Overvoltage. What next?

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aldo
Posts: 4
Joined: Sat Mar 11, 2017 1:49 am

Overvoltage. What next?

Post by aldo »

Hello,

Everything was going fine with soldering the DSO SHELL when I did one fatal mistake. I did not test the output voltage of the brand new 9V power supply I had bought the previous day. I measured the voltage control points and they were not far from the expected values. So I continued to next step for the adjustment of C3 and C5, where I did not get the correct signal. But after two minutes not being able to adjust the capacitor, I check again the previous step and then I discovered bad voltage values. This time, I measured the power supply to find I was feeding 16.5 V to the DSO and made it die...

Now, I've replaced the faulty power supply by a regulated one that outputs a steady 9.2 V. But I think that some parts of the kit have died. The digital card seems to work correctly: the DSO boots and buttons seems still active. But it seems that the analog card has some components dead. Can I resuscitate the DSO if I buy a replacement analog card? What would be step to heal that kit?
  • Input: 9.16 V
    V+: 8.21 V
    AV+: 5.69 V
    V-: 0.18 V
    AV-: 0.65 V
    V1: 2.08 V
    V2: 5.13 V
    V3: 2.93 V
    V4: 3.94 V
    V5: 3.80 V
Thanks for any advice.

Lesson learnt: don't trust stickers and data sheets; always test!
jye1
Posts: 1221
Joined: Wed Feb 20, 2013 4:58 pm

Re: Overvoltage. What next?

Post by jye1 »

The high voltage must have killed U5 on the analog board. U5 can take only 10V maximum. Replacement analog kit is available here http://accudiy.com/index.php?main_page= ... ifhpluh1n7 .
aldo
Posts: 4
Joined: Sat Mar 11, 2017 1:49 am

Re: Overvoltage. What next?

Post by aldo »

I've received the replacement analog card and built it yesterday. Now with a brand new switched power supply too, voltages conform to the expected values:

Input: 9.16 V
V+: 8.21 V
AV+: 6.79 V
V-: -7.41 V
AV-: -6.08 V
V1: 0 V
V2: 0 V
V3: 0 V
V4: 1.49 V
V5: -1.02 V
V6: 6.12 V
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