Old digital clock radio display fault - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

paulsherwin · 23rd Jun 2022, 8:26 am

Normally they're just different coloured LEDs. Some of the green ones used a VFD, and later backlit LCDs became common.

petervk2mlg · 23rd Jun 2022, 9:30 am

Thanks Paul. So the VFD ones use a vacuum tube type display?

paulsherwin · 23rd Jun 2022, 9:32 am

Yes. It's not a great technology for a clock display that's permanently on, as the display wears out and goes dim.

SiriusHardware · 23rd Jun 2022, 9:52 am

By green, do you mean bold green or turquoise blue-green?

If bold green, that just means that green LEDs were used in the display module instead of red ones. The colour is determined by how the LEDs are made.

There are other types of display which are sometimes used in clock radios which typically have a pale blue or greenish blue hue, sometimes with orange elements or indicators. These would be Vacuum fluorescent Displays, a completely different display technology. They were not especially common in clock radios and were more often found in Hi-Fi equipment and video recorders.

Edit: Crossed with others

Mooly · 23rd Jun 2022, 9:54 am

Green displays are usually VFD (vacuum fluorescent display) and these are totally different to LED's. They are a glass envelope like a valve and they also have small heaters (filaments) like a valve. Old VCR's and the like usually used these.

https://en.wikipedia.org/wiki/Vacuum...escent_display

Having said all of that... you can get green and yellow LED 7 segment displays but I've never seen them used in clock radios.

Mooly · 23rd Jun 2022, 9:56 am

Oops... looks like I didn't turn the page....

petervk2mlg · 23rd Jun 2022, 10:40 am

Thanks gentlemen.
I was thinking red and green as in these two Sony clock radios

paulsherwin · 23rd Jun 2022, 11:04 am

I'm pretty sure both of those are LED, though you'd have to look inside to be certain.

Generally speaking, VFD displays are custom made for the application, and will have graphical symbols for AM/PM, alarm status etc. LED displays just have a single LED as a PM indicator.

SiriusHardware · 23rd Jun 2022, 10:49 pm

Quote:

I'm pretty sure both of those are LED

Agree, the Sony with the green display is using green 7-segment LEDs.

Mooly · 24th Jun 2022, 9:04 am

I suspect red (and quite dim) is probably a preferred colour option for something lit up at night.

Richard_FM · 24th Jun 2022, 9:32 pm

I remember my Dad's clock radio had an auto dim feature so it didn't dazzle him at night.

23rd Jun 2022, 8:26 am	#21
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 24,064	Re: Old digital clock radio display fault Normally they're just different coloured LEDs. Some of the green ones used a VFD, and later backlit LCDs became common.

23rd Jun 2022, 9:30 am	#22
petervk2mlg Heptode Join Date: Jan 2007 Location: Parkes, NSW Australia Posts: 828	Re: Old digital clock radio display fault Thanks Paul. So the VFD ones use a vacuum tube type display? Last edited by petervk2mlg; 23rd Jun 2022 at 9:33 am. Reason: typo

23rd Jun 2022, 9:32 am	#23
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 24,064	Re: Old digital clock radio display fault Yes. It's not a great technology for a clock display that's permanently on, as the display wears out and goes dim.

23rd Jun 2022, 9:52 am	#24
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 8,628	Re: Old digital clock radio display fault By green, do you mean bold green or turquoise blue-green? If bold green, that just means that green LEDs were used in the display module instead of red ones. The colour is determined by how the LEDs are made. There are other types of display which are sometimes used in clock radios which typically have a pale blue or greenish blue hue, sometimes with orange elements or indicators. These would be Vacuum fluorescent Displays, a completely different display technology. They were not especially common in clock radios and were more often found in Hi-Fi equipment and video recorders. Edit: Crossed with others Last edited by SiriusHardware; 23rd Jun 2022 at 10:06 am.

23rd Jun 2022, 9:54 am	#25
Mooly Octode Join Date: May 2011 Location: Lancashire, UK. Posts: 1,155	Re: Old digital clock radio display fault Green displays are usually VFD (vacuum fluorescent display) and these are totally different to LED's. They are a glass envelope like a valve and they also have small heaters (filaments) like a valve. Old VCR's and the like usually used these. https://en.wikipedia.org/wiki/Vacuum...escent_display Having said all of that... you can get green and yellow LED 7 segment displays but I've never seen them used in clock radios.

23rd Jun 2022, 9:56 am	#26
Mooly Octode Join Date: May 2011 Location: Lancashire, UK. Posts: 1,155	Re: Old digital clock radio display fault Oops... looks like I didn't turn the page....

23rd Jun 2022, 10:40 am	#27
petervk2mlg Heptode Join Date: Jan 2007 Location: Parkes, NSW Australia Posts: 828	Re: Old digital clock radio display fault Thanks gentlemen. I was thinking red and green as in these two Sony clock radios Attached Thumbnails

23rd Jun 2022, 11:04 am	#28
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 24,064	Re: Old digital clock radio display fault I'm pretty sure both of those are LED, though you'd have to look inside to be certain. Generally speaking, VFD displays are custom made for the application, and will have graphical symbols for AM/PM, alarm status etc. LED displays just have a single LED as a PM indicator.

24th Jun 2022, 9:04 am	#30
Mooly Octode Join Date: May 2011 Location: Lancashire, UK. Posts: 1,155	Re: Old digital clock radio display fault I suspect red (and quite dim) is probably a preferred colour option for something lit up at night.

24th Jun 2022, 9:32 pm	#31
Richard_FM Octode Join Date: Sep 2017 Location: Stockport, Cheshire, UK. Posts: 1,727	Re: Old digital clock radio display fault I remember my Dad's clock radio had an auto dim feature so it didn't dazzle him at night. __________________ Hello IT: Have you Tried Turning It Off & On Again?