nec ca245c replacement

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Hi
    I am trying to have a weight pickup repaired for a kobelco Crain the
only active components on the board are 2 NEC c254a and 1 NEC 1541 A
quick look at the thing makes me think they are op amps. They donít show
up in any of my X over books though. Any ideas on a replacement.

Re: nec ca245c replacement



"dron" < snipped-for-privacy@adam.com.au
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**  What is stopping you from describing them  ????

     What package type  -  how many pins etc ??




...........   Phil
 



Re: nec ca245c replacement


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6 Pins old can type IC a bit smaller diameter than a 5 cent piece

Darren

Re: nec ca245c replacement



"dron"
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 **  Sounds like a TO5 style package.

 Likely to be dual transistors or dual fets with 6 pins.

 Normal op-amps all have  8.

 The numbers all come up blank on Google - so just how antique are they ??





............   Phil




Re: nec ca245c replacement


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The Crain is from 1985 but the electronics look old even for that time.
I have the pick up at a local industrial tecks workshop and am going by
memory on the pin numbers. The unit compares 2 inputs from mechanical
pressor sensors and gives a single output. Runs from a 12v +/- supply
and gives a dc +/- output to the weight scale. The bord is about 50mm by
75 mm in a steel case. 1 new one left in the world and they want $6000
for it.

Re: nec ca245c replacement


finger to keyboard and composed:

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You have "ca245c" in the subject but "c254a" in the body of your
message. Now you are not sure of the numbers of pins??? Not meaning to
offend, but maybe you should confirm all the data before you have us
looking for something that never existed.

It may help to know which pins connect to what, ie inputs, outputs,
supply rails. I suspect the first IC may indeed be an 8-pin
instrumentation op-amp. If so, then maybe you can substitute an
OPA111AM (Farnell, p/n 400-671, $47) or better.

See http://www.hardware.dibe.unige.it/DataSheets/OPA111.pdf

Is it possible the 1541 is really a 1741? If so, then it's probably a
general purpose 741 in a TO-99 package.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

Re: nec ca245c replacement



C254a and c1542 are the correct numbers. I will call the teck that has
the unit to check the pin numbers Monday. He told me they should be op
amps. The numbers were good and did list on 1 of his suppliers sights.
Their was no data on them or local availability though.

Dont pretend to know a lot mysealf but the if the link to the pdf from
Franc Zabkar is corect it will help

Thanks I will post the corect pinout asap

Re: nec ca245c replacement



"dron" <
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**  They could easily be factory code numbers   -   secret by intention.



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**  It is the  ***number of pins***  we want to know  -  you illiterate
prick.


    BTW     The abbreviation for technician is  " tech "   !!!!!!



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**   So it is all bloody hearsay  !!!




.............    Phil



Re: nec ca245c replacement


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Hay toasterboi  still falating roddles each evening in the loo down
queens park ?
  I hear you two go pretty hard at the anal right around 8 pm ?

Re: nec ca245c replacement


Hi,
could be upc254a -  instrumentation amp, as far as my data sheet indicates ,
it has 8 pins in both dip and can type.

if that's it, datasheet can be found here for a while:

http:// members. iimetro .com .au / ~gcd / upc254.pdf

Can't find any nec reference with 1541 or 1541a, any prefix on that like d
etc?

Greg


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Re: nec ca245c replacement


been there long enough - gone now

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,



Re: nec ca245c replacement


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dont ask phil, all he does is insalt everyone.

Re: nec ca245c replacement


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Donít worry every group has one like Phil. I reply to a question or two
in the aus.car group in the interest of helping people from within my
field and it seems there is plenty of those who think they are to good
or maybe to insecure to play nice.

    For those who donít fall into this group I checked out a 2nd unit today
( also faulty). It was older but the same design. The ICís were the same
( 2 of NEC c254a and 1 of c1541 ) and sorry they do have 8 pins. A 12v
+/- supply and  the older board is marked op amp 1 2 and 3 so I guess
they may in fact be op amps. If anyone has an old crossover book listing
an equivalent that would be grate.

Thanks

Re: nec ca245c replacement


finger to keyboard and composed:

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Your statement that "the unit compares 2 inputs from mechanical
pressor sensors and gives a single output" suggests to me that the
uPC254A, an instrumentation opamp, amplifies the output of each
sensor, and the uPC1541 is probably a general purpose opamp wired as a
differential amp. A little bit of circuit tracing should tell you
whether you could substitute a 741 or better for the latter, and a
suitable low offset, FET-input, low bias current equivalent for the
former.

BTW, the OPA111 opamp I alluded to elsewhere differs from the uPC254A
in the offset nulling pins. Check whether your circuit uses these
before attempting a substitution.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

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