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<p>Hello everyone, and thank you all for your helpful responses.<o:p></o:p></p>
<p>I’ve finally managed to repair the PSU. I desoldered all the major components and discovered capacitor fluid underneath the main transformer — an area that couldn’t be properly cleaned from the sides. This fluid likely caused a short circuit, triggering
the immediate shutdown.<o:p></o:p></p>
<p>I thoroughly rinsed the board with soapy water and cleaned the fluid from all components. After reassembling everything, it now works perfectly.<o:p></o:p></p>
<p>Best regards,<o:p></o:p></p>
<p>Jan<o:p></o:p></p>
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<p class="MsoNormal"><b><span lang="EN-GB" style="font-size:12.0pt;color:black;mso-ligatures:none;mso-fareast-language:EN-GB">From:
</span></b><span lang="EN-GB" style="font-size:12.0pt;color:black;mso-ligatures:none;mso-fareast-language:EN-GB">Jan Liška <liska@peterkapartners.cz><br>
<b>Date: </b>Friday 6 June 2025 at 14:42<br>
<b>To: </b>"rescue@sunhelp.org" <rescue@sunhelp.org><br>
<b>Subject: </b>SUN IPC PSU - still not working after recap<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-GB" style="mso-ligatures:none;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-GB" style="color:black;mso-ligatures:none;mso-fareast-language:EN-GB">Hello,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:black;mso-ligatures:none;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:black;mso-ligatures:none;mso-fareast-language:EN-GB">I’ve started recapping my IPCs using locally sourced low-ESR capacitors. However, both PSUs I’ve recapped so far exhibit the same issue:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:black;mso-ligatures:none;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:black;mso-ligatures:none;mso-fareast-language:EN-GB">They power on for a very brief moment (about 0.1 seconds), the 5V rail voltage rises to 2–3V, and then the unit shuts down. I checked the units for cold
solder joints and significant corrosion damage on trails but found none.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:black;mso-ligatures:none;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:black;mso-ligatures:none;mso-fareast-language:EN-GB">I’ve been advised that either one of the TLP634 optocouplers may be faulty, or the capacitors I used might not be truly low-ESR as claimed by the seller.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:black;mso-ligatures:none;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:black;mso-ligatures:none;mso-fareast-language:EN-GB">I doublechecked the capacitors and they seem to be OK - I used mostly Panasonic low-ESR capacitors like CE 3300uF 16V EEUFR1C332L. I replaced all capacitors
except for the largest 400V one.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:black;mso-ligatures:none;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:black;mso-ligatures:none;mso-fareast-language:EN-GB">Before I proceed with replacing more components, I would greatly appreciate any advice.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:black;mso-ligatures:none;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:black;mso-ligatures:none;mso-fareast-language:EN-GB">Thank you!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:black;mso-ligatures:none;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="color:black;mso-ligatures:none;mso-fareast-language:EN-GB">Jan<o:p></o:p></span></p>
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