Unknown IC in power control circuit.

[ChrisKnight]

I have discovered that the IC in a scroll saw power controller is faulty. Unfortunately the number on the chip has mostly melted and I cant read the number.

I am pretty sure it is an op amp or a PWM chip, but perhaps not.

The chip is a National Semiconductor and what can be read of the number is;

LM*#2?N

The * is a narrow number or letter.
The # is a round bottomed number (0, 3, 5, 6, 8 or 9)
The ? looks fairly narrow as well.

The controller is perhaps a few years old and so it may be a discontinued chip, but I have had no luck tracing it.

As a matter of interest it is a REXXON scroll saw and the motor is a fraction horsepower.

Any detectives out there ?

Regards
Chris

 

[gordonl]

You need to find someone with the service manual for the saw. A tool repair shop may be willing to share this info with you. A shot in the dark, if it is a variable speed saw it may be a Pulse-Width-Modulator chip such as those used in switching power supplies.

 

[jbartos]

Suggestion: Check

http://www.national.com/

It may also be under obsolete items if it is for old saw.
Do you have more info about REXXON?

 

[ChrisKnight]

Thanks gordonl and jbartos,

I contacted REXXON and unfortunately there is not an Australian supplier for this component. They did offer to replace the whole module for US$60 (about A$120) which for a 5 year old A$200 scroll saw seemed a bit excessive (particularly for a $2 IC).

I had already tried the national semiconductor site but unfortunatelt their search engine is a little limited in how you can search.

For instance it would be handy to not have to wade through a lot of different ICs when you know it is a 14 pin DIL package.

I guess I was mainly looking for someone who had an extensive list of ICs that I could sort by package size and wild card part numbers etc.

Thanks for your help
Chris

 

[jbartos]

Suggestion: Contact REXXON again and ask them to read you the IC data.

 

[ChrisKnight]

jbartos,

Thanks but that was my first approach method a couple of weeks ago. They were pretty keen to sell me the $60 module.

Ta
CHris

 

[jbartos]

Suggestion: What I actually meant "keep on trying". Sometimes, sending a fax or speaking with the Manager helps. Do not forget that people are changing in the business.