Hantek DSO5072P Power Supply Issue

[Lew1]

Hello,
My PS board has on it: DSO5000 Series Power, 2013/05 Ver 1.0.  Would anyone possibly have a schematic for this unit or know where I could get a copy of it?   Any help would be greatly appreciated...

Thanks,
Lew1

Edit:  Does anyone know what the value of the 3 chip resistors on the bottom of the PS are. (R14 x 3) and also the value of R13?

[Lew1]

Thanks Peter.  I have seen this one but mine seems a bit different.  However, some parts seem the same too?  Mine doesn't have any 3-Term regulators on it  either. (see picture below)  I have Q1 removed as I think it may be bad?  The three chip resistors on the back (R14 X 3) looks to have been warm.  The value is hard to see on them and that's why I wanted to know if anyone could tell me what their value "should" be?

Thanks much...

[tautech]

Like with many SMPS identify the controller IC (N2 ?) and get datasheets for it and you might find your supply is a close copy of a suggested layout in the datasheet, component values and all !

[Lew1]

Well, I dug up the  info on the one they are using.  CR6850T  Trying to look into in now.  It looks like they did some screwy things on the design I have though.  I see quite a few R's on it where the have // 3 and sometimes 4 resistors to get a total R.  Trying to figure it out now.   Any other ideas you may have, please go ahead and post them.  I'd like to get this thing working if possible?

A pic of the back of my board is attached.


Thanks again.

[tautech]

Resistor dropper chains are quite normal for the VDD supply from high voltage DC. One will occasionally go open causing the IC not to start as it has a 15.3V under voltage lockout.
First check is to see if the required VDD is supplied.

Datasheet:
http://belchip.by/sitedocs/08484.pdf

[robert.rozee]

hi Lew1,
    i have an identical power supply to yours here, unfortunately with exactly the same failure mode. the 3x R14 resistors are fried, as is R11 (notice that your R11 is damaged too). i also have some vapourised traces prior to the bridge rectifier.

i also suspect that the CR6850 is blown, along with the bridge rectifier. C2 on the one here also looks suspect, and is the likely source of the smoke that the owner mentioned to me.

from the datasheet, it looks like the paralleled up value of the three R14 will be somewhere in the region of 0.5 to 2 ohm. but this is the least of the problems. i've had no luck finding a schematic beyond the info already provided to you by others.

the scope belongs to a friend, and i've been discussing with him the idea of converting it to battery operation instead of repairing the PSU. if anyone reading this has a DSO5000P series scope that they have opened up, i'd be very keen to find out what the current draw on the various supply rails are, these being +14v, -8v (analog), 5v, 3v3. in theory it should be possible to cobble together something based upon buck/boost modules from ebay: a 7.2v NiMh battery pack (6-cells) bucked down to 5v with a LM2596 module, and then a linear regulator down to 3v3. a +/-12v module swinging about 3v3 could give +15.3v/-8.7v for the analog stuff, provided the current requirement is suitably low.


cheers,
rob   :-)

[Lew1]

Hi Rob,

Thanks for replying too.  Well, I think I have finally got the power supply but the  scope still doesn't boot up!  Your issue is exactly what I had on mine.   I had to replace the 6850 PWM controller, the power MOSFET replace the burned trace on the back as well as the chip R's.  What I did with mine was I used a 40 ohm on the gate lead and I found a 3 ohm chip R to use for the sense lead.  I checked basically everything else in the circuit because I thought for sure, I had opened on of the coils, but it looked like they survived for some reason. 
I had been in contact with Hantek because they think I have a firmware issue?  However, the gave me a process to wire a TTL to USB converter to the J801 points on the bottom board.  I did that and I guess when you power up the board, you are supposed to get some traffic out that serial connection.  Well, I do get some "traffic" but I don't think  it's anything meaningful at this point?  It just does that and then halts.  It does nothing else, so I'm really at a loss as to what to do now.  I'm waiting to see if I get anything back from Hantek on what they think, but it's difficult to anything out of them and I'm better they just tell me to send it in somewhere...
I couldn't find the MOSFET so I just looked up one with about a 20A rating and used it.  It seems to work fine now.  However, you need to use the same case style that has the "isolated" case.  The heatsink solders to "ground"...
Please let me know if you have any other options or ideas.  I would like to share with you and maybe we can get 'both" these things running?   Who knows...

Lew
 

[robert.rozee]

hi Lew,
    a few questions:

have you checked that the voltages on each of the supply rails coming out of the PSU are approximately correct (14v, -8v, and in particular 5v and 3v3)?

did the PSU fail while the scope was running, immediately when you turned it on, or a short time after turn-on while it was still booting?

and are you able to post what comes out of the serial port - assuming it is readable text? i've a feeling the serial port runs at 115k, 8 bit, no parity, 1 stop bit. if the speed is wrong, you'll likely see garbage characters. you can use TeraTerm as a terminal emulator, and it is able to log to a file.


cheers,
rob   :-)

[Lew1]

Hello,

Yes, it failed when I turned it on but nothing had come up on the screen yet.  I do have all the voltages back now and look pretty good.  Yes, it is 115K, N,8,1 on the data.  I have pasted some of it below.
I  use an emulator they sent me called SecureCRT.  This is after initial power on but nothing else happens.?

[SERIAL-TRACE] : COMM-EVENT [brk]
[SERIAL-TRACE] : COMM-ERROR: A break signal was detected.
[SERIAL-TRACE] : COMM-STATE: 0 bytes waiting to be read; 0 bytes pending for transfer.
[SERIAL-TRACE] : COMM-EVENT [brk]
[SERIAL-TRACE] : COMM-ERROR: A break signal was detected.
[SERIAL-TRACE] : COMM-STATE: 0 bytes waiting to be read; 0 bytes pending for transfer.
[SERIAL-TRACE] : COMM-EVENT [brk]
[SERIAL-TRACE] : COMM-ERROR: A break signal was detected.
[SERIAL-TRACE] : COMM-STATE: 0 bytes waiting to be read; 0 bytes pending for transfer.
[SERIAL-TRACE] : COMM-EVENT [brk]
[SERIAL-TRACE] : COMM-ERROR: A break signal was detected.
[SERIAL-TRACE] : COMM-STATE: 0 bytes waiting to be read; 0 bytes pending for transfer.
[SERIAL-TRACE] : COMM-EVENT [brk]
[SERIAL-TRACE] : COMM-ERROR: A break signal was detected.
[SERIAL-TRACE] : COMM-STATE: 0 bytes waiting to be read; 0 bytes pending for transfer.
[SERIAL-TRACE] : COMM-EVENT [brk]
[SERIAL-TRACE] : COMM-ERROR: A break signal was detected.
[SERIAL-TRACE] : COMM-STATE: 0 bytes waiting to be read; 0 bytes pending for transfer.
[SERIAL-TRACE] : COMM-EVENT [brk]
[SERIAL-TRACE] : COMM-ERROR: A break signal was detected.
[SERIAL-TRACE] : COMM-STATE: 0 bytes waiting to be read; 0 bytes pending for transfer.
[SERIAL-TRACE] : COMM-EVENT [brk]
[SERIAL-TRACE] : COMM-ERROR: A break signal was detected.
[SERIAL-TRACE] : COMM-STATE: 0 bytes waiting to be read; 0 bytes pending for transfer.
[SERIAL-TRACE] : COMM-EVENT [brk]
[SERIAL-TRACE] : COMM-ERROR: A break signal was detected.
[SERIAL-TRACE] : COMM-STATE: 0 bytes waiting to be read; 0 bytes pending for transfer.
[SERIAL-TRACE] : COMM-EVENT [brk]
[SERIAL-TRACE] : COMM-ERROR: A break signal was detected.
[SERIAL-TRACE] : COMM-STATE: 0 bytes waiting to be read; 0 bytes pending for transfer.
[SERIAL-TRACE] : COMM-EVENT [brk]
[SERIAL-TRACE] : COMM-ERROR: A break signal was detected.
[SERIAL-TRACE] : COMM-STATE: 0 bytes waiting to be read; 0 bytes pending for transfer.
[SERIAL-TRACE] : COMM-EVENT [brk]
[SERIAL-TRACE] : COMM-ERROR: A break signal was detected.
[SERIAL-TRACE] : COMM-STATE: 0 bytes waiting to be read; 0 bytes pending for transfer.
[SERIAL-TRACE] : COMM-EVENT [brk]
[SERIAL-TRACE] : COMM-ERROR: A break signal was detected.
[SERIAL-TRACE] : COMM-STATE: 0 bytes waiting to be read; 0 bytes pending for transfer.
[SERIAL-TRACE] : COMM-EVENT [brk]
[SERIAL-TRACE] : COMM-ERROR: A break signal was detected.
[SERIAL-TRACE] : COMM-STATE: 0 bytes waiting to be read; 0 bytes pending for transfer.
[SERIAL-TRACE] : COMM-EVENT [brk]
[SERIAL-TRACE] : COMM-ERROR: A break signal was detected.
[SERIAL-TRACE] : COMM-STATE: 0 bytes waiting to be read; 0 bytes pending for transfer.
[SERIAL-TRACE] : COMM-EVENT [brk]

[robert.rozee]

did you see anything other than the repeated three messages:

[SERIAL-TRACE] : COMM-EVENT [brk]
[SERIAL-TRACE] : COMM-ERROR: A break signal was detected.
[SERIAL-TRACE] : COMM-STATE: 0 bytes waiting to be read; 0 bytes pending for transfer.

are you able to post a photo of where you have the TTL to USB bridge wired up to? did anything appear on the scope screen, even if just the backlighting turning on. or did the scope behave as if it hadn't even been turned on?

try using TeraTerm instead of SecureCRT. with TeraTerm you should be able to connect the Rx and Tx lines on your TTL to USB bridge together, and then see characters you type on the keyboard looped back. this verifies that the bridge is working. then connect it to the scope, set TeraTerm to log incoming data, and power up the scope.

if there is any sort of output, then it should be possible to load new firmware. there is a user on here called tinhead who seems to be a bit of an expert on the hantek firmware.


cheers,
rob   :-)

[Lew1]

Well, every now and then, when I power up the scope, I get a couple hyroglific(sp) characters but nothing else.  No front panel lights, fan is running, the 3V, -8, and 14V looks ok.  I also have the timing trace on "TR-AC"
I have TeraTerm active now but I really haven't used it before.  I'm getting nothing back from the scope. I can loop the TX and RX on the TTL adapter and get that on the PC but nothing when I'm connected directly to the scope?  Any other ideas?

Thanks for the help also.  I've heard nothing back from Hantek, so I think they have given up on me.(I think I have a "failure to communicate with them too" ...ha ha ha  if you know what I mean?)

[robert.rozee]

i have made a little more progress,  getting the scope up and running again (more-or-less) using an ATX power supply that deliveres 3v3, 5v, +12v, -12v. half a dozen diodes in series with the -12v line dropped it down to -8v, while the +12v was sufficient for testing.

interestingly, the scope was pretty happy to run with only 3v3 and 5v connected, but of course all the analog stuff was non-functional without the analog supplies: 14v/-8v.

i did discover that the big diode labelled D9 that feeds the 14v rail was a dead short. this showing up up because i'm just feeding  the external supply voltages into the dead PSU - when i hooked the 12v output of the ATX PSU to the 14v rail, the ATX PSU refused to start up! this suggests the failure mode my have been that D9 initially shorted, and that caused the 230v front end to blow up.


with all supplies connected, the current draws (measured with a DC current clamp) were as follows:
3v3: 100mA
5v:   2A
14v: 400mA
-8v:  200mA

this is the info i need to plan around converting to battery operation. the scope seems functional, able to display the calibration output on both channels. there was some noise spikes present on the traces, but then the main PCB shielding wasn't fitted and there were wires everywhere.


are you absolutely sure the 3v3 and 5v from your repaired PSU are good, and clean enough to power the scope? you might like to try using an ATX PSU to just provide 3v3 and 5v as i have - leaving the 14v and -8v rails disconnected. if using an external 3v3 and 5v still produces nothing out the serial port, things are not looking good and hantek may be right that the firmware is corrupt - a corrupted boot block would cause no traffic on the serial port.


cheers,
rob   :-)

[Lew1]

Thanks Rob for all your help and info.  I will also double check those voltage levels and see if I can get another scope on them to see if they are noisy, etc.  I haven't heard any more from Hantek and I've sent them two other emails,  Still waiting on a response.

Thanks again,
Lew

[ngaju]

hello my friend

can i know the number of this part bcause mine was blowing

thank you

[Razvan_N]

Hi Rob,

thanks for the current values. I also plan to convert it to battery power (20V, 4 Ah power tool Li-Ion battery). I've got the necessary DC-DC converters
and a 3D-printed hot shoe to physically mount the battery to the oscilloscope. When done, I would post all the details.

BUT, I have noted that the PSU output also has a "TR-AC" pin, which comes from the AC mains via some resistors and optocoupler.
How "mandatory" could this this signal be? Should we emulate it with a 50/60 Hz oscillator (depending on where we live), or just ignore it?

[robert.rozee]

i think it is only used for triggering off the 50/60Hz mains. this is a fairly standard triggering mode from the old old days of CRT scopes, and probably not likely to be used often today. i'd not worry too much and just leave it disconnected.

cheers,
rob   :-)

[Razvan_N]

I wanted to build an internal supply board for my Hantek DSO5202P that would take 18Vdc and produce all the internal voltages, to power the scope off a power tool battery.
There is plenty of space inside. Battery power would have obvious advantages, like mobility and mains isolation.
But I ended up building an external module that takes the said battery, via a 3D-printed hot shoe, and outputs 120 Vdc - which is within the voltage domain needed to power the scope.
The heart of it is an inexpensive DC-DC converter from Aliexpress, BT900W. It has three potentiometers: one for adjusting the output voltage, one for the maximum current and one for the
input undervoltage threshold (that prevents overdischarging the battery).
The scope has an internal SMPS, so it can take either AC or DC. The module, placed inside a makeshift case built by stacking 3 Gewiss power socket enclosures, can also be used to power
other things (signal generator, other measuring instruments, laptop, etc.)

Measured values:

input voltage: 19.75 Vdc
input current: 850 mA (max.) - meaning an autonomy of more than 3 hours on a 4 Ah battery
output voltage: 120 Vdc
output current: 130 mA (max. absorbed by the scope)