musical fidelity repair - Page 2

mistamovie · 2nd March 2005, 04:55 PM

IC3 is an LF353N, 249A, which i think is the opamp? causing the problem

jacco vermeulen · 2nd March 2005, 05:32 PM

Alps pot channel difference can be up to a decibel or more.

The LF353n is a dual opamp, pin compatible with a NE5532.
If the opamp is broken you might consider swapping for a better one, the LF353n is rather cheap.

mistamovie · 3rd March 2005, 07:39 AM

would i need to change anything else other than the chip?
are there any differences between the manufacturer of the chips? so i could do a straight swap for an ne5532..
is it best to use a solder sucker when removing chips? i can see myself getting into a mess trying to get all 8 pins hot at once!! or should i just cut the old one out, get rid of the cut pins and then re-drill to get rid of any solder left in the holes?

jacco vermeulen · 3rd March 2005, 10:25 AM

I use a roll of stranded copper wire for removing solder, 50p
Put the end on the pin, place the soldering point on it, the solder flows into the copper strands, voila.
Simple mechanical solder suckers dont work, imho.

The NE5532 is a straight swap-in, it is the most used opamp for pre-amplifiers.
Even used for the front end of quite a bunch of power amplifiers.
There are different manufacturers, you can cross reference the datasheets at www.alldatasheet.com

The 5532 has a bandwidth of 10 MHz, more than twice of the LF353, slewrate is a bit lower.
An NE5532 can be had nowadays for 50p.
Analogue Devices also has a number of excellent dual opamps.
Above that is something like the OP227, a dual OP27 opamp.
The best are Burr Brown models, the opamps have BB stamped on them.
And Linear Technology has LT models.

I would settle for the NE5532 in your preamplifier, the 5532 has been used in 1500 PS preamps.
Go higher and you will probably be rebuilding the entire amplifier.

mistamovie · 3rd March 2005, 11:19 AM

right then, i think i am set.
i reckon there should be stars available to award people for helpful posts!
i will get on with the ordering of the part, have a go at fitting them and be back here with smileee faces if it works!

2nd March 2005, 05:32 PM	#12
jacco vermeulen diyAudio Member Join Date: Oct 2004 Location: At the sea front, Rotterdam or Curaçao	Alps pot channel difference can be up to a decibel or more. The LF353n is a dual opamp, pin compatible with a NE5532. If the opamp is broken you might consider swapping for a better one, the LF353n is rather cheap. __________________ Not so much,.......if it says "ZM" in the corner.

3rd March 2005, 10:25 AM	#14
jacco vermeulen diyAudio Member Join Date: Oct 2004 Location: At the sea front, Rotterdam or Curaçao	I use a roll of stranded copper wire for removing solder, 50p Put the end on the pin, place the soldering point on it, the solder flows into the copper strands, voila. Simple mechanical solder suckers dont work, imho. The NE5532 is a straight swap-in, it is the most used opamp for pre-amplifiers. Even used for the front end of quite a bunch of power amplifiers. There are different manufacturers, you can cross reference the datasheets at www.alldatasheet.com The 5532 has a bandwidth of 10 MHz, more than twice of the LF353, slewrate is a bit lower. An NE5532 can be had nowadays for 50p. Analogue Devices also has a number of excellent dual opamps. Above that is something like the OP227, a dual OP27 opamp. The best are Burr Brown models, the opamps have BB stamped on them. And Linear Technology has LT models. I would settle for the NE5532 in your preamplifier, the 5532 has been used in 1500 PS preamps. Go higher and you will probably be rebuilding the entire amplifier. __________________ Not so much,.......if it says "ZM" in the corner.

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2nd March 2005, 04:55 PM	#11
mistamovie diyAudio Member Join Date: Feb 2005 Location: Bracknell	IC3 is an LF353N, 249A, which i think is the opamp? causing the problem

3rd March 2005, 07:39 AM	#13
mistamovie diyAudio Member Join Date: Feb 2005 Location: Bracknell	would i need to change anything else other than the chip? are there any differences between the manufacturer of the chips? so i could do a straight swap for an ne5532.. is it best to use a solder sucker when removing chips? i can see myself getting into a mess trying to get all 8 pins hot at once!! or should i just cut the old one out, get rid of the cut pins and then re-drill to get rid of any solder left in the holes?

3rd March 2005, 11:19 AM	#15
mistamovie diyAudio Member Join Date: Feb 2005 Location: Bracknell	right then, i think i am set. i reckon there should be stars available to award people for helpful posts! i will get on with the ordering of the part, have a go at fitting them and be back here with smileee faces if it works!