Compaq Presario CQ62 410c US power supply Question

[sam_sam_sam]

I have a Compaq Presario CQ62 410 US power supply
The out ring is (-) and a inter ring is (+) that wll power the computer

What dose the center pin do it is (+)

How ever if you power that pin to the (+) side then the computer shut down and will not charge and the computer will not power ON

When you remove the battery from the computer and reinstall it every thing come back to life

Question I do have is

Do I need to use the center pin and if I do.....> How do I do it ?

I want run this computer off of some 18 volt tool batteries that I have I have done this before but not a computer that has three wires



Thank to any one that can help

[sam_sam_sam]

Re: Compaq Presario CQ62 410c US power supply Question

Dose any one have idea what the center pin is for and if it is need

[999999999]

Re: Compaq Presario CQ62 410c US power supply Question

It might be like the center pin found on some Dell laptop PSU, a data signal that identifies to the laptop that a valid PSU, capable of enough current to run it at full speed and charge the battery, is plugged in instead of some who-knows-what power source.

If that is the case you might check the bios menu to see if there is a way to disable it but there may not be, the laptop may be forced into a low speed mode and unable to charge its own battery.

[mattbrad2]

Re: Compaq Presario CQ62 410c US power supply Question

It does transmit some sort of signal. For example, an HP laptop will not respond with a Dell charger even though they fit perfectly. Ironically, a common problem with some newer HP's is the TI power management IC will start to fail. When this happens, you can either replace it or jumper the center pin of the DC jack to 19v and the laptop will charge again. So yes, it is HP specific but it's anyone's guess as to what exactly it's purpose is.

[sam_sam_sam]

Re: Compaq Presario CQ62 410c US power supply Question

Thanks for the Info

All that relpy

[b700029]

Re: Compaq Presario CQ62 410c US power supply Question

How ever if you power that pin to the (+) side then the computer shut down and will not charge and the computer will not power ON

That was a very risky thing to do, a look at the schematic shows that the pin basically goes directly to an input on the EC, with very little protection besides a diode up to the 3.3v rail. You're lucky it didn't kill the EC, because it probably tripped the OVP. The EC is a KB3926 for which I don't have the datasheet, but the similar KB926 and KB3930's datasheets show that 3.6V is the maximum that pin should ever experience.

As to its function, since that's an input-only pin and can be configured as ADC, I think the adapter ID is implemented by nothing more than a voltage divider in the adapter. Different wattage adapters will output different voltages on that pin for the EC to sense via the ADC. This is cheaper than the Dell system with the ID chip (1-wire EEPROM).

When this happens, you can either replace it or jumper the center pin of the DC jack to 19v and the laptop will charge again.

It depends on the model but this is a very risky move as I said above. Maybe it has no ill effects because the input is protected with a zener and resistor, but in general I would not recommend doing that without consulting the schematic or at least tracing the signal on the board. If it weren't for that diode, this guy's laptop would be dead now.

[mattbrad2]

Re: Compaq Presario CQ62 410c US power supply Question

b700029 - I see what your saying but all (at least in my experience) newer "dell-type" HP adapters have the center pin at ~14v. Just to make sure, I went and tested the 3 different models I have laying around here and they are all 14v, not 3v. Shorting it to 19v certainly isn't ideal but it is in fact a work-around.

[b700029]

Re: Compaq Presario CQ62 410c US power supply Question

It depends on the exact model of laptop they were designed for, some were probably designed to have that voltage on the middle pin and so would have appropriate circuitry in the laptop. The voltage divider also may be a high impedance source, draw any significant amount of current and the voltage drops. That would also explain the 24.3K to ground I saw in the schematic above. But the 19v main power is a low impedance source, so it will not have the same characteristics.

Not saying your idea is invalid, but it's prudent to be cautious especially when fixing customer's laptop.

[sam_sam_sam]

Re: Compaq Presario CQ62 410c US power supply Question

b700029

Is there a work-around for this and is this pin need if you are running off of battery power

Thank for any and all info that you can give me in this matter

The frist laptop I had it was easy to hook up a power tool battery pack I would like to do the same thing on this laptop if I can that is why I am asking is there a work-around for this

[999999999]

Re: Compaq Presario CQ62 410c US power supply Question

^ take apart existing power adapter and reverse engineer what it would take to power that data subcircuit (then do so).

[b700029]

Re: Compaq Presario CQ62 410c US power supply Question

Try it without the center pin connected to anything first.

[sam_sam_sam]

Re: Compaq Presario CQ62 410c US power supply Question

^ take apart existing power adapter and reverse engineer what it would take to power that data sub-circuit (then do so).

I did that on a replacement power supply and all I saw was two resisters in series which came up 220 meg ohm (+) to center pin and the same from the
center pin to the (-)

So I do not know if two 220 meg ohm resistor wired in series between (+) and the (-) terminal and hook the center pin in the middle of the two 220 meg ohm resistor

Would this work or not ?



Thanks for every one help in this matter

[999999999]

Re: Compaq Presario CQ62 410c US power supply Question

It seems as though there ought to be something more connected to the center pin than only these resistors which seem to only be forming a voltage divider.

[b700029]

Re: Compaq Presario CQ62 410c US power supply Question

220M is extremely high for a (relatively) low-voltage consumer application like this, and resistors in those values are also quite rare. What markings do they have?

When plugged into the laptop you'll have basically a 220M - 24.4K divider (through R108 and R109 above) which gives ~2mV at the ADC input (neglecting the input impedance, which will probably be significant with a 220M source impedance --- so in reality it would be much lower). This looks too low.

220K seems like a more likely value - gives ~1.7V at the ADC input.

[sam_sam_sam]

Re: Compaq Presario CQ62 410c US power supply Question

220M is extremely high for a (relatively) low-voltage consumer application like this, and resistors in those values are also quite rare. What markings do they have?

When plugged into the laptop you'll have basically a 220M - 24.4K divider (through R108 and R109 above) which gives ~2mV at the ADC input (neglecting the input impedance, which will probably be significant with a 220M source impedance --- so in reality it would be much lower). This looks too low.

220K seems like a more likely value - gives ~1.7V at the ADC input.

I measure this with a DMV meter and got this value
But this make scent what you have above f you think this would work

[b700029]

Re: Compaq Presario CQ62 410c US power supply Question

What multimeter are you using and did you set it to the 1M range and saw 220 on the display? That's likely 220K, not 220M. A multimeter that can measure a 220M resistor is quite high-end; most of them can't go higher than 200M.

[craciunaero]

Re: Compaq Presario CQ62 410c US power supply Question

Hi all ! I am having some problems with the same laptop. I have connected the center pin directly to the 19 volts supply and now the laptop is dead. Later I foud out that the center pin is actually connected to the +19v rail throght a 390k resistor. I hope this helps.

B700029 can you tell me any advice on the motherboard. Should I replace the KB chip? or where should I look for signs of trouble?

[spidey]

Re: Compaq Presario CQ62 410c US power supply Question

i use 220k resistor between +19 and center pin. i didnt have any problem with it. U can safely use that way.