Re: Power supply build quality pictorial. part 2
I've got a decently build AT PSU:
SP2-425F EMACS.
Has an automatic input voltage selection circuit.
Very decent EMI input filtering.
Input buffer capacitors are Rubycon USR 680uF.
Half bridge switching two 2SC2625 NPNs.
Center tapped 44 size main transformer.
Some of the output capacitors are swollen, all PCE-TUR .
TL494 PWM for primary switching.
LM339 in the secondary for protection and voltage supervision.
Lots and lenghty peripheral conectors. AWG 18...
pdavid
Badcaps Veteran
Last Activity: 12-04-2023, 04:49 AM
Joined: 01-30-2011
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Re: Power supply build quality pictorial. part 2
Sorry, 7905 was a typo. It is a L7805C positive voltage regulator. It is visable on the pictures. The ic has that simple piece of metal screwed on for heatsinking. The pcb silkscreening suggests a TO-92 device instead of TO220 that is crammed in there....Leave a comment:
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Re: Power supply build quality pictorial. part 2
A saved an old ATX power supply from recycling last week.
The casing is damaged, has dents, a broken fan but the insides are intact.
EverPower brand with a 235W Channel Well Tech guts from 1997.
There is a seperate transformer attached to the casing that looked like passive PFC at first but it isn't. The 5V standby has 100mA current capability and it is generated using this trafo, rectifier and a 7905 regulator. I haven't seen this "cheap" method before.
The standby trafo...Leave a comment:
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Re: Videoton VT-110, XT clone PSU repair
Recently I was quite busy with work, then taking a vacation and family and all
The motherboards I tested the PSU with generated their own power good signal and worked just fine.
I'm planing to make some simple power good circuit though...
Some other AT unit has it like this:
Probably going to etch a board and use smd components. Good enough....Leave a comment:
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Re: Videoton VT-110, XT clone PSU repair
Hey thanks! I'd really hate to see old historical stuff like this ending up on some e-waste pile. I also have some old Astec units. Even some server grade ones with APFC, from 1995!
Managed to continue a bit with the repair.
A tab from the heatsink goes under the main trafo. I speculate that if too much pressure is applied by the fastened screws the ferrite core might crack again. I put some thin insulation tape around that tab so it won't interface hard with the core.
Taps coming...Last edited by pdavid; 07-08-2019, 06:40 AM.Leave a comment:
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Re: Videoton VT-110, XT clone PSU repair
The fan might not be the original after all. Maybe the psu was serviced before. All I know is that the Videoton PC production was halted in 1989.
You are correct. I've drawn back the and it is in fact half bridge configuration. The FETs are switched through TR2.
There are separators between the core halves on FT2 and it's bonded together with silicone.
...Leave a comment:
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Re: Videoton VT-110, XT clone PSU repair
Attached the missing pictures of the internals/parts.
I'll need to gather some minor parts like proper sized silicone heat transfer/insulation pads, small caps, spacers, etc. Probably going to reassamble and test the unit this weekend....Leave a comment:
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Re: Videoton VT-110, XT clone PSU repair
Just noticed that most of pictures don't show up in the first post. I'll try to get it fixed.Leave a comment:
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Re: Videoton VT-110, XT clone PSU repair
Reassambled the main trafo with the new cores:
This time with some silicone too. Hopefully it's going to keep the bobbin and the cores from sliding around.
Got several old electrolytic caps of the same brand but the parameters are kind of crap. These just won't do as replacement. I have to use modern parts.
Also going to use real X2 and Y rated capacitors for the EMI stage.
For the primary bulk these capacitors will be much better then the originals I think:
...Leave a comment:
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Videoton VT-110, XT clone PSU repair
I was having trouble repairing [URL="https://www.badcaps.net/forum/showpost.php?p=873384&postcount=2977"]this[/URL] unit and while searching for info I came across another Videoton design. It came with the pc case and it was a cheap local sale so I picked it up, out of curiosity.
This one is a full AT size unit that is functional but gave a strange whine/buzzing right from startup. After some poking around it was determined that the noise came from the main transformer. There was also a rattling sound when the unit is rotated or shaked. It turned... -
Re: Power supply build quality pictorial. part 2
Date codes on parts are ranging between 83-89. Lots of Ukranian/Russian resistors. Inductors/magnetics, electrolytic capacitors are from Hungary. Back then the the COCOM list was in effect, so a lot of advanced western parts weren't allowed or quantity was limited to be imported to the USSR and it's allied states.
I'm going to create a separate thread for this historical piece and about the restoration process. It's going to take some time....Leave a comment:
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Re: Power supply build quality pictorial. part 2
We have 230V since 1997 before it was good old 220V.
These capacitors are connected in series so they could handle the rectified ac even now.
But most of the electrolytic caps have to go. Some measured so leaky and high esr that could be part of the many problem the unit has.
Btw Line and Neutral are fused since there wasn't really a standard how the AC socket was wired.
Check out how the primary of the main transformer is connected. That modification...Leave a comment:
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Re: Power supply build quality pictorial. part 2
IMB PC compatible power supply from the late 80s Hungary.
75W total power. Currently not functional. I dissasambled it and several parts proved to be faulty.
The construction and parts used is very reminiscnet of the era.
There are some "western" parts since analogs were too difficult for cccp to produce so it had to be licensed or bought if possible...
Some 220V line emi filter parts:
Siemens 2x47nF capacitor in some sealed and rounded barrel type enclosure.
Bifilar choke of unknown...Last edited by pdavid; 01-10-2019, 06:33 AM.Leave a comment:
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Re: Power supply build quality pictorial. part 2
Sector IBP-200-N AT power supply from '97-'98. Young Year OEM model IBP-42c REV 3.
Maybe it should go to the guttles topic due to all the corner cuttings and missing parts in construction.
Fan is using some clamp cutouts to be held in place.
No EMI filter, just two unrated ceramic caps.
Bifilar coil traces are bridged.
No inrush current limiter. Traces bridged.
No bridge rectifier just some diodes tangled together.
Genuine 105C NCC primary caps!
13007 primary...Leave a comment:
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Re: Power supply build quality pictorial. part 2
Well I have other AT units from Seventeam that have 5V standby and 3.3V DC-DC plus PS-on wired to to the circuit to make it work like ATX. There were plenty of similar solutions in mid 90'. Some really horrible ones too.Leave a comment:
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Re: Power supply build quality pictorial. part 2
Seventeam ST-220WT-P large AT unit.
Standard half bridge topology from 1991.
Proper EMI input filtering.
2x470uF Nitsuka primary caps.
2x13009 transistors.
IR3M02 PWM driver
ER35 main transformer.
Seperate transformer for current sensing
CEC PCE-TUR caps on secondary
LM339 comparator on the secondary.
5V rectified by S30C45.
12V rectifiedby C33-02C.
-12V rectified by FR205.
-5V by L7905C voltage regulator from -12V output....Leave a comment:
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Re: Power supply build quality pictorial. part 2
VIP ST-235ATX 250W ATX.
After 20 years of service it was time to retire this unit. It won't start anymore.
I'm not sure who the OEM is but that XF marking on the main transformer and those stickers are something I see from time to time. The 555 based fan controler is familiar too.
I was really impressed to find a TOP210 in such an old noname unit.
No PFC
Primary rectification: 4x IN5406
Primary capacitors: 2x 220uf Capxon
Primary switchers: 2x E13007 ;half bridge topology...Last edited by pdavid; 04-20-2018, 02:26 AM.Leave a comment:
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Re: Enermax Liberty ELT500AWT fails to turn on
I had two of these units with the symptom you described! Turned out to be a shorted npn smd transistor on the secondary. I don't remember it's location... but it had 6F marking on it. I hope this helps....Leave a comment:
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Re: Power supply build quality pictorial. part 2
I couldn't find any info on the manufacturer. There are model numbers and revision on the PCBs. I found half dozen other units like this on Ebay and they all seem to be different platforms.
In hindsight I added some 200nF capacitors and 100Ohm resistors for snubbig those 12V rectifiers. The ones that failed measured 2.5V forward voltage from cathode to anode and 0.0640V to the other direction or something like that.
The guy is using this same psu with the same rig... in a damp basement....Leave a comment:
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Re: Power supply build quality pictorial. part 2
[B]PC POWER Phantom RAIDERS MP1800X..[/B]
This is fully modular pure chineseum "mining" psu. A colegue decided to use one of these. "How bad can it be.. sitting in the basement 24/24 with four R9 295X2".
For a few weeks it worked. And then it stopped working.
There is standby, but unit doesn't turn on.
I did some autopsy. It turns out two of the 12V double diodes were shorted.
EMI filtering is ok.
16A glass-body fuse without any shielding right on...Leave a comment:
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