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Old 6th Jan 2017, 10:15 pm   #81
roverp6
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Default Re: Tandberg Huldra 8 valve failure

here is the volt reading across the fuse holder T1160mA250V. this powered up running through the dim bulb tester 60w bulb
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Old 6th Jan 2017, 10:52 pm   #82
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Default Re: Tandberg Huldra 8 valve failure

That's good. All you need now are some 160mA fuses.
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Old 7th Jan 2017, 1:07 am   #83
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Default Re: Tandberg Huldra 8 valve failure

Thanks Graham will report back when the supplies come in and to all who helped so far
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Old 11th Jan 2017, 9:12 pm   #84
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Default Re: Tandberg Huldra 8 valve failure

i need to order some capacitors from Just Radios here are the original values: replacements in bold
0.01 uF 1000V (Rifa brand)
replacement 0.01uF 1000V Tubular Axial Metalized Polyester/Polypropylene Film Capacitor

0.022 uF 400V (Rifa brand)
.022 uF at 400 V 2G 223J Mylar Polyester Film "Green Dips" ( 400V)


32 uf 350v (Electrolyte PEG 1081 E/74 Rifa)
33 uF at 350V axial E-caps @ 350 Volts

are my choices right?
noticed he has capacitor kits is this a good option?
if i cant find 400V capacitors in the specification can one go up to 630V? in the correct uF value.

Clive
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Old 11th Jan 2017, 10:15 pm   #85
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Default Re: Tandberg Huldra 8 valve failure

The caps you've chosen will be fine.

There is no harm in using caps of a higher voltage rating than the originals.
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Old 11th Jan 2017, 11:02 pm   #86
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Default Re: Tandberg Huldra 8 valve failure

Thanks Graham
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Old 18th Feb 2017, 3:14 am   #87
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Default Re: Tandberg Huldra 8 valve failure

Brief Update: put the new fuse in and capacitor plug in to the dim bulb tester.
no flashes,smoke. the magic eye did move with signal strength on FM, that's the only band i used...........first noticeable observation no audio nothing even moving from record player and back to radio. one valve i noticed doesn't appear to light up all the other 4 do it is identified as EF89 see section of diagram were it is located, is it in he amplifier section? and how do you check for continuity? which pins.
Thanks

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Old 18th Feb 2017, 3:27 am   #88
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Default Re: Tandberg Huldra 8 valve failure

Pins 4 and 5, as shown on your diagram.
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Old 18th Feb 2017, 9:17 am   #89
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Default Re: Tandberg Huldra 8 valve failure

The EF89 is used as a Radio Frequency amplifier. It could explain the blown fuse if it had an internal structure short.
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Old 18th Feb 2017, 11:08 am   #90
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Default Re: Tandberg Huldra 8 valve failure

Yes, correct, the output of this valve feeds the FM discriminator and then on to audio amplification and output. If this valve is not lit then there will certainly be no audio.

As the magic eye is responding this is a good indication that the radio is receiving signals.

We are close now. Get a replacement EF89.

Cheers
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Old 18th Feb 2017, 11:24 am   #91
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Default Re: Tandberg Huldra 8 valve failure

I'm confused as to why the magic eye would work when tuning FM if the EF89 was duff?

Lawrence.
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Old 18th Feb 2017, 11:31 am   #92
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Default Re: Tandberg Huldra 8 valve failure

Am I right in thinking that the EM87 gets its signal from the EAF801 output via D201 which is before the EF89 demodulation stage?

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Old 18th Feb 2017, 11:35 am   #93
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Default Re: Tandberg Huldra 8 valve failure

Yes, so far as I can make out on AM, on FM it appears to be via R220 and R221.

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Old 18th Feb 2017, 11:37 am   #94
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Default Re: Tandberg Huldra 8 valve failure

Ah hold on, looking at the circuit it would seem that I have described how the EM87 gets its signal on AM!

It looks indeed as though the EM87 gets its signal from the output of the discriminator on FM so yes, I cannot see how it is working with a dead EF89.

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Old 18th Feb 2017, 6:23 pm   #95
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Default Re: Tandberg Huldra 8 valve failure

ordering a replacement EF89 will be my next step, then we shall see how we progress, excellent support as usual.

Clive
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Old 19th Feb 2017, 2:32 am   #96
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Default Re: Tandberg Huldra 8 valve failure

here are some pics of readings taken from the valve base pins 2 and 3 of EF89, and the magic eye tuned to a FM station.
Clive
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Old 19th Feb 2017, 2:42 am   #97
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Default Re: Tandberg Huldra 8 valve failure

You're numbering the valve pins the wrong way.
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Old 19th Feb 2017, 3:09 am   #98
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Default Re: Tandberg Huldra 8 valve failure

Graham so the pins i listed should be 9,8,7 corrected picture
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Old 19th Feb 2017, 6:22 am   #99
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Default Re: Tandberg Huldra 8 valve failure

Yes, exactly. Valve pins are numbered in the same fashion as IC pins; increasing anticlockwise from the break, as you look down into the valveholder. (This sounds a bit wrong, because valves were around before ICs, but you know what I mean; semiconductor manufacturers just adapted the existing numbering scheme for valve pins.) However, valves are conventionally viewed from underneath the chassis; so on this side, the pins numbers increase clockwise from the break.
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Old 19th Feb 2017, 8:07 am   #100
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Default Re: Tandberg Huldra 8 valve failure

I thought that the EF89 wasn't lighting up? That being the case you need to check the voltage BETWEEN pins 4 and 5 of the valveholder and the resistance between pins 4 and 5 of the valve.
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