Siglent SDS 1052DL Oscilloscope Knobs not Registering - Page 1
Forum section: electronics / testgear

author: Squirrelish
author_rank: Newbie
timestamp: June 30, 2019, 12:50:21 am
content: I have had my Siglent SDS 1052DL oscilloscope for a few years now, and when I turned it on today none of the knobs were registering. If I enter the "keyboard test" mode (Utility -> Do Self Test -> Keyboard Test), the buttons all work (including the switch portion of the knobs), but none of the knob rotations themselves for any of the knobs are being sensed. As such I don't think there is any kind of software lock on them. Has anyone experienced the same issue? I did a quick tear-down to see if anything obvious was wrong, but didn't find anything at first glance. The rotary encoders all appear to be operating as expected. I haven't been able to do much more debug of the PCB because, well, I don't have a working scopeAny thoughts? I can attempt to draw the keyboard PCB schematic by tracing it manually, but was hoping someone might know exactly where to start looking. Thanks!

author: tautech
author_rank: Super Contributor
timestamp: June 30, 2019, 01:19:29 am
content: A few years meaning it's out of it's 3 year warranty ?First I'd reseat the internal connectors especially the ribbon cable between the mainboard and keypad PCB that the encoders are mounted on.For that you'll probably have to completely dismantle the scope to get to the keypad PCB connector.If you have a 9/16" or 14mm deep reach socket that will make removing the nuts off the BNC's much easier however it can be done with some stout long nose pliers if you're rough and in a hurry.You can use the CNL service manual as a very good guide:https://www.siglentamerica.com/download/2710/We can probably organize a replacement PCB if it's not repaired with these checks.

author: Squirrelish
author_rank: Newbie
timestamp: June 30, 2019, 03:07:30 pm
content: tautech, thanks for the reply! When I tore it down yesterday, I did clean and re-seat the ribbon cable from the mainboard to the keyboard PCB but that didn't help. I am not sure how to know which board the issue is on, the mainboard or the keyboard PCB.It seems the keyboard PCB has a pair of 8-bit shift register ICs (HC595 series), a pair of 8-bit analog/digital multiplexer/demultiplexer ICs (74HC4051D), and a dual 4-bit binary counter IC (HC353 series). My guess is that if anything is bad on the keyboard PCB it would be one of these ICs (since the passives appear isolated to a particular knob/button), but I haven't done a full trace to see which set is handling the rotary encoders yet. The 16-pin ribbon cable connecting the mainboard to the keyboard PCB seems to only have 8 unique signals (power and ground are two of these unique signals, taking 4 and 6 pins respectively), leaving 6 pins for actual IO through the cable. So I guess what I'm trying to figure out, again without a scope to validate, is what "half" of the IC and signal sets is dealing with the rotary encoders? I assume that they are logically split that way because all of the buttons still work, but none of the rotary encoders do. Though, even with that information, there might be some mainboard processing between the buttons and rotary encoders that is distinct as well - so how can I isolate which PCB actually has the problem before replacing parts?Thanks!

author: tautech
author_rank: Super Contributor
timestamp: June 30, 2019, 07:34:32 pm
content: Quote from: Squirrelish on June 30, 2019, 03:07:30 pmI'm reasonably confident the issue is with the keypad PSU.In the service manual linked earlier there's checks to do on the mainboard and PSU. Some require a scope so you can't do those but you can measure a # of voltage rails and check for bad ripple on the PSU.Monday here and the factory will be up and running in a few hours so I'll shoot a query to them any about further checks you can do.

author: Unknown
author_rank: Unknown
timestamp: July 08, 2019, 02:00:02 pm
content: Quote from: Squirrelish on June 30, 2019, 12:50:21 amHello,Please contact us atinfo@Siglent.comWe would certainly like to take a look at the problem and ship your keyboard back to the factory to analyze. We will replace your keyboard.Thanks.