Dial light to LCD panel. Your thoughts please.

[TerryG]

Sirs,


Before starting this question, I voice complete agreement that any modifications to a radio are best made in a reversible and non-destructive way. They further need to be respectful and empathetic of the original design. Anything less maybe indistinguishable from vandalising our rich radio heritage.


So, many have opted to change incandescent bulbs used as dial lights with LEDs and so gain around 50,000 hours of continuous use before replacing the dial lights.


I’m about to try a different solution for illuminating the dial of a lovely gem of a radio, a 1946 HMV 467SB, sitting on the bench next to me.


This radio has eight dial lights. One each to indicate which of the 5 wave bands is selected and a further three along the bottom edge.


Instead of moving to LED dial lights, I’m replacing the white backboard behind the dial glass with LCD flat panel screen of matching size. As the user selects a wave band, the LCD screen will light up only that band with a continuous smooth band of light. A Raspberry PI or Arduino with FPGA can easily control the screen illumination by sensing any voltage present at the wave band dial light sockets.

So as not to reinvent the wheel, has anyone tried this before? If so, might you kindly share your thoughts and experience?

Kind regards,
Terry.


Valve line up:


1. KTW63 (RF Amp),
2. X61M (Converter),
3. KTW63 (IF Amp),
4. EBC33 (Detector, AGC),
5. 6V6G (Audio Output),
6. 6X5GT (Full wave Rectifier)
7. 6U5 6G5 (Magic Eye)


The HMV 467SB radio pictured below is the exact same model as mine.
   

[ppppenguin]

Terry, I see nothing wrong with your approach provided that it doesn't inflict any irreversible changes on the set.

BUT

It seems like an awful lot of trouble, cost and effort to subsitute for a few dial lamps. What's wrong with using a few LEDs?

[Terry]

Not relevant to the matter in hand but I'm wondering if V1, 2 & 3 are the originals and the others later replacements?

I grew up with an HMV radio which used X63 KTW63 DH63 KT63 & U50. From comparing the appearance of your radio with the one I knew, I'd say yours is a few years younger!

It was an HMV model 658. There was no RF amplifier or tuning indicator but it had 6 presets - 4 MW & 2 LW. - as well as full Long, Medium and Short Wave coverage.

[ppppenguin]

For those who are interested in the detail of this specifically New Zealand model here's the service manual: https://www.vintageradio.co.nz/static/im...-_19xx.pdf

The valve line-up shown in that manual is:

[boater sam]

Its your radio, your choice.
But for me it will remove so much of the original design and production technique that it would offend me.
The model originates in the Thermionic age not the silicon era, use of individual LEDs may be acceptable but unnecessary as long as the bulbs are available.
But to introduce the silicon spiders into a valve set I feel is a step beyond the pale.

[Terry]

For those who are interested in the detail of this specifically New Zealand model here's the service manual: https://www.vintageradio.co.nz/static/im...-_19xx.pdf

The valve line-up shown in that manual is:

Interesting that US numbered valves are shown for the Osram numbered ones in the set and the Osram types in the manual are US types in the set itself!

[TerryG]

Thanks so much for your responses. Individual replies are coming.


No irreversible changes will be made. None of the mods would take more than a few minutes to remove without trace.


We agree, there’s nothing wrong with a few LEDs and in itself, a LCD panel is overkill for illuminating the selected dial band. But the LCD panel is one of a package of quick reversible mods (listed below) aimed squarely at making the radio survive the next 80 years by becoming relevant and kid friendly.


I’m facing what might be known as the “eternal” problem. With but a few years left above ground, I have a ton of vintage tech gear to try to find a new home for (see attached poorly focused photo. That’s the HMV out of it’s chassis in the foreground awaiting its turn on the workbench to be re-capped and aligned).


If the HMV is to avoid becoming landfill soon after myself, then it will have to do more than play A.M. With a few easily reversible mods, this will be achieved, while keeping the same look and feel of the original.


The HMV has a phono socket at the rear which can be rigged to a bluetooth receiver hidden under the chassis. In this way the next generation can play music on the HMV from their mobile devices.

The HMV has a sort of faux symmetrical cabinet layout. There are left and right speaker grills, but only one speaker is fitted, installed on left. This is a similar design to famed GEC BC 4750 from 1947. On installing a matching second speaker and additional 6V6G audio output stage behind the right hand side speaker grill, the HMV will reproduce stereo quality audio for its new owners..

The new owners could then also stream audio content from the web with the HMV. At the moment, I have a web browser open at http://websdr.ewi.utwente.nl:8901/, This web page gives access to a multi-user Software Defined Radio that picks up radio broadcasts local to the SDR. BBC Radio 4 on 198 kHz in tuned in as I write. A web enabled HMV will sound like an authentic long wave receiver even though the HMV was never designed for long wave reception.

If you use the Raspberry PI option to control the LCD panel illumination, then the HMV gets WIFI and/or Ethernet connections to the Web and is thus enabled to play any of the tens of thousands of radio stations that stream across the Internet, including those that play music from the time the HMV was welcomed into the home of it's first owner. 

Using a font and colour that matches the dial glass lettering, the LCD panel could discretely and subtly display on voice command, such messages as time, date, frequency etc or other messages in an unused part of the dial.


For now, the LCD panel and other mods will remain outside the radio in case it can be sold as is. But I feel strongly that this beautiful HMV's best chance at survival is to add a few mods while remaining unchanged in outward appearance.


Kind regards,
Terry

[ppppenguin]

This is a very different proposition to using a R-Pi sledgehammer to crack a dial lamp nut. You're turning the set into an internet radio, something that's potentially a good use for a high quality vintage set. This is high quality and creative upcycling, a far cry from the hideous "steampunking" of Avos into lamps and suchlike.