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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 31st Aug 2018, 1:46 pm   #1
Geoff 555
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Default Trio 9R-59

Hello all. Sorry to bother you but I have a couple of problems that I would be most grateful for any help you may be able to give please.
First is a circuit diagram, I did down load one but it was unreadable, the second problem is a audio hum which starts as soon as it is switched on (it is imediate).
So far I have replaced the 5Y3, the old one produced a crackle if it were gently tapped.
The two 40 mF @ 300V. was replaced by two at 32 mF @ 500V. The max. for the 5Y3 being 32. The can was the original one that read 43 mF.
All the valve holders etc. were cleaned.
There is a crackle if the chassis is touched with a screwdriver.
There is no earth connected and the only one I have is a mains one, if I connect the radio earth to the mains earth the the trip trips.
Cheers and thank you.
Geoff.
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Old 31st Aug 2018, 3:59 pm   #2
ukcol
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Default Re: Trio 9R-59

There is a good quality schematic available for download FOC at radiomuseum.

https://www.radiomuseum.org/r/trio_kenwo_9r_59.html

They also have diagrams for the DE and DS versions.
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Old 31st Aug 2018, 4:12 pm   #3
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Default Re: Trio 9R-59

Search the forum for this model, plenty posts and advice.
Modifications in Radio Constructor
https://www.americanradiohistory.com...RC-1970-10.pdf
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Old 31st Aug 2018, 6:22 pm   #4
buggies
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Default Re: Trio 9R-59

The radio museum circuit portion I looked at was for 117v mains but had a single capacitor, C28, from the switched side (line?) to chassis but nothing from neutral.
I would imagine, even if the cap is not leaky, it might trip a sensitive RCD when you earth the chassis.
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Old 31st Aug 2018, 7:40 pm   #5
Andrew2
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Default Re: Trio 9R-59

The later 9R59D sets were well known for giving a bit of a 'buzz' if touched lightly by the back of the hand! I suspect the earlier version was similar.
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Old 1st Sep 2018, 8:46 pm   #6
James Duncan
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Default Re: Trio 9R-59

check the grid of the output valve for dc volts.
if there is any then change the capacitor that you will find attached to the grid.
MM0HDW
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Old 1st Sep 2018, 10:06 pm   #7
Geoff 555
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Default Re: Trio 9R-59

Many thanks gentlemen, at least I now have a diagram I can read. I have found 1 thing, Hum was present when using earphones but was not present when used with a speaker!!Thank you again now I can have a look and see what is going on.
Cheers.
Geoff.
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Old 2nd Sep 2018, 3:27 pm   #8
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Default Re: Trio 9R-59

To reduce the 'tingle' you could try reversing the mains lead at the plug but better still fit a three wire mains lead.

One source of hum, particularly on headphones, never seems to get a mention. The volume control is before the triode amplifier which has a very high gain and is sensitive to hum pickup. It would be better if the volume control was after the triode amplifier.
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Old 5th Sep 2018, 9:21 pm   #9
Geoff 555
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Default Re: Trio 9R-59

Hello See Mos reversing the mains lead made not a lot of difference, fitting a earth lead presents a bit of a problem. There is a link from A2 (aerial) to the Earth terminal which improves the signal, here there is a reception problem, connecting an Earth lead results in the trip tripping.
Leaving the earth lead off seems to be the answer.
Cheers.
Geoff.
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Old 12th Sep 2018, 10:01 am   #10
See_Mos
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Default Re: Trio 9R-59

With the earth connected you could try lifting one end of the capacitor that goes from the live to chassis. If you don't get even more hum when tuned to strong stations just leave the capacitor out.

Alternatively try moving the earthy end of the capacitor to the neutral side of the mains.

The capacitor is probably OK but it might be worth checking it for leakage while it is disconnected. Use an insulation tester if possible, an analogue AVO on the high range is OK but a digital meter is not much use for checking leakage.
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