Siglent SDM3065X repair

[Schwalbe]

Hi!

I got my hands on an Siglent SDM3065X with a broken resistance measurement circuit. The digital switch ADG633 is broken as well as a row of PNP transistors (Q18,19,20,22,23,25,26,37), a double diode Q7 and an inductor LA9. Does anyone of you know the exact models of these components?

Thanks a lot!

Schwalbe

[tautech]

Welcome to the forum.

Pics of SDM3065X are here but may not give sufficient detail to read the part #'s:
https://www.eevblog.com/forum/testgear/siglent-new-bench-dmm-sdm3055/msg1329966/#msg1329966

[Kleinstein]

The double diode is most likely a BAV199 as a low leakage diode.
The 8 PNPs for the protection should be relative high voltage types (e.g. >= 300 V rating) ideally with a good forward SOA.
There is a chance to also find a broken P -channel FET and a bad OP-amp or 2. 

The induction is there to help with stability when measuring the resistance of an inductinge DUT. The exact type should not be that critical, but chances are at the lable should still be readable.

[Schwalbe]

Thank you very much for the replies! I will trey with these components and will let you know about further findings.

Do you have any hint whichh OpAmps and MosFETs on the board might be damaged?

[skander36]

I don't know the exact model. You must search with the code printed- 2Zu (SOT23)

[Kleinstein]

The OP amp that is somewhat suspect is U101  (e.g. AD8622). The FETs are a bit more tricky - it depends on how the circuit is actually build. It would be the parts around U500 that are somewhat suspect. They may still be good, but it could make sense to check before ordering parts and if they are simple parts a one may get some just in case. The FET(s) / transistors are likely not especially expensive types.

I don't know what the 2Zu part is, but my guess for the protection would be something like MMBTA94 as one of the few SOT23 higher voltage PNPs that are easily available.

[delvo]

Of course that is not a 100% confirmation, but this transistor does come with that marking: https://www.onsemi.com/pdf/datasheet/mmbt6520lt1-d.pdf

[2N3055]

MMBT6520L is transistor used in such circuit in KS34401.....

It might be useful to look at KS34401 schematic.. this looks inspired by that...

[Martin72]

Hi,

The burned U500 is a ADG633 YRU:already mentioned.
https://www.analog.com/media/en/technical-documentation/data-sheets/ADG633.pdf

The transistors in my SDM3065 are marked with 2Z (p).

[Martin72]

Measured with diode test function, the transistors are PNP types, so chances are high that these are the already mentioned MMBT6520L.

[Schwalbe]

Wow! Just seeing all the replies now! I got the FMMT6520 transistors  already without knowing that they are the right ones    .
I'll start to repair now. Will let you know!
Thanks a lot!

[Schwalbe]

Works again!

[orzel]

Works again!

[tautech]

Works again!

 

[MathWizard]

What was on these, a 2-3 year warranty ? I think I got my 3065X in 2020, I should open it up to clean the dust out, and maybe swap the fan once I order a quieter, suitable one.

[tautech]

What was on these, a 2-3 year warranty ? I think I got my 3065X in 2020, I should open it up to clean the dust out, and maybe swap the fan once I order a quieter, suitable one.

https://siglentna.com/service-and-support/warranty-information/