of shaft where the 50hz spring should fit on. With this info maybe I can machine a metal bushing to fit inbetween these two parts. Suggestions and tips are wellcome.
In the meanwhile I covered the shaft top as good as possible with tape, and fitted the spring to this. My speed is still a bit too low and I have some vibrations in my music.
One last question: some records that play OK on my AMI H100 seem to have problems on the Conti: the needle keeps hanging in one groove, always at the same place on the record. Which of the adjustment parameters (needle height, tone arm weight, tone arm pivot,.......)is responsible for this, or is it better to check all of them?

Regards,
Michel

Hello Michel,

the automix version in Your machine is different to the description in Your manual. I think You have the newer version and this version is more common. I have never seen the other version. I will try to explain it once more:

33RPM: The pin on the center puck ist pushed and opens the microswitch. The solenoid is disactivated. The plunger with the idler wheel stays in the UPPER position (held by the spring as You described) and the turntables speed is 33RPM.

45RPM: The pin is not pushed, the large microswitch stays closed. If the gripper arm activates the second (small) microswitch, the solenoid will be energized and and pulls the idler wheel in the LOWER position (against the spring force).

This is all like in Your description with one exception: The solenoid dosn't pull the idler wheel in the lower position. This can be caused by one of the two microswitches (clicks, but has no continuity), a defective coil, incorrect wiring or missing voltage. The plunger must be easy to move. If You push the plunger manually down, the idler wheel must move to the middle of the lower spring. On the solenoid connections should be aproximately 28V (DC I think), while playing a 45RPM record.

Once more: Your motor shaft is correct and you don't need a bigger spring. You have to find the cause of the malfunktion.

To Your second question: The tone arm must be easy moveable both harizontally and vertically, without any bindings. Take care that the tonearm cable doesn't obstruct the horizontally movement. The needle must be in a good condition and the needle carrier must stand exactly between the two magnetic poles.

The weight adjustment is some tricky. The weight is affected by a spring and the spring force is progressively. You have to measure the weight in the playing position, not higher. It is best to remove the record from the turntable and pull the tonearm with the tonearm gauge just some millimeters, to read the weight. The weight should be between 7 and 10g (if You have the original cartridge GE VR22). In case of doubt You can compare with Your AMI H. It has the same tonearm and a comparably cartridge.

Good luck and best regards

Charly





1 mal bearbeitet. Zuletzt am 14.04.07 03:08.