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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 Feb 2019, 4:34 pm   #1
jimboradio1
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Default Grundig TK141 very low sound

I have a TK141 R to R. All seems to operate fine, but it won't play louder.
I have the service pack with it (not that I'd know what to do with it).

Any generic faults on these?
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Old 15th Feb 2019, 10:27 pm   #2
TIMTAPE
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Default Re: Grundig TK141 very low sound

Is the playback head face very clean and the tape making excellent intimate contact with the tape head face?
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Old 16th Feb 2019, 10:25 am   #3
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Default Re: Grundig TK141 very low sound

I will check that, what would be an acceptable cleaner for the head?
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Old 16th Feb 2019, 11:25 am   #4
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Default Re: Grundig TK141 very low sound

A cotton bud which has been dipped in Iso-propyl alcohol. This cleaner is otherwise known as Propanol or IPA and can be bought from a Chemist's shop.

When cleaning don't put to much IPA on the bud - ie not dripping wet! - and then rub carefully making sure that you get right into the corners of both the heads and the tape guides.

Give it a few minutes to fully dry off.
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Old 16th Feb 2019, 12:38 pm   #5
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Default Re: Grundig TK141 very low sound

Ok tape appears to be making good physical contact with the heads and have obtained IPA cleaned and dryed.. No change.
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Old 16th Feb 2019, 6:17 pm   #6
Edward Huggins
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Default Re: Grundig TK141 very low sound

When you say "it won't play louder", what does this really mean?
Do you have to use it with the volume, say, at maximum to get an acceptable level?
If so, there may be attendant issues with hum/hiss/noise when used on full.
It might be any electronic problem with record/replay levels or a low HT supply....
What is your skill level in fault finding on old mains operated equipment like this?
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Old 16th Feb 2019, 7:11 pm   #7
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Default Re: Grundig TK141 very low sound

The official BBC method for cleaning tape heads was something like this:
  • Use any alcohol-based solvent (ordinary methylated spirits was generally used on audio equipment; isopropanol or special mixtures might have been used for video machines. If in doubt follow manufacturers' recommendations. Or just use methylated spirits.) applied on a cotton bud.
  • Use a fresh cotton bud for each head, tape guide, the capstan and pinch roller. When the cotton bud is as dirty as it can get, use the other end.
  • When the cotton bud does not appear to be getting any dirtier, move on to the next tape path element.
  • Now the tape heads are only slightly filthy. Repeat from the beginning, using twice as many cotton buds as you used the first time.
Seriously, though, it's a mistake to stop just at the point you can't see any more dirt coming off. There might yet be one more stubborn bit, and that really is all it takes to ruin the tape-to-head contact.
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Old 17th Feb 2019, 9:44 am   #8
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Default Re: Grundig TK141 very low sound

Thanks for that Julie,Will give another try.
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Old 17th Feb 2019, 9:59 am   #9
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Default Re: Grundig TK141 very low sound

Edward the the sound has to be up full to hear anything at all and then can only just hear it, So volume control is working, head is playing, I'm just not getting any amlipfied sound if that makes sense.

My knowledge of electrical fault finding is OK, Knowledge of electronic fault finding is limited (Only got through six months of 2240 before work commitments forced me to stop).

I under stand the basics of components and circuits just wouldn't know where to start testing although I do have the service pack with it if somebody has the time to point me in the right direction it would be very much appreciated.
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Old 18th Feb 2019, 2:56 pm   #10
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Default Re: Grundig TK141 very low sound

When you say "Service pack", do you mean the Service Sheet which should show the circuit diagram and the associated voltages? If so, you can start checking the HT voltages coming from the rectifier that supplies power the amplifier circuit.
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Old 19th Feb 2019, 11:54 pm   #11
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Default Re: Grundig TK141 very low sound

This is what a have, Says service manual not service sheet is this what I need
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Old 20th Feb 2019, 8:51 am   #12
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Default Re: Grundig TK141 very low sound

What you have said might be caused by the tape facing backwards.

This may be due to several reasons, especially on a long unused machine.

As to the loudness of the machine, it might be checked by setting up to record with the microphone. Observe the recording meter.

You might also try advancing the volume carefully to see if the machine and mike act as an amplifier.

Here is a link to a video. https://www.youtube.com/watch?v=kcDHKxn-g_I
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Old 20th Feb 2019, 11:08 am   #13
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Default Re: Grundig TK141 very low sound

It's worth selecting play with no tape and touching the head's wire to the track switch at full volume. There should be a noticeable hum which will bellow when you touch the wire! No shock hazard here. Also the switch should crackle when the tracks are selected.
If this isn't the case it's an amplifier fault, though the speaker could be the problem. It's a fairly basic transistor amplifier so shouldn't be too complicated to fix if that's the problem, though of course go through the cleaning procedure described above.
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Old 21st Feb 2019, 4:24 pm   #14
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Default Re: Grundig TK141 very low sound

Ok.. With no mic available engage record and now have volume tone and rec volume and the hiss coming from the speaker.
On play ( Tape is the correct way round ) can only just hear sound with the volume up full, no real noticeable increase in sound if I brush my finger across the pick up terminals.

So is this now pointing towards an amp fault?
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Old 21st Feb 2019, 8:11 pm   #15
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Default Re: Grundig TK141 very low sound

I also did give the heads a good clean.
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Old 22nd Feb 2019, 11:20 am   #16
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Default Re: Grundig TK141 very low sound

Using a Q-Tip, try the following:

While the tape is playing with a muffled sound, try gently
pressing the the tape against the tape head.

There are two heads, erase and play.


Another test, while a tape is playing, (one you do not want) ,
stop the tape. Then press the recording button and let run for
a few feet of tape.

Rewind it back over that spot, try playing it, and see if the
sound that was there has been erased.
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Old 27th Feb 2019, 1:06 pm   #17
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Default Re: Grundig TK141 very low sound

Pressing the tape against the head has no affect, recording over a section of tape does errase it.
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Old 27th Feb 2019, 2:05 pm   #18
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Default Re: Grundig TK141 very low sound

Could some kind soul help me what to start checking please.
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Old 27th Feb 2019, 2:52 pm   #19
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Default Re: Grundig TK141 very low sound

Make sure the heads are actually clean, some magnification is needed to be sure, what can happen to the untrained is that they apply a cotton bud soaked in cleaner to the heads and start rubbing and either no muck comes off or fair bit of brown muck comes off to start with then nothing, either way they think the heads are clean....not always so....what can happen is that the real stubborn muck (it doesn't take much to screw up recording) has hardened and some times has "glazed" over making its removal more difficult than normal, hence a check with a magnifier is advisable, my weapon of choice was a magnifying dental inspection mirror, also indispensable for checking proper cleaning of the tape guides, tension arm, capstan etc and general tape path alignment etc

Lawrence.
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Old 27th Feb 2019, 6:59 pm   #20
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Default Re: Grundig TK141 very low sound

Thanks for that Lawrence ,I currently have it upside down for voltage and transistor testing but if I draw a blank I'll be back to the heads with a magnifier.

Jim.
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