Gateway 900G frustration

[arpcentralone]

Re: Gateway 900G frustration

WOW, that is some really good information that I didn't know about the 100, 200, 300, and 400 components. Thanks! Here are some pics of the back side.

[arpcentralone]

Re: Gateway 900G frustration

Thanks for that bit of info that I didn't know about the 100,200,300,400 components! I have a pic of the back side right here.. take a look at it and get back to me. I did a solder bypass and forgot to remove it as you can see.

[arpcentralone]

Re: Gateway 900G frustration

okay, i've tested most of the 300 and 400 components and can't find any that are bad. What is the most common failure prone component of the inverter that usually goes out? I cannot replace this part because I cannot find one online without buying a new monitor and the darn thing has the psu and ccfl inverter integrated into the same board. SO, I cannot use a universal unit without too much modification. Any help is appreciated! Thanks!

[PlainBill]

Re: Gateway 900G frustration

okay, i've tested most of the 300 and 400 components and can't find any that are bad. What is the most common failure prone component of the inverter that usually goes out? I cannot replace this part because I cannot find one online without buying a new monitor and the darn thing has the psu and ccfl inverter integrated into the same board. SO, I cannot use a universal unit without too much modification. Any help is appreciated! Thanks!

It may not be the inverter; it could be the CCFLs. The scenario where any time you cycle the power button the display comes on for a few seconds can be either. IIRC, I've heard of one case where it was nothing more than the CCFLs were hooked up to the wrong connectors on the inverter after the cap replacement.

I've heard of several troubleshooting approaches. One is to buy a case mod CCFL kit and use the inverter to power the monitor CCFLs one at a time to see if they all work. Another is to hook the kit ccfls to the monitor inverter and see that all outputs are working.

I've even heard of an exotic approach where you use a scope to see why the inverter is turning off.

PlainBill

[EGuevarae]

Re: Gateway 900G frustration

... I've heard of several troubleshooting approaches. One is to buy a case mod CCFL kit and use the inverter to power the monitor CCFLs one at a time to see if they all work. Another is to hook the kit ccfls to the monitor inverter and see that all outputs are working. ...

I've done that. I took two narrow female CCFL connectors from a dead Proview/Sylvania 700P PSU/Inverter Board way beyond repair, and using them, modified a case CCFL kit using a two output inverter. I attach that modded inverter to a modded too ATX PSU to fire up CCFLs and see if they are the problem. It is a cheap and easy way to test CCFLs. I also have 15" LCD CCFLs to test inverters, taken from a dead Viewsonic VE500. That kind of things can ve very useful. I suspect too that you may have bad lamps in there.

[arpcentralone]

Re: Gateway 900G frustration

I read about the mod kit inverter and ccfl tests and also the scope test. I am going to purchase a light kit mod and try to test my ccfl's. Thanks alot for this info, however, if I do test the ccfl's and they are okay, then i am to assume it's the inverter. Is there a common part that fails? Maybe a transformer or mosfet? Or is it likely something random? I'm kinda new to getting this deep into the electronics, and trying to understand how each part works together with the others to accomplish something. Any info is greatly appreciated. Thanks! You rock!

[PlainBill]

Re: Gateway 900G frustration

I read about the mod kit inverter and ccfl tests and also the scope test. I am going to purchase a light kit mod and try to test my ccfl's. Thanks alot for this info, however, if I do test the ccfl's and they are okay, then i am to assume it's the inverter. Is there a common part that fails? Maybe a transformer or mosfet? Or is it likely something random? I'm kinda new to getting this deep into the electronics, and trying to understand how each part works together with the others to accomplish something. Any info is greatly appreciated. Thanks! You rock!

One common failure in an inverter would be the transistors BUT that blows the fuse. The failure you are describing indicates the inverter is 'seeing' a fault condition and shutting down. Possible faults include one CCFL drawing too much or too little current, or a shorted turn in a transformer.

PlainBill

[arpcentralone]

Re: Gateway 900G frustration

One common failure in an inverter would be the transistors BUT that blows the fuse. The failure you are describing indicates the inverter is 'seeing' a fault condition and shutting down. Possible faults include one CCFL drawing too much or too little current, or a shorted turn in a transformer.

What part of the circuit allows it to "see" a fault? Would there be a shunt regulator or something that sends the overflow of current to a control circuit? Sorry about this, and I don't mean to beat the bush into the ground, but I want to know exactly what cuts the inverter on or off, is it some type of micro controller? I will check the transformer until I get my ccfl mod in the mail to test the lamps/inverter with.

Thanks!

[PlainBill]

Re: Gateway 900G frustration

What part of the circuit allows it to "see" a fault? Would there be a shunt regulator or something that sends the overflow of current to a control circuit? Sorry about this, and I don't mean to beat the bush into the ground, but I want to know exactly what cuts the inverter on or off, is it some type of micro controller? I will check the transformer until I get my ccfl mod in the mail to test the lamps/inverter with.

Thanks!

Wow!!! Lots of questions. Teacher mode ON!!

There are many designs for backlight inverters. The essential elements are a pulse width modulated oscillator driving a step up transformer. Typically the input and output include capacitance to form a tuned circuit for greater efficiency. Protection elements may include sensing the drive current into the transformer, the output voltage of the transformer, and the current flow through the CCFLs. Pulse width modulation is used to control brightness.

The Fairchild FAN7311 is one 'purpose designed' controller. This application note is an example of a typical design. In particular note the links OLR, FB, and OLP1 through OLP4. The student is expected to discern the purpose of these through the product's data sheet.

While this provides information on one IC, searching for data sheets and application notes can SOMETIMES yield information on other ICs. Sometimes application notes and even data sheets are unavailable. And in many cases the design of an inverter is not based on the published application note. Still, the aspiring student can often glean information about the circuit.

Teacher mode OFF

PlainBill

[arpcentralone]

Re: Gateway 900G frustration

Thanks for the detailed explanation there PlainBill, wow. My CCFL mod kit is comming today and I will tinker with it and get back to you with the results. I think I understand about how the inverter operates now after the help from everyone on this thread and reading the internet, google is my best friend, sometimes. Anywho, I will be back on when I get the tests complete and show my findings.

Thanks Again! Yall are super! (pardon the southern)

[koshposh]

Re: Gateway 900G frustration

the 5v bounces from 0 to 5 in time with the ticking

Hi,
What do you mean by ticking?

[PlainBill]

Re: Gateway 900G frustration

Hi,
What do you mean by ticking?

Like a clock. Tick....Tick....Tick....

A common feature of a switching power supply is that the control IC gets power from two sources. A high value resistor is used to charge a cap from the rectified mains supply. This cap holds only enough energy to run the control IC for a fraction of a second.

When the voltage gets high enough the control IC sends a series of pulses to the power FET. This in turn drives the transformer. One of the transformer windings feeds power back for the control IC. This output is rectified and filtered. It provides the power to run the control IC in normal operation. If the cap that does the filtering is bad, the start-up cap discharges and the control IC shuts down. The cap recharges, and the whole thing starts over again.

The exercise for YOU is to explain why the use such a high value resistor in the start-up circuit.

PlainBill

[koshposh]

Re: Gateway 900G frustration

The exercise for YOU is to explain why the use such a high value resistor in the start-up circuit.
PlainBill

umm let's see... with a higher the resistance, more power is dilivered to the cap... maybe. thats my guess

Like a clock. Tick....Tick....Tick....
PlainBill

so... I'm supposed to be hearing a ticking sound?

I have a 900G gateway monitor and it dies on me the other day... I took it apart and all the caps look fine, so I dont know where to go next. and I dont hear any ticking noises... How would I check the 5V and 12V supplies on the 2x5 pin header with a multimeter?

Thanks
Koshposh

[EGuevarae]

Re: Gateway 900G frustration

... How would I check the 5V and 12V supplies on the 2x5 pin header with a multimeter? ...

Pins are marked for testing.

[PlainBill]

Re: Gateway 900G frustration

[QUOTE=koshposh]umm let's see... with a higher the resistance, more power is dilivered to the cap... maybe. thats my guess [/QUOTE}

BZZZZ!! Wrong. Do not collect $1,000,000

so... I'm supposed to be hearing a ticking sound?

I have a 900G gateway monitor and it dies on me the other day... I took it apart and all the caps look fine, so I dont know where to go next. and I dont hear any ticking noises... How would I check the 5V and 12V supplies on the 2x5 pin header with a multimeter?

Thanks
Koshposh

Plug logic card into power supply / inverter, hook up power. It may be necessary to prob from the solder side of the board.

Black arrow - black lead of multimeter
Red arrow - red lead of multimeter to read 5V
Yellow arrow - red lead of multimeter to read 12V

If 5V pulses every few seconds replace cap in blue circle. It would be a VERY good idea to replace all electrolytic caps on power supply / inverter.

If no 5V / 12V, with power unplugged check continuity of fuse.

PlainBill

[EGuevarae]

Re: Gateway 900G frustration

[QUOTE=PlainBill]

umm let's see... with a higher the resistance, more power is dilivered to the cap... maybe. thats my guess [/QUOTE}

BZZZZ!! Wrong. Do not collect $1,000,000



Plug logic card into power supply / inverter, hook up power. It may be necessary to prob from the solder side of the board.

Black arrow - black lead of multimeter
Red arrow - red lead of multimeter to read 5V
Yellow arrow - red lead of multimeter to read 12V

If 5V pulses every few seconds replace cap in blue circle. It would be a VERY good idea to replace all electrolytic caps on power supply / inverter.

If no 5V / 12V, with power unplugged check continuity of fuse.

PlainBill

I've tested this PSU unhooked from logic board, to measure 12 & 5v outputs.

[PlainBill]

Re: Gateway 900G frustration

[QUOTE=eguevarae]

I've tested this PSU unhooked from logic board, to measure 12 & 5v outputs.

I seem to remember having done the same. On the other hand, I seem to remember Kathy Ireland asking if she could come over and take care of my pool. I am sure one memory is incorrect, so why not both?

PlainBill

[EGuevarae]

Re: Gateway 900G frustration

[QUOTE=PlainBill]

I seem to remember having done the same. On the other hand, I seem to remember Kathy Ireland asking if she could come over and take care of my pool. I am sure one memory is incorrect, so why not both?

PlainBill

Kathy can't clean a pool right. Better ask for Anna Kournikova ....

[koshposh]

Re: Gateway 900G frustration

loll thanks, I'll give it a try

[koshposh]

Re: Gateway 900G frustration

ok so when unplugged from power, both 5V and 12V sit at 4 mV

when power is plugged in the 12V sits at 4.4 mV and the 5V jumps randomly anywhere between 338 and 78 mV without any particular order...

I'm getting volatages nowhere near 5 or 12 V