| Products > Test Equipment |
| An investigation about ripple current of Kunkin KP184 |
| << < (7/18) > >> |
| burkm:
I've held mine up to the light and discovered this "hidden" button position (shadow behind the front panel "mask") you mentioned too, but if it's not supported by the original firmware it won't do anything useful. Don't have any idea, what it should be used for, may be a "reserve" for some possible extension not known at the time of designing the front panel... |
| burkm:
I checked the Kunkin web site. They got a color model similar to the KP184, the KP184C, which uses an identical front panel and has an additional key at this position (LAST). This is probably the reason for this empty space... |
| atarian:
Hi, newbie around here. I acquired KP184 in 2020, but really have not used it until recently. As anyone here, I have quickly found out that it exhibits quite a lot of noise on input sockets, even unloaded. Unless I am reading my measurements incorrectly, I see ripple with Pk-Pk value over 1V. Of course, this "property" defeats the whole purpose of this unit for me as I my intention was to use it benchmark PSU designs, including ripple & noise across their output range. Ergo, I would like to get rid of it, so I did a little bit of digging on my own and I have also evaluated all the tricks users here tried and reported some level of success with it. In my case, top PCB revision is 004. Firmware has been updated to 20210720A thanks to user who posted the FW in this thread. Other then FW update, I have tried to remove C58, or C57, played with their values too. I have tried GND wire trick too. I have put low ESR cap in parallel to front panel power rail cap. None of above helped even a bit. The ripple is still there, same levels. With and without front panel and/or fan disconnected - no change. What I have also realized when scoping across the top PCB that basically ripple with that same signature is present all across the board, on all power rails: +5V, +3V3, +12V,-12V I mean its kind of crazy to see the 0,5V ripple on 3.3V rail, right on STM32 microcontroller pins. Same ripple signature can be also seen on input of 7805, so basically on output of rectifier bridge of 18V AC transformer output (diodes D12, D14, D16, D17). Seeing it basically on these places I am thinking - this can not be all just an induced signal from a digital section, or can it? Either I am going crazy, or this mess can all be traced back to a transformer. Can someone please confirm my finding on your unit? |
| dophuc:
I measured the noise at the KP184 input jack (no load). My Kp184 is the 2020 version, nothing has changed since I bought it. |
| electr_peter:
@atarian, what do you measure when scope probe is on output connector, but DC load is turned-off on the back (but still connected to mains)? |
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