Stereo indicator lamp, vintage receiver

Jan 02, 2006 12 Replies
M

Stereo receiver, vintage 1973, with uPC554C (ECG1142) FM demodulator chip. Sounds fine, but the stereo indicator lamp (newly replaced) is on nearly all the time, when any FM signal is tuned in (even a very weak one), but never at full brightness. That is not how I remember it behaving, years and years ago.



Specified bulb is 8 V 40 mA; actual bulb is 8 V 35 mA.



There is no potentiometer to adjust anything to do with the stereo indicator lamp.



Any thoughts? I plan to replace all the electrolytic capacitors in the system, a few of which are around the uPC554C. Perhaps one of them is leaky.


Vote
Twitter Facebook LinkedIn
E

I have a thought. Who needs FM anymore? I takes it it has RCA inputs, so if I were you, I would get a Sirius Satellite Receiver listen to that.

Vote
Twitter Facebook LinkedIn
C

Why would he want to pay for something he can get for free?

The e-mail address in our reply-to line is reversed in an attempt to minimize spam. Our true address is of the form che...@prodigy.net.
Vote
Twitter Facebook LinkedIn
D

FM is still a very viable medium for entertainment... just because one person might think it's the cat's meow doesn't mean that it's obsolete. The adjustment, if any, would be for the pilot level, pilot frequency, or something similar. I couldn't find a datasheet for either the uPC554 or the NTE1142, so it's hard to visualize the circuitry around the IC. If you have a copy of the schematic for your receiver, scan the FM portion and post it on alt.binaries.schematics.electronic Replacing the capacitors may help, especially if the unit has been on the shelf for many years. It may fix problems than you don't even realize that you have.

Dave M MasonDG44 at comcast dot net (Just substitute the appropriate characters in the address) Never take a laxative and a sleeping pill at the same time!!
Vote
Twitter Facebook LinkedIn
J

Is there a transistor to drive the lamp? It's possible it's become leaky. Your replacement lamp should work just fine so there's some fault in the receiver. It's remotely possible it was damaged when the original lamp failed.

Vote
Twitter Facebook LinkedIn
J

Come on now, quit feeding the trolls, at this rate I'm gonna end up with half the people in this group killfiled.

Vote
Twitter Facebook LinkedIn
E

Because it's all 100 percent commercial free music.

Vote
Twitter Facebook LinkedIn
E

have fun talking to yourself then.

Vote
Twitter Facebook LinkedIn
R

all

years

indicator

Until they get a substantial listener base.

Vote
Twitter Facebook LinkedIn
M

Thanks. I haven't actually gotten around to doing that, but it's in the queue.

Vote
Twitter Facebook LinkedIn
M

The driver transistor is inside the uPC554C.

Vote
Twitter Facebook LinkedIn
F

On Mon, 2 Jan 2006 11:32:47 -0500, "DaveM" put finger to keyboard and composed:

Pin # Function

----------------------- 1 19kHz tank 2 19kHz tank 3 Input 4 Stereo switch 5 Mute switch 6 Lamp drive 7 Ground 8 NC 9 Vcc

10 38kHz tank 11 Left channel out 12 Right channel out 13 38kHz tank 14 Filter net

- Franc Zabkar

Please remove one 'i' from my address when replying by email.
Vote
Twitter Facebook LinkedIn

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required