Antec SL350P - component forensics

[SpecialK]

Hi, I'm trying to fix an Antec SL350P that suffered from a blown 5VSB capacitor. I've identified the broken components, but there are two that are burnt beyond recognition. The first one is R18; it's a 1 watt resistor that's in parallel with that capacitor. The other component is Q6, which is located close to the two optocouplers of the main circuit. Can anyone identify those two components?

I've found the schematic with the DM311 mod, but based on pictures here on this forum, when installing this mod most of the original components (like the capacitor, diodes, transistors) are left in place. Shouldn't they be removed if you're going for the mod?

Regards,
Kelly

[everell]

Re: Antec SL350P - component forensics

I have looked at a SL400 and could not locate either component you are asking about. Everything is so crowded on this power supply. Your power supply is most likely equipped with a power factor correction circuit. Mine does not have that circuit. So post us some pictures and we can better help you.

The DM311 mod is (in my opinion) very straightforward. It is not necessary to remove ALL of the old components in the 5vsb circuit, just the ones that might affect the DM311 circuit. That doesn't mean that you can't remove them. I just don't like busy work, removing components when it is not necessary.

If Q6 is the big transistor connected to the heat sink, it is not used when doing the DM311 mod, so you won't need to replace it. When you post a picture of the pc board, circle the damaged resistor you need information about.

[SpecialK]

Re: Antec SL350P - component forensics

Hi everell, thanks for your reply. Attached you'll find a picture of the supply (I stripped out most of the broken components plus the heatsink).

I'm looking for the transistor on the left, and the resistor (that's already removed) next to the bulging capacitor on the right.

Kelly

[everell]

Re: Antec SL350P - component forensics

R18 is 470 ohms. Q6 is UTC (brand) 2SA684.

[everell]

Re: Antec SL350P - component forensics

I added the DM311 mod to an Antec SL400 two years ago. Here are a couple of pictures and some drawings.

The drawings show the original 5vsb circuit, a drawing showing which components needed to be removed (by using white out and removing them from the original drawing!), and a drawing showing how the final modified circuit should look.

[SpecialK]

Re: Antec SL350P - component forensics

Thanks! This completes my shopping list. I must say the DM311 mod sounds appealing, because even if I just want to repair the supply, I'll have to replace quite a few components.

This is what's broken:
Q3 SSS4N60B
Q5 2SC945p
Q6 2SA684
C8 47 uF, 35V
ZD3 22V 500mA
D? 1N4148
R18 470R 1W
R23 180R
R22 1k

So leaving the two-transistor design and just implementing the mod may not be a lot of extra work.
I'll sleep on it

[everell]

Re: Antec SL350P - component forensics

For further reference, here are two pictures showing the board layout of the DM311 mod. The heat sink is a piece of tin cut out from a mixed nuts can. The mixed nuts were great. Isn't it nice when even the can is used instead of being total trash! Please note that all tin cans will NOT take solder, but the solder will bubble up and not stick. The ones to use will easily take solder, and you will see the solder flow.

This board is attached to the heat sink on a Bestec power supply, but it is the same board layout I use on all power supplies I put this mod on. Just a matter of where and how it is attached.

[370forlife]

Re: Antec SL350P - component forensics

Altoids tins take solder, not very well but it sticks.

[SpecialK]

Re: Antec SL350P - component forensics

I think I have some leftovers from copper pipes laying around; that seems a lot easier