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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 May 2021, 5:20 pm   #21
ms660
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Default Re: Grundig tk 24

Unless I've missed it no one's mentioned contact W2, that connects the ground side of the head winding to ground for the tracks selected during playback, if that is open circuit or very high resistance there would be no or very little output when playing back a tape that has a known good recording on it, it wouldn't affect an input to the Phono or Radio input sockets, might be worth eliminating that possibility first along with the possibility of any other discontinuity between the head and the input to the EF86 such as contacts D1 not changing back over properly.

Lawrence.

Last edited by ms660; 15th May 2021 at 5:49 pm. Reason: extra info
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Old 16th May 2021, 1:10 am   #22
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Default Re: Grundig tk 24

Quote:
Originally Posted by ms660 View Post
Unless I've missed it no one's mentioned contact W2, that connects the ground side of the head winding to ground for the tracks selected during playback, if that is open circuit or very high resistance there would be no or very little output when playing back a tape that has a known good recording on it, it wouldn't affect an input to the Phono or Radio input sockets, might be worth eliminating that possibility first along with the possibility of any other discontinuity between the head and the input to the EF86 such as contacts D1 not changing back over properly.

Lawrence.
I will check it and update Thank you sir for next level fault finding
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Old 16th May 2021, 9:07 am   #23
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Default Re: Grundig tk 24

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Originally Posted by DMcMahon View Post
I find contact B4 confusing as it appears to always be closed apart from when switched to Fast Rewind.
It's because fast erase is only on Fast Forward.

Lawrence.
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Old 16th May 2021, 11:53 am   #24
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Default Re: Grundig tk 24

Thank you Lawrence, I did not know it does fast erase.

David
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Old 16th May 2021, 11:56 am   #25
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Default Re: Grundig tk 24

Quote:
Originally Posted by ms660 View Post
Unless I've missed it no one's mentioned contact W2, that connects the ground side of the head winding to ground for the tracks selected during playback, if that is open circuit or very high resistance there would be no or very little output when playing back a tape that has a known good recording on it, it wouldn't affect an input to the Phono or Radio input sockets, might be worth eliminating that possibility first along with the possibility of any other discontinuity between the head and the input to the EF86 such as contacts D1 not changing back over properly.

Lawrence.
Yes bad W2, D1 etc contacts would certainly cause tape playback problems.

David
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Old 16th May 2021, 3:04 pm   #26
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Default Re: Grundig tk 24

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As for as Blue Tooth is concerned I used it for injecting a signal through audio input /Radio socket for to check Audio amplifier ;where as if same BT wire connected to head Terminals in Playback Mode audio become too low I applied this logic to find out the Head issue I dont have other head to check there fore when Phono switch is pressed full volume(BT) if change over to playback mode droped volume ;
Regards
Krishna
OK so it sounds like with your Bluetooth signal injected into the Phono input you get good sound volume (no distortion ?), so this is with the machine in Record mode and the sound is the record signal monitored sound, the volume of which can be adjusted by the Monitor volume (same rotary control as the machine on/off switch) which is the the tone control in Playback mode.

David
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Old 16th May 2021, 3:14 pm   #27
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Default Re: Grundig tk 24

Is the EM 84 Magic Eye display working OK. With machine powered up it should look similar to the attached photo.

With your Bluetooth inject into the Phono input are you able to adjust the record level control (the volume control in Playback mode) to get the EM 84 display dark section to narrow down ?

David
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Old 16th May 2021, 4:13 pm   #28
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Default Re: Grundig tk 24

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Originally Posted by DMcMahon View Post
Is the EM 84 Magic Eye display working OK. With machine powered up it should look similar to the attached photo.

With your Bluetooth inject into the Phono input are you able to adjust the record level control (the volume control in Playback mode) to get the EM 84 display dark section to narrow down ?

David
Now I did certain modification by bypass the d1 and directly I connected BT Now the issue is when Playback mode audio is too low when Other modes it has full volume in this case signal given directly to el86 by removing input wire from d1 switch now I am totally confused the vintage technology.. fault can not be traced out In this case totally all inputs switches are bypassed then where the fault exists god knows ....
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Old 16th May 2021, 4:22 pm   #29
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Default Re: Grundig tk 24

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Originally Posted by DMcMahon View Post
Is the EM 84 Magic Eye display working OK. With machine powered up it should look similar to the attached photo.

With your Bluetooth inject into the Phono input are you able to adjust the record level control (the volume control in Playback mode) to get the EM 84 display dark section to narrow down ?

David
every thing working fine no issue volume varies in both modes but in play back mode full volume low sound but in phono it is perfectly controlled volume

yes em84 light glow correctly as shown in the picture actually my confusion why volume dropped on play back mode
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Old 16th May 2021, 10:35 pm   #30
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Default Re: Grundig tk 24

So you still have the low volume on playback (with Bluetooth inject into the EF 86) Yes / No ?

Have you tried playing back a tape ?

David
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Old 16th May 2021, 10:41 pm   #31
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Default Re: Grundig tk 24

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So you still have the low volume on playback (with Bluetooth inject into the EF 86) Yes / No ?

Have you tried playing back a tape ?

David
Yes Sir Both results are same I inject Bluetooth only because repair can be done easily I removed motor belt reversed the unit inject signal my logic is if bt out put is normal in both mode then naturally when i connect Head it is also gives correct output please sir tell me is any wrong with me

Regaeds
Krishna
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Old 17th May 2021, 7:45 am   #32
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Default Re: Grundig tk 24

I am not sure I fully understand your question Krishna and I do not understand if the motor belt reversal has anything to do with the issue in question.

If the PB head is not open circuit and not severely worn and is really clean, then it will provide adequate signal through to the EF 86 assuming all associated wiring and contacts are also good.

David
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Old 17th May 2021, 8:51 am   #33
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Default Re: Grundig tk 24

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I am not sure I fully understand your question Krishna and I do not understand if the motor belt reversal has anything to do with the issue in question.

If the PB head is not open circuit and not severely worn and is really clean, then it will provide adequate signal through to the EF 86 assuming all associated wiring and contacts are also good.

David
I mean I cant play Tape while reversed the unit it will fall down ;hence instead head output I given Bt signal so that i can easily check wiring voltages hence I removed Belt so that unit is on but pickup wheels are not rotate thats all

Regards
Krishna
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Old 17th May 2021, 9:19 am   #34
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Default Re: Grundig tk 24

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Originally Posted by DMcMahon View Post
I am not sure I fully understand your question Krishna and I do not understand if the motor belt reversal has anything to do with the issue in question.

If the PB head is not open circuit and not severely worn and is really clean, then it will provide adequate signal through to the EF 86 assuming all associated wiring and contacts are also good.

David
Now as already told i given signal directly to ef 86 ;now the problem is when playback mode volume is too low(here i used bt insted head signal) while in same connection if i press Phono/radio the volue is full without any change in input connection, my logic has come to an end further my mind is black please guide if any thing is possible
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Old 17th May 2021, 9:58 am   #35
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Default Re: Grundig tk 24

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Originally Posted by reartech View Post

I mean I cant play Tape while reversed the unit it will fall down ;hence instead head output I given Bt signal so that i can easily check wiring voltages hence I removed Belt so that unit is on but pickup wheels are not rotate thats all

Regards
Krishna
So are you saying that with the motor belt fitted the tape goes in the reverse direction ? that sounds very strange.

David

Update - Looking at the top of the flywheel shaft what direction is it rotating, clockwise or counter-clockwise ?

Last edited by DMcMahon; 17th May 2021 at 10:01 am. Reason: Update
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Old 17th May 2021, 10:49 am   #36
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Default Re: Grundig tk 24

I think he might be saying that he can only play a tape with the tape recorder in the horizontal position (normal operating position) ?

Lawrence.
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Old 17th May 2021, 11:13 am   #37
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Default Re: Grundig tk 24

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I think he might be saying that he can only play a tape with the tape recorder in the horizontal position (normal operating position) ?

Lawrence.
No sir dont get confusion to trace the problem I reversed the unit and in this stage i cant play tape due to gravity spool tape will fall down hence i connected BT there is no issue with machanisum it is ok
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Old 17th May 2021, 11:21 am   #38
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Default Re: Grundig tk 24

Quote:
Originally Posted by DMcMahon View Post
Quote:
Originally Posted by reartech View Post

I mean I cant play Tape while reversed the unit it will fall down ;hence instead head output I given Bt signal so that i can easily check wiring voltages hence I removed Belt so that unit is on but pickup wheels are not rotate thats all

Regards
Krishna
So are you saying that with the motor belt fitted the tape goes in the reverse direction ? that sounds very strange.

David

Update - Looking at the top of the flywheel shaft what direction is it rotating, clockwise or counter-clockwise ?

No sir every thing is ok no issue with Machanisum I tilted the unit i cant load spooltape due to gravity it will fall down if without tape; if I play pick up wheels rub the ground hence i removed main belt to stop the play machanical process My only aim is If bt out put comes with full volume then 100% i will get full volume with play back Head signal
Regards
Krishna
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Old 17th May 2021, 11:36 am   #39
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Default Re: Grundig tk 24

[QUOTE=ms660;1375057]
Quote:
Originally Posted by reartech View Post
Quote:
Originally Posted by ms660 View Post
I think he might be saying that he can only play a tape with the tape recorder in the horizontal position (normal operating position) ?

Lawrence.
No sir dont get confusion to trace the problem I reversed the unit and in this stage i cant play tape due to gravity spool tape will fall down hence i connected BT there is no issue with machanisum it is ok
Which is basically what I was implying.

Could you feed your signal in again at the junction of contacts D1 and D4 (the input to C13) with the control set to Playback and report back with the result.

Lawrence.

Last edited by ms660; 17th May 2021 at 11:42 am. Reason: to make clearer
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Old 17th May 2021, 12:42 pm   #40
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Default Re: Grundig tk 24

[QUOTE=ms660;1375059]
Quote:
Originally Posted by ms660 View Post
Quote:
Originally Posted by reartech View Post
No sir dont get confusion to trace the problem I reversed the unit and in this stage i cant play tape due to gravity spool tape will fall down hence i connected BT there is no issue with machanisum it is ok
Which is basically what I was implying.

Could you feed your signal in again at the junction of contacts D1 and D4 (the input to C13) with the control set to Playback and report back with the result.

Lawrence.
Yes sir you are cached my point I given BT input to c13 directly now think that d1 is on audio is very low and if push d4 same signal audio is in full volume then i am not in a position to trace out what happens while d4 released audio became very low with same setting
Please guide me is my logic is correct
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