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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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20th May 2018, 5:49 pm | #21 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
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Re: Restaurare Leak III ST Refurbishing
Nice case Ken, congratulations for your work.
By the way, did you change the ancien antena conector for a modern 75 ohms? How? |
20th May 2018, 7:16 pm | #22 |
Octode
Join Date: Mar 2015
Location: Yorkshire, England.
Posts: 1,294
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Re: Restaurare Leak III ST Refurbishing
No, I have a ribbon aerial connected across the 300 ohm
Screws. It's all l need as I'm only a quarter of a mile from the local repeater transmitter.
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Regards, Ken. BVWS member |
20th May 2018, 7:22 pm | #23 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
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Re: Restaurare Leak III ST Refurbishing
You are using the One Thing.... decoder? are you happy with?
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21st May 2018, 12:19 pm | #24 |
Octode
Join Date: Mar 2015
Location: Yorkshire, England.
Posts: 1,294
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Re: Restaurare Leak III ST Refurbishing
Yes. I should really do a write up and post it in success stories. This was my first restoration and l spent almost 60 hours on it, spaced over a seven week period.
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Regards, Ken. BVWS member |
21st May 2018, 12:25 pm | #25 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
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Re: Restaurare Leak III ST Refurbishing
What do you think about Neville Roberts restauration kit? published on HIFI-Collective
Has anyboady an oficial part list for the Leak III ? |
21st May 2018, 12:38 pm | #26 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
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Re: Restaurare Leak III ST Refurbishing
How did you conect it? directly to the MPX out using a coupling capacitor, or throu the cathode follower?
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21st May 2018, 2:53 pm | #27 |
Octode
Join Date: Mar 2015
Location: Yorkshire, England.
Posts: 1,294
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Re: Restaurare Leak III ST Refurbishing
I honestly don't remember! I'll dig out the notes and write it up next week!
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Regards, Ken. BVWS member |
21st May 2018, 3:25 pm | #28 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
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Re: Restaurare Leak III ST Refurbishing
OK, thanks.
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23rd May 2018, 4:27 pm | #29 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
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Re: Restaurare Leak III ST Refurbishing
Parts are ariving, first the PSU capacitors from F&T
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11th Jun 2018, 11:17 am | #30 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
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Re: Restaurare Leak III ST Refurbishing
Now I stared up with my restoration.
First stepp was measuring resistors (all of them) Pulling out the tubes I asume i can check all of them without unsoldering. The result was not verry promising as many of them were out of 10% tolerance. The worst were: R2=166k(220k) R3=115k(100k) R5=30,7(33) R7=380k(680k) R8=378k(680k) R9=14k(68k) can be a mesuring fault, I have to unslder R10=41k(33k) R11=18k(47k) can be a mesuring fault, I have to unslder R15=123k(100k) R19=206k(470k) R25=452k(470k) R25=121k(100k) R27=52k(47k) R30=815k(680k) R36=56k(47k) R38=12k(10k) All cheramic capacitors I asume are all right The electrolotics I have allready changed all with modern one as well as the C47 and C53 with MKp. As I intend to use an external MPX decoder from Fisher(MPX 100) I did not care about the internal decoder compoments. Your opinion shall be usefull to me. Shall I change all resistors or else? |
11th Jun 2018, 12:44 pm | #31 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Restaurare Leak III ST Refurbishing
If you are measuring the resistors with them still connected in circuit there will be some parallel resistance paths.
Lawrence. |
11th Jun 2018, 5:01 pm | #32 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
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Re: Restaurare Leak III ST Refurbishing
I knew it from the beginning, but having a close look to the diagram and excluding the tubes, only the capacitors can make some changes but not too significant. I marked the nevralgic points where I have to unsoler.
Unsoldering such a spatial structure, can damage sometimes much more than out of tolerance resistors. |
11th Jun 2018, 5:23 pm | #33 | |
Dekatron
Join Date: Sep 2003
Location: Near Swindon, North Wiltshire, UK.
Posts: 3,595
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Re: Restaurare Leak III ST Refurbishing
Quote:
Of course, in the RF stages, you must be very careful to fit the new resistors in exactly the same positioning as the originals. Make careful drawings, before fitting replacements, to avoid disturbing the RF circuit’s alignment. Last edited by dazzlevision; 11th Jun 2018 at 5:25 pm. Reason: Added text. |
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11th Jun 2018, 5:47 pm | #34 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Restaurare Leak III ST Refurbishing
Just to be clear, if measuring the resistors while connected in circuit R2, R7, R8 and R19 in your list all have parallel resistance paths in the schematic, for example:
R2 has a resistance in parallel due to R19 and R20. R7 has a resistance in parallel due to R8, R6 and R9 (R9 is connected across the HT for temperature compensation) R8 has a resistance in parallel due to R7, R6 and R9. R19 has a resistance in parallel due R20 and R2. There are others too, notably around the discriminator. Lawrence. |
11th Jun 2018, 7:58 pm | #35 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
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Re: Restaurare Leak III ST Refurbishing
I cant say contrary, but what do you suggest......unsoldering all my cause a mass....what shall I do?
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11th Jun 2018, 8:57 pm | #36 | |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Restaurare Leak III ST Refurbishing
Quote:
You can do the same calculation for the others, here's the calculator I use: http://www.sengpielaudio.com/calculator-paralresist.htm Lawrence. |
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11th Jun 2018, 9:02 pm | #37 | ||
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
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Re: Restaurare Leak III ST Refurbishing
Quote:
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11th Jun 2018, 9:32 pm | #38 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Restaurare Leak III ST Refurbishing
You cannot check a capacitor properly if there is a parallel path unless you disconnect it, to test for leakage it should be tested at it's rated voltage or at least it's working circuit voltage if possible.
Ceramic capacitors are usually reliable, especially in tuned or low voltage circuits. Lawrence. |
13th Jun 2018, 8:02 am | #39 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
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Re: Restaurare Leak III ST Refurbishing
Hi Lawrence,
I had remake the calculations, you was right, large part of resistors revial better tolerances than 10%. Nevertheless R9 was too low and athers where too high especialy R3, R10, R26, R27, R30, R36 R38, Which I suppose are out of range. I shal start slowly, slowly to unsolder and change them with Kiwame as they are carbon type and claim to be noninductive. I can use also AB as I have a lott but I am afraid not to be so stabile. Last edited by victor54; 13th Jun 2018 at 8:12 am. |
14th Jun 2018, 6:22 pm | #40 |
Triode
Join Date: May 2018
Location: Bucharest, Romania
Posts: 46
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Re: Restaurare Leak III ST Refurbishing
Having a look inside
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