what lamps used in dial pointer of Realistic sta-90

[jancumps]

Who knows what lamps are used in the dial pointer of realistic STA-90.
I know that the dial back light is served by these:
http://www.vintage-electronics.cc/vlamp.html (search for "Meter Lamp 8v 250ma" ). But I have not found specs for the amber and red light used in the dial pointer - and how to get at those lamps.

 

[jancumps]

Oh no. I don't have friends.

 

[dgwojo]

I'd measure the AC volts going to it, most dial pointers are 50ma - 60ma, 8v is pretty common, Dave.

 

[whsh93a]

My data bank tells me that your STA-90 does not use any fuse lamps at all. It uses fuse-like 8V wired lamps. They are glass with bare wires that solder into a circuit board.
My data is blank on the pointer. Do you think it could be a bi-colored LED?

DH

 

[jancumps]

My data bank tells me that your STA-90 does not use any fuse lamps at all. It uses fuse-like 8V wired lamps. They are glass with bare wires that solder into a circuit board.

DH

Yes. I have put a link to those lamps in my first post. It's number 23 in the list.

My data is blank on the pointer. Do you think it could be a bi-colored LED?

I will try to open the pointer today. But it is a small plastic particle. I'll have to be careful.

 

[jancumps]

progress wxith pictures

Progress so far:
I managed to open the dial pointer, by bending back four small tags with a thin knife.
Inside i found two tiny bulbs, one behind an amber and the other behind a red plastic filter.

Measuring over the lamps gives me 8.5 volt dc. There is a resistor in series with the lamp, but since the lamp is defect, I measure full voltage (open circuit).
Because I can't measure the resistance of the lamps, I can't yet calculate the current through the circuit,
I am currently digging up the manual of my sta-82. It has the same mechanism for dial pointer lighting, and the manual has the schema.

EDIT: The STA-82 uses 6v 65 mA

 

[jancumps]

I'd measure the AC volts going to it, most dial pointers are 50ma - 60ma, 8v is pretty common, Dave.

It's part of a circuit with a transistor and a resistor in series. Because the lamp is open circuit, I measure the full voltage over it: 8.5V.
These are tiny tiny bulbs inside the dial pointer. One should switch on when receiving mono, the other should work when receiving stereo radio signal.

 

[whsh93a]

Interesting.
I have added that data to my giant lamps data base.

I'd replace them all with LED based lamps to avoid future brain injury . PM me if you want more inf.

DH

Progress so far:
I managed to open the dial pointer, by bending back four small tags with a thin knife.
Inside i found two tiny bulbs, one behind an amber and the other behind a red plastic filter.

Measuring over the lamps gives me 8.5 volt dc. There is a resistor in series with the lamp, but since the lamp is defect, I measure full voltage (open circuit).
Because I can't measure the resistance of the lamps, I can't yet calculate the current through the circuit,
I am currently digging up the manual of my sta-82. It has the same mechanism for dial pointer lighting, and the manual has the schema.

EDIT: The STA-82 uses 6v 65 mA