AC/DC power supply with 19.5V 7.9A issue

[johnb2713]

Spikey! All prices are inflated to people of our age, be it a car wash or a boiler install. I don't work for £1.50, I bearly work at all. Bit I guess this is more about you and how you justify your charges (to yourself)

Nah, not about me I'm retired. We do still have a family IT business though and have just put our prices up to £40 per hour, no customers have complained but comments like yours do tend to niggle me. when you consider the wages, premises, stock holding, insurance, rates, energy and more it soon eats the profits. Local companies have started up, undercut our prices and then gone under, their customers coming to us to get things sorted, things that would have been covered by warranty if they'd purchased from us. So what have they gained? OK, they saved £5 per hour on labour but it's cost them many times that amount when we have to sort out their problems.
A bit of a throw away line the "Sadly, buying a new unit is usually cheaper if you are paying today's inflated 'engineer' prices." with little thought about the true big picture. We aim to make a very small profit each year and provide competitive sensible prices for customers.
The PSU really doesnt warrant engineers time, we have good used ones on the shelf for the same cost as 30 minutes labour, why do the work, it's not cost effective?

 

[johnb2713]

Indeed. A failed diode was not uncommon in early Sony stuff. Quite dramatic too. The real point of mentioning it is to give an easily understandable example of the hard ware. Hoping to build up readers confidence and encourage personal learning. Kind of opposite to many of the superior toned posts

It is sort of false hope though, should you really be encouraging them to head to a fall? The diodes if failed wont cause the fault experienced, chokes easy to test but again wont cause this fault. Capacitors again, unlikely. So what has the OP gained from following your advice? possibly a burn on his hand if the capacitor on the input side hasnt been discharged, wasted money buying parts and wasted his time.

 

[Richard-the-Ninth]

Just a friendly reminder to all, do not make it too personal This is the UK friendliest forum

 

[binky]

Spikey! All prices are inflated to people of our age, be it a car wash or a boiler install. I don't work for £1.50, I bearly work at all. Bit I guess this is more about you and how you justify your charges (to yourself)

Not spikey, just pointing out the cost of a new power supply makes it uneconomical. Fair enough if you like taking electronics apart and fiddling as a hobby, fill your boots! But I think most of us on here have tried such things before, and found out it's not worth the effort for the small financial gain. On top of that, most power supplies are sealed, so you have to hack them open, just not worth the bother. I recently tried fixing my tumble dryer, found the burnt out component, replaced it, and it went pop about 5 seconds later . Complete new board was £200, didn't fancy finding out the board wasn't the issue and popping £200 , plus the dryer was getting on a bit. Put the money to a new heat pump dryer - I calculated the energy savings would payback the purchase in around 2 years, and that was before energy skyrocketed. So I'm quids in and saved a lot of hassle. It's experience like that we base our answers on.

 

[SPECIAL LOCATION]

On top of that, most power supplies are sealed, so you have to hack them open, just not worth the bother.

I can't remember the last time I saw a PC PSU that was actually openable with a few screws???

As said..
Most are sealed units NOT intended to be opened up and/or repaired??

It would be interesting to see a photo of the power supply in question?

 

[spark45]

I can't remember the last time I saw a PC PSU that was actually openable with a few screws???

As said..
Most are sealed units NOT intended to be opened up and/or repaired??

It would be interesting to see a photo of the power supply in question?

It has screws, do you like a photo of internal components?

 

[Bruspark]

Give me some days. I will change 450v 100uf x1 (the big brown : ) ), 25V 220uf x2 and 25V 1000uf x2 capacitors

What ESR are you looking for ?
What ripple current rating?

What makes you think the rest of the PSU is still within its design life now some components are failing?

Are you happy if you prolong its life to then experience an overheating type failure

The power block is easily replaced. End of ..

 

[Geoff1946]

To be fair to the OP the objective isn't always the most reliable or cost effective way to resolve a failure.
My introduction to electronics in my early teens was taking discarded items apart to see how they worked and maybe even repair something, giving much satisfaction.
Granted these would be simple radios or similar. The complexity of switch mode power supplies was undreamed of then.
However there was always a learning experience, even if it was only that capacitors could bite if you didn't discharge them!
What I'm saying is, don't be too hard on someone who wants to try just for the satisfaction of doing so.

 

[spark45]

You win, I lose.

Changed all this capacitors and same issue...

 

[Andy1733]

There's no winners and losers m8. Just lessons.

 

[spark45]

Now the issue is the replacement.
This 19.5V 7.9A 150W has a 7.4x5.0mm plug without centre pin.
The computer, an AIO system with Asus H81T board, has the female with centre plug hole.

It is very difficult to search for a power supply with this wattage and plug without centre pin (plug is L form, not straight).

It is compatible any power supply from Dell, or Sony, or HP with lower wattage (130W) or upper (180W) with this plug centre pin? There is no info on Asus mainboard manual.

Thanks again

 

[Richard-the-Ninth]

It is very difficult to search for a power supply with this wattage and plug without centre pin

Depends where you look Loads on Amazon

 

[johnb2713]

Now the issue is the replacement.
This 19.5V 7.9A 150W has a 7.4x5.0mm plug without centre pin.
The computer, an AIO system with Asus H81T board, has the female with centre plug hole.

It is very difficult to search for a power supply with this wattage and plug without centre pin (plug is L form, not straight).

It is compatible any power supply from Dell, or Sony, or HP with lower wattage (130W) or upper (180W) with this plug centre pin? There is no info on Asus mainboard manual.

Thanks again

If you could post a picture of the tip and the spec side of the power supply, I'll check our shop stock for you tomorrow if that helps.

 

[spark45]

If you could post a picture of the tip and the spec side of the power supply, I'll check our shop stock for you tomorrow if that helps.

Check #6 post on this thread.
I'm from out of UK, so I can't buy to your shop.
Thanks!

 

[Richard-the-Ninth]

I'm from out of UK

So, what part of the world are you in? Your location (set by you) says Glasgow

 

[johnb2713]

Check #6 post on this thread.
I'm from out of UK, so I can't buy to your shop.
Thanks!

No problem, good luck.

 

[spark45]

So, what part of the world are you in? Your location (set by you) says Glasgow

Now it's Ok

 

[runningpiglet]

You win, I lose.

Changed all this capacitors and same issue...

As I wrote earlier the fault was most likely a resistor in the startup dropper gone open circuit!

 

[Bruspark]

Give me some days. I will change 450v 100uf x1 (the big brown : ) ), 25V 220uf x2 and 25V 1000uf x2 capacitors

So if you asked me as an electronics engineer to decide which high voltage electrolytic would be a safe choice to install and leave down the back of a desk for another 10 years I'd politely decline the job. The supply was built with an expected life that has now passed. By replacing the capacitors you bring it back to life (probably still running too hot inside) so something else can fail next time. Yes, you can research what type and specification of capacitor they were, and what is required but it's a modular unit and can be swapped for a new one with no more complication than potentially splicing the DC output to the original plug.