Diode Identification

[Shortbus]

I want to say thank you for having me here....  I think I only know enough to make things worse so looking for some advice.  Please and Thank you.

I have an old 1970 Otis elevator in the building I work in.  The repair company said the diode board is discontinued and we should replace the elevator as a result.  I don't want to say how much that costs, but surely a shorted diode costs much less to replace.  I certainly want to try.

The diode has a GI 612B2 on it.  I have searched a few of the more popular datasheets and obviously google...  but I don't even know where to start based on the age.  I am not looking for folks to do my work for me... just help on a place to start.  Apologize for my ignorance.  New to the forums and it seems even the beginner discussions are a bit over my head.

I have attached an image of the diode board as well as a schematic for the equipment showing the orientation. Thank you for any input.

[bdunham7]

They're 1A 400PIV rectifiers, pretty generic.  You could replace them with standard 1N4007, or if you wanted to go up to a 3A 1000V version, use 1N5408.

OTIS actually lists this part along with an updated part number in a different manual, see page 8 of:

https://otiswave.otis.com/Documents/SPL/10-7900BC.pdf

So selling you a new elevator seems lazy and opportunistic.

Edit:  forgot to say, if you buy and install them yourself, ONLY buy them from someplace like Mouser, Digikey, Arrow, etc.  DO NOT buy them from eBay, AliExpress or Amazon and the like.

[BillyO]

I think you should give bdunham7 10% of the new elevator cost.   Seem fair.  He's in the market for an 8.5 digit DMM.

[Shortbus]

Thank you for the response.  I was a bit irritable when I finished the investigation... expected a far more complicated scenario than I found.  3 elevator companies denied trying to fix the issue... all saying the same thing.. your elevator needs to be upgraded.  Let us send you a proposal... 2 of the 3 being national companies.  Shame that no one tries to fix issues other than throwing parts at a problem.

Your time is greatly appreciated.  I will research the link.

[srb1954]

This is standard modus operandi for an elevator company.

I find that they typically only supply parts for the electronics in a system for about 10 years after a system is installed. If any part of the controls fails after that you generally are faced with installing all new electronics. The cars and the motors should be good for 25 years though.

However, if you get repairs done by someone other than the official elevator service people you may run into problems getting the elevator safety certified. The service people will say that the electronics is no longer standard as it doesn't have officially approved parts in it and they will probably refuse to certify it.

[floobydust]

I would say the techs want to just replace a board, not troubleshoot a component.

OP's diode has a house part number for Otis, it seems to have been updated from glass to plastic package. From "612B2" to "AAA612AF2" "diode w/sleeves 400PIV".
I did see in other Otis docs p/n 1N5060 given as original part number 2A 400PIV, harder to find but higher voltage 800V part 1N5062 lots in stock.
Or just use a larger 1N5408. It's not critical. Just seems to be for DC power to the field winding.
If it eats these diodes, could be problems with the field brushes and note there is not much for (diode) surge/transient protection, your schematic shows a gas tube used for that. I'm not sure if they last many decades long, or why Otis didn't use a capacitor or something to better handle spikes.