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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 15th Jan 2023, 10:37 pm   #81
ubaldojhp
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Default Re: Grundig tk 23 L speed issue

One last question. Is there a way to change the belts? I have downloaded the manual but it is in German and I don't see any section for this repair
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Old 16th Jan 2023, 4:25 pm   #82
DMcMahon
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Default Re: Grundig tk 23 L speed issue

The only procedure I have seen is this extract (attachment 1) from the English TK23L Service Manual, this procedure somewhat oversimplifies the process, i.e. it makes it sound easier than it actually is.

The counter belt of course is very simple.

To replace the 2 belts that go around the flywheel you have to lift up the sound channel plate (hinge upward/swivel sideways) that the heads are mounted to (similar to attachment 3), so that the new belts can go over the capstan shaft then around the flywheel body.

You have to disconnect the Pause key lever (easy) and the the Start key levers. The Start key levers can be tricky, take careful note of how they fit before disturbing. First you also have to unsolder the wire that connects to the EOT (End Of Tape) brass sensor post on the left side of the heads plate (unless you cable is extra long).

David
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Old 16th Jan 2023, 4:43 pm   #83
ubaldojhp
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Default Re: Grundig tk 23 L speed issue

thank you. Your help has been very useful from the beginning. very thankful
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Old 31st Jan 2023, 11:22 pm   #84
ubaldojhp
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Default Re: Grundig tk 23 L speed issue

Hello again, I've been enjoying the grundig a lot for a few days and I was wondering if some kind of adjustment could be made to improve the sound. I have seen in the manual some possible adjustments in the rear. Any advice? Thanks and best regards
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Old 1st Feb 2023, 10:55 am   #85
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Default Re: Grundig tk 23 L speed issue

The TK 23 sound is not Hi-Fi but should be more than acceptable for a basic tape recorder, unless there is a fault/bad set-up in the head alignment or electronics.

If everything is basically set-up correctly and no faults exist then the sound cannot really be improved.

R45 Humdinger is for minimalizing the hum level, in my experience humdinger adjusting does little (in terms of audible or measured hum) on TK 23 type machines.

R37 Erase head voltage - adjust for 9V across head using valve voltmeter.

R61 (Threshold) is set to approximately mid position for automatic recording control.

R62 (Sensitivity) adjustment is for automatic recording level and can affect the frequency response.

R67 is for setting the record modulation level at the EM 84 Magic Eye.

C24 (not shown on your image) is for adjusting the record bias (65V across the head) in record mode. Bad bias set-up can affect the frequency response, signal to noise ratio and distortion level.

David
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Old 1st Feb 2023, 11:01 am   #86
ubaldojhp
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Default Re: Grundig tk 23 L speed issue

Thanks again David. The sound is not bad considering what you say and that I am using used tapes. The problem that I notice is a small lack of treble in the reproduction but it can be something normal
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Old 15th Feb 2023, 12:03 am   #87
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Default Re: Grundig tk 23 L speed issue

Attached is scanned copy of electrical set-ups from the manual.

David
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Old 18th Feb 2023, 11:49 am   #88
ubaldojhp
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Default Re: Grundig tk 23 L speed issue

Thanks again David
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