Rotary encoder replacement in BK Precision 2500 and Agilent DSO3000A scopes

[hanakp]

I'm posting this because I couldn't Google it directly, so maybe it will help some novice hobbyist. A friend asked me to check out a BK Precision 2530 scope because its front panel knobs didn't work properly. As I soon noticed, the BK Precision 2500 oscilloscopes are based on the same Rigol platform as Agilent DSO3000A series (2005-2010). I know because I (unsuccessfully) attempted to un-brick Agilent DSO3202A a few years back, they use Analog Devices ADSP-BF531 DSP and Altera EP1C6Q240C8N FPGA. Curiously, Rigol apparently never marketed these scopes under their own brand, or at least not with the same front panel layout.

Like many other Rigol instruments, the scope suffered from rotary encoder rot. There are 8 encoders in total, 3 with mechanical detents and switch (larger knobs for volts/div and time/div) the rest without (smaller knobs). All have 24 pulses per rotation; the smaller ones were completely dead, the larger ones were  missing pulses. Other Rigol replacement guides usually recommend metal Bourns PEC11R encoders with threaded bushing, but the BK Precision scopes use cheaper plastic ones with smooth shaft sleeve. In the end, I used these part numbers:

• SR Passives EC12E20-24P24C-SW for the 3 detent/switch ones. The detents are slightly stiffer than original, but it felt like improvement. I think Bourns PEC12R-4220F-S0024 would be the closest match among the "respectable" producers.
  
  
• Alps EC12E24104A6 for the 5 ones without detents and switch. I actually tried an encoder with detents first (SR Passives EC12E20-24P24C), but the smaller knobs became uncomfortable to operate. From Bourns, the closest equivalent is probably PEC12R-4020F-N0024.
  

A word of advice - don't attempt to desolder the old encoders the usual way. Their signal leads are a tight fit in the PCB holes and you'll have hard time removing all the solder, even with professional desoldering gun. Instead, snip off the signal leads  near the encoder body with fine pliers and only desolder the two thick mounting ones. Then desolder the signal lead stubs one by one and clean the holes.

Anyway, here are some keywords so this thread is easier to find:

Board marking SAT7.820.269E
BK Precision 2530
BK Precision 2532
B&K Precision 2530
B&K Precision 2532
Agilent DSO3062A
Agilent DSO3102A
Agilent DSO3152A
Agilent DSO3202A