transistor equivalence


Dear All,

I have recently opened two topics, one was for the classic power supply and the other was for the restoration of an HP67.

In both cases, I need to replace some of the transistors present on the boards.

Jaques, but I guess is not the only one, was able to find a cross reference from the classic power supply's transitors, into some ECG-XXX models.

For example : the 0393-338 can be replaced with a ECG-189

which has several equivalents that can be found for example here :

Semiconductor Cross Reference Search

or even better here :

Semiconductor Cross Reference

Does anyone know how it can be done for the rest of the transistors ?
On the HP67 I'm working on, there are :

0413-393 which is the one between the cathode and anode driver

0414-668 (qty two) on the back side of the same pcb

0124-094 on the same side, right corner.

Thank you very much for any help provided, take care Alberto


Take a look here.

I have the vague recollection of reading how HP codes some of their transistors: add a leading zero on the last 3 digits and ignore the leading 4 digits.

So a 0413-393 would translate to: XXXX-0393 and you'd find that this is is equivalent to a 2N3330

However it's more than possible that I'm totally wrong about this, so perhaps someone else can jump in here.


ciao Katie,

thank you very much for the pdf document, it is very very nice,

if the original HP part number is known it works like a charm.

But I did some tries adding the leading zero to the second part
of the item read from the transistor and it doens't always work.

For instance, if you take 0414-668, and search for 0668 you will find :
1853-0668 01698 TIPP115
1855-0668 02883 BS170
1820-0668 * TTL IC
the third is obviuosly wrong, since it's an IC and we are looking for a transistor.

So that the question could also be, does anyone has a complete list of the HP part numbers including the used transitors for a given model ??

thanks again, Alberto


Some general information on HP part numbers :

HP assembly part numbers (like PCBs, etc) have part numbers consisting of 2 5-digit groups, the first groups seems to be the model number of the instrument that first used that assembly, with leading zeros added. So the CPU Control PCB in an HP98x0 is a 09810-66513 (it was first used in the HP9810 calculator).

HP component part numbers consist of 2 4-digit groups. The first group gives the type of component. There are tables in a few HP instrument manuals, but not all.... Anyway, for transistors :

1850-xxxx = Germanium PNP

1851-xxxx = Germanium NPN

1853-xxxx = Silicon PNP

1854-xxxx = Silicon NPN

1855-xxxx = FET

1858-xxxx = Transistor array

To save space on small transistor packages, sometimes only the last digit of the first group and the 'significant digits' of the second group are printed on the package. So if you find one marked 4-471, that's an 1854-0471 silicon NPN transistor.

I wonder if one of the groups of digits on the OP's transsitors is actually a date code.



Here's my best shot at it:

0413-393 would be an 1853-0393, and 041 is the date code

0414-668 would be 1854-0668, date code 041

0124-094 would be 1854-0094, date code 012.

I haven't found any of them in the various cross-reference listings I have, maybe someone else has some information on these part-numbers?

I hope this helps!

Joel Setton


Ciao Alberto,
I can give you only this little help.
From the very good pages of Jack Laporte I can report:

1854-0094 NPN Silicon ---> PN3646

1854-0550 NPN Silicon ---> 2N3904

1853-0020 PNP Silicon ---> 2N3702

Nothing to do for the other (HP 67/97):

1854-0668 switcher

1854-0071 regulation

1853-0395 ??

Take a look at this link

Good evening.


Edited: 24 Jan 2011, 2:12 p.m.


Thanks everybody !!!

Now I only need the time to go buying this stuff

and see if I can make any serious progress on my two open projects

Thanks again, Alberto

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