LC-B400ATX Power Supply

[japlytic]

This morning, I decided to check all of the electrolytic capacitors inside my computer. All of the electrolytics on the boards were good, but there was one bulging in the power supply (C23 - 2200uF 10V, with the brand which appears to be "DON" RK series). I decided to replace this with a 3300uF 10V Rubycon unit, and as a good measure, added C28 and C22 (both 3300uF 10V Rubycon units, which were not originally fitted), as well as replacing C1 and C2 (both 470uF 200V Gincon GR series units) with Nippon Chemi-Con units. C1 and C2 were not bulging, but were replaced with better quality units as a good measure.

Fortunately, I did this before it was too late!

Does anyone know about the Gincon brand of electrolytic capacitors?

[PeteS in CA]

Re: LC-B400ATX Power Supply

Haven't heard of Gincon or DON brands. If that's supposed to be rated at 400W - guessing, based on the model # - I'd be really careful of cooling. Those heatsinks look pretty insubstantial for 400W.

[gg1978]

Re: LC-B400ATX Power Supply

That's a Deer Power supply.. Given their tendency to selfdestruct, and take the parts attached to them with it, i'd highly recommend replacing it..

[japlytic]

Re: LC-B400ATX Power Supply

I decided to upgrade all of the electrolytics in this supply (board space permitting), as well replacing the voltage reference device (PJ431) with a better quality TL431 unit.

ORIGINAL UPGRADED RAIL/USE

C1 470uF 200V Same value Primary filter
C2 470uF 200V Same value Primary filter
C5 2.2uF 50V Same value Feedback
C6 2.2uF 50V Same value Feedback
C8 22uF 50V

C11 2.2uF 50V Same value Voltage Reference
C13 Not fitted 1000uF 10V +5V Standby
C15 47uF 50V Same value
C17 1uF 50V Same value
C18 1000uF 10V Same value +5V Standby

C21 47uF 50V Same value
C22 Not fitted 3300uF 10V +3.3V
C23 2200uF 10V 3300uF 10V +3.3V
C25 2200uF 10V 3300uF 10V +5V
C27 2200uF 16V 4700uF 16V +12V

C28 Not fitted 3300uF 10V +5V
C29 470uF 16V 1000uF 10V -5V
C31 0.22uF 50V Polyester
C32 470uF 16V 1000uF 16V -12V

Rail Filtering Capacitance Comparison

HIGH-POWER OUTPUTS
ORIGINAL UPGRADED % INCREASE
+3.3V 2200uF 6600uF 200
+5V 2200uF 6600uF 200
+12V 2200uF 4700uF 113

LOW-POWER OUTPUTS
ORIGINAL UPGRADED % EXTRA
-5V 470uF 1000uF 112
+5V 470uF 1000uF 112
+5VSB 1000uF 2000uF 100

[AK0R]

Re: LC-B400ATX Power Supply

Two questions:
1. How does the cost of your upgrades compare to the cost of a new, high-quality power supply?
Low cost: Why won't the manufacturers give us, the consumers, good stuff?
High cost: And people wonder why these are called "disposable" goods!
2. How well does it work, compared to before?

[Rainbow]

Re: LC-B400ATX Power Supply

C8 is probably the cap-of-death. Just for fun, check the old one (if you still have it) using a meter - if it's crap, it might already have decreased value.

[japlytic]

Re: LC-B400ATX Power Supply

C8 is the capacitor connected between the cathode and reference pins of the programmable voltage reference device, which affects feedback. I would replace all of the low-value capacitors anyway.

[japlytic]

Re: LC-B400ATX Power Supply

When I searched for a LC-B400ATX, I found a similar power supply schematic on http://narod.yandex.ru/100.xhtml?ele...Y-B200-ATX.zip

U1 is an optocoupler (It is a PC817 in mine). The "2003" device seems to be a bit strange, and it is apparantely proprietory to the manufactures of this supply. Good ones have a SMPS controller from a well-known manufacturer (eg. TL494).

I think I might scrap this apparantely fake power supply (should I? ), and use the SMPS controller in a bench power supply (If I know how to wire it up). Good parts from it would also be salvaged for other projects.

[japlytic]

Re: LC-B400ATX Power Supply

Update: Found a very similar one on http://www.eserviceinfo.com/download.../L&C_400W.html

The SMPS controller is a DR0813 (another proprietory chip).

Should I still scrap the LC-B400ATX power supply?

[arneson]

Re: LC-B400ATX Power Supply

japlytic, Thanx , Ive been hoping to find this info.
Especially the first one.
Very well drawn.

[kc8adu]

Re: LC-B400ATX Power Supply

the chip with the odd number is usually something standard remarked.
often a poor job grinding the old number gives it away or you can look at the design and figure out what it is.why do they bother?
all they did was build some reference design anyway.

[gg1978]

Re: LC-B400ATX Power Supply

:all they did was build some reference design anyway.:


Hahaha.. Yeah, i suppose they did do that, then rip out half the toroids, filter caps, and use shitty components. At least every single Deer/LC/Foxlink/etc PSU i've seen has had missing parts, especially in the output section..

Best constructed PSU i've ever seen are Delta's.. I've got a pair of 2000 vintage DPS300BB's, with huge transformers, Nichicon caps, and enough toroids to make it weigh at least double of a cough "300W" PSU from the shit manufacturers..

[Rainbow]

Re: LC-B400ATX Power Supply

Yes, you can roughly compare PSU quality by weight (provided that they don't have PFC - because passive PFC inductor can be heavy). If you have 2 PSUs and you don't know which one to choose, just choose the heavier one
This often works with other devices - CRT monitors, keyboards, optical drives...

[Newbie2]

Re: LC-B400ATX Power Supply

Thanks for the power supply schematic japlytic! I was looking for that for a very long time.

[linuxguru]

Re: LC-B400ATX Power Supply

> When I searched for a LC-B400ATX, I found a similar power supply schematic on http://narod.yandex.ru/100.xhtml?el..._Y-B200-ATX.zip

Nicely drawn schematic, but there are some minor errors (no doubt, it is a reverse-engineered
schematic). For instance, the polarity of the lower winding of T2.2 is inverted (Q1 needs to be conducting when Q2 is off, and vice-versa, in a push-pull half-bridge topology).

In this case, the polarity is not a problem (since the transformer can only be inserted in
one orientation physically) - but it would be a problem for capacitors. Please check the schematic against the PCB very carefully before placing too much reliance on it.