Siglent shock!... - Page 1
Forum section: electronics / testgear

author: jimblair
author_rank: Newbie
timestamp: September 19, 2021, 04:18:36 pm
content: I've had my Siglent SPD3303D for a 1/2 dozen years now (Software version: 1.01.01.01.06, Hardware version: V1.1) and I got the shock of my life the other day. I went to grab my channel probes on channel 1, with channel 1 set to 7 VDC and the current limited to something around 700 mA. I inadvertently grabbed the probe metal and got what I believed was a live power shock! I couldn't believe it, because the channel was not set to on, but I got an almighty shock.I immediately pulled out my multimeter and I was doubly shocked to see that my channel one terminals were reading 20 VDC, without being powered on. It now doesn't matter what i set Channel 1 to, regarding voltage or current...the channel one terminals always present 20 vdc and they show "CC" continuously, as soon as the channel is turned on.I have searched around for anyone else having trouble with their 3303D, but haven't found anyone online with a similar problem. I have measured voltage on both Channel 1, Channel 2 and Channel 3, even when the whole scope is powered on, but there are no channels activated.....is this a "normal" condition for this power supply? I am shocked (no pun intended) to find any voltage present on the channel terminals, when the channel is deactivated...am I missing something?Thx, Jimps. there are no warning dialogs/messages anywhere, or any fault messages posted/warned about, but the fact that the channel is showing CC when the channel is active but the channel probes are disconnected, tells me there is something seriously wrong...

author: AVGresponding
author_rank: Super Contributor
timestamp: September 19, 2021, 06:07:38 pm
content: This most definitely not normal.With no channels turned on, but with the unit powered up, I measure only a few mV of DC and a few hundred mV AC between any two terminals, which is what I would expect to see.Congratulations, you have a fault to find, and a repair to make!

author: H.O
author_rank: Frequent Contributor
timestamp: September 19, 2021, 06:33:55 pm
content: Well, something is wrong with the supply, that's for sure. But 20VDC won't give very much of a shock (if any) so there "must" be some capacitively leaked AC on the terminal(s) or something. Have you checked AC voltage between terminals (and to ground)?Is the supply properly connected to a grounded outlet?

author: Kean
author_rank: Unknown
timestamp: September 19, 2021, 06:51:25 pm
content: Or maybe the initial "shocK' was an ESD event which has caused some damage. I have no idea how susceptible these devices are to ESD.

author: tautech
author_rank: Super Contributor
timestamp: September 19, 2021, 10:25:55 pm
content: Quote from: H.O on September 19, 2021, 06:33:55 pmThis is the first thing to suspect ^I can't find a service manual for the OP but maybe he still has the CD it was shipped with and has the manual already.AFAIK all outputs are relay switched on these older models and as all secondary's are LV as these are a linear PSU so how any significant voltage large enough to shock the user can get through is a mystery.