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Old 18th Dec 2016, 3:24 am   #1
roverp6
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Default Tandberg Huldra 8 valve failure

Hello, new to this forum. Just got a Huldra 8 shipped from Norway to me here in Canada. Changed the voltage selector to 110 and it worked perfectly. Had it running 10 minutes and saw the flash and smell, quickly turned off and found the "Electric Eye" EM87 had blown, and one fuse T160/250. If the valve EM87 does it kill the ability of the radio working, or is it just for tuning the radio? As you can tell, I have limited experience with these, although I have a large collection of Reel to Reel equipment and such. I see I can get the exact replacement EM87, or exact replacement 6HU6. Should I stay away from the Chinese made ones. Any help would be appreciated.

Clive
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Old 18th Dec 2016, 9:24 am   #2
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Default Re: Tandberg Huldra 8 valve failure

The EM87 is purely a tuning indicator, so removing it will have no effect on reception, or on tuning, other than having to tune purely 'by ear'. I cannot comment on Chinese made Tuning indicator valves, having no experience of them. The fuse you mention may have blown simply because the EM87 failed, although I'm not familiar with the Tandberg Huldra, so it may be wise to check other components connected to the 'load' side of the fuse in question.
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Old 18th Dec 2016, 11:12 am   #3
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Default Re: Tandberg Huldra 8 valve failure

Magic eye tuning indicators just get progressively dimmer. Never heard of one 'blowing' before. Flash bang and smoke are surprising, unless it got cracked.

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Old 18th Dec 2016, 11:22 am   #4
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Default Re: Tandberg Huldra 8 valve failure

Hi Clive it may just be your terminology but what does "blown" mean

Its not terribly common for valves (tubes) to fail in a physical way that you can easily see.

The fuse that's blown is the HT fuse.

The Huldra 8 is a hybrid with 5 valves and 20 transistors

http://www.radiomuseum.org/r/tandberg_huldra_8.html

The loss of the HT fuse would mean the magic eye would not be lit.

Have you identified the component(s) that emitted the smoke?

Cheers

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Old 18th Dec 2016, 11:33 am   #5
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Default Re: Tandberg Huldra 8 valve failure

It will work perfectly without the eye. I would also be very surprised that even if the eye had 'blown', that it would have blown a fuse....the power requirements for the eye are very very low. What indications do you have that the eye has blown? Never heard of that before unless as previously stated it's cracked.

It's much more likely that something else has failed like the rectifier which may have flashed and sparked.
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Old 18th Dec 2016, 12:22 pm   #6
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Default Re: Tandberg Huldra 8 valve failure

If you can find a Chinese equivalent do then try one, the cost will not be high.
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Old 18th Dec 2016, 1:43 pm   #7
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Default Re: Tandberg Huldra 8 valve failure

Are some of the old Tandberg Huldras and Sølvsupers still worth going for sound wise? I have had a few very bad experiences with older speakers, which sounded horrible compared to new. I know turn tables can often be well worth fixing up, depending on the quality.

Old Tanberg stuff turn up here, the later stuff they made turn up much less frequent.
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Old 18th Dec 2016, 2:12 pm   #8
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Default Re: Tandberg Huldra 8 valve failure

There are plenty of good old speakers around. One problem is that those with plastic foam surrounds have suffered from the breakdown of the polymers. But the remains of the old ones can be carefully pared away and new ones glued in. There are replacement kits for most popular sizes of drive units. With a torn surround, the sound would have been horrible.

There have been some improvements in speaker technology as well as in design methods, but these aren't a substitute for physical size. Older speakers were not under the same pressure from fashion for small size, so if you have the space, a big older speaker can be a very good choice. My transmission line jobs are about the size of a 3-drawer filing cabinet, each.

The Huldras are nice old things but fairly rare in the UK. If shopping around, you can get better tuners and amplifiers for very little money. Few people know what old equipment is good and what was junk, so armed with some knowledge you can find bargains.

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Old 18th Dec 2016, 2:24 pm   #9
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Default Re: Tandberg Huldra 8 valve failure

Quote:
Originally Posted by Radio Wrangler View Post
...If shopping around, you can get better tuners and amplifiers for very little money. Few people know what old equipment is good and what was junk, so armed with some knowledge you can find bargains.
I'm trying to get an over view and I suppose I need to listen to different ones to get to know the difference.
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Old 18th Dec 2016, 3:50 pm   #10
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Default Re: Tandberg Huldra 8 valve failure

Listening might not be a good guide. Most things of this age will have suffered some degradation and not all by the same amount, so you really have to make a good choice based on what the thing will be like once put into good condition. I haven't a clue how this could be done with any confidence.

Looking at what people have said about various models back in their era is also of mixed value. Back in the seventies there were some trustworthy reviewers who were also technically competent, but from the eighties onwards opinion has been largely dominated by people with some very strange beliefs, a lot of disposable income, and very loud mouths. This group is a rather pleasant refuge from such silliness. I find that people here discuss reliability, weak-points, quality of construction and overall effectiveness in a rational and non-confrontational way. There is more emphasis on good engineering than there is on the latest fashionable adjectives.

Have a look around and see what's available locally. Auction sites tend to pump prices up to that which the keenest person on the planet will pay for a thing. This makes them by far the best place to sell, and maybe the worst place to buy. Bargains mostly happen locally.

Despite what a lot of people say, once you get above a reasonable level of amplifier, and have plenty of power for your needs, there isn't a great deal of difference. This goes against the might of the advertising industry, and countless thousands of people who will feel a little easier about THEIR purchases if only they can persuade you to buy one too. It proves that humans have a gregarious instinct.

Our village physician had a Huldra setup and I serviced it when needed. The tuner/amp was fine, the speakers weren't my style. It took me a while to realise that logo really was a girl with a cow's tail.

Me? I took the coward's way out and designed my own. It's funny if a visitor turns out to be an audio aficionado. There are no badges, no brand names, so they don't know how they're supposed to describe the sound. I find this hilarious.

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Old 18th Dec 2016, 5:55 pm   #11
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Default Re: Tandberg Huldra 8 valve failure

First off thank you for all the replies, here is a pic of the magic eye and you can see the broken filament. When the flash and smell happened I was watching from the front so I was unable to see where exactly it happened. Once the case was off I only was able to see the magic eye valve discoloured and removed it and the fuse that was shot. At first I was going by burnt smell sleuthing (amateur I know) someone mentioned the "rectifier" don't know where that is, I will take some pics of the inside you might be able to point it out for me. I have the schematics, but that will be a learning curve for me, have to start somewhere. While I did have it running it had excellent tone, and sensitivity to pull in stations. 1250 Kr was a lot of money in 1965. I am prepared to repair it and do the work myself if I can find replacement parts or modern equivalents.

The other Tandberg equipment I have are TP41, 10XD, 2075, 3014 and 2025.

Clive
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Old 18th Dec 2016, 7:41 pm   #12
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Default Re: Tandberg Huldra 8 valve failure

That is NOT a broken filament! The part you are indicating is a spring support for the electrode assembly....there is an identical one on the other side of the valve and these help to keep the assembly central within the envelope . The heater (filament assembly) is not really visible. Please just take my word for it. That EM87 of yours is probably OK. See the attached picture of a brand new Telefunken EM87 from my stock (and I guarantee that mine is OK)!

Actually the two heater (filament) supports/connections are shown from centre left diagonally to top centre.

You have another problem. It's not this valve but perhaps what caused the problem was another component mounted close by that was reflected behind or in the glass.

that looks like a perfectly good valve. The so-called discolouration (on the florescent strip) is caused by normal usage. The rest of the valve looks fine.
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Last edited by Sideband; 18th Dec 2016 at 7:48 pm.
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Old 18th Dec 2016, 8:00 pm   #13
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Default Re: Tandberg Huldra 8 valve failure

You can test the filament by checking for continuity between pins 4 and 5.

http://www.r-type.org/exhib/aad0128.htm
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Old 18th Dec 2016, 8:10 pm   #14
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Default Re: Tandberg Huldra 8 valve failure

Sideband, thanks for the reply, showing my ignorance . having a quick look around the web the "germanium AD150" seem to give problems from old age, but i havent found the problem yet

Clive
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Old 18th Dec 2016, 10:44 pm   #15
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Default Re: Tandberg Huldra 8 valve failure

checked the valve as digested and getting continuity on pins 4 and five, now i just have to search for a 160mA slow fuse, when plugged in again i can see power in the EM87 but no electric eye working probably because of the blown fuse? here are some pics of the underside and top view.

Thanks

Clive
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Old 18th Dec 2016, 11:18 pm   #16
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Default Re: Tandberg Huldra 8 valve failure

Use your nose! (with the power off) There may still be a bit of smell to guide you to the area the smoked component lives in.

David
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Old 18th Dec 2016, 11:27 pm   #17
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Default Re: Tandberg Huldra 8 valve failure

Hi Clive.

If you damage the mains transformer on this set it will be very difficult to replace it.

Are you going to attempt to repair this yourself?

If so don't do anything rash get or make yourself a lamp limiter

Read this:
http://www.vintage-radio.com/repair-...ing-power.html

Although you have had this running it was clearly faulty and you need to consider what you do before you replace the fuse.

You can get the circuit from the Radiomusem I already linked I think as a guest you can download 3 pages.

Next question can you read a circuit diagram?

Everyone here will pitch in to help but you need to do a bit of swotting to make it less frustrating for all.

Your going to need a multimeter.

And as Radio Wrangler has said No1 Eyeball and your Nose are a great start!

Cheers

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Last edited by Cobaltblue; 18th Dec 2016 at 11:29 pm. Reason: Sniff out that smoked part :)
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Old 19th Dec 2016, 12:08 am   #18
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Default Re: Tandberg Huldra 8 valve failure

Mike, all good points, I am allowed dumb questions if the transformer was damaged would the valves and illuminating light work as they do know?
I have good fluke meter and reading circuit diagrams is new to me, willing to learn. I take on the diagrams the prefix R 105 330k would indicate resistor and the value of it. I do plan repair it myself possibly with help, if I can find someone, we are now on the cusp disappearing repair technicians especially the "old school stuff" thank goodness for sites like this. because I just joined some of my replies might be slow in getting posted.

Clive
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Old 19th Dec 2016, 1:34 am   #19
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Default Re: Tandberg Huldra 8 valve failure

Transformers of themselves are pretty reliable. Most dead ones died because something else caused overheating in them. Possible causes are failed rectifiers (diodes gone short-circuit) and reservoir capacitors gone short. With valve output stages in old radios and hifi, certain small capacitors can turn the output valves on hard enough to ruin both the valves and two transformers.

The fuse blew because something is taking too much current.

Now a really hard short usually takes so much current that fuses blow almost instantly. A more resistive fault takes more current than it should and the fuse takes longer to blow. During this time, other (innocent)components can get overheated.

So there is a worst sort of fault. If it had taken less current, the heating would have been less. Had it taken more current, the fuse would have stopped the thing sooner.
The fact that you got smoke says that your fault is of this sort of magnitude.

Transformers are tough beggers. They survive an amount of abuse, so yours may still be OK, but repeat performances with fresh fuses may be too much for it.

Consequently, the advice to power the unit with a 40W light bulb in the mains live feed. Maybe a bigger bulb on 110v. This drops the voltage to the unit, especially if it's taking too much current. This acts to improve the life expectancy of a faulty unit to give you some time to do basic tests.

Oh, REAL light bulbs, not energy saving fluorescents, not LEDs

David
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Old 19th Dec 2016, 5:44 pm   #20
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Default Re: Tandberg Huldra 8 valve failure

I thought the name Huldra rang a bell.

Just looked in the Amp rountuit cupboard and there's a Huldra 9 that I had sort of forgotten about.

No Magic Eye on the 9 it's been replaced by a meter and the valve count is only 3

This thread has made me consider what to do with mine.

Cheers

Mike T
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