Vintage hi-fi gear can be very attractive, particularly compared to modern stuff. However, when this stuff starts getting into its third or fourth decade after production, things start to wear out. Chief among them—the little incandescent bulbs that light up the dials with such a beautiful glow. [Piffpaffpoltrie] was suffering just this problem on an old Technics amp, and decided to go for a more modern upgrade.
Replacing the original bulb with a like unit was undesirable—even if many last for decades, [Piffpaffpoltrie] didn’t want to have to tackle this job again in the future. Instead, an LED swap was the order of the day. A short strip of warm-white LEDs seemed to be the perfect solution, with three LEDs in series being just about right for the 11-volt supply used for the original bulbs. The only problem was that the stereo supplied the bulbs with AC, not DC. Thus, a quick bridge rectifier circuit was thrown in, along with some series resistors. This wrangled the voltage into a straighter line and delivered the right voltage level to drive the LEDs nicely and smoothly.
The result is a nicely-illuminated set of power meters on this vintage Technics amp. We’ve seen some neat LED swaps in the past, too, including this tricky motorcycle lamp upgrade. Meanwhile, if you’re slogging it out to bring your vintage gear more up to date, consider dropping us a note on the tipsline.
Did similar on my Christmas tree: was using a 12V 20W halogen bulb and the power supply was getting very hot, so replaced it with a 12V 10W LED cob. Saves on my bill and PSU not getting nearly as hot.
“Saves on my bill..” Yeah. Saves at least 0,15 cents per hour, if not more!
That’s about 3,4 cents per 24 hour or about 10 cents over three days (24-26 Dec)! Yay! 🥳
On other hand, your heathing in the room has to work more because the 20w halogen lamp nolonger spends its warm light.
If someone says they already did so on the 22nd, then it can’t possibly be only three days unless they take it down before Christmas has even occured? (22-24) And not everyone who speaks english is using heating right now, fwiw.
That said, the bigger improvement would be the lower chance of something melting and catching fire if it was overloaded before.
Many places where it’s cold in the winter have more cost effective means to heat than resistive electrical heating.
And burning down your house because your Christmas tree got super hot is not a great way to spend the holidays.
I love finding “junk” 70s/80s audio from eBay, etc. and recently did a similar thing with blue LEDs to match the spectrum analyzer on a SH-8055 that I also fixed up.
“bringing vintage gear up to date”….. that’s like putting a PT6 turbine engine in a P51 Mustang (to replace the Merlin), and calling it a “vintage P-51” …….. disgraceful ! but hey have at it … maybe rip out the analog power supply and throw in a new switching unit, why not ? …. what was that conversation here awhile back? – the ship of theseus ?
I feel the same. I for one would dearly miss the warm glow of incandescent lamps.
There are nice “warm” LEDs to replace incandescents in hifi equipment, and unlike the old bulbs they should last a very long time. Replacing the power supply in most instances is just silly, because it’s unlikely that it’s already failed. If it has failed then it’s usually a bad capacitor; just replace that. Furthermore, a switching supply is much more complicated and thus more likely to fail. A switcher is likely to produce electrical noise, both audio and RFI, which will degrade the equipment performance.
Nice meter lighting.
On an old Technics receiver I rehabilitated, there were incandescent bulbs with bluish vinyl covers. I replaced them with violet LEDs; looks awesome.
The one thing I struggle with on old receivers is old switches in the audio path – rotary selectors, eq in/out, and record monitor. Spraying with contact cleaner, or adding some diluted contact enhancer helps somewhat, but they still are flaky anc crap out from time to time.
In my experience, most switches with the problems you describe have silver-plated contacts. They’re great until they oxidize, and then they’re terrible. Typical spray contact cleaners don’t do much to remove the ‘patina’.
If you can remove the switch, try applying Tarn-X to the contacts, then moving the switch through its full range, then rinsing VERY thoroughly with warm water while again exercising the switch. Shake and blow the water out, and let it air dry. Better yet, put it into an oven at 150F for an hour. THEN, if you have Stabilant 22 or some other contact enhancer, apply it.
And you want to be really sure you’ve rinsed all of the Tarn-X out – otherwise it may eventually make the problem worse. Some switches can be taken apart, and in that case I always disassemble them to make cleaning easier and more thorough.
Sometimes, but not always, a white vinyl eraser – the kind with no abrasive added – can clean larger contacts effectively. Of course the abrasive ones clean better and faster – but they also roughen the contact surface, which is not good.
Note that applying Tarn-X to carbon tracks in pots is probably not a good idea.
How about using dielectric grease to protect the contacts from oxidation once you have them cleaned?
I did exactly the same on my ’70s Pioneer amp, with blue LEDs. The contrast with the orange needles of the dials is lovely.
I respect the idea of renovating old gear. To each his own so I will not criticize. I do not understand the reasoning behind all the technical knowledge and work that went into this change versus say installing a copper IEC inlet and replacing/upgrading the capacitors.
I have a mixer board with 4 big meters with those little glass wire-at-each-end bulbs. The wire corrodes with age and breaks off as well as burning out. These are inside the meters of course. I tried LED strip in place of the bulb for OK results, then I realized that the meter case was white plastic with a printed scale and lit them from the back. Now they have a uniform glow instead of the rising sun effect at the bottom, and are very readable.
A trick for using spray/aerosol cleaners in tight spots. Take the extension tube (usually a thin red tube) Now gently melt one end closed. Now heat a sewing needle or similar sized piece of wire and carefully pierce the side of the tube near the closed end of the tube.
You’ll likely need to angle the needle so that it points back towards the other end of the tube.
What you’re making is a tube/nozzle that squirts almost backwards, towards the can.
This modified tube can help you reach underneath some things that would otherwise be a pain to reach the openings in their cases, or require removal from the circuit board to access the holes.
I have also curled a few tubes into odd twists, but this is best done while at room temp so as to not collapse the tube and block the flow through it.
Remember that the sprays are now pointed at your face and eyes with this modification.
Plus some control bodies and shells can route a bast of the spray back at you, regardless of any tube/nozzle changes.
So Don’t forget your eye protection with any spray can usage.
Good tip!
I’ve used insulin syringes for similar purposes, e.g. getting lubricant into narrow spaces, though bending the needle much more than about 45 degrees is sometimes risky or difficult (they’ll simply break or collapse).
Being a Type 1 diabetic was just coincidental. ;)
You need a filter cap greater than 22uF to prevent flicker as the upgrader used. Sigh.
Flickering LED’s on a power/VU meter looks terrible. So do blue LED’s on vintage gear.
I’m upgrading my Marantz 2252b the fuse lamps have died and I’m spending lots on white high CRI LED’s, custom PCB and a DC feed for no flicker. First I’d tried eBay offerings and they are not worthy – bad colour temp, viewing angle and flicker, as well as brightness that was not as good and blotchy.
Blue is the original color on McIntosh equipment.
When adding LEDs to audio gear, remember that they’re two-way devices. You can introduce 120 Hz buzz into audio circuits just from the flickering of the lights in your room.
I did this with an old power supply’s ammeter. I have come to regret using blue, though.
[where’s my edit button? It’s 2025 almost, already! I had an edit function on my BBS forums in 1992!]
…although I do have to say that whatever orange paint they used on the needle brilliantly fluoresces in the light of the blue LED.