Author Topic: SMPS shuts off  (Read 672 times)

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Offline dannemange_

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SMPS shuts off
« on: July 11, 2020, 03:52:25 pm »
I got this Sony DHR-1000 miniDV recorder that didn't power on. Opening it up I saw that R115 was split in two so I replaced that, and measured that Q101, Q102 and Q103 were bad so I replaced those too. Plugging it in gave the correct voltages, until I tried turning the machine on. No more output voltages. I replaced PH101 but that didn't help. I replaced all the capacitors and now when plugging it in, I get the correct voltages for about a second then it disappears. No chance of turning the machine on. What am I missing here? I've tried swapping the power supply with a good one just to make sure the rest of the machine works, and it does, so it's something on this board that's making my head hurt.
 

Offline dannemange_

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Re: SMPS shuts off
« Reply #1 on: July 11, 2020, 04:38:41 pm »
R110 was a little high. Ok to replace with a higher W or will that disrupt the sensing in any way?
« Last Edit: July 11, 2020, 04:41:24 pm by dannemange_ »
 

Offline dannemange_

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Re: SMPS shuts off
« Reply #2 on: July 11, 2020, 04:46:16 pm »
Will do that, thanks for your help!
 

Offline SeanB

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Re: SMPS shuts off
« Reply #3 on: July 11, 2020, 05:22:46 pm »
R102. R103 and C102 are also suspicious, measure the resistors and replace if high in velue, and with the capacitor easiest to just replace with a new one, as it likely is low in value and high in ESR. Check the output capacitors as well, especially C202 and C203, as they can cause issues with the feedback.
 

Offline dannemange_

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Re: SMPS shuts off
« Reply #4 on: July 11, 2020, 06:13:58 pm »
Must've mixed up the pdf files here. The above picture shows the US version and this is the EU one I'm trying to fix. Either way I'll go over the resistors and see what they're up to.
 

Offline dannemange_

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Re: SMPS shuts off
« Reply #5 on: July 28, 2020, 11:12:15 pm »
After measuring all of the resistors and not finding anything weird, I decided to still replace them as I've tried everything else. Still no luck... turned out that the new C206 I put in which measuring fine, didn't do its job. Put in a new one and everything works as it should. Don't know if this will help anyone else, but I'm glad I got some guidance here. Thanks guys!
 

Offline tautech

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Re: SMPS shuts off
« Reply #6 on: July 30, 2020, 07:19:15 am »
Hmmm, how could that happen.  :-//
Did you have the cap installed backwards ?
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I can offer help and advice on Siglent equipment as available spare time and other commitments allow.
 

Offline dannemange_

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Re: SMPS shuts off
« Reply #7 on: August 17, 2020, 08:02:48 pm »
No sir. Installed it the same way and worked just fine.
 


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