Sony STR-6800 receiver - stiff tuning, dial lamps and...

[Radio Wrangler]

Glad the Gallium and the Arsenic in your fridge are well constrained!

THe bulb in my oven will be a harder one to replace. The oven goes to 500C for 150 minutes on the self-clean cycle.

David

[turretslug]

Ouch! Can you fire pots with that?

The world is one's oyster nowadays as far as LEDs are concerned, with small, wide-angle, very efficient types being very cheap in a merry array of colours in both wire-end and SMD- I've used various types in various situations with gratifying success. For a festoon replacement, I'd have a go at low-profile button 5mm (not the traditional quite tall ones orientated around panel-mount clips) or SMD wide-angle green types in a row of about 4 in series on a sliver of stripboard, even 10mA is likely to be plenty bright. Generating green light from the outset would be more efficient than filtering "white" from an LED source, which is probably spectrally spikey anyway. Reduced power in lighting= less work for the transformer= what can be a surprising difference in internal running temperature.

Do I take it that the "11V" supply is LVAC?

[Radio_Dave]

Here's a picture of my STR-6036 which I changed all the bulbs for LED's.

For the tuning scale I put about 5 or 6 LED's on a strip of matrix board, which then clipped into the three festoon bulb holders with plastic rods.

David

[Radio Wrangler]

There's quite a few different green colours available. Some people I know have to match the colours of some displays to other (older tech) equipment in an aircraft instrument panel. Blue-y greens are efficient, yellow-y greens seem to have been left behind a bit on the efficiency front.

Filtering white isn't a good approach, the green content can be off the peak of your green filter. LEDs emit spiky spectra, while old hot filaments emit broadband noise like spectra.

David

[sp10mk11]

Radio_Dave
Hey! yes the LEDs have worked well on that, way way back in 1974 I worked for my dad for two weeks on a building job he had taken on to buy the same tuner amplifier off my mate's uncle, it was the first piece of hi-fi I had, and I loved it and looking at yours I am getting all sentimental

[sp10mk11]

oi! stop scaring me Mr Dave....what gallium and arsenic, do you mean that LED bulb that saves the planet? I put in.

I have an AEG oven aswell but the bulb in that easy to get and put in, self cleaning oven.......oh I wish........envy envy

[Radio Wrangler]

Yup! tiny amounts in the LED diodes. Well sealed, quite safe, but funny to think about.

David

[sp10mk11]

ha ha it is a joke isn't it............oh well so providing I don't go mad and smash the bulb inside the fridge all should be ok

Gary

[stevehertz]

Originally Posted by Radio_Dave

Here's a picture of my STR-6036 which I changed all the bulbs for LED's.
For the tuning scale I put about 5 or 6 LED's on a strip of matrix board, which then clipped into the three festoon bulb holders with plastic rods.

Dave that's excellent! If I don't find any proper bulbs - looks unlikely - then I'll have to tap you up for more details of your fabulous design mod.

[Radio Wrangler]

This is one of the Farnell/Multicomp ones. The ones I used are smaller boards and lower power. The reverse of the board has a little regulator, a bridge rectifier and a couple of reservoir capacitors. They seem constant brightness across 10-30v AC or DC.

David

[Nickthedentist]

Those certainly look useful, David.

I presume they don't do any fuse-style ones too?

[sp10mk11]

Hello Steve yes Davids LEDs have worked well, but I found using festoon fittings with LEDs in them did not work as well even though I could turn the LEDs to face the end of the glass display the light was not evenly spread along it.

Where as the layout of the bulbs on the 6036 is different and they are further back from the display window

But all that was about 18 months ago when I was fiddling the lights on my ST-5950 which uses the same 360ma bulbs as your STR-6800 so maybe LED festoon lights have improved

Gary

[Radio Wrangler]

This is what the LEDs did to the Revox. With normal festoon bulbs they were a bit dingy, but now....

David

[sp10mk11]

Yes David the LEDs have worked well there.
Having seen the 6036 and your beautiful Revox tuner

Maybe I will have a fiddle again

Gary

[stevehertz]

But they (the LED ones) are not available commercially in the size and rating that I'm looking for I take it?!

[Radio Wrangler]

The ones I photographed were the big version. I fitter the smaller diameter lower power ones in the tuner. In these, the width of the PCB bit is equal to the diameter of the regular festoon bulb.

The full range with dimensions is on the Farnell website.

In my tuner, the bulbs were running at 35v, so I did a bit of reconnecting to put the pair in series and found that they balanced satisfactorily with equal voltages.

The LED wattage ratings will be a lot less than those of filament bulbs simply because they are so much more efficient. If they come out too bright, dropper resistors could be added and the total heat will still be much less than the original filaments gave.

Next up for LEDification is the blown S-meter bulb in the IC765.

David

[sp10mk11]

the original Sony 11v supply is AC only so you will need a diode on one the rails to Dc it for driving the LED festoons

Gary

[Radio Wrangler]

The LED festoons I showed above include bridge rectifiers and smoothing capacitors.

They work fine on AC or DC-either-way-round.

David

[stevehertz]

Right, I've dismantled the front panel. The bulb on the left hand side of the dial (that was working) came out minus one end cap (just my luck), I guess the cement holding it in place was old and tired. Hopefully I can glue the end cap back on and - having first removed the solder from the end cap - resolder the end wire that was not damaged in the mellee. The right hand bulb is o/c. On examination, there's some card shrouding that sits around the bulbs and due to heat, it is badly burned - see photos. So that would have 'leaked' white light around the dial even more. Also, you can see that the green edge to the glass has also disappeared just in the middle region ie right next to the bulb - vapourised?! So I can paint those or affix a suitable piece of green filter.

So, I'm stuck for one bulb. I'm not sure if those LED ones would fit - if indeed a suitable sized one is available anyway. There may be orientation issues as well wrt the direction that the LEDs throw out light, and not being able to rotate the unit in the holder. Anyway, I'll get that one bulb repaired and I also need to replace those card shrouds with hopefully something more heat resistant, but equally compliant and easy to work with for this purpose - any ideas? The bulbs are photographed against a 5p coin and are a measured 28mm long.

[stevehertz]

I've now repaired the bulb, quite easy really, and it works. See Photo. You can clearly see now where the green paint has frazzled and fallen off adjacent to that hot bulb. On further examination, the cardboard shroud nearly (well, it did before it was burnt) goes all the way around the bulb, leaving a narrow slot for light to hit the side of the dial glass.

I'm thinking of remaking the shrouds using very fine wet and dry paper with the rough side towards the bulb? I can't think of any other material that has similar properties to cardboard - for making purposes - and maybe is a tad better at resisting heat?

But I'm still short of a bulb..