Hi all,
I'm looking for help to find an equivalent to this part: RKM14L492-103F. It comes from a Boss guitar pedal (DD-2) and the service manual (https://www.synthxl.com/wp-content/uploads/2018/04/Boss-DD2-DD3-Service-Notes.pdf) says it is an "R-2R ladder network"
I took it out and measured the connections from pin 1 to all the others, and they started at ~10k and went up in ~5k increments until the second to last which was ~65k and the last one was also ~65k.
Does anyone have an idea what an equivalent part might be? What are some search terms that would guarantee I find one on Mouser?
Thanks!
Try looking for resistor "networks" or "arrays". Some R/2R info here: https://www.bourns.com/docs/technical-documents/technical-library/networks/application-notes/r2rap.pdf.
You can see the insides in context in the SDE-1000/3000 repair notes (PDF page 17):
(https://i.postimg.cc/3ygZjghr/RKM14-L492-103-F-in-SDE1000.gif) (https://postimg.cc/3ygZjghr)
https://www.vintagesynthparts.com/wp-content/uploads/2018/01/SDE-1000_SDE-3000_SERVICE_NOTES.pdf
(same designer?)
With Gord's help you can probably pencil-in values in the right places.
(I never remember which is R and which is 2R.)
I think the Bourns pinout is different from the one BOSS used?)
I don't see any on offer.
I think you can roll yer own with a fistful of 10k resistors (two series for 2R). One nice thing about R-2R DACs is no exxtreme ratios and no critical matching. Common 1% may even be "too good" but a few inches of parts-tape won't cost much.
Ah, no, a 12-bit R2R DAC needs the MSB resistors far-far better than 1%.
https://en.wikipedia.org/wiki/Resistor_ladder
Do a search on:
precision R2R 12-bit
Suppose you targeted +/-0.01% tolerance. For a 10k resistor that's +/-1 ohm.
The point is if you have chip driving the R2R ladder then the switches/gates resistance need to be matched to less than +/-1 ohm in order not to impact on the overall tolerance. You will find a lot of chips aren't that good. So the chip resistance matching can end up having more effect than the resistor array.
Thanks guys!