If you've been following my thread on repairing the oscilloscope, you know I'm more than a little confused and frustrated by the difficulty in knowing what parts can be swapped for other parts presumed to have failed. Fundamentally, it's a problem of cross-referencing one manufacturers part numbers with others, until you get to one that can be readily obtained.
Here's an example. In order to repair the ailing 48V rail, I want to replace the 4 transistors in that rail. The HP part numbers are:
1853-0080
1854-0071
1854-0215
1854-0358
Of those, I could only find a cross-reference for the 1854-0215 (which is a standard 2N3904). The others don't seem to cross reference, which left me feeling I had no choice but to buy expensive replacement parts from vendors that specialize in obsolete replacement parts. Yet something in me screams that if I only knew how to cross reference this I could get a 67 cent replacement part instead of spending $5 for the one from the obsolete parts vendor (and incur the annoying wait time).
Another unrelated example. I bought a semiconductor grab bag full of of Motorola HEP parts. I did the research on those and found that three of them (HEP-S0019, HEP-S0031 and HEP-F2005) are deemed equivalent to the 2N3906. That, in and of itself, isn't too surprising. But the question lingers why make so many variations of the same thing if they are functionally equivalent? Are there situations in which they aren't functionally equivalent?
One of the pieces from the grab bag (HEP-F9003) comes up in the cross reference documents as a silicon diode, not a transistor. Uh... okay... so maybe they put it in a three legged package for a reason that escapes small brains like mine?
I'm finding that datasheetarchive is helpful, but not always. I find that the sites trying to get RFQs out of you are useless. Some sites that want to sell you stuff CAN offer hints as to the replacement parts (e.g. VETCO), but that information isn't always reliable.
Are there other sources of information I could reference? I hate asking specific cross reference questions every time I hit a dead end on Google.
Here's an example. In order to repair the ailing 48V rail, I want to replace the 4 transistors in that rail. The HP part numbers are:
1853-0080
1854-0071
1854-0215
1854-0358
Of those, I could only find a cross-reference for the 1854-0215 (which is a standard 2N3904). The others don't seem to cross reference, which left me feeling I had no choice but to buy expensive replacement parts from vendors that specialize in obsolete replacement parts. Yet something in me screams that if I only knew how to cross reference this I could get a 67 cent replacement part instead of spending $5 for the one from the obsolete parts vendor (and incur the annoying wait time).
Another unrelated example. I bought a semiconductor grab bag full of of Motorola HEP parts. I did the research on those and found that three of them (HEP-S0019, HEP-S0031 and HEP-F2005) are deemed equivalent to the 2N3906. That, in and of itself, isn't too surprising. But the question lingers why make so many variations of the same thing if they are functionally equivalent? Are there situations in which they aren't functionally equivalent?
One of the pieces from the grab bag (HEP-F9003) comes up in the cross reference documents as a silicon diode, not a transistor. Uh... okay... so maybe they put it in a three legged package for a reason that escapes small brains like mine?
I'm finding that datasheetarchive is helpful, but not always. I find that the sites trying to get RFQs out of you are useless. Some sites that want to sell you stuff CAN offer hints as to the replacement parts (e.g. VETCO), but that information isn't always reliable.
Are there other sources of information I could reference? I hate asking specific cross reference questions every time I hit a dead end on Google.
