Phonoland

After ruling out timetable motor grommets as a source of motor noise, I notice that the 50hz speed change here doesn't quite look right

I've posted a video of what it looks like stationary and running:


http://youtu.be/lQVXXnywj2s

It looks very much like a bodge job and would appear to be the source of the vibrations. I've ordered the correct conversion spring which effectively widens the motor shaft, but not sure if this TT motor shaft is missing something? If so I guess I need to replace the whole motor?

Any thoughts would be helpful. I accept you US fellas probably don't see this much!

Hi
Yes the spring looks like it could be causing problems, it wouldn't be doing the idler wheel any good, may be putting small indentations in it. Any conversion motor i have seen, the spring is very tight on the shaft, have also seen other conversion jobs whereby a hollowed out metal shaft or piece of hollowed ot plastic was used, they seemed to work, all about getting the diameter right
regards
Clones

After viewing the video--it appears to me that the idler wheel, is making contact with a "solid"portion of the spring, that's wrapped on the motor shaft--if that's the case, I see "no problem" there--However, it also appears to me that the idler wheel is being forced up against the motor shaft, and is being held, very tightly, with an over-sized spring ?
This ain't no good--know how,if true !! Ron Rich

At best this sort of solution is going to be halfassed. A spring is not as smooth as a milled shaft and the coil is always working to raise/lower the puck causing a rumble.

Ron's question about spring tension is worth checking. Another possible approach is to take a small contact file and hold it against the spring while the motor is running. Do this only briefly as it will decrease the diameter and thus slow the t-t slightly, but it will smooth the surface a bit.

Also, in the video I hear rumble when the motor is turned on. There should not be any sound if the puck is not dried out and the motor armature is balanced. Is there still any noise when the puck is held away from the shaft?

Even when all is perfect, these idler drives are never as quiet as a direct or belt driven turntable...or a Seeburg. Back when these things were new most people had idler drive turntables at home and thus were used to a slight rumble on records. CD's and better turntables have kind-of spoiled it for us. I know I have no patience for turntable noise anymore.

Rob/NYC

Thanks for your input as always guys

Ron - In normal operation the idler runs slightly lower, I think I had pulled it up a little when examining it, as it seems to pop down again. On the whole it does make contact ok, but there is a slight tick felt in the base of the turntable as it passes the end of the spring coil! Thanks for pointing out the idler spring, I wonder if someone replaced it to hide a worn idler? I have a correct replacement spring on its way from Stamann, along with the "correct" speed change spring. If the idler slips guess I'll buy one of their repro idlers too!

Rob - Most of the that noise is actually from the amp, im rebuilding it stage by stage and hope to resolve that hum or reduce it. I did also have my mobile phone right near to a speaker, so perhaps the hum was heard louder or worsened by the smart phone. There is some motor noise which I think is a combination of the spring Ron mentioned and the crappy looking spring on the motor shaft. I agree its half-assed (or arsed as we would say in England!), but theyre all modified this way for UK operation, though the springs youre supposed to use have thinner wire and more turns which I guess makes the effect you describe less of an issue. It would be nice if there was another way of doing this, but I imagine they used springs as they fix firmly in place. Shame Rockola didnt just make 50hz motors for these export models, but I guess adding a spring is far cheaper and it oftens comes down to the bottom line!

Thanks for that pic Bob, you're right it does look like thicker gauge wire, very much a bodge. I'm assuming it originally came from Rockola with the right spring, so no idea what happened...

From your pic am I correct in thinking there should be something on top to screw it down? Its a little out of focus. Im beginning to wonder if Im going to need a new motor to resolve this

The guy who sold me this is still punting "fully working" "restored" Jukeboxes on ebay, though much smaller quantities now. I wonder if he had other "satisfied" customers!

Thanks for that! Yeah, the 468 conversion looks far more professional than those pesky springs. But if I can bring this horrible motor noise down to reasonable levels with the correct spring I will stick with that.

That looks as if it was a "homemade" item to me--looks good, except I don't like the screw sticking out--think I would install a "grub screw" there---Ron Rich

I received the correct springs (idler tension and 50hz speed spring) last night and fitted them.

Immediately I noticed poor speed (idler slip) and a cyclical "thump". The thump was caused by an indentation in the idler the size of the motor shaft. I expect this was caused when the jukebox was in "storage" (garage) for years and possibly with an over tensioned idler spring pushing it into the motor shaft.

I cleaned the edge of the idler with some isopropyl, and also the rim of the turntable itself. The thump doesnt seem apparent now and speed is fairly consistent, but I'd say overall the speed seems slow.

The newer conversion spring is definitely smaller, so this would reduce the speed, but I'd still expect more or less the "correct" speed - to me it sounds slow.

I'm going to order a new idler wheel as I guess this old one could do with replacing anyway. But if the idler was causing the problem I'd expect more fluctation in speed than consistently slower??

I have pics of the old and new parts, which I'll post when I can get them off my phone.

I will also stick my strobe disk on the deck to see how close to 45rpm we are. This is probably overkill, I know that these old idler drive turntables were never perfect in terms of speed, but its the best I can do to make sure I'm not imagining it.

Its either that or time how long a record plays and compare it to the same record on another deck!

Doghouse,
Dual speeds--I would assume ?
Ron Rich

Ron Rich wrote:Doghouse,
Dual speeds--I would assume ?
Ron Rich

Yes, that's why I said earlier,

Presumably this would have been used where there was a facility to play 33 1/3rpm records, but you can see there's no sign of this ever being available on this machine, nor does any information suggest there was this option. So either a replacement motor at some time, or a "one size fits all" production practice.

Doghouse,
I would assume, "someone" made these up for dual speed use, and also sold it for single speed use ?
Ron Rich