A little help on my DBX 286A
farukhcasy2
Posts: 1
TL;DR - I am looking for a replacement pot for pot #1 (the Gain pot) for this unit.
Well, I bought a used USA made DBX286A from eBay. Long and short of it, it came in damaged. I worked it out with the seller that I got a partial refund and got to keep the unit as I advised I could likely fix it. Great seller and I'm stoked to get it for $50!
It had 3 broken pots (#1, #2, and #3) and the SSM2017 had been replaced with an SSM2019 - poorly - cold solder joint and all. I tracked down some information and eventually found that Harman would sell direct replacement pots for #2 and #3, but not the original gain pot. I had temped some resistance in where the pots broke and was able to confirm that the unit was worth tossing parts at
I ordered the pots for #2 and #3 from Harman as well as an SSM2019 replacement (which arrived in the wrong form factor) I also ordered (Mouser) all replacement electrolytics for this (Nichicon 105c) and I also ordered the proper SSM2019 (DIP package) The only thing that I haven't sorted is the 6 or 8 non-polar caps that tricked this home-gamer in to ordering standard caps instead. I left the non-polar alone for now.
I'm still waiting on the DIP packages to arrive so I can replace the new pots and the chip. I suspect the chip is partially defective as it works, but the mic pre-amp doesn't have nearly enough gain to get to a yellow or red light on the display LEDs. I'm using an MXL990 mic. If I crank the gain pot, I can get in to the yellow, but only with overly-loud speaking.
My sticking point is pot #1. Harman advises that the original pot was "p/n 40-2131 POT 5K 5C 16mm ROT 41 CLK 15mm D-SFT HOR" and that it's no longer available. They also advised looking for a "Taiwan Alpha Electronics p/n RV16AF-20-15FW-05C5K-3FP1" I bought a pot from Mouser that is a 05C5K pot that fits, but it doesn't drive the gain like I have seen in numerous demo videos. Again, I suspect that 2019 is hooped. It also was covered in flux and had a cold solder joint.
If the one I ordered works, I will keep it in, but it does not have the detents that the factory pots do. I am terrible at shopping the electronics warehouses really and Mouser was a 2 hour shopping trip for caps.
Hope it wasn't too bad of a wall of text. Yes, I do have the schematics and the original BOM.
Thanks for reading and any help!
Comments
I know on the 286s which was the next successor to the 286a, the Gain Pot on the Mic Pre is part no. 40-0053 and rated at 10k. It might work, but not sure. You may want to contact some of the authorized service centers for dbx, they are not official Harman but they might still work on the old models and have a solution as well.
https://pro.harman.com/service_centers?utf8=✓&q[state_eq]=&q[service_groups_name_eq]=dbx&commit=Search