Enermax EG701AX-VH shutting down when powered

[mitchmaster]

Hello guys,

I have had this PSU since September 2005 and it has always worked fine without any interventions, occasional cleaning aside. It is rated for 600 W.

Yesterday morning I powered up my PC after that I had left the PSU unplugged for the night because of a thunderstorm, it ran for a few seconds and then shut down. I said "uh oh" and hit the power button again, it powered on fine and then I used it all day. Then before going to sleep I unplugged it again to see if it would fail to power up again this morning.

Today upon pressing the start button the PC would turn on for a couple of seconds and then turn off. If I tried again it would either turn on for a time up to two seconds or not at all. If I tried to switch it off from the back of the PSU and back on it would turn on again, still for a couple of seconds and then off. Note that in all this standby LEDs on the motherboard light up as usual.

I unplugged everything but the fans and it would still behave that way. So I took it off the case and tried to power a single fan but it still turns off.

You should also know that this PSU has a feature that makes its fans keep spinning for a while after the system has shut down in order to cool the internal components. Well, that works. If I try to turn on the PSU with nothing connected its fans start spinning at full speed for the usual two seconds, then when the PSU would shut down the output to the rest they keep spinning for a while at reduced speed, which is totally normal for this PSU.

Now I have taken the PSU apart in order to check it and take pictures but I can't see anything wrong with it, everything is identical to the last time I took it apart which was in February when I recapped my motherboard.

Do you have any idea why it may behave this way?

Thank you.

[ReeceyBurger123]

Re: Enermax EG701AX-VH shutting down when powered

Possibly dry start up caps. Have you an esr meter ?

[mitchmaster]

Re: Enermax EG701AX-VH shutting down when powered

I don't have one but I can see if I can find it. What caps are you talking about?

[ReeceyBurger123]

Re: Enermax EG701AX-VH shutting down when powered

The small ones, but you should change all the Pcetur brand caps.

[stj]

Re: Enermax EG701AX-VH shutting down when powered

not worth testing 11year old startup caps - just change them.

and get rid of the conductive glue on the chips!!

[mitchmaster]

Re: Enermax EG701AX-VH shutting down when powered

not worth testing 11year old startup caps - just change them.

Yeah that's a good point, I may just recap the whole PSU while I'm at it. Now I am going to make a list of the capacitors.

and get rid of the conductive glue on the chips!!

About that... I have removed some brown crap off a couple of diodes and another component labelled Q10 and I have noticed that their terminals seem corroded... I have attached a picture. Should they be replaced as well?

I find the yellow glue harder to remove. What is it for anyway? It seems applied randomly.

[stj]

Re: Enermax EG701AX-VH shutting down when powered

it's for timed self-destruct as far as most of us are concerned.

the problems with it have been well known for far to fucking long for it to be accidental!

[ChaosLegionnaire]

Re: Enermax EG701AX-VH shutting down when powered

I find the yellow glue harder to remove. What is it for anyway? It seems applied randomly.

its meant to hold down the components during wave soldering at the factory. however, manufacturers also use it for another insidious purpose: planned obsolescence. it slowly turns conductive over time and shorts out the power supply in a spectacular fireworks display. now u need to buy a new psu! the manufacturers want you to keep it up. they love milking your money and making you pay and pay over and over again.

[mitchmaster]

Re: Enermax EG701AX-VH shutting down when powered

its meant to hold down the components during wave soldering at the factory. however, manufacturers also use it for another insidious purpose: planned obsolescence. it slowly turns conductive over time and shorts out the power supply in a spectacular fireworks display. now u need to buy a new psu! the manufacturers want you to keep it up. they love milking your money and making you pay and pay over and over again.

Well this PSU has been running for nearly 11 years so something must have gone wrong with Enermax's evil plans. I can't seem to remove it anyway, it is hard and comes away only in small pieces, also it is in hard to reach places. The brown corrosive stuff I have removed earlier instead broke when I touched it and came away easily, I'll just replace the components with the corroded leads.

Now, about the caps, I have made a diagram of the caps used so you can see it.

There are 22 caps of 13 different types and I have checked how much it would cost to buy caps of the exact values, and it is too much because the place I buy them from (RS) sells them in packs of 5 when I need one or two per type.

So I would like somebody to help me understand if and how I can group caps of similar values so that I can buy fewer types and optimize the expense. Is it possible? And how would that change the behavior of the PSU?

Thank you.

[stj]

Re: Enermax EG701AX-VH shutting down when powered

start with anything under 470uf

[mitchmaster]

Re: Enermax EG701AX-VH shutting down when powered

start with anything under 470uf

I would try that if I had the caps or if I could buy them in a store around here, but since I have to buy them online I would like to get them all with a single order, possibly not spending 50 euro for 60 caps when I need 20. That's why I would like to know if I can replace different types of caps with a single one.

I have pulled the transistor and the two diodes with the corroded leads. The transistor is labelled A928A Y-E22, the two diodes are 1N 5819 but looking for a replacement I have seen they come with different voltages, from 450 mV to 900 mV. Which ones should I get?

Thanks.

[stj]

Re: Enermax EG701AX-VH shutting down when powered

just clean the legs with a fibre pencil or fine sandpaper.

[mitchmaster]

Re: Enermax EG701AX-VH shutting down when powered

just clean the legs with a fibre pencil or fine sandpaper.

Oh I cut them

[stj]

Re: Enermax EG701AX-VH shutting down when powered

[mitchmaster]

Re: Enermax EG701AX-VH shutting down when powered

Well I have replaced the caps up to 220 uf plus the two diodes and the transistor with the corroded leads and now the PSU appears to be working fine. I have put it back in the case and the pc turns on fine, it doesn't explode or catch fire if I try playing a game so thank you for pointing me in the right direction

Now that I have half new caps and half 11-year-old caps I would like to know how urgently I should complete the recap replacing the output caps and the main filter, because I'm not going to have time for that for a few weeks. What do you think?

[sam_sam_sam]

Re: Enermax EG701AX-VH shutting down when powered

I would recap the other one before they start showing up with problems Those caps are tried after all they are 12 years old

[ReeceyBurger123]

Re: Enermax EG701AX-VH shutting down when powered

Awesome work, I suggest you recap the rest of them though keep it lasting longer

[PeteS in CA]

Re: Enermax EG701AX-VH shutting down when powered

The two most likely culprits were either that very brownish glue partly on that one IC, or one or more start-up caps - among the small caps you replaced.

The larger O/P caps are of a vendor known for producing mediocre or worse parts. Definitely find datasheets for them and cross-match to some good Nichicon or United Chemicon parts, if you intend to keep using this P/S for a while.

Also, at 11 years old, that fan is getting really old. If you haven't already I'd suggest researching a similar ball-bearing fan from a good brand.

[dmill89]

Re: Enermax EG701AX-VH shutting down when powered

The two most likely culprits were either that very brownish glue partly on that one IC, or one or more start-up caps - among the small caps you replaced.

The larger O/P caps are of a vendor known for producing mediocre or worse parts. Definitely find datasheets for them and cross-match to some good Nichicon or United Chemicon parts, if you intend to keep using this P/S for a while.

^x2, though I have one of these in my HTPC that still has all its original CTC (jpce-tur/jpce-tul) caps, but if I ever have to repair it for any reason the caps are all getting replaced. Like you said these are mediocre caps, but still better than a lot of the crap (fuhjyyu, etc.) that was common in PSUs from that time period.

Also, at 11 years old, that fan is getting really old. If you haven't already I'd suggest researching a similar ball-bearing fan from a good brand.

These PSUs came with good ball-bearing fans (92mm top intake, 80mm rear exhaust) so they are probably fine.

[PeteS in CA]

Re: Enermax EG701AX-VH shutting down when powered

^x2, though I have one of these in my HTPC that still has all its original CTC (jpce-tur/jpce-tul) caps, but if I ever have to repair it for any reason the caps are all getting replaced. Like you said these are mediocre caps, but still better than a lot of the crap (fuhjyyu, etc.) that was common in PSUs from that time period.
...

Mediocre parts, used conservatively with good cooling can last quite a while. Delta seems to get away with using so-so caps in some of their power supplies; other good vendors may as well. How heavily loaded a P/S is compared to its power rating can make a big difference as well.