I recently had some fireworks inside one of my Macron MPT-350P psus. The switching transistor for the standby voltage had failed, 3 resistors were burned, the driver transistor exploded, one zener-diode shorted and finally the 2R2 MOX resistor interrupted the power supply for te standby circuit and put an end to the destruction.
I cleaned everything, replaced all defective components, turned the unit on and the damage happened all over again a second and a third time.
The switching transistor Q2 is a 2SC5027 (Fairchild). I ordered some that are made by "isc".
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Majestyk
Senior Member
Last Activity: 07-13-2020, 12:33 AM
Joined: 11-15-2013
Location: Frankfurt
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Re: ASUS DSBF-DE Dual 771 dead?
So this is not going to be "piece of cake"
I tested the board with 2 x 2 GB FB-DIMM and 2 Xeons E5410.
It started up, which is a progress, I was also able to update the BIOS from 1003 to 1006 so the Xeons are recognized properly now.
But only one CPU is detected (the one in socket 2), the second one stays cold.
When (gently!) bending the damaged pin of the first LGA 771 socket back and adjusting it, the tip broke off.
It is Pin "G19", the datasheet says this is
...Last edited by Majestyk; 07-12-2015, 12:39 PM. -
ASUS DSBF-DE Dual 771 dead?
I acquired an Asus DSBF-DE dual Xeon Socket 771 mainboard recently. The board is "dead", doesn´t start as I was told. So why not give it a try?
First I removed the heatsinks to find the thermal compound was dry and shrunk under the northbridge heatsink while it had dropped down to the bottom under the southbridge´s heatsink. (This of course is not the reason for not starting up.)
I nevertheless cleaned everything and applied some fresh thermal grease.
Next I found a pin in one of the LGA sockets that had been bent over backwards, some more pins...Last edited by Majestyk; 07-08-2015, 03:12 AM. -
Re: Be Quiet Straight Power E7 700W revision
Thanks for putting this right, Stefan!
(I hadn´t seen the insides of older E-models for quite a while.)Leave a comment:
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Re: Be Quiet Straight Power E7 700W revision
With the E7 Series Be Quiet switched from Topower to FSP.
Yes, it´s a dual layer PCB and I had to do some "needlework" to clear two or three holes where a lot of wires were soldered nearby.
There is generally far too little space for the secondary caps in this series. Panasonic, Rubycon or Nichicon don´t offer long life, low impendace 105° caps with the required capacity and voltage in these form factors at all. Probably because it´s not compatible with the laws of physics. CapXon and Fuhiyyu...Leave a comment:
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Be Quiet Straight Power E7 700W revision
Last week one of my PSUs in a workstation startet to fail. Not a big surprise, since it has 36° centigrade in downtown Frankfurt at the moment.
It´s a 700W Be Quiet Straight Power of the "E7" series that I purchased around 2009. Sometimes it wouldn´t start, sometimes it would give some weird noises as if popcorn was being made inside of it.
Before there was any serious trouble, i opened it, blew out the dust and had a closer look.
The power switch turned out to be the reason for the noises, the contacts had loose connections. So I replaced the...Last edited by Majestyk; 07-05-2015, 10:42 AM. -
Re: Tagan TG480-U01 480W ATX PSU
Yea, but that´s all assumptions that might apply here or might not. We do not have the schematics of most PSUs and we do not know, what the developers' intentions and calulations have been.
From a more superficial point of view the design of the secondary side of a 2008 PSU doesn´t differ too much from one built in 2012. Many designers seem to be quite conservative here.
But, as Karl Marx said "When theory and practice don´t match, practice rules".
I for one have encountered no oscillations...Leave a comment:
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Re: Tagan TG480-U01 480W ATX PSU
By the way: Nichicon are recommending their "HW-Series" specially for switching power supplies with high temperatures / long life / high ripple.Leave a comment:
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Re: Tagan TG480-U01 480W ATX PSU
I Keep that in mind! Here there was enough space for 12.5 but often there is not.
If you are near Prague you can almost throw them over to me
I know, some people had problems with very low ESR caps in PSUs - I haven´t so far.Leave a comment:
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Re: Tagan TG480-U01 480W ATX PSU
Sorry, typo! -> 2 x 3300µ 16VLeave a comment:
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Re: Tagan TG480-U01 480W ATX PSU
Yes, Nichicon HW is a quite new series (End 2012) 10.000h, low impedance, high ripple, Long life:
[url]http://www.nichicon.co.jp/english/product_news/new130.html[/url]
Here I used 2 x 3300µ 16V and 3 x 2200µ 10V
The Panasonic are "FR" indeed 2 x 4700µ 10V. (I just looked in my stock.) 12,5 x 30
They are made in Malaysia by the way.Re: Tagan TG480-U01 480W ATX PSU<br ..., high ripple,Last edited by Majestyk; 07-01-2015, 07:35 AM.Leave a comment:
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Re: Tagan TG480-U01 480W ATX PSU
The glue has been generally removed in areas, where there´s contact to higher voltages. I left some traces on coils and tranformers to avoid mechanical or chemical demage when removing them. The bleeder resistors of the primary filter caps have some traces left on their outsides also but the pcb is clean.
But, you´re right - there´s still glue on the PFC board. I will take care of this soon. (see picture)
As for the capacitors, I used Nichicon GG on the primary side (not enough space for GX), Rubycon ZLJ (the...Last edited by Majestyk; 07-01-2015, 06:10 AM.Leave a comment:
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Re: Tagan TG480-U01 480W ATX PSU
Yes, it´s a very nice PSU now with very little noise and enough power for most common systems. It has got a railsplit switch for +12V also.
With all the high quality capacitors it should now be ready for a considerably long lifetime.
I´m quite sure the TL3842P PWM-controller was the real reason for this PSU to stop working. The secondary filter caps (ASIA-X) all had a capacity of several hundred uF left so they probably would have led to instabilities but the PSU suddenly stopped worrking compltely - because the PWM-controller...Last edited by Majestyk; 07-01-2015, 02:11 AM.Leave a comment:
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Re: Tagan TG480-U01 480W ATX PSU
The PWM Controller (TL3842P) was indeed the culprit here.
After replacing it, the PSU works flawlessly again.
Here is the finished product:...Last edited by Majestyk; 06-30-2015, 03:58 PM.Leave a comment:
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Re: Linkworld(?) LPJ19-25E
A passive PFC made of true iron!
The Chinese use to sometimes "replace" iron and copper by cheaper materials, as you can see here:
[url]http://www.overclock.net/t/1246964/hardware-secrets-hantol-psu-fake-pfc-made-of-cement[/url]
and even worse here
[url]http://www.pcpop.com/doc/0/294/294565_all.shtml[/url]
It´s unfu#*ing belivable...Re: Linkworld(?) LPJ19-25E<br /> <b...imes "replace"Last edited by Majestyk; 06-29-2015, 12:10 PM.Leave a comment:
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Re: Delux ATX-450W extreme upgrade
I would kick this one out of the PSU, Asia´X Caps are made by Fuhiyyu....Leave a comment:
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Re: Tagan TG480-U01 480W ATX PSU
I´m repairing a Tagan 480W PSU at the moment.
After replacing all the bloated "Asia`X" = Fuhiyyu capacitors the PSU still wouldn´t start. No secondary voltages, no standby voltage.
I found the PWM-Controller (a TL3842P) to have a resistance of about 100 Ohms between Vcc and Gnd.
I have ordered a replacement and will report the results....Last edited by Majestyk; 06-28-2015, 02:31 AM.Leave a comment:
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Re: Netgear GSM7224 Switch might need Reflow / Reballing
There are several capacitors and two inductors on the downside in the processor-area. I resoldered all of them carefully, but the problem persists.
I also took a look at the layout of the bga pads of the processor. Most of them are located near the edges of the chip, only a few in the center. And the right half of the rear edge is whrere the thing responds to light pressure.
It´s amazing when you search Youtube for bga reballing. There are guys in China, Pakistan and elsewhere who do this job...Leave a comment:
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Re: Netgear GSM7224 Switch might need Reflow / Reballing
I don´t think it is getting THAT hot during normal operation. I don´t know what´s happening on hot summer days under heavy data traffic though.
I´m afraid the soldering was not made perfectly in the factory. Maybe the soldering heat wasn´t appropriate or a solder ball was faulty, maybe the flux had not been dispensed properly.
I have seen similar embedded units before that showed problems with the BGA soldering without ever running too hot. It´s just lousy manufacturing I assume.
...Leave a comment:
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Re: Netgear GSM7224 Switch might need Reflow / Reballing
Did that already. The caps on the mainboard are all new. I also checked the ones in the psu, everything´s fine there.
This must be a mechanical / contact issue since the CPU is tender to the touch.Leave a comment:
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