Updating 555 timer chip.

Rod Beauvex · 28th October 2011, 06:38 PM

Would there be any benfit to replacing an older 555 timer chip with a more modern unit?

This unit in question is in a mid seventies reciever, and I believe is part of the tuner section. (At the very least, I can't imagine what it would do for the pre or power amp section

)

Mooly · 28th October 2011, 06:48 PM

I can't imagine what it does in the tuner either...

I would say no, leave it be. Reason why, it may be used as a pulse generator/monostable etc and replacing with a low power version would alter it's characteristics slightly maybe needed a realignment of something else.

You need to know what it does ?

I have never come across commercial kit that used a 555 tbh. Could it be used as a negative rail generator (charge pump) ?

Rod Beauvex · 28th October 2011, 06:59 PM

It's not hugely important, really. This is an old, low-power reciever (Lafayette Lr310)I've had my eye on to refresh once I got the money to do so. The goal here would be to improve performance.

Thanks for the answer though. I never realized that there were so many different variations of this chip. The one in question is a metal can type, something I've never seen done with an IC. "C555a 2"

simon7000 · 28th October 2011, 07:57 PM

It is most likely not a timer IC! It is an rf IF IC also called a 703 originally by Fairchild!

Elvee · 28th October 2011, 08:14 PM

Quote:

Originally Posted by simon7000

It is most likely not a timer IC! It is an rf IF IC also called a 703 originally by Fairchild!

Never mind, replacing it with a plain 555 might have interesting results, like converting an old analogue tuner into a top class DAB receiver. You never know.

Enzo · 28th October 2011, 11:56 PM

I'm willing to believe Simon, but if we have to have a 555 timer IC, I could see it as a delay for a speaker relay or similar application. Or as a blinker for some indicator light.

Rod Beauvex · 29th October 2011, 05:26 PM

Well well, this has turned out to be an interesting discussion.

I took another look at it, and it is on the edge of the tuner, where it ends and the amp begins (they're on the same board). I opened up my little tiny Integrated amp, which is also a Lafayette, and it does not have one of these.

The little metal can chip in question was made by NEC, and the reciever itself was made between 74 and 78.

indianajo · 29th October 2011, 05:38 PM

The original NE555 timer was Signetics, not Fairchild. I don't remember a TO5 like can version. I remember P & D(ceramic) dips. I do have an original Signetics catalog but can't reach it.

Mooly · 29th October 2011, 06:30 PM

Supply on pin 8 and ground on pin 1 would go some way to identifying it for sure.

There are only a few configurations the 555 is used in normally so easy to tell from the parts around it.

Close up pic of the chip and surrounding area maybe...

siliconray · 1st November 2011, 02:42 AM

It's quite strange that there's a NE555 in a receiver. Maybe it's configured as a trigger, or flip-flop, controlling buttons :-P

28th October 2011, 06:38 PM	#1
Rod Beauvex diyAudio Member Join Date: Dec 2009	Updating 555 timer chip. Would there be any benfit to replacing an older 555 timer chip with a more modern unit? This unit in question is in a mid seventies reciever, and I believe is part of the tuner section. (At the very least, I can't imagine what it would do for the pre or power amp section )

28th October 2011, 06:48 PM	#2
Mooly diyAudio Member Join Date: Sep 2007	I can't imagine what it does in the tuner either... I would say no, leave it be. Reason why, it may be used as a pulse generator/monostable etc and replacing with a low power version would alter it's characteristics slightly maybe needed a realignment of something else. You need to know what it does ? I have never come across commercial kit that used a 555 tbh. Could it be used as a negative rail generator (charge pump) ? __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

29th October 2011, 05:38 PM	#8
indianajo diyAudio Member Join Date: Jan 2010 Location: Jeffersonville, Indiana USA	The original NE555 timer was Signetics, not Fairchild. I don't remember a TO5 like can version. I remember P & D(ceramic) dips. I do have an original Signetics catalog but can't reach it. __________________ Dynakit ST70, ST120, PAS2,Hammond H182(2 ea),H112,A100,10-82TC,Peavey CS800S,SP2-XT's, T-300 HF Projs, Steinway console, Herald RA88a mixer, Wurlitzer 4500

29th October 2011, 06:30 PM	#9
Mooly diyAudio Member Join Date: Sep 2007	Supply on pin 8 and ground on pin 1 would go some way to identifying it for sure. There are only a few configurations the 555 is used in normally so easy to tell from the parts around it. Close up pic of the chip and surrounding area maybe... __________________ ------------------------------------------------------- *A simulation free zone.* *Design it, build it, test it.*

1st November 2011, 02:42 AM	#10
siliconray diyAudio Member Join Date: Sep 2011	It's quite strange that there's a NE555 in a receiver. Maybe it's configured as a trigger, or flip-flop, controlling buttons :-P __________________ www.siliconray.com High Quality Audio Enclosures, Amp Kits, Amplifiers, PCB Fab Services Chat with me


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28th October 2011, 06:59 PM	#3
Rod Beauvex diyAudio Member Join Date: Dec 2009	It's not hugely important, really. This is an old, low-power reciever (Lafayette Lr310)I've had my eye on to refresh once I got the money to do so. The goal here would be to improve performance. Thanks for the answer though. I never realized that there were so many different variations of this chip. The one in question is a metal can type, something I've never seen done with an IC. "C555a 2"

28th October 2011, 07:57 PM	#4
simon7000 diyAudio Member Join Date: Nov 2008 Location: Oakmont PA	It is most likely not a timer IC! It is an rf IF IC also called a 703 originally by Fairchild!

28th October 2011, 11:56 PM	#6
Enzo diyAudio Member Join Date: Sep 2004 Location: Lansing, Michigan	I'm willing to believe Simon, but if we have to have a 555 timer IC, I could see it as a delay for a speaker relay or similar application. Or as a blinker for some indicator light.

29th October 2011, 05:26 PM	#7
Rod Beauvex diyAudio Member Join Date: Dec 2009	Well well, this has turned out to be an interesting discussion. I took another look at it, and it is on the edge of the tuner, where it ends and the amp begins (they're on the same board). I opened up my little tiny Integrated amp, which is also a Lafayette, and it does not have one of these. The little metal can chip in question was made by NEC, and the reciever itself was made between 74 and 78.

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