Electronics > Repair

Siglent Oscilloscope SDS2104X repair help

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DaJMasta:
If there's actually no trace for the channel displayed at all (not just clipped to one rail or something), I'd actually start with checking the ADC.  If you see a channel trace and it is just unresponsive, then it's likely something in the front end (which is much more typical of overvoltage damage).  Now there's a chance that if one of the chips in the frontend doesn't respond to commands it just disables the trace - in which case looking at them would be a reasonable choice - but if you're really not seeing anything, it may be a digital domain issue, which would mean pretty extensive damage.  If it were just blown passives/dumb programmable gain amps/relays/etc., I would still expect to see some kind of trace displayed, it just wouldn't show any signal, or it would show an entirely wrong signal.

Gaktyt:
Hi DaJMasta!


--- Quote from: DaJMasta on January 06, 2020, 11:39:45 pm ---If there's actually no trace for the channel displayed at all (not just clipped to one rail or something), I'd actually start with checking the ADC.

--- End quote ---

There is NO trace whatsoever, nada, nista, niente, ничто, nichts. And the only way I can think of to check the ADC would be to swap the inputs of ch3 and ch4 (which goes to the same ADC), but it's a BGA component on a minimum 4 layer pcb, so chances for success are slim.



--- Quote from: DaJMasta on January 06, 2020, 11:39:45 pm ---Now there's a chance that if one of the chips in the frontend doesn't respond to commands it just disables the trace - in which case looking at them would be a reasonable choice

--- End quote ---

I guess that is the chance I'm hoping for. The most tangible and workable fact so far is:

On INLO (low input of diff amp, pin 16) on the AD8370 there is no square wave signal, only something that resembles a floating pin. Which obviously means there is no square wave on the output of the AD8370.
 



--- Quote from: DaJMasta on January 06, 2020, 11:39:45 pm --- - but if you're really not seeing anything, it may be a digital domain issue, which would mean pretty extensive damage.

--- End quote ---

Or it could be the worst of worst case scenarios, both digital & analog problems.

DaJMasta:
Yes.... if an overpower event happened and you managed to cook your ADC, the whole input section would likely be charcoal...


Hoping for the PGA or something in the path just not returning usable info to the monitoring systems!

Gaktyt:
After some more measurement I decided to try replace the following three components, but I need some help to translate the smd marking codes into part numbers so that I can order them.

K52G - SOT-23 I believe it's a transistor of some sort NPN/FET
AUE 6683 - SOIC-8 I believe it's a op-amp
T4 -  I believe it's a diode

Can you please assist?

goaty:
K52G could be BAV199
T4 could be 1N4148

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