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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

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Old 13th Aug 2018, 4:53 pm   #21
PJL
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Default Re: LMT 67 radio.

And unless you are lucky, the tuning indicator will have black soot on the inside and you won't be able to see the neon illumination.
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Old 13th Aug 2018, 5:04 pm   #22
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Default Re: LMT 67 radio.

It looks immaculate thankfully. I'll keep you all informed as to what's what.
Thanks
R
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Old 13th Aug 2018, 5:08 pm   #23
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Default Re: LMT 67 radio.

Just a thought, the 66 has an indicator bulb switched in when PU is selected.

Lawrence.
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Old 13th Aug 2018, 5:16 pm   #24
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Default Re: LMT 67 radio.

Aha! That sounds plausible. I'll fit valves to 63 spec and dim bulb test..
Thanks again

R
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Old 15th Aug 2018, 12:38 pm   #25
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Default Re: LMT 67 radio.

I have a few 0.5MF caps to replace - the existing are rated at 800v CC (presumably continuous current?), the schematic calling for 1500v. The highest voltages I've managed to find so far are only 630v. Can anyone point me in the right direction please?
Cheers

R
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Old 15th Aug 2018, 1:07 pm   #26
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Default Re: LMT 67 radio.

Herewith a photo of one. Above is a glass cap with no visible markings. It doesn't apper to be on the schematic for the LMT 63. Any way to ascertain it's value?
Cheers
R
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Old 15th Aug 2018, 1:15 pm   #27
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Default Re: LMT 67 radio.

CC = Max working DC voltage.

Ignore 1500 (volts) in the schematic components list, 630 volt rating will be fine for all the old paper capacitor replacements except for C29 and possibly C21.

If replacing C21 some folks would use a 1,000 volt DC rating.

C29 (if fitted) needs to be Y Class.

EDIT: There should be some markings on that glass capacitor somewhere.

Lawrence.
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Old 15th Aug 2018, 2:34 pm   #28
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Default Re: LMT 67 radio.

The black tar has covered all except what appears to be a "0".
It appears to be between aforementioned bobine L6 and pin 2 of the 89 (assuming I've read it correctly from underneath?). There is another wire going to chassis from the end connected to L6.
The other side of the bobine goes to C22 C23 and R20

RR

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Old 15th Aug 2018, 3:03 pm   #29
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Default Re: LMT 67 radio.

89 valve pinout from underneath here....fat pins are 1&6:

https://frank.pocnet.net/sheets/021/8/89.pdf

Lawrence.
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Old 15th Aug 2018, 3:17 pm   #30
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Default Re: LMT 67 radio.

Pin 3. Sorry
R
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Old 15th Aug 2018, 3:21 pm   #31
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Default Re: LMT 67 radio.

That's looking like C20 on the 63 schematic.

Lawrence.
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Old 15th Aug 2018, 3:36 pm   #32
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Default Re: LMT 67 radio.

Absolutely, but that leaves the 0.5MF beneath it in the photo which sort of appears on the schematic covering C3 ("C3 au dessous"), but not really numbered...unless that is "C9" bottom left of C3 dotted line? Have we cracked it?
R
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Old 15th Aug 2018, 3:49 pm   #33
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Default Re: LMT 67 radio.

C9 hides C3 on the schematic component layout, C9 is 0.5uF, I suspect that the capacitor with the unknown value is C20 (0.5uF) That would fit the bill for a screen grid de-coupling capacitor.

Lawrence.
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Old 15th Aug 2018, 3:55 pm   #34
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Default Re: LMT 67 radio.

Thank you for sharing your knowlege with tolerance!

R
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Old 18th Aug 2018, 1:14 pm   #35
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Default Re: LMT 67 radio.

I was about to replace coupling cap C18. However, where C18 should be is this cap branded Alter marked 1200 on one side and 1500 AC and CM on the other. Assuming this means 1200 cm, and that equates to approx 1200pf, this is nowhere near the prescribed 0.1µf C18.
Any suggestions?
Cheers
R
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Old 18th Aug 2018, 5:48 pm   #36
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Default Re: LMT 67 radio.

If it is the output valve's grid coupling capacitor then for a common value replacement use a 0.0015uF, the value given in the components list for the grid coupler (0.1uf) seems too high to me, not usually that high in value, normally 0.01uF to 0.05uf fitted in most valve receivers but lower than 0.01uf is not unheard of.

Lawrence.
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Old 18th Aug 2018, 10:31 pm   #37
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Default Re: LMT 67 radio.



R
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