Re: Tandberg Huldra 8 valve failure
 

My feeling is what you saw was the reflection of the fuse blowing, this was visible through the magic eye.

here are the two parts of the circuit patched together

Re: Tandberg Huldra 8 valve failure
 

Stephen, that sounds like a good answer, because I have seen no indication of burning or discolouration, because it would probably light up like a bulb. now I just have to work out making a light bulb power supply and find the right fuses 30mm x 5 mm seem not to be as common, probably could fit 25mm x 5mm alright. did find the complete service manual online only in Norwegian I don't think they ever made an English version, maybe someone here knows?
in the meantime I will Google the text and cut and paste the diagrams 44 pages should keep me quiet. apparently there is no easy way of taking a PDF and translating it automatically, first to word for text. :idea:

Clive

Re: Tandberg Huldra 8 valve failure
 

Hi Clive,

I think I would tackle the set this way, start by removing the fuses, check to see if you have all the appropriate voltages between ground and at that point, after that, if you take your time, work through the circuit in a methodical manner, and if necessary unsolder components or leads at one end and check. It may seem a little daunting at first but I am sure you will get there, it also may be worth checking those electrolytic capacitors.

Best wishes and seasons greetings

Ken

Re: Tandberg Huldra 8 valve failure
 

Update, managed to get a couple of things done, made a dim light tester, had more trouble trying to find clear 100w bubs, still waiting on the fuses ordered some from England, best i could find was 5 x 20mm T 160mA240v ad some 6 x 32mm T 160mA240v. original was 20 x 30mm. i plugged the radio in without the fuse and the bulb did dim, so i think from where the fuse that went everything before that is OK, but it is very close to the transformer. now looking at the AM area on the radio inside i noticed this, a capacitor if i have identified correctly look like this...........see photo. in the picture you can see a wire going off to nowhere is this correct?? In the service manual it is identified as C216-HB 330pf 10% 500V Ceramic GIZ 606 LC. any suggestions welcome:wave: Happy New Year

Clive


Re: Tandberg Huldra 8 valve failure
 

So far as I can make out it's C220 (25pf-300pf) Haven't studied its function in detail but it looks like its part of a tuned filter circuit.

It's a wire type variable capacitor, the inside of the ceramic tube will have a metalized film inside which is one plate, the wire wrapped around the outside being the other plate, the number of turns of the wire being the adjustable bit.

Lawrence.

Re: Tandberg Huldra 8 valve failure
 

I think we have still missed something here, I agree that the fuse most probably emmitted the flash that was seen through the EM87 when it blew but for a fuse to emit a visible flash it means that it blew with a considerable overload. (i.e a short somewhere)

There is also thefact that you mentioned a burning smell that was detected when it happened, this seems to have since been forgotten.

I think that the HT rectifier and main smoothing capacitor need to be identified and checked as if this failed in a manner where it was supplying AC current into the smoothing capacitor it could well be responsible for emmitting the smoke and smell and the blowing of the fuse.

Cheers

Re: Tandberg Huldra 8 valve failure
 

Correction to my previous post: In the schematic I'm looking at the variable capacitor (C220) is connected in parallel with an inductor (L211) but I can't see that inductor in the board layout in the manual, it's possible that the wire end is part of the inductor, hard to call at the moment, let's see what the rest of the gang have to say.

Lawrence.

Re: Tandberg Huldra 8 valve failure
 

Canada has 120VAC 60Hz mains so the 130VAC selector might have been a better setting.

Re: Tandberg Huldra 8 valve failure
 

Here's the manual for what I assume is the correct one:

http://sportsbil.com/tandberg/huldra-8-sm.pdf

Lawrence.

Re: Tandberg Huldra 8 valve failure
 

Found L211 in the chassis layout on page 18 of the manual, on the board layout further on in the manual there are no connecting wires shown to connect the board to L211.

Based on that, then what I said in my original post still stands.

Lawrence.

Re: Tandberg Huldra 8 valve failure
 

Reading through this thread I find it astonishing that no attempt has been made to check the HT voltage or check for shorts across the HT supply, even though it has been suggested by several contributors. The OP has a meter which he used to check for continuity of the EM87's heater.

I reckon the OP will fit a new fuse and it'll blow again.

Re: Tandberg Huldra 8 valve failure
 

The rectifier fed from the 160mA fuse is component ref. D702, sometimes if they go short circuit they will split and emit a puff of smoke and a smell, best to check that first.....EDIT: Along with C703.

Lawrence.

Re: Tandberg Huldra 8 valve failure
 

Them rectifiers are ******* at letting the smoke out. Its a real problem getting the smoke back inside. Best fit a new one. :beer:

Re: Tandberg Huldra 8 valve failure
 

Just to add to the discussion on Magic Eye failures. The EM84 on my Philips B5S12A failed a few days into renovation.

I tested the resistor closest to it, R22 (560k) and found it to measure to infinity. After replacing the resistor, the Magic Eye works better than it did prior to the resistor change.

The old resistor was in the process of failing and even on a strong station the two sides barely reached their midway points. Now, a strong station almost has the two sides touching.

Re: Tandberg Huldra 8 valve failure
 

Hetrodyne mentioned i should have tried 130VAC instead of the 115VAC which i used, i made a mistake here i originally wrote 110VAC it is 115VAC:wall: would running at 130VAC make a difference? i haven't checked the HT voltage because i was waiting to get the dim bulb tester made...........i would be correct to use this device to check for shorts? as you can see i have missed some steps that most of you would have done automatically, i am on a learning curve here, so you will have to bare with me on missed steps.

Clive

Re: Tandberg Huldra 8 valve failure
 

If your meter has a diode test function then test D702 a shown in post #1 in this thread:-

https://www.vintage-radio.net/forum/...ad.php?t=42194

Do this with the unit powered down.

Re: Tandberg Huldra 8 valve failure
 

Thanks Graham, i have the same meter series II, on another note i see you do classic car restoration...........same here collect english cars and motorcycles. your avitar pic looks like a 25Pdr? I work in collections at the Royal Canadian Artillery Museum here is a link, been here for 17 yrs. http://en.rcamuseum.com

Re: Tandberg Huldra 8 valve failure
 

Hi roverp.

The picture of the gun was taken outside a military museum in St Petersburg Russia a few years back. I have no more details. Discussions about weapons are outside the scope of the forums.

Please let us know the result of the diode testing so we can progress this repair.

Re: Tandberg Huldra 8 valve failure
 

Graham, point taken on off topic. now here are two photos of the Fig 47 in the manual marked on the circuit board # 10047 mine is marked 10047-2, underside view do i have them correctly identified. here is photo topside same board marked as i think is right. function test on D 702 continuity on the left side as you look at it in the pic, now with power on, but remember there is no fuse in that went got a reading of 11.38 maybe i don't have this right

Re: Tandberg Huldra 8 valve failure
 

found this picture of a BY112 Silicon rectifier 400 V, 0.7 A made by AEG which is listed in the manual as D702.
looking at this it doesn't match what i marked as D702, is this what i should be looking for