Help needed to Identify & locate part

[subseauk]

Hi
I am trying to identify and locate a replacement chip on a Combi Boiler controller PCB.
I think it may be a Fairchild component but i have had no response from them.!

It is a 4 leg/pin chip with the following markings:

V921Y
f817A

the f is like a lower case italic which makes me think it may be the Fairchild logo??

The board is in a Remeha Avanta 28C ECO combi boiler ( and no, they have not replied either!!! )

Any help really appreciated.
Rgds
Kev

 

[Resqueline]

Pictures please, top & bottom. Or a more detailed physical description with sizes. Could it be a relay of some sort?
No reply is normal btw..

 

[shrtrnd]

This is probably not going to help, but any info is probably better than no info:
Your IC was made when Fairchild was really Fairchild (1981, 7th week). Since then fairchild was bought by somebody else, who dumped them years later. The new company is called Fairchild, but they don't support ANYTHING the original real Fairchild made. You've got a proprietary part number, which only the equipment manufacturer had the rights to (so 'Fairchild' couldn't give you any info on it either).
Knowing what Fairchild made in the 1980's, my bet is you're looking at an optocoupler, or possibly a bridge rectifier. Your board is so old, the original mfgr probably doesn't support it any more either (planned obsolesence). If you're as desperate as I get on these things sometimes, follow the trace on the board, and try to determine the device-type, by the connected components. If you look-up the voltage/current capability of the connected components,... you might be able to find a compatible equivalent.
Only other thing I can think of, is to find somebody else who uses your boiler, and see if they have a schematic on your circuit.
Good luck, you'll need it. (the small 'f' IS Fairchild)