IBM Thinkvision 6736-HC9 No power

[eckertb83]

Since I will Be placing an order for parts soon I figured I would try and save another 2 monitors in the process. I found this IBM Thinkvision in great condition got it home and NO Power. I took it a part and nothing obvious is bad, so I pulled out my DMM and started testing components.
Having remembered the ausus ve205 you guys helped me with a few months ago I started checking the voltage regulator and MOSFET along with the fues and resistor near the mosfet and filter cap.


All settings on DMM 200 Ohms
Fuse- good
Resistor in and out of circuit-good
Mosfet
black probe pin
1 to 2 = 1
1 to 3 = 1
2 to 3 = 1

and the same vise versa

also the same with the regulator

So I would assume that once again I need a new mosfet and regulator?
Now Ive never seen a board like this before theres 2 Filter caps attached to it is there something else I should check?
Posting pics of the board in a few mins..

[selldoor]

Re: IBM Thinkvision 6736-HC9 No power

What voltages do you get on the connector to the main board?
If none what voltage do you get on the BIG caps - care high voltage

I think that test on mosfet and regulator is only for shorts so they look ok to me.

[eckertb83]

Re: IBM Thinkvision 6736-HC9 No power

The Asus i posted about had the same issue no power, and turned out to be the mosfet shorted and took the regulator. I will plug the board in and check voltage though and you mean where I plug my 110 line in right?

[eckertb83]

Re: IBM Thinkvision 6736-HC9 No power

Ok with Power plugged in and testing the 2 tabs on the back of the plug I get NO voltage
Then check the 2 BIG caps with DMM set to 1000DCV I get a reading of 002 on both.

[Davi.p]

Re: IBM Thinkvision 6736-HC9 No power

Mosfet seems shorted, can you test it with diode tester 'cause it's more clear to me? I don't know what do you mean for the resistor, if is R019 is right and for regulator..
"Power plugged in and testing the 2 tabs on the back of the plug I get NO voltage"
you must set to Vac the dmm to test A.C., the bigger caps in Vdc

[eckertb83]

Re: IBM Thinkvision 6736-HC9 No power

When my other monitor was showing no power I think BUDM also suggested I check the resistor just in case both in and out of circuit. That's all I meant.

[Davi.p]

Re: IBM Thinkvision 6736-HC9 No power

Yes BUT which resistor? If is the R019 ok.. usually goes open when main mosfet broke. And what do u mean for regulator?? Test also other semicondictors in primary side and dual diodes (2) in to220 on secondary on heatsink.

[eckertb83]

Re: IBM Thinkvision 6736-HC9 No power

Yes R019 resistor and Im sorry I meant the bridge rectifier I think. Its the black thing on the heat sink next to the big caps.

[eckertb83]

Re: IBM Thinkvision 6736-HC9 No power

Trying to get the part number from the mosfet now and I think I found the main Issue....theres a small web in between the 2 contacts.... The numbers on the mosfet are 07n701 and 415235 I checked digikey with those numbers and didnt come up with anything. I actually still have one left from the last time I ordered and extra but not sure if they are interchangeable.

[eckertb83]

Re: IBM Thinkvision 6736-HC9 No power

The 2 diodes are good just checked them.

[Davi.p]

Re: IBM Thinkvision 6736-HC9 No power

Maybe it's my low knowledge of english but i don't uderstand: "Im sorry I meant the bridge rectifier I think. " I said regulator but you meant Diode Bridge? Tell me what's the part number of the mosfet that you have as an extra.

[eckertb83]

Re: IBM Thinkvision 6736-HC9 No power

I dont know why I was thinking regulator i did mean bridge rectifier and you said diode bridge....probably the same thing just different terms. The 2 diodes I tested are on the other heat sink and they were good.

Part no on my extra mosfet
http://www.digikey.com/product-searc...&formaction=on

[budm]

Re: IBM Thinkvision 6736-HC9 No power

Since you are getting 0V on those two main filter cap, but just to be sure that you are measuring them directly on the positive and the negative legs of the cap? if that is the case make sure that the rocker power switch on the back of the unit is in the ON position, it seems top me if the fuse F001 (FUSE enclosed in the black shrink tubing) is good but it is not getting the AC input to the bridge ~ terminals. Make sure that the small 2-pin connector which goes to the power switch is connected.

[Davi.p]

Re: IBM Thinkvision 6736-HC9 No power

"Mosfet
black probe pin
1 to 2 = 1
1 to 3 = 1
2 to 3 = 1"

Anyway if those "=1" was 1ohm ie [ 1,00] the mosfet is broken

[eckertb83]

Re: IBM Thinkvision 6736-HC9 No power

Budm I did have the power switch connected when I was testing and it was turned on. I actually checked it both ways. When it was off I got nothing for a reading and 002 when switched on.

[budm]

Re: IBM Thinkvision 6736-HC9 No power

OK, then trace out the connection as shown in my pictures to see if you do get 120VAC the 2 (~) pins of the main bridge rectifier and about 170vdc at the two legs of the caps, you need to get the DC voltage on the main filter caps first before going further.

[selldoor]

Re: IBM Thinkvision 6736-HC9 No power

Already covered

[budm]

Re: IBM Thinkvision 6736-HC9 No power

"Ok with Power plugged in and testing the 2 tabs on the back of the plug I get NO voltage" Which TABs are those, the IEC AC inlet? You should be able to read low resistance between the AC plug HOT (L) and one of the ~ of the bridge, same for AC plug Neutral (N) to another ~ of the bridge.

[eckertb83]

Re: IBM Thinkvision 6736-HC9 No power

Budm I was checking the voltage on the back of the terminal where the 110 line plugs in. for some reason I didnt get voltage there but once I filpped the board over and checked the L and N points I was getting 119.0v. I'm gonna check the points you circled and trace it down.

1. Just to make sure do I keep the red probe on the Live (L) point then proceed to check the points circled in your trace? ALL on ACV correct?

[selldoor]

Re: IBM Thinkvision 6736-HC9 No power

Yes you are working on VAC
I dont think he is asking you to test at every joint at this stage.
I think he wants you to have another go at testing the middle two joints on the Bridge Rectifier.
On Budms drawing it is bottom right corner - there are 4 joints in a row with
a large "+" at one end. This is where his testing ends on the two middle ones.

Just put one probe on the second joint of the four and the other probe on the third joint.
doesnt matter which probe.

This is HIGH Voltage so the less probing the better and if that comes up at 120VAC you dont need to do the rest.

If it doesnt show at 120VAC then we can talk you through a resistance check on the circuit with the power off - so much safer to work at.