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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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18th May 2021, 5:56 pm | #61 |
Triode
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Re: Grundig tk 24
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18th May 2021, 6:20 pm | #62 |
Dekatron
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Re: Grundig tk 24
Other voltages aside, pins 2 and 7 should be 0v or almost 0v when measured with respect to ground, any positive voltage on those pins will reduce the anode voltage, measure pins 2 and 7 again with the valve removed, if they still measure positive I would check the coupling capacitors to the control grids (C17, C18, C20)
Lawrence. Last edited by ms660; 18th May 2021 at 6:29 pm. Reason: extra info |
18th May 2021, 8:14 pm | #63 |
Dekatron
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Re: Grundig tk 24
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18th May 2021, 10:18 pm | #64 |
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Re: Grundig tk 24
If you have not already done it, it is important also to check the Control grid voltage of the EL 95 output pentode at pin 1. As per the ECC 81 Control grids, if any +ve voltage then best to replace both C22 (0.1uF) & C26 (0.047uF).
David |
18th May 2021, 11:07 pm | #65 | |
Triode
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Re: Grundig tk 24
Quote:
Krishna |
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18th May 2021, 11:08 pm | #66 |
Triode
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Re: Grundig tk 24
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18th May 2021, 11:09 pm | #67 | |
Triode
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Re: Grundig tk 24
Quote:
Krishna |
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18th May 2021, 11:49 pm | #68 |
Dekatron
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Re: Grundig tk 24
Watching your video I find the point where you lift up the relay to get good playback sound confusing.
The relay is the Playback/Record relay (W) which is energised in Playback mode. It looks like you are lifting up the relay armature plate which is the same as the relay being de-energised which equates to Record mode but this seems to be when you get good volume, to me this appears to be the opposite of what you were describing ? David |
19th May 2021, 12:06 am | #69 | |
Triode
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Re: Grundig tk 24
Quote:
Krishna |
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19th May 2021, 12:14 am | #70 | ||
Triode
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Re: Grundig tk 24
Quote:
cap leg removed from pin 2 shows 150v cap leg removed from pin 6 shows 4 volts What next ? Krishna |
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19th May 2021, 7:42 am | #71 |
Dekatron
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Re: Grundig tk 24
Definitely replace C20, it is very electrically leaky indicated by the 150V measurement.
I assume your "cap leg removed from pin 6 shows 4 volts" should have read "cap leg removed from pin 7 shows 4 volts". The 4V (1V when connected) shows that both C17 and C18 are both somewhat electrically leaky so best also to replace C17 & C18, they will only get worse with age anyway. David Last edited by DMcMahon; 19th May 2021 at 7:49 am. |
19th May 2021, 8:09 am | #72 | |
Triode
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Re: Grundig tk 24
Quote:
Regards Krishna |
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19th May 2021, 8:36 am | #73 |
Dekatron
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Re: Grundig tk 24
Still strongly recommend to check the output pentode Control grid voltage as per Post 64.
If C22 and C26 are electrically leaky or become leaky later then worse case scenario is that the output transformer could get damaged. If you have an insulation tester/Megger then you could test the coupling capacitors (out of circuit) for their resistance. Test at their rated voltage or at least their circuit working voltage, you will see that new capacitors will be virtually infinite (> 100s MOhms) and old/bad capacitors will be much lower value. David |
19th May 2021, 8:40 am | #74 | |
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Re: Grundig tk 24
Quote:
David |
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21st May 2021, 11:07 pm | #75 | ||
Triode
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Re: Grundig tk 24
Quote:
thank u regards krishna |
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21st May 2021, 11:54 pm | #76 |
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Re: Grundig tk 24
You do not have to use old capacitors, even if you source NOS (New Old stock) due to age they can be bad as well.
Any good quality modern capacitors such as Polyester, Ceramic, Polypropylene etc will do. I personally prefer Polypropylene Metal Film, I use 630VDC rated axials but not the expensive Hi-Fi audio grade type. David Last edited by DMcMahon; 22nd May 2021 at 12:13 am. Reason: Typo correction |
6th Oct 2021, 9:21 am | #77 |
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Re: Grundig tk 24
Krishna, how is the TK 24 ? hopefully you were able to resolve the issue (s).
David |