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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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16th Aug 2022, 11:58 pm | #21 |
Dekatron
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Re: Grundig TK 8/3D Check Out
The recordings above were all done at 3 3/4 ips because the TK 5 is only a single speed machine.
So I must do some recordings on the TK 8 at 7 1/2 ips and compare the results with the same music recorded at 3 3/4 ips on the TK 5. David Last edited by DMcMahon; 17th Aug 2022 at 12:03 am. |
17th Aug 2022, 9:27 am | #22 |
Dekatron
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Re: Grundig TK 8/3D Check Out
Previoulsy while checking HT voltages, found an intermittent problem with the mains ripple voltage at main HT reservoir capacitor C32 (40uF), sometimes it was normal/good and at other times the ripple would increase a lot to around 35 volts peak to peak (plus ripple frequency would increase and waveform become messy plus HT DC voltage would drop somewhat).
Replacing C32 with a new 47uF 450 volt cured the issue. Monitoring the HT voltages during the record howl problem, they all remain clean and stable. David |
17th Aug 2022, 12:11 pm | #23 | |
Dekatron
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Re: Grundig TK 8/3D Check Out
Quote:
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17th Aug 2022, 2:14 pm | #24 |
Dekatron
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Re: Grundig TK 8/3D Check Out
Thank you Ted, I can now see the blanking plate fitted in one of the photos in the Service manual but am struggling to get it to clip into the top of the speed change slider.
I have not yet closely looked at the heads condition (plus I am not good at interpreting head wear) but think the TK 5 heads look more worn, will post some photos. David |
18th Aug 2022, 7:04 pm | #25 | |
Dekatron
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Re: Grundig TK 8/3D Check Out
Quote:
David |
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18th Aug 2022, 7:12 pm | #26 |
Dekatron
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Re: Grundig TK 8/3D Check Out
TK 5 and TK 8 Head photos.
David |
18th Aug 2022, 10:30 pm | #27 |
Dekatron
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Re: Grundig TK 8/3D Check Out
Erase heads seldom cause trouble. The TK8 R/P head looks pretty fair - some asymmetrical wear but the polepieces are still of full width. Something has been at the TK5 head, I'd say, whether it be a hardened pressure pad wearing it unevenly or a sharp instrument. The RH polepiece is starting to erode, too. A thorough clean would distinguish dirt from damage, and perhaps a gentle re-lap with crocus paper would help.
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19th Aug 2022, 10:19 am | #28 |
Dekatron
Join Date: Apr 2019
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Re: Grundig TK 8/3D Check Out
Thank you Ted for your head wear/condition analysis.
The felt pressure pad on the TK 5 that presses up against the PB/Record head is a little hard but no worse than the TK 8 pressure pad. Because the playback sound on the TK 5 sounds pretty good I think at this stage I will not attempt any re-lapping. David |
19th Aug 2022, 10:36 am | #29 |
Octode
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Re: Grundig TK 8/3D Check Out
Re the TK5 head I agree with Ted, an abnormal wear pattern especially on the lower side. Hard to be sure though. The lighting may be exaggerating the extent of the wear. Regardless, it looks like a great candidate for a careful relap to at least remove the ridges.
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19th Aug 2022, 11:22 pm | #30 |
Dekatron
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Re: Grundig TK 8/3D Check Out
I have never done any head relapping work before so a bit wary of trying it, especailly when it sounds OK to my hearing, i.e. would not want to screw it up with over zealous relapping attempt.
Once I find my crocus paper I may have a go after doing another thorough head clean. David |