Radeon 4870 3-pin fan connector

[promaty]

Hello, I accidentally ripped off 3-pin fan connector when I was cleaning the dust..

 

I've managed to solder it back, but the tachometer wasn't working anymore, no software responds to it, and the fan is now always running on full power (very loud, I'd guess more than 5000 RPM)

 

When I took a closer look, I saw that 12V wire for tachometer was going into an empty spot on the circuit board like black wire for the ground, so nothing happens when I solder back it back, computer receives no signal about fan's rpm.. Can anyone explain me this?

 

Front: http://img827.imageshack.us/img827/8199/pic11h.png Back: http://img521.imageshack.us/img521/9830/pic12a.png

 

Perhaps someone could post similar picture clearly showing 3-pin connection on the both sides of the board? (something similar to 4870 is OK) Thanks.

[KenB]

Hi,

 

The 4870 cards that I found had 4 wires - blue / yellow / red / black ( in that order )

 

Are you sure that you don't have a dry joint on the soldering?

 

With a voltmeter .....find a Ov connection.

Use a straight pin and push it through the insulation of the yellow / red wires.

Use this to check if you have 12v / 5v through the connecting wires.

[promaty]

Thanks for reply.

 

Unfortunately I don't have a voltmeter.. I'm not sure about the voltages, but I know that power goes through red/black wires, because fan forks without connecting the yellow one, so that is definitely one for tachometer signal. On the photo you can see, that yellow wire goes in to an empty spot and is not connected any further, so tachometer signal doesn't reach its destination. Why is it like that?

 

Any other ideas how to reduce fan's rpm?

[KenB]

that yellow wire goes in to an empty spot and is not connected any further

The yellow wire must connect to something.

When you ripped the connector off the board where there 3 pins?

 

If you are correct with the red / black wires then the yellow will, as you suggest, control the fan.

This will probably be an analogue voltage ( changing )

 

From your photos it looks as if the centre connection has been totally ripped out.

When you made the repair did you re-solder 3 connections?

 

This looks like a double-sided board.

Have you checked both sides for a possible track to solder the yellow wire to?

 

When you soldered the connection back - are you sure that you didn't bridge the tracks?

 

Any chance of a photo of the repair?

[promaty]

Back: http://img573.imageshack.us/img573/1921/48262530.png Front: http://img825.imageshack.us/img825/1286/52881783.png

 

So the fan works, when I solder bottom two wires (black and red) , but nothing changes whether I solder yellow one or leave it hanging.. It just not connected to any tachometer signal receiver on the board. I have no idea how it was working before..

 

Maybe there are some alternative solutions for lowering fan's rpm?

[KenB]

I still suspect a problem with the re-attachment of the pins.

 

If the card was working properly prior to you accident with it then the only logical conclusion is that there is a connection problem.

 

Take a close look at the tracks. ( Use a magnifying glass if you have one )

By ripping the pins out you could well have a hairline crack in one of the tracks.

I cannot make the copper tracks out from your photo but it should be obvious which track is connected to each pin.

 

The only conclusive way to test this is to borrow a meter and check the voltage on the two leads using the pin method described earlier.

If you are not getting a voltage then the problem lies with the joint / track

If you are then your soldering has been successful and the problem lies elsewhere on the board.

 

If you are not getting a voltage on the yellow wire ( say ) then disconnect the plastic connection and test the pin.

If no voltage on the pin then trace the track back a little and put the sharp pin through the coating to make contact with the track. If you get a voltage at this point work back towards the soldered connecting pin. Using this method you can locate the break in the track ( if there is one ).

 

I cannot see any other way around this.

[promaty]

Well I gave up on finding track for tachometer signal. My friend suggested adding some resistance to the fan's input wire, guess that would be the solution. No fan control, but at least not so loud. Thanks for the help though.