Most ornamental equipment?

[Radio Wrangler]

That's far too nice looking to be left as an ornament, Paul.

It's nicely engineered, nicely styled. Maybe there is no great audible difference from something more modest, but there is satisfaction in knowing what you've got running. Besides, it's taking up a lot of room, and if you have it going you can tell visitors what it cost you!

Transistors aren't the spawn of Be'elzebub. They're just different. There is a degree of culture shock in getting your head around how they work, they are alien creatures if your background is entirely valve-based.

So that lump is big, full of alien stuff and damned intimidating.

That's usually enough to put most people off.

The world of education decided long ago to always start people off in solid state electronics by dropping them straight in the deep end of semiconductor physics.... particle physics, energy levels and quantum mechanics. So that put a lot of people off.

As an alternative you could build up a mental model of how a transistor behaves without worrying about quite how it does it internally. This defuses all the intimidation.

It's a stereo amp, so you only have to handle one channel at a time, so the job is only half as big as it looks. It's only the power amp section as well. And being stereo you probably have the other channel as a working one to compare things against.

Repairing solid state power amps has a stinker of a reputation and it's fully deserved. Many people have been driven to desperation by the things.

The reason is that they are direct coupled so one fault in one stage can blow up its neighbours. If you try to replace one part at a time, the bad neighbours blow up your new part immediately on power on. You don't see anything happen, move onto the next part and replace it and you get trapped in a perpetual loop replacing again and again the same parts. Once things seem weird, most give up.

Once you know about the loop of failures trap you see that you have to find and fix all faults, power OFF before you ever dare power it up.

The second gotcha is that the things have a lot of gain in the core amplifier, brought down to a reasonable amount by feedback. This is needed to bring the distortion down to decent levels, and it also stabilises the DC voltages around the whole loop. Indeed, without feedback there is so much DC gain that even a perfectly good amplifier with acceptable match between devices (input ones are dominant here) will ram its output right to one power supply rail or the other. To start getting sensible measureable voltages you need the feedback loop running. This means you can measure and check the voltages on a good amplifier which doesn't need repairing, but they aren't any help on a failed amplifier which you're trying to repair.

Life seems unfair.

Trying to interpret the bad voltages is difficult because the whole thing is a loop. You see a bad voltage, now have you probed the seed of the trouble ? Maybe. Have you probed downstream of the seed of the trouble? It can also look so. But have you probed upstream of the seed of the trouble and the bad voltage you measured is due to the real fault throwing the input stages off via the feedback loop? This is another gotcha.

It's big and intimidating, but it's actually no more complicated and no more difficult (other than turning it over on the bench) than much smaller amplifiers.

There are several people on the forum who can handle solid state amplifier faults. There are ways to defuse the gotchas. Others have been got up the learning curve on these things so there is plenty of help available. So long as you don't try any short-cuts you should be able to get there, and acquire a new string to your bow along the way.

It's not difficult, it's just different.
Big uns are no harder than little uns
You don't have a big investment tied in it

So, a good place to learn. Just start a thread for it.

David

[m0cemdave]

Originally Posted by Paul_RK

I'm more likely sooner or later to have a go at bringing my scarce and rather becoming, to me if to no one else, Wharfedale WHF-20 back to life.
Paul

Same here, plus the matching tuner. Looks like a fiddly job, been putting it off for about 30 years...

[Malcolm G6ANZ]

Joe I recognize the CX1154 thyratron and possibly a TY2-125. I've got a couple of thyratrons in my collection. A well as an electron gun and a flattening filter from a linac.

Malcolm

[jamesperrett]

Originally Posted by Radio Wrangler

As an alternative you could build up a mental model of how a transistor behaves without worrying about quite how it does it internally. This defuses all the intimidation.

The last time I was there, the Winchester Science Centre had a display describing electronic components with a model of how the transistor works. They were using a fluid flow analogy so the transistor was actually more like a FET. It certainly made sense to our lad who was then confident enough to create his own crude transistor circuits using Snap Circuits components.

[Pilot Mariner]

Maybe a bit crazy but I have a selenium rectifier from an old Murphy V330 TV as an ornament on my mantle piece. I remember the TV in action, and when it broke down and was beyond repair I was given the TV to strip down. I was about 11 years old at the time.
It brings back happy memories.

[Joe_Lorenz]

Well, for sure one of the best ideas of what to do with a selenium rectifier. Much better than keeping those in operation!

[mark_in_manc]

Originally Posted by knobtwiddler

Thank you for the heads-up on diyaudio, David. I have dropped Mr Pearl a line. Fingers crossed!

If I don't get it fixed, it'll remain in the hallway so that visitors can amuse themselves popping the keyboard in and out.

Hi Knobtwiddler. I used to work in acoustics, and my house is full of the detritus I scavenged from the skip over the years (and, incidentally, furnished in Iroko fittings which look like they belong in, errrrr, a 1970s lab).

It turns out I have a 'user's manual' for a 2133 which is in a white B&K 4-ring binder in 5 volumes, altogether about 2" thick. There appears to be no service info - this is just how to drive the thing. If you want it for cost of postage (which will not be cheap, it weighs about 3.5kg without boxing it up) then feel free to PM me.

(With a lot of patience perhaps you could scan it and swap it with the online Hungarian for his 'service manual part one?' ).

cheers
Mark

[ChrisGadg]

The putting of people off technical aspects...

A fascination remains often, there are products which strongly hint at a scientific theme or advanced functioning but most definitely are just show. I'd be surprised if J. Dyson made a radio device which became collectable by the rationally minded.

I think those who are averse to the technical aspects show their fascination in ways like their phone answering manner... "Speaking!".

Sadly, scientific minds have been employed many times to do just this, steer people away.

[stuarth]

For ornamental hifi tuner amps, the Armstrong 426.
Yes, I know it’s full of AL102s and AF11x’s, but the control knobs are a decent size, and the glow of the tuning scale in a dimly lit room........
Unfortunately, most of the public didn’t like the styling, so the innards were taken out of the very interesting 400 series to become the very boring 500 series.

I also have a (moderately interesting) B&O Beomaster 3000-2, but I’m not madly keen on slider controls (and its dial doesn’t light up).

The Eddystone 870 cabin radio appeals, it’s nice and compact, but becoming less useful these days with the demise of AM broadcasts and the rise of EMI ( the interference, not the company).

If replacing the covers with something transparent so you can see the PCBs and other innards is allowed, then, as others have said, Tektronix stuff must be high up on the ornamental scale.

Stuart

[Ted Kendall]

Originally Posted by m0cemdave

Same here, plus the matching tuner. Looks like a fiddly job, been putting it off for about 30 years...

I've always had a soft spot for the other Collinson Wharfedale design, the 100.1 receiver, with its combination of sloping and vertical control panels and sculpted cabinet sides. It didn't last long in the market, falling victim to the Rank rationalisation, but is a good bit of kit. I was pleased to find a near mint example for a song a few years ago.

[knobtwiddler]

Hi Mark,

Thank you for the kind offer. I have sent you a PM.

[The General]

I have this one, a Philips EL6420 70W amplifier from 1952. Unusual styling especially with the single EM34 eye glaring balefully at the user. The styling I would say is Streamline Moderne which is a bit anachronistic for 1952. It's the only amp I've seen with a cast aluminium chassis & top cover. Outputs are a pair of EL34s.
Oh and 800V HT on the anodes. Nice.
Mark

[Radio Wrangler]

It might be a little ahead of its time... it definitely has a touch of Dalek to it and they didn't debut until 11 years later.

David

[Jez1234]

Originally Posted by stuarth

For ornamental hifi tuner amps, the Armstrong 426.
Yes, I know it’s full of AL102s and AF11x’s, but the control knobs are a decent size, and the glow of the tuning scale in a dimly lit room........
Unfortunately, most of the public didn’t like the styling, so the innards were taken out of the very interesting 400 series to become the very boring 500 series.

I also have a (moderately interesting) B&O Beomaster 3000-2, but I’m not madly keen on slider controls (and its dial doesn’t light up).

The Eddystone 870 cabin radio appeals, it’s nice and compact, but becoming less useful these days with the demise of AM broadcasts and the rise of EMI ( the interference, not the company).

If replacing the covers with something transparent so you can see the PCBs and other innards is allowed, then, as others have said, Tektronix stuff must be high up on the ornamental scale.

Stuart

Ah yes the one with the round tuning dial and the purple bits. I really like the styling of those. I have one of the later 500 series tuners which worked 15 years ago but may not now as it's full of AF114, and 117's which may have gone the way of the tin whisker by now...

[William78]

Ok, my favourite item I have is a large insulator from Barton power station, Trafford park, Manchester.

The power station was built in the early 1920s and was fitted out by British Thomson-Houston.

The insulator has the initials BTH cast into the porcelain in a circle (lower middle in the picture). The power station was pulled down in 1978/79 and I lived nearby.

I keep it on display on the window sill upstairs and think it looks cool.

See the attached photo with a PP3 battery for scale.

William

[ChrisGadg]

Originally Posted by William78

Ok, my favourite item I have is a large insulator from Barton power station, Trafford park, Manchester.

I saved this from landfill:


I've worked at power stations before and marvelled at the geometry of the engineering. Not radio engineering but I felt charged with energy on those walks. Not electromagnetic but nonetheless induced

[knobtwiddler]

Originally Posted by The General

I have this one, a Philips EL6420 70W amplifier from 1952. Unusual styling especially with the single EM34 eye glaring balefully at the user. The styling I would say is Streamline Moderne which is a bit anachronistic for 1952. It's the only amp I've seen with a cast aluminium chassis & top cover. Outputs are a pair of EL34s.
Oh and 800V HT on the anodes. Nice.
Mark

I've never seen a toaster with so many controls!

As a Streamline Moderne fancier, I have to agree about the 1952 date being very late in the day and almost too early for a revival of such styling. It seems to be a curious hybrid between SM and a more conventional '50s ethos.

The Al casting appears to be in very good nick, so it likely has a low zinc content, or it would be affected by the annoying 'zinc pest'.

[The General]

Ha ha, yes it does look a bit toaster-esque, and I agree that the styling is an amalgamation of Streamline Moderne (which I also like) & 1950s industrial. The castings are indeed in good condition (although grubby) & I think they are ali & not Zamak or similar. Since the photos were taken I've given the cover a good scrub, the dark grey came up well but I resprayed the light grey with some paint I had left over from another project which was fortunately an excellent match.
I have all the parts for a rebuild, so it'll be a winter project hopefully.
Mark

[Nuvistor]

As a desk object I have these 4 valves, PC88, PC86, PC97 and PC900, some of the first frame grid valves for UHF/VHF tuners used in the UK. I don’t know if the valves are good but the vacuum are intact. Valves holder are new so could be reused, if the valves are good again could be used and the block of wood will make a good door stop if I ever want to dismantle it.

[G6Tanuki]

In the very early 1980s I remember INTeL giving out cufflinks each of which had an 8008 processor semiconductor wafer, presumably a production line reject, set into the visible part, entombed in clear epoxy.