Generic Laptop power brick

[Colt45ws]

I bought a used Lenovo T500 about a month ago and it came with a generic ebay adapter. Something that always bugged me about it is the Lenovo power software shows it as a 90W adapter, when the label clearly shows it being rated 3.25A@20V.
Well, just recently, probably within the last day or so, it has developed a irritating ringing-like noise at low loads (sleep mode) which of course only myself can hear. Its very high pitched. If my hearing was more normal at high frequencies I dont think I would hear it.
Any ideas what that could be? I cracked the case out of curiosity and I came across interesting. The primary cap appears to be a Chemi-Con. Im just going by color and negative stripe since its buried. But Im pretty certain thats what it is. The output caps, though, were "Lucky" brand. I turned over the supply and the bottom of the PCB has markings that seem to indicate its made by Lucky as well.
What should I do with this piece? Buy a Lenovo one and toss this one or is it fixable do you think? I was going to get a genuine one but then I ran across complaints that shows a lot of people are having trouble with the cord failing right at the connector. So, I just put it off.

[sam_sam_sam]

Re: Generic Laptop power brick

I would try to repair it if you can
Can you post some photo of this power supply

[b700029]

Re: Generic Laptop power brick

Lenovo power software shows it as a 90W adapter

Does the adapter have more than +/- outputs? It might be one of those with an EEPROM ID in them, and of course the manufacturer can write whatever they want in there.

it has developed a irritating ringing-like noise at low loads

Varnish the transformer and output inductors. Probably a loose winding.

[Colt45ws]

Re: Generic Laptop power brick

I pulled the heatsink off to take some pictures. Unfortunately, the transformer appears to have overheated. You can see in my last picture the exposed copper of the output side of the trasformer along with some browning of the yellow tape along the bottom on that side.
It does not have a communication wire. Just the output. This thing looks very basic to me, but Im no expert.

[Scenic]

Re: Generic Laptop power brick

Looks like the usual "replacement PSU" ebay junk.
The fact that the transformer got hot enough to discolor the tape would make me grab an original Lenovo charger ASAP..
The laptop might have switched to something like a fast-charge mode because it falsely detected a 90W PSU instead of a 65W one, overloading this cheapo. Or it's just so trashy that it couldn't cope with 3.25A load on the long run and overheated.

The 65W one is FRU # 92P1211
The 90W one is FRU # 92P1107

Looks quite hard to get a genuine lenovo one.. at least on ebay. (link to the 90W one)
Too bad ebay USA doesn't seem to have a filter to exclude commercial sellers from the search results and only show auctions from private (average joe) sellers. Would be much less likely to get a fake one then.

[b700029]

Re: Generic Laptop power brick

I've seen transformers like that, with some sort of brown liquid residue on there, and they work fine. It might not be heat damage.

Run it under load and measure the case temperature. It will be warm but should not be so hot you can't keep your hand on it.

[Colt45ws]

Re: Generic Laptop power brick

If I switch to discreet graphics and play a game, it gets very hot. I cant hold onto it.

[b700029]

Re: Generic Laptop power brick

Then it is being overloaded. The CPU draws ~35W at full load, and the GPU another 30W. Add another 10-15W for everything else and you're looking at 75-80W total.

The laptop originally shipped with a 90W adapter for a reason. I think that's what the software is telling you, that you should use a 90W adapter, because with only +/- there is no way of ID'ing what's plugged in. It will still work with a 65W one most of the time, because the 75-80W is at full load and idling it will draw much less than that.

Get a 90W adapter if you plan on using the laptop intensively, a 65W one will not last long under those conditions.

[Colt45ws]

Re: Generic Laptop power brick

Then it is being overloaded. The CPU draws ~35W at full load, and the GPU another 30W. Add another 10-15W for everything else and you're looking at 75-80W total.

The laptop originally shipped with a 90W adapter for a reason. I think that's what the software is telling you, that you should use a 90W adapter, because with only +/- there is no way of ID'ing what's plugged in. It will still work with a 65W one most of the time, because the 75-80W is at full load and idling it will draw much less than that.

Get a 90W adapter if you plan on using the laptop intensively, a 65W one will not last long under those conditions.

Okay, I bought a 90W lenovo adapter.

[ratdude747]

Re: Generic Laptop power brick

Okay, I bought a 90W lenovo adapter.

I hope it is OEM...

[momaka]

Re: Generic Laptop power brick

If this is a standard 19.5V adapter with a standard plug (those with the outter and inner barrel contacts and center wire), then any genuine 90W adapter from a big company should work fine.

I've seen transformers like that, with some sort of brown liquid residue on there, and they work fine. It might not be heat damage.

The brown residue is varnish to make the transformer quiet.

Colt45ws: Some adapters (even high-quality OEM ones) still produce a high-pitched sound when under a light load - this is normal. But since your adapter only started doing that recently, probably something overheated inside.

[Agent24]

Re: Generic Laptop power brick

I pulled the heatsink off to take some pictures. Unfortunately, the transformer appears to have overheated. You can see in my last picture the exposed copper of the output side of the trasformer along with some browning of the yellow tape along the bottom on that side.
It does not have a communication wire. Just the output. This thing looks very basic to me, but Im no expert.

"Lucky" brand capacitors?

Lucky if they work... heh heh

[Scenic]

Re: Generic Laptop power brick

If this is a standard 19.5V adapter with a standard plug (those with the outter and inner barrel contacts and center wire), then any genuine 90W adapter from a big company should work fine.

It isn't.
The 90W adapter is 20V 4.5A and the connector is one of those with a barrel outside and a pin on the inside. It also seems to have 3 wires, probably to identify the PSU wattage.
http://www.kawakami-ca.com/images/20v_dc_plug.jpg

Here's a list of the different PSU outputs and compatible IBM/Lenovo laptops
http://www.thinkwiki.org/wiki/Power_Connector

[Colt45ws]

Re: Generic Laptop power brick

Ill crack the "lenovo" one I bought open when I get it. See if it looks authentic.

[b700029]

Re: Generic Laptop power brick

It isn't.
The 90W adapter is 20V 4.5A and the connector is one of those with a barrel outside and a pin on the inside. It also seems to have 3 wires, probably to identify the PSU wattage.
http://www.kawakami-ca.com/images/20v_dc_plug.jpg

Here's a list of the different PSU outputs and compatible IBM/Lenovo laptops
http://www.thinkwiki.org/wiki/Power_Connector

According to the schematic for the similar T410i, there IS an ID input on the laptop that's connected to the embedded controller inside (the laptop). However, it's probably just pulled down to ground with a resistor of some value in the adapter, and not as sophisticated as Dell's 1-wire EEPROM. It being connected to an analog input of the EC suggests that too.

Lenovo used to only use 2-pin no-nonsense +/- adapters. I have an X60 that does not use the adapter ID.

According to this the ID circuitry/resistor/whatever is in the plug, not the adapter.

[pdi]

Re: Generic Laptop power brick

it's probably just pulled down to ground with a resistor of some value in the adapter

You are right. I ripped one 170w power to my other project and took a picture of the connector.
The resistor is 1.5k ohm.
65w and 90w power supplys have 10k ohm resistor when measuring center pin against gnd.
Resistor just tells to the laptop what kind of charger is connected.

Here is picture of 170w connector.
http://www.saunalahti.fi/~peke5/Leno...wer_supply.jpg


-PDI-