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Rigol DHO804 Test and Compare Thread

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2N3055:

--- Quote from: ebastler on December 18, 2023, 12:57:07 pm ---
--- Quote from: Fungus on December 18, 2023, 12:31:44 pm ---
--- Quote from: ebastler on December 18, 2023, 06:47:39 am ---Indeed, that's less than I expected. The DHO1000 dialog shows much more info.

--- End quote ---

Not really. All it says is that "ambient temp" is a degree or two less than chip temp.

What's "ambient temp" anyway? was that screenshot taken in a room at 45 Celsius?

--- End quote ---

Umm -- when I look at the dialog, I also see temperature measurements for the ADC and (presumably) the leftmost and rightmost front-end amplifier?

The "ambient temperature" readings are obviously not room temperature, but apparently the immediate environment of the respective chips. I have wondered about those too: Did Rigol actually populate NTCs next to each of these four chips? It's the first model using the new chipset, so maybe they wanted to play it safe?

Not my own screenshot, btw. I took it from another thread which discusses tweaking the DHO1000 fan via its PWM control.

--- End quote ---

Most chips with any complexity have built in temp measurements. Otherwise, mostly diodes are used as measurement sensors on PCBs.

ebastler:

--- Quote from: 2N3055 on December 18, 2023, 01:09:04 pm ---Most chips with any complexity have built in temp measurements. Otherwise, mostly diodes are used as measurement sensors on PCBs.

--- End quote ---

Did you look at the screenshot? For each chip there's an internal temperature readout (obvioulsy from a built-in sensor) plus an "ambient" temperature. It's the latter which we were discussing.

Whether it's a diode or a temperature-dependent resistor, it looks like Rigol went to the effort of populating four of them (plus providing some readout), so they can monitor all chips attached to the central heat spreader. Looks like they planned for a nice, temperature-controlled cooling solution for the DHO1000 and 4000, since PWM control for the fans has also been prepared. Unfortunately it is not enabled in software so far; the fans run at a constant and relatively high speed.

Randy222:

--- Quote from: Fungus on December 18, 2023, 12:36:03 pm ---
--- Quote from: core on December 18, 2023, 08:03:57 am ---Depends. If there is a buck power supply outside the single heatsink and the airflow in the case is too low, an overheat and a fault in this regulator will cause a major malfunction. The voltage at the input can reach the output. I have seen laptops in this situation.

--- End quote ---

A 100mm fan stuck to the back is going to have far more overall airflow than that little fan stuck to the heatsink.

(which isn't directly moving any air in/out of the case at all, it just moves it across the heatsink and convection does the rest)

--- End quote ---
It does push air out the top and bottom vents on my 804, can noticebly feel air being forced out.
Since it's a 2-wire fan I don't see how the rpm's are monitored, so my goal is to slow the internal fan and use an external 90x15mm to push air in.

Fungus:

--- Quote from: Randy222 on December 18, 2023, 02:02:35 pm ---It does push air out the top and bottom vents on my 804, can noticebly feel air being forced out.

--- End quote ---

Yeah, you're right. There's air coming out under the handle where the heatsink fins are very close to the vent.

There's nothing on the vents at the top though, which is where the "power" components mentioned are.

2N3055:

--- Quote from: ebastler on December 18, 2023, 01:28:56 pm ---
--- Quote from: 2N3055 on December 18, 2023, 01:09:04 pm ---Most chips with any complexity have built in temp measurements. Otherwise, mostly diodes are used as measurement sensors on PCBs.

--- End quote ---

Did you look at the screenshot? For each chip there's an internal temperature readout (obvioulsy from a built-in sensor) plus an "ambient" temperature. It's the latter which we were discussing.

Whether it's a diode or a temperature-dependent resistor, it looks like Rigol went to the effort of populating four of them (plus providing some readout), so they can monitor all chips attached to the central heat spreader. Looks like they planned for a nice, temperature-controlled cooling solution for the DHO1000 and 4000, since PWM control for the fans has also been prepared. Unfortunately it is not enabled in software so far; the fans run at a constant and relatively high speed.

--- End quote ---

Sorry, didn't look at screenshot 5 posts above..
What you are saying does not contradict with what I said. There are bunch of chips that have on chip and aux external temp sensors. RK3399 has built in 2 ADC channels for temp sensors (all you need is few analog multiplexers and you can have 16ch of temp no problem). Sensors are cheap and it is good that they populated them all. That is always better then too little. I don't know what is your room temp, but temps shown are not very high. Let's hope they provide temp regulation in code, it certainly looks like there is headroom for it on DHO1000...

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