Rigol DHO914S high temperature / overheating probe inputs

[maher8]

Hi guys!
Yesterday, my new Rigol DHO914S oscilloscope arrived. It works well, and I didn’t experience any software bugs during my short testing time. However, I noticed that the unconnected probe inputs on the oscilloscope feel hot to the touch (the AWG output on the back too). It causes pain if I hold them for too long, at around 50-60°C. The oscilloscope is warm on the outside. Is this normal for this oscilloscope? I have limited experience with oscilloscopes as a firmware developer, but the probe inputs on any scopes I’ve worked with before never got warm, let alone hot. Is this a typical Rigol issue, or should I return it before something burns due to the high temperature?

The cooling fan is working, the oscilloscope is on my desk with good airflow, my room temperature is around 23-24°C, and I’m using the standard power adapter that came with the scope. The scope was running for 2 hours, and the temperature remained stable, with the probe inputs staying at 50-60°C the entire time.

[Fungus]

Doesn't sound normal to me.

My DHO804 BNCs don't get much above ambient.

[Elextro]

My oscilloscope, which is a DHO 802, also get a little hot at the BNC inputs and at the rear AWG output. It is not a very high temperature, but I confirm that it does heat up. I think that the front inputs get hot because they are screwed to the frontal metal chassis which acts as a heatsink and shielding at time. Greetings

[Fungus]

My oscilloscope, which is a DHO 802, also get a little hot at the BNC inputs and at the rear AWG output. It is not a very high temperature, but I confirm that it does heat up. I think that the front inputs get hot because they are screwed to the frontal metal chassis which acts as a heatsink and shielding at time. Greetings

They're above room temperature, sure, but do they burn your fingers?

[maher8]

Little status update...
Yesterday it was a little late when I was testing this. At the end, I did firmware update to the newest version available, as last resort.

Today, the scope is performing normal. I tested it with IR thermometer and it's 32-33°C at probe inputs, after 2 hours of working. It is warm to the touch, but nothing too hot.
It looks like firmware update did something good. Maybe something stuck in a loop. I will check temperatures every now and then, and post update if it goes wild again.

Thanks for useful info!

[ebastler]

There are internal temperature sensors in the DHOs, and some way to read them through the GUI. It's been a long time since I returned my DHO1000, so I don't recall where the monitoring dialog is in the menus and whether it is hidden or locked in some way. Maybe a DHO800/900 owner could post a reminder?

[csuhi17]

If you mean what is in "Utility->self Check->Board Test", then it is not hidden. But it only writes the temperature of the processor.
After a few hours of running.
CPU_CHIP_TEMP:68.3
CPU_AMBIENT_TEMP:65
I measured 52 degrees directly in the BNC sockets with a contact probe.
Based on my feeling, tested with the thinner layer of skin on my hand, it burned.
With the end of my new ones, I just felt warm.

DHO924S, the AWG not active.

[Fungus]

What firmware was it before/after?

[csuhi17]

I now have 1.03.00.06.
But I was already warm with the very first one, but I didn't deal with it because I didn't see a problem with the measurements.

[ebastler]

If you mean what is in "Utility->self Check->Board Test", then it is not hidden. But it only writes the temperature of the processor.

Thanks! Ah, right -- that was one of the differences between the DHO1000 and its smaller siblings. The 1000 have several dedicated temperature sensors, including in each of the analog front ends, giving a total of 8 or so temperature readings.

[ptluis]

I now have 1.03.00.06.
But I was already warm with the very first one, but I didn't deal with it because I didn't see a problem with the measurements.

This is the problematic firmware version that bricks the scope when xy window is used and the scope shutdown? or it happens only on the dho8xx version?

[csuhi17]

Yes, that's it, I haven't dared to try yet, I don't know.
I press the Default button before turning it off.
I had a problem with this too, because after I updated it kept crashing in XY mode.
 It was set to always load Default, but it seems that was not enough. I also had to press the button.

[maher8]

What firmware was it before/after?

I don't know which specific firmware was before, but in About section it was 00.01.01 I think. Now I upgraded to 00.01.02.00.02, latest available from their website.

[Fungus]

I now have 1.03.00.06.
But I was already warm with the very first one, but I didn't deal with it because I didn't see a problem with the measurements.

This is the problematic firmware version that bricks the scope when xy window is used and the scope shutdown? or it happens only on the dho8xx version?

It's the exact same firmware for both.

[maher8]

A few days ago, I mounted my DHO914s using a VESA mount, and I noticed the high temperatures returned. This might be an issue for some users. Even though the VESA mount left enough space for the fan to pull in air, it still didn’t seem to be sufficient. Now, I’ve remounted it as shown in the attachments, and the temperatures are much better.

In case anyone finds this useful, here’s the hardware I used:
- 4x M4x35mm screws
- 4x M5x20mm metric extension nuts (so the M4 screws can pass through freely)
- 12x wide M4 washers