IBM L170 17" monitor "2 second on then black"

[budm]

Re: IBM L170 17" monitor "2 second on then black"

We need to trace out where pin13 and 18 go to, so as RTECH said, GOOD AND FOCUSED pictures of both sides of the board are needed to trace out the connections.

[ilikesteel]

Re: IBM L170 17" monitor "2 second on then black"

selldoor-Rtech,

for what it's worth I measured the two transformers as follows:

the one closest to the power plug reads:
the two pins on the 6 pin side with the wires attached read 0 ohms or short between the two pins.
the opposite end the reading between the two larger outside pins reads 1.04 ohms.

transformer #2 reads as follows:
the two pins on the 6 pin side with the wires attached read 0 ohms or short between the two pins.
the opposite end the reading between the two larger outside pins reads 1.10 ohms.

I've looked at the underside of the board to try and trace signal paths from the 13V pins on 9 pin connector over to bit3105 pin 13 and 18. there may be another layer between the top and bottom of the board. no distinguishing physcical connections I can see. If I check continuity between pin 13 & 18 of bit3105 and the 13V at the connector it's reads as an open circuit.

hope this helps....

[ilikesteel]

Re: IBM L170 17" monitor "2 second on then black"

originally the problem occurred while the monitor was conencted to the pc. power was cycled off and on the the breaker in the electrical box. now I'm tesing without any connection to the interface. I can connect it to a pc if neccessary.

[selldoor]

Re: IBM L170 17" monitor "2 second on then black"

No - sorry doesnt help much you will have to do it the long way round
Meter on 2000 ohms.
Number your pins (Diagram helps but in your head will do) Measure 1>2 1>3 1>4 1>5 1>6 1>7 1>8 2>3 2>4 2>5 2>6 2>7 2>8 3>4 3>5 and so on you are looking for something usually between 300 -1200 ohms but could be over 2000 so any offscale re test with meter on 20000 ohms.

I would connect it when doing voltage tests

[ilikesteel]

Re: IBM L170 17" monitor "2 second on then black"

ok selldoor,

attached is a diagram of the transformer as it appears on the foil side of the board. This is the way I numbered pins.

Transformer # 1 closest to input power connector.

1-2=0, 1-3=nc, 1-4=nc, 1-5=0, 1-6=0, 1-7,8,9=nc
2-1=0, 2-3=nc, 2-4=nc, 2-5=0, 2-6=0, 2-7,8,9 nc
3-1=nc, 3-2=nc, 3-4=0, 3-5,6,7,8,9=nc
4-1=nc, 4-2=nc, 4-3=0, 4-5,6,7,8,9= nc
5-1=0, 5-2=0, 5-3=nc, 5-4=nc, 5-6=0, 5-7,8,9=nc
6-1=0, 6-2=0, 6-3=nc, 6-4=nc, 6-5=0, 6-7,8,9=nc
7-1,2,3,4,5,6,7,8=nc, 7-9= 1.043 ohms,
8-1,2,3,4,5,6,7,9=nc
9-1,2,3,4,5,6=nc, 9-7=1.043 ohms, 9-8=nc

transformer # 2

1-2=0, 1-3=nc, 1-4=nc, 1-5=0, 1-6=0, 1-7,8,9=nc
2-1=0, 2-3=nc, 2-4=nc, 2-5=0, 2-6=0, 2-7,8,9 nc
3-1=nc, 3-2=nc, 3-4=0, 3-5,6,7,8,9=nc
4-1=nc, 4-2=nc, 4-3=0, 4-5,6,7,8,9= nc
5-1=0, 5-2=0, 5-3=nc, 5-4=nc, 5-6=0, 5-7,8,9=nc
6-1=0, 6-2=0, 6-3=nc, 6-4=nc, 6-5=0, 6-7,8,9=nc
7-1,2,3,4,5,6,8,=nc, 7-9= 1.111 ohms
8-1,2,3,4,5,6,7,9=nc
9-1,2,3,4,5,6=nc, 9-7=1.111 ohms, 9-8=nc

cross my finers ......

[jetadm123]

Re: IBM L170 17" monitor "2 second on then black"

Below the right side inverter transformer is U302 and above the yellow main transformer is Q102. What are the part numbers of both devices?

[selldoor]

Re: IBM L170 17" monitor "2 second on then black"

Transformers look ok - assuming it is 1043 ohms and 1111 ohms.

[ilikesteel]

Re: IBM L170 17" monitor "2 second on then black"

jetadm123-selldoor,

doubled checked my transformer resistance readings. original readings were 1.043 and 1.111 ohms. I'm using a Fluke D802 meter. it was set on the 2K range, also the diode checking range.

I checked them at the 200 ohm range (lowest) and it read open.

I then checked them at the 20K ohm range and it read 1.04 and 1.11.

it must be 1043 and 1111 as you suggest selldoor.

also checked the the two components that adm123 wanted me to check. they are both KIA 431A, KIA431A - BIPOLAR LINEAR INTEGRATED CIRCUIT (PROGRAMMABLE PRECISION REFERENCES) - KEC(Korea Electronics).

thanks again........

[budm]

Re: IBM L170 17" monitor "2 second on then black"

That is the same as TL431 commonly used for Voltage regulation feedback circuits in switching power supply.

[Rtech]

Re: IBM L170 17" monitor "2 second on then black"

With your voltages varying as they are, it is most unlikely to be the inverter transformers, and as advised before,and seconded by Budm, you need somehow to split the cct up.If you measure across the electrolytics(not the big one) but those after the Schottky, you can determine which is the ones smoothing the 13V plus output,and by following the +ve side of them, should be able to identify what links you have to unsolder to prevent the voltage going to the Inverter stages,and then check the 5v line,to see what that is now like.

[ilikesteel]

Re: IBM L170 17" monitor "2 second on then black"

Rtech-budm,

I'm doing this repair solely as a learning experience and to maintain and repair my own equipment. I've had some experience repairing TV's and other electronics. I can solder very well and I think I can troubleshoot fairly well. With the right schematic, this may have been less painful. I cannot find the schematics. the model number of the monitor is 9818-AC0.

with the 13V and 5V voltages variying while the monitor is cycling between screen flash and blank screen, can the bit3105 be detecting a problem and causing the screen splash on and the blank screen through it's sensing circuits?

which component is the Schottky? (sorry)

without a schematic, where would the input to the inverters be, which component?

If the consensus is that the inverters may be bad, I may be able to get a used power board. What are your thoughts? do you thinks it's strictly a power problem and not a logic problem originating on the other board?

can we rule out lamps?

fortunately this monitor has only two boards beside the front panel button board. the power board has the inverters on it.

The power board is readily available, but I have not identified the logic board to see if it's available.

thanks guys..... saga is continued.

[budm]

Re: IBM L170 17" monitor "2 second on then black"

When I see 2 seconds to black, since I have test lamps, I will plug the test lamp into all the lamp sockets, it my test lamps stay on, then I know it is not the inverter board problem, if it does not then I will troubleshoot the board. Thsi save me so much time try to figuering out if I have bad board or bad lamps. That is why I suggested you to build or find a set of test lamps.

[jetadm123]

Re: IBM L170 17" monitor "2 second on then black"

The reason I asked about the transistor part numbers is because I was wondering if there is some type of switching transistor that turns on the 13V to the BIT3105 and the rest of the inverter circuit.

[selldoor]

Re: IBM L170 17" monitor "2 second on then black"

I thought the inverter transformers were good the circuitry may not be.
I attach a picture which actually shows the BIT3105 wiring in this PS Board so that might help.
Have you access to any ccfls (Old screen broken laptop) or a working screen you could try these ccfls in?

[budm]

Re: IBM L170 17" monitor "2 second on then black"

So far we do not get to see the good clear pictures of both sides of the board to be able to trace out the connection to the VCC pin of the PWM IC yet. So far the picturs of the board had palstic shiled covering the the board, plus the glare from the flash.

[ilikesteel]

Re: IBM L170 17" monitor "2 second on then black"

ok, thanks guys,

here are a couple of photos of the foil side.

are ccfl's expensive? is it worth buying 4??? I have no access to any damaged monitors with good ccfl's.

I appreciate all you efforts.

[budm]

Re: IBM L170 17" monitor "2 second on then black"

OK, that is a big help, now I can try tracing the VCC lines to the PWM IC.

[selldoor]

Re: IBM L170 17" monitor "2 second on then black"

As you have the boards out can you check the part numbers on the two mosfets - bottom side of the power suppy board - little rectangles with 8 legs.
Do they look burnt at all. Number may include sp8m3

[budm]

Re: IBM L170 17" monitor "2 second on then black"

OK, see the redline: You need to see if the Inverter ON is still present when the lamps turn off.

[killian6pk]

Re: IBM L170 17" monitor "2 second on then black"

ok, thanks guys,

here are a couple of photos of the foil side.

are ccfl's expensive? is it worth buying 4??? I have no access to any damaged monitors with good ccfl's.

I appreciate all you efforts.

Tom66 has a website with Service Manuals for mostly tvs, but I gave him a bunch of monitors and they are their also. One of the manuals I gave him was for this model. IBM L170. www.tgohome.com/ServiceManuals