Dual 1228 Turntable speed issue

bberkom

bberkom

AK Subscriber
Subscriber
I picked up a nice-looking 1228 this weekend for a few bucks. After cleaning and relubricating all parts of my 1228 with appropriate lubes, I am still encountering an issue with the speed. I took a video in the link below so you can see what I am talking about, but around every 4-8 or so turns of the platter, the speed suddenly slips and I lose about a bar on the strobe. Otherwise the speed is pretty steady, but it just gets these dips in speed every several rotations. I put a piece of post-it on the platter so you can see how many times it is rotating as it passes in the upper left-hand corner of the video. You probably can't hear it in the video, but when the speed slips, I can hear a slight rubbing sound coming from somewhere under the platter. I can't tell if it's the main bearing or part of the idler. I have tried just about everything I know to do on these Duals and every suggestion I can find on AK.

Slips happen at approx. 8, 15, 34, 41, and 53 second marks of video.

Specifically, I have cleaned and relubricated the main bearing, idler bearing, and I disassembled the motor, cleaned and relubed those bearings, even flipping the divoted plate in the lower bearing housing. The thing runs as quiet as my 1229, just seems to be slipping. I have also cleaned/polished the motor pulley, polished and cleaned the inside rim of the platter and sanded the edge of the idler wheel with 400 grit sandpaper. Speed is more stable than before all of this, but still slips intermittently.

I also happened to have another 1228 that holds speed perfectly. I switched platters, and the table with the speed issue was still slipping with the new platter while the original platter ran true of the other 1228. Must be something with the idler, but I don't know what! Thanks for any help.
 
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ggregg said:
Change out the idler with a different one and see if it does the same thing.
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Unfortunately, the other 1228 is at a friend's now, so I don't have another idler to swap and he picked the other table up before I could try that. I still suspect it's something with how the idler is contacting the platter, although the more cleaning and fidgeting I do, the problem seems to be steadily improving, although it is slightly intermittent.
 
Did you ever remove the idler arm? Not the idler itself but the last pivot point that hides under the rubber. That part gets gummed up. It comes off with a circlip. I find many Dual tts need that cleaned to get proper contact. If it won't easily come off heat it with a lighter and that will soften the gunk inside.
 
Montycat said:
Did you ever remove the idler arm? Not the idler itself but the last pivot point that hides under the rubber. That part gets gummed up. It comes off with a circlip. I find many Dual tts need that cleaned to get proper contact. If it won't easily come off heat it with a lighter and that will soften the gunk inside.
Click to expand...

That's one area I think I need to give some more attention. I wouldn't be surprised if there's still some gunk in there that may be preventing the idler from making full contact the whole time it's running. I've done a couple of Duals now, but this one seemed to be way more gunky than the others I've come across. Thanks for the tip.
 
Be sure the idler is running true and parallel with the platter. If it's not, it will move down the platter rim till the arm the idler's on forces it back, in a "slip/stick" condition. This would explain the dropout in speed after multiple revolutions.
 
Son-of-Vere said:
Be sure the idler is running true and parallel with the platter. If it's not, it will move down the platter rim till the arm the idler's on forces it back, in a "slip/stick" condition. This would explain the dropout in speed after multiple revolutions.
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Great suggestion. I had thought that maybe my idler was warped and riding up the motor pulley, causing the slip, but it is very flat and stays put on the motor pulley with very little fluctuation with the platter off. I didn't check to make sure it was perfectly perpendicular to the platter rim, though. It does make more sense that it would be slipping on the platter and not the motor with how often the slip is occurring. I'll have a look at that tonight, and what you are describing seems consistent with the slippage I'm seeing. Thanks.
 
bberkom said:
That's one area I think I need to give some more attention. I wouldn't be surprised if there's still some gunk in there that may be preventing the idler from making full contact the whole time it's running. I've done a couple of Duals now, but this one seemed to be way more gunky than the others I've come across. Thanks for the tip.
Click to expand...

It's an area that is not addressed in the service manuals or the repair guide that's here in the digital docs area. However I often find it's critical. I posted a thread on it some
time ago.

Usually a clue is consistent speed on 78 or 45 but not 33. Those sections of the capstan are fatter and cause more pressure to be exerted between idler and platter.
 
Montycat said:
Here's where the doc is FYI
Click to expand...

Thanks for the photo. Makes it very clear where I need to look, and I definitely haven't gotten in there yet. The speed exhibits some slippage at 45 rpm, but it is much less drastic than at 33 rpm.
 
I think I may have tracked down the main cause of the speed issue. I set the turntable up so I could observe it from below while it was running. The idler seemed to be running nicely, but I could hear a rubbing noise coming from the main bearing. I had suspected this earlier and moved on from it, but the little donut bearing that the platter rests on was a little frozen up I think. I had cleaned some hard grease out from around it, and I suppose some had gotten in this bearing. The ring inside the bearing that the platter rests on wouldn't move smoothly. I used a small dental cleaner and managed to get some stuff out of it and free it up. I then flushed some oil in it a few times and cleaned it out more. This vastly improved the issue and has been the only think to make a real difference so far.

There is still a bit of an audible wobble when it's playing, but the big swings are gone. I hope a little more cleaning will do the trick. What is the best way I can get this bearing out so I can clean it completely and inspect it? Where would I get a replacement?
IMG_5613.JPG
 
It was the thrust bearing as I suspected! I ended up removing the spindle assembly completely to get to the bearing. I had cleaned most of the dried grease from the upper race of the bearing, but there was still a lot of gunk in the lower race that I couldn't get to without removing the bearing. I took the bearing apart so that I could get all of the grease out from between all four layers of the bearing, oiled it up, reassembled, and it's holding speed perfectly. I actually think the bearing itself was spinning erratically while the races were frozen, which was causing the irregular slips in speed.

At some point, someone put a lot of grease in this turntable. It's the gunkiest I've seen, and they decided to put it all over this bearing. It was nice and hard after however many years. The fix ended up being something fairly simple, but all the troubleshooting I had to do means this turntable is very well maintenanced now and should be running for years to come!
 
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