HP DESKJET 3820 PRINTER

[gearmate]

My printer's power supply failed and I found a shorted FET, open resistor, open 1N4148 diode and a sm resistor on the solder side of the PCB burnt beyond recognition.

Does any one knows its value. It is right under the filter cap C5: There are 3 105R, 2 334R, 1 124R and one missing. The PSU is an ASTEC model AA20550, PART # C6426-60081.
Please help it is my only printer and i need it

 

[(*steve*)]

Your best bet is to find a similar power supply and see what component is in that position.

Are you absolutely sure there was a component there? The solder there doesn't suggest it to me, unless you've already removed it.

 

[gearmate]

Thanks for your reply mate
Yeah Steve I did remove it and it is quite small.
I've tried to but couldn't find as it is quite of age.
I tried to find the schematic but with no success
I might have to scrap it, but may be I can use an 18 volt external suuply, won't it work?

 

[(*steve*)]

What resistance do you read across the removed resistor? Or was it completely destroyed?

I guess an appropriately rated power supply would work. I can't imagine the HP one does anything other than supply power.

 

[gearmate]

Hi Steve,
It is completely destroyed (open) no reading at all

 

[Qwaki]

RES

Hi Steve,
It is completely destroyed (open) no reading at all

resistor is 472

 

[gearmate]

resistor is 472

Hi Qwaki,
Thank you so much for your reply, and generosity.
It will be of great benefit to me, now i will try to restore life to my printer.

 

[Ron Wolpa]

Well fellows , it is my 1st post here.
I found this site particularly by means this post.
My printer , a hp950c , recently developed a fault and guess which is the switching power supply that powers up it?
Exactly the model on the pictures above : ASTEC model AA20550.
I took it apart to check whether it works and measured 18,5 volts.
It looks fine to me but the damn printer does not turn on.
Does anyone know what is the right output voltage for this power supply ?
Thank you for you attention.

 

[gearmate]

Hi Ron,
I'm the owner of this post, if you look on the board just above the fuse the is some voltage specifications there. Check on your board it should read 18v.

 

[Ron Wolpa]

Hello gearmate,
On my board there is not any voltage indication.
I measured from the output pins 18,5 volts, that means it is working , what makes me think that the problem is somewhere else.
If I find the problem is on main board I can throw the printer on the scrap pile.
This hp950c has very few use and it is really a pitty.
Thanks for your answer.