Lamp To Illuminate Cassette Deck Display - UK Vintage Radio Repair and Restoration Discussion Forum

kelvinmunson · 10th Nov 2011, 1:48 pm

The display on my Yamaha KX-300 cassette deck is not illuminated and having had a look inside it looks to me as if the lamp has been removed ?

Couple of pics below show the PCB and in the pic on the right, under "54" looks like an empty lamp holder bearing the code 103 (or 703) ?

Can anybody advise if this is correct and what part I need to illuminate the display ? Is it possible to identify a lamp from the holder ?

Would it be a miniature wedge type lamp ?

Vicboduk · 10th Nov 2011, 2:11 pm

That is not a lamp holder it is a preset potentiometer with a value of 10k Ohm.
Seeing that there are two of them on that board I would guess that they are there to calibrate the left and right channels of the VU meter. It was very common for LED VU meters NOT to be back lit. It is most likely that there never was a back light!

Vic

AndiiT · 10th Nov 2011, 2:11 pm

Hi,
The component under the number 54 isn't a lamp-holder at all but is a "pre-set" variable resistor, which will be intended for the adjustment of something or other in that area of the circuit.

The 103 indicates that this pre-set has a resistance value, along the length of its track, of 10 Kilohm's; The digit 3 at the end being the multiplier which indicates the number of noughts after the preceding digits.

Regards

Andrew

kelvinmunson · 10th Nov 2011, 2:18 pm

Thanks for that, it's not easy to use the deck with no backlight as the nomenclature and scales are not visible. I'll have to use a torch.

paulsherwin · 10th Nov 2011, 2:22 pm

An LED bargraph like that should light itself, as with any LED. If it's completely dark then you have a fault somewhere.

kelvinmunson · 10th Nov 2011, 2:48 pm

Thanks Paul, I wasn't sure. I will investigate !

10th Nov 2011, 1:48 pm	#1
kelvinmunson Pentode Join Date: Jul 2010 Location: Scunthorpe, Lincolnshire, UK. Posts: 159	Lamp To Illuminate Cassette Deck Display The display on my Yamaha KX-300 cassette deck is not illuminated and having had a look inside it looks to me as if the lamp has been removed ? Couple of pics below show the PCB and in the pic on the right, under "54" looks like an empty lamp holder bearing the code 103 (or 703) ? Can anybody advise if this is correct and what part I need to illuminate the display ? Is it possible to identify a lamp from the holder ? Would it be a miniature wedge type lamp ? Attached Thumbnails

10th Nov 2011, 2:11 pm	#2
Vicboduk Hexode Join Date: Aug 2007 Location: S.W. London, UK. Posts: 416	Re: Lamp To Illuminate Cassette Deck Display That is not a lamp holder it is a preset potentiometer with a value of 10k Ohm. Seeing that there are two of them on that board I would guess that they are there to calibrate the left and right channels of the VU meter. It was very common for LED VU meters NOT to be back lit. It is most likely that there never was a back light! Vic

10th Nov 2011, 2:11 pm	#3
AndiiT Octode Join Date: Aug 2005 Location: Saltburn-East, Cleveland, UK. Posts: 1,786	Re: Lamp To Illuminate Cassette Deck Display Hi, The component under the number 54 isn't a lamp-holder at all but is a "pre-set" variable resistor, which will be intended for the adjustment of something or other in that area of the circuit. The 103 indicates that this pre-set has a resistance value, along the length of its track, of 10 Kilohm's; The digit 3 at the end being the multiplier which indicates the number of noughts after the preceding digits. Regards Andrew

10th Nov 2011, 2:18 pm	#4
kelvinmunson Pentode Join Date: Jul 2010 Location: Scunthorpe, Lincolnshire, UK. Posts: 159	Re: Lamp To Illuminate Cassette Deck Display Thanks for that, it's not easy to use the deck with no backlight as the nomenclature and scales are not visible. I'll have to use a torch.

10th Nov 2011, 2:22 pm	#5
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,943	Re: Lamp To Illuminate Cassette Deck Display An LED bargraph like that should light itself, as with any LED. If it's completely dark then you have a fault somewhere.

10th Nov 2011, 2:48 pm	#6
kelvinmunson Pentode Join Date: Jul 2010 Location: Scunthorpe, Lincolnshire, UK. Posts: 159	Re: Lamp To Illuminate Cassette Deck Display Thanks Paul, I wasn't sure. I will investigate !