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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc.

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Old 1st Sep 2022, 4:53 pm   #61
frsimen
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Default Re: Grundig tk 23 L speed issue

It's reasonably easy to check the speed of your tape recorder by using a measured length of tape.

To do it, preferably on a tape that isn't of any importance to you, make a mark on the back of the tape somewhere near the start of the tape. You can use a chinagraph pencil, a wax crayon or a marker pen. Measure along the tape 190.5cm from the mark you have made and make a second mark at that point.

Thread the tape onto your tape recorder and line the first mark up with the exit point from the head cover. Play the tape and measure the time until the second mark appears at the exit point from the head cover.

If the tape is running at the correct speed, it should take 20 seconds. If it is running fast it will take less time and it will take longer if running slow. The test should allow you to determine if it is the Akai or the Grundig that is running at the wrong speed.

Paula
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Old 1st Sep 2022, 5:55 pm   #62
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Default Re: Grundig tk 23 L speed issue

Thank you Lawrence. Learn something new every day!

Graham, you're spot on. In trawling through Facebook, I can see the 50/60Hz control is between the spools.

Paula, you're a star. Your recommendation should nail the issue.

Chris

Last edited by simpsons; 1st Sep 2022 at 6:04 pm. Reason: Additional information
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Old 1st Sep 2022, 7:41 pm   #63
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Default Re: Grundig tk 23 L speed issue

The TK 23L and all its numerous associated series siblings are not idler drive.

The motor pulley drives a belt that directly drives the flywheel, the capstan being part of the flywheel.

There is a single rubber tyred idler wheel that is driven by the motor pulley and then the idler wheel drives the Take Up reel table in Fast Forward wind.

David
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Old 1st Sep 2022, 7:59 pm   #64
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Default Re: Grundig tk 23 L speed issue

Most single motor decks require an idler somewhere to obtain the opposing direction wind / rewind.

An exception was the EMI TR50 series where the take up was B wind (oxide out) but then it used idlers to the spools anyway.....
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Old 1st Sep 2022, 8:09 pm   #65
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Default Re: Grundig tk 23 L speed issue

For the Grundigs in question the motor pulley directly drives the Supply reel table in Fast Rewind.

David
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Old 1st Sep 2022, 8:43 pm   #66
ubaldojhp
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Default Re: Grundig tk 23 L speed issue

Quote:
Originally Posted by frsimen View Post
It's reasonably easy to check the speed of your tape recorder by using a measured length of tape.

To do it, preferably on a tape that isn't of any importance to you, make a mark on the back of the tape somewhere near the start of the tape. You can use a chinagraph pencil, a wax crayon or a marker pen. Measure along the tape 190.5cm from the mark you have made and make a second mark at that point.

Thread the tape onto your tape recorder and line the first mark up with the exit point from the head cover. Play the tape and measure the time until the second mark appears at the exit point from the head cover.

If the tape is running at the correct speed, it should take 20 seconds. If it is running fast it will take less time and it will take longer if running slow. The test should allow you to determine if it is the Akai or the Grundig that is running at the wrong speed.

Paula
Okay. According to what I have measured the Akai takes 24 seconds and the Grundig 20 seconds. It's then Akai's problem all this time. Could it be a belt problem?

Last edited by ubaldojhp; 1st Sep 2022 at 8:48 pm.
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Old 1st Sep 2022, 8:45 pm   #67
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Default Re: Grundig tk 23 L speed issue

Result!!

24*50/60 = 20 .

or

20*60/50 = 24 .
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Old 1st Sep 2022, 8:49 pm   #68
ubaldojhp
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Default Re: Grundig tk 23 L speed issue

The akai as far as I know does not have a 50hz/60hz selector
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Old 1st Sep 2022, 8:51 pm   #69
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Default Re: Grundig tk 23 L speed issue

This is the Akai
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Old 1st Sep 2022, 9:17 pm   #70
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Default Re: Grundig tk 23 L speed issue

I have never seen a 4000DS that does not have the 50Hz/60Hz adjustment, all mine have it.

Post a photo of your rear panel ident label.

David
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Old 1st Sep 2022, 9:34 pm   #71
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Default Re: Grundig tk 23 L speed issue

Here you have them mate
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Old 1st Sep 2022, 9:43 pm   #72
ubaldojhp
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Default Re: Grundig tk 23 L speed issue

I got it a few years ago in a barter and the previous owner told me that nothing had ever been done to it. Since I didn't have another one and it worked well, I've been leaving it but I've been wanting to do a set-up for a long time. This may be a good time
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Old 1st Sep 2022, 10:21 pm   #73
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Default Re: Grundig tk 23 L speed issue

Hi Ubaldo

My Spanish isn't too good but should I be you, finding it was the Akai that was faulty, which at least could record and playback OK, made me think "maldito."

Chris
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Old 1st Sep 2022, 10:21 pm   #74
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Default Re: Grundig tk 23 L speed issue

So your 4000DS machine is 50Hz only but appears to be running like a 60Hz machine.

Checking one of my dual frequency 4000DS's I see that the flywheel and also the motor pulley has 2 steps of slightly different diameter.

For 50Hz running the drive belt runs on the smaller step of the fly wheel and the larger step of the motor pulley and the complete opposite for 60Hz running.

So if (maybe a big if) your machine has the same 2 step flywheel and 2 step motor pulley, then one feasible explanation could be that at some time the drive belt has been replaced/disturbed and manually incorrectly fitted on the 60Hz steps.

The photos show the belt position on the flywheel, could not see the motor pulley well enough to take photo but you can feel the different step diameter and the belt should go straight across (not at an angle) from the flywheel to the motor pulley. First photo is 50Hz with the belt on the smaller step of the flywheel and second photo is 60Hz with the belt on the larger step of the flywheel.

David
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Old 2nd Sep 2022, 10:12 am   #75
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Default Re: Grundig tk 23 L speed issue

Quote:
Originally Posted by ubaldojhp View Post
Quote:
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Yes Post 20, the underside of the bottom panel also the mains voltage linking information.

David
So the wiring would be correct.
Yes if your local mains voltage supply is 230/240V 50Hz.

David
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Old 2nd Sep 2022, 10:14 am   #76
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Default Re: Grundig tk 23 L speed issue

The Spanish mains frequency is 50Hz.
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Old 2nd Sep 2022, 10:26 am   #77
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Default Re: Grundig tk 23 L speed issue

I want to thank everyone for your help and apologize for my mistake. I'm going to repair my Akai and I'll tell you
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Old 2nd Sep 2022, 6:02 pm   #78
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Default Re: Grundig tk 23 L speed issue

Just for completeness of information.

The 50/60Hz dual frequency Akai 4000DS in addition to the mechanical 50/60Hz setting also has an electrical 50Hz/60Hz switch setting.

When switched to 60Hz the voltage supply to the motor/run capacitors is increased from 100V to 120V and the 0.5uF run capacitor is disconnected from the 2uF run capacitor that it is paralleled to in 50Hz setting (the 2 run capacitors are in a dual can), i.e. 50Hz = 2.5uF, 60Hz = 2uF.

David
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Old 14th Jan 2023, 11:44 pm   #79
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Default Re: Grundig tk 23 L speed issue

Hello again. Finally the problem was the Akai. I took it to do a set-up, belts, lubrication, adjustments etc and some capacitors that were out of value. Now it works correctly and the recordings are heard perfectly on both the grundig and the Akai. Thanks to everyone for the tips
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Old 15th Jan 2023, 11:33 am   #80
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Default Re: Grundig tk 23 L speed issue

Good news, well done.

David
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