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Dual cs 505 3. Slow platter speed

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Dual cs 505 3. Slow platter speed

Postby molebobski » 14 Jan 2016 19:26

Hi I have a Dual cs 505-3 that I bought in 1990. It had been in storage for the past 10 years and when I set it up recently I found out the toothed belt had perished. I bought and replaced the belt but it now plays too slowly.

Mike
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Re: Dual cs 505 3. Slow platter speed

Postby Username_506 » 15 Jan 2016 02:47

If you only replaced the pitch belt and not the drive belt then get a new drive belt. A ten year old drive belt will be slack.

After *drive* belt replacement, if you do have a problem with the pitch control, here was my experience:

I have a Dual CS 506. It's a belt drive with pitch control. (My pitch problem may apply to your Dual 505...)

The pitch is a dial type control at front left of the deck. My problem was that I was able to twist the dial in one direction only - then not move it back in the opposite direction due to slipping toothed pitch belt.

First turn off/ unplug the turntable and move it to a work area with good light.

To fix my pitch, I had to assist or ease the pitch mechanism by pressing down on top of the mechanism's brass/metal bracket with one finger while at the same time turning the pitch dial back using my other hand. (The pitch and the belt pulley share the same bracket mechanism).

The bracket for drive belt capstan and pitch belt and is front left, underneath the platter. I removed my platter but there are platter access holes under the platter mat. You could use an access hole (with the mat off) to reach in and press the bracket without removing the platter, I believe.

.
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Re: Dual cs 505 3. Slow platter speed

Postby Minstrel SE » 16 Jan 2016 01:26

Hi

Yes a new drive belt would be a good idea and a strobe disc for the platter top.

Then you may have to get very familiar with the way the pitch control works. There is some adjustment with the top nut but it should be all working as intended if nobody has altered it.

You could nip that top nut down one or two rotations but it shouldnt take more than that. Be prepared to restore it back to its original position near the top of the thread.

Running too slow suggests the plastic spindle isn't splaying out far enough but its all fine adjustments and nothing too drastic

There is a little dot on your pitch adjustment knob that you can use as a reference setting point so you can go + or -6%

As long as your main drive spindle hasnt slipped on its grub screw, it should be alright. You have to factor in older compressed motor rubbers and it could just be slightly out of adjustment
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Re: Dual cs 505 3. Slow platter speed

Postby molebobski » 18 Jan 2016 21:20

Hi All,

Thanks for your help so far. I now have a new drive belt and it works ok at 33 rpm but it's still too slow at 45 rpm even when I adjust the pitch. Any ideas why?

Mike
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Re: Dual cs 505 3. Slow platter speed

Postby Minstrel SE » 18 Jan 2016 23:36

Yes your adjustment is out and it often shows up on 45rpm.

The plastic isnt splaying out enough or your belt isnt sitting in the right area of the drive spindle.

It could also be your belt being too tight for the current adjustment. If you push the brown top piece down it should spring up. You should nip that top nut slightly down to start with. That should boost your max speed but only if everything else is working correctly. Im hoping it all hasnt slipped down on the grub screw which would need a real job...fingers crossed that shouldnt have moved as its factory tightened on a grub screw

Really you will have to familiarise yourself with the workings of the pitch control while going through a checklist.

All the best with it
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Re: Dual cs 505 3. Slow platter speed

Postby molebobski » 18 Jan 2016 23:49

Thanks for that. I'll have a look tomorrow night
Cheers

Mike
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Re: Dual cs 505 3. Slow platter speed

Postby molebobski » 06 Feb 2016 18:34

Hi,
Finally got around to sorting it out and it turns out that when I changed the speed the spring didn't move and so the belt wasn't moved to the correct part of the spindle. But now it works. Now that is sorted just got to sort out the poor sound quality and so am about to put new cables to the amp.

Mike
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Re: Dual cs 505 3. Slow platter speed

Postby Minstrel SE » 06 Feb 2016 23:12

Thats good. Its usually something fairly obvious that becomes clear when a test is done with the platter off.

It should sound really good if all the wires and connections are fine. Its a good turntable to service back to tip top condition.

All the best with it
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Re: Dual cs 505 3. Slow platter speed

Postby barneymusician » 17 Feb 2017 14:34

Hi there,
I have the same issue that the small toothed belt that operates the 45rpm speed had perished (brittle and cracked). Do you or anyone know where I can source a replacement? I only seem to find the main belts (unless I'm mistaking what I'm seeing?) at Thakker and TurntableNeedles..
I do have a second linked issue...whilst removing the perished smaller belt a thin metal bushing/clip slipped out and down inside the hole it placed in. Any ideas on how to access this? Go "down" and remove the sub-platter or "up" from the base?
Any help hugely appreciated (this my first post)
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Re: Dual cs 505 3. Slow platter speed

Postby Minstrel SE » 17 Feb 2017 20:20

Hi barnymusician.

Its an interesting one as Ive seen pitch belts on 35 year old Dual 505s which look as good as new. Others seem to perish because they have probably been mishandled at some point or a previous owner has been twisting the pitch knob like it spins forever

If you cointact Dualfred in Germany they will have the pitch belt. Its best to go for an original but a dealer in the UK sells some O rings as a solution

The best thing is to familiarise yourself with taking the platter off and then lifting the top chassis out. I wont advisre you any more until you have seen how it works from underneath if possible

Its all a learning process which reaps rewards with you feeling satisfied that you can service your turntable.

You have to check a few things from your speed control bar to the pitch mechanism.

I dont know the bushing you mean but it can only have dropped into the base of the turntable as long as it hasnt fallen in the motor or something.

Its an enjoyable turntable to work on so angle thoose transport screws and you will see it lifts out. Great care is needed so if you are a confident DIY bod you will get pleasure from doing the work yourself.

All the advice is here and just dont do anything or remove anything you havent fully studied and asked about

Best wishes with it
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