HP w2007 PTB-1773 - Where to start?

[maverick530]

Re: HP w2007 PTB-1773 - Where to start?

Ok, I got the new TEA1530AT part in and replaced it (See pic). I think I did a great job soldering it in. It looks clean for such a tiny part. I plugged it in and did an initial test, and got 11v solid across pins 1 (VCC) & 2 (GND)! Between pins 8 (Drain) & 2 (GND) showed a nice solid 160v, so I was ecstatic. Also checked some of the output voltages, and saw some at 5v!

So I plugged in the power board to the monitor, and the power light to the monitor flashes for a quick millisecond (should stay on) and no joy.

I disconnected the power board (powered, but not under load from the logic board) and now see that all of my voltages are oscillating back and forth. In chiasmic fashion, I checked the output voltages, and now see a constant fluctuation between 1.43v and 1.85v. I checked pins 1&2 and found a fluctuation between 9v and 10.5v. I checked pins 2&8 and found a fluctuation of 150-160v. Now when I check voltages between the huge cap (C805) I get a fluctuation still as well where it used to be more solid.

What is going on? What could cause this oscillation so early on in the PSU? What else can I probe that may reveal something?

[Bobdee]

Re: HP w2007 PTB-1773 - Where to start?

My first thought on this was,
What makes you so sure that the original PWM was a TEA1530AT to me this was never realy resolved
If this is the correct replacement then the bridge rectifier would be worth looking at, now that big cap (C805) is fluctuating, (just a thought)
Bob
BTW nice job on IC, but what is up with that solder joint on the cap just above IC and to the right a bit (or is it just the picture)

[maverick530]

Re: HP w2007 PTB-1773 - Where to start?

BTW the solder joint mentioned in the picture does look weird. I resoldered a capacitor there, and probably didn't do the best job, but looking at it closely--it looks to me like a solid solder, it's just a little ugly, like I got the PCB too hot with too little flux.

Can you please point me to the Bridge Rectifier? I'm not sure what part/where that is.

Remember how I thought the reading on the IC (I801) was: 'CA1530A'? Well upon looking at the replacement TEA1530AT-- these replacements actually have 'EA1530A' written on them. And now that I see that, I actually think the old IC really did say 'EA' as the first two letters. I really think I have the right part for IC I801.

With that being said, the datasheet does say Pin 1 (VCC) Vstart value should be 11v, which it was, until I connected it to the logic board. What's interesting to me is the following paragraphs in the TEA1530AT datasheet regarding 'latch protection':


The PROTECT input (pin 3) is a multi-purpose (high-impedance) input, which can be used to switch off the IC and create a relatively long timing function. As soon as the voltage on this pin rises above 2.5 V, switching stops immediately. For the timing function, a current of typically 50 mA flows out of pin PROTECT and charges an external capacitor until the activation level of 2.5 V is reached. This current source is only activated when the converter is not in regulation, which is detected by the voltage on pin CTRL (VCTRL < 0.63 V). A (small) discharge current is also implemented to ensure that the capacitor is not charged, for example, by spikes. A MOSFET switch is added to discharge the external capacitor and ensure a defined start situation. The voltage on pin CTRL determines whether the IC enters latched protection mode, or safe restart protection mode:
• When the voltage on pin CTRL is below 0.63 V, the IC is assumed to be out of regulation (e.g. the control loop is open). In this case activating pin PROTECT (VPROTECT > 2.5 V) will cause the converter to stop switching. Once VCC drops below VUVLO, capacitor CVCC will be recharged and the supply will restart. This cycle will be repeated until the fault condition is removed (safe restart mode).
• When the voltage on pin CTRL is above 0.63 V, the output is assumed to be in regulation. In this case activating pin PROTECT (VPROTECT > 2.5 V), by external means, will activate the latch protection of the IC: The voltage on pin VCC will cycle between Vstart and VUVLO, but the IC will not start switching again until the latch protection is reset. The latch is reset as soon as VCC drops below 4.5 V (typical value) (this only occurs when the mains has been disconnected). The internal overtemperature protection will also trigger this latch.


Is the IC going into this protection mode because it can't charge an external capacitor? Could this be because of the faulty resolder job on the nearest two capacitors (C807 & C829)?

[Bobdee]

Re: HP w2007 PTB-1773 - Where to start?

Bridge rectifier is along side (C805) its got 4 legs in straight row
If you are unsure how to test let us know

The picture of C807 looked to me like there was no right leg or solder

As for that PWM, Phewwww
A faulty diode or resistor could be problem, SMT cap,
sometimes thats all you can do is check the parts that you are capable of checking
Bob

[maverick530]

Re: HP w2007 PTB-1773 - Where to start?

Ok I checked the bridge rectifier. Let me know if this is wrong, but to check it, I checked pins + with one of the center pins, then reversed the probes. It read about .6 (on Diode test) in one direction, then infinity (1) in the other. Tested with the other center pin, and it was the same. Tested pins - with one of the center pins, and then the other, all with the same result. I believe this means it checks out, unless I didn't do it right.

Nevertheless, I resoldered the 4 leads on the Bridge Rectifier by completely removing the solder and reapplying new solder. After that, I still get oscillation.

Not sure what else to try. Anybody have any more ideas?

[PlainBill]

Re: HP w2007 PTB-1773 - Where to start?

Ok I checked the bridge rectifier. Let me know if this is wrong, but to check it, I checked pins + with one of the center pins, then reversed the probes. It read about .6 (on Diode test) in one direction, then infinity (1) in the other. Tested with the other center pin, and it was the same. Tested pins - with one of the center pins, and then the other, all with the same result. I believe this means it checks out, unless I didn't do it right.

Nevertheless, I resoldered the 4 leads on the Bridge Rectifier by completely removing the solder and reapplying new solder. After that, I still get oscillation.

Not sure what else to try. Anybody have any more ideas?

Pulsing outputs usually indicate one of two problems: Insufficient power being fed back from the transformer to the controller; or excessive load.

Lecture mode: Refer to figure 3 in the TEA1530AT datasheet here. This is a simplified schematic of the supply.

The diamond shaped device labeled Vi in the upper left corner is the bridge rectifier. Cvin is the large 100 uF, 450 Volt capacitor. At startup the regulator pulls power from the main supply via pin 8. Pin 6 drives the power FET, pin 5 monitors the current flowing through the FET and the primary winding of the transformer.

The IC cannot draw enough current from pin 8 for normal operation without overheating. For normal operation it gets it's power from pin 1. Note capacitor Cvcc and also the tertiary winding on the transformer and the diode connected to it.

At the upper right of figure 3 is the secondary of the transformer, the rectifier diode, and the filter cap. The power supply you are dealing with actually has two secondaries, and a slightly more complicated filter arrangement.

The circuit at the lower right corner senses the output voltage. When it reaches the intended output voltage the shunt regulator starts to conduct, pulling current through the LED, which turns on the photo transistor, and raising the voltage at pin 4.

Also note figure 8, and the discussion in the application section.

Suggestions for testing

Don't operate the power supply without load. I'd suggest something like a 10 ohm 5 watt resistor across the 5 volt output. Check the voltage at pin 1. Check the electrolytic cap Cvcc. Check your soldering!!!

PlainBill

[maverick530]

Re: HP w2007 PTB-1773 - Where to start?

Suggestions for testing

Don't operate the power supply without load. I'd suggest something like a 10 ohm 5 watt resistor across the 5 volt output. Check the voltage at pin 1. Check the electrolytic cap Cvcc. Check your soldering!!!

PlainBill

Please bear with me as you lost me completely on testing with a load. I have no idea how to place a resistor across a 5 volt output. How is this done? What kind of resistor do you recommend? Can you link me to one I can purchase? Also, which 5V output should I place it across? And define 'across': where do I place the negative end?

Which Capacitor is Cvcc? C807 (82uF 50v) or C829 (1uF 50v)? How can I tell? My guess is it's C807, as it is most closely aligns position-wise on the PCB with pins 1 & 2 of the IC. If so, is my next step to resolder C807 since it looks odd anyway?

Is there any chance I got a bad TEA1530AT installed, and at what point should I simply try resoldering in a new one?

[PlainBill]

Re: HP w2007 PTB-1773 - Where to start?

Please bear with me as you lost me completely on testing with a load. I have no idea how to place a resistor across a 5 volt output. How is this done? What kind of resistor do you recommend? Can you link me to one I can purchase? Also, which 5V output should I place it across? And define 'across': where do I place the negative end?

Which Capacitor is Cvcc? C807 (82uF 50v) or C829 (1uF 50v)? How can I tell? My guess is it's C807, as it is most closely aligns position-wise on the PCB with pins 1 & 2 of the IC. If so, is my next step to resolder C807 since it looks odd anyway?

Is there any chance I got a bad TEA1530AT installed, and at what point should I simply try resoldering in a new one?

From the testing you did before and the results you are getting now we know the original IC was dead. The new IC seems to be trying to work, but either overcurrent protection or power supply issues are preventing it.

For a load resistor I would suggest something like a Radio Shack 10 Ohm 10W 5% Wirewound Resistor (2-Pack) Model: 271-132 | Catalog #: 271-132. They should have them at your local Radio Shack - Excuse me, they're called 'The Shack' now, I believe. Any 10 watt or greater resistor in the 5-10 ohm range will work. It is connected from the 5 Volt output of the power supply board to ground.

I believe C807 is Cvcc.

PlainBill

[maverick530]

Re: HP w2007 PTB-1773 - Where to start?

Your requirement of placing the board under "load" to test it is intriguing to me and I want to learn. What is the advantage of doing so? Is it bad if I don't? Because I didn't place the board under load when I first tested it after I soldered in the new IC--and it registered good/working, but then failed when I put it all together. Did this action cause something to fail?

[EGuevarae]

Re: HP w2007 PTB-1773 - Where to start?

Your requirement of placing the board under "load" to test it is intriguing to me and I want to learn. What is the advantage of doing so? Is it bad if I don't? Because I didn't place the board under load when I first tested it after I soldered in the new IC--and it registered good/working, but then failed when I put it all together. Did this action cause something to fail?

I believe that a load is required for the power supply to startup, just like a load is required for a computer ATX power supply to start. Just a small load so not to overload the power supply but enough to get it running and test components on a live power supply.
Perhaps some of our seniors that really know electronics (I'm just a Wells Fargo Teller ..LoL!) can either clarify, correct me, or give a more specific & appropriate example.

[PlainBill]

Re: HP w2007 PTB-1773 - Where to start?

I believe that a load is required for the power supply to startup, just like a load is required for a computer ATX power supply to start. Just a small load so not to overload the power supply but enough to get it running and test components on a live power supply.
Perhaps some of our seniors that really know electronics (I'm just a Wells Fargo Teller ..LoL!) can either clarify, correct me, or give a more specific & appropriate example.

A switching mode power supply (SMPS, the type of supply we are dealing with here) requires a load to work properly. Without a load, I would expect them to produce some output, but voltages could be off and regulation would be poor.

As a rule of thumb the load should be between 10% and 110% of rated output current. Since the inverter draws very little current when the backlights are off AND the regulator circuitry ties into the 5V supply, we would load that. A few monitor supplies that I remember were rated at 3A. A 10 ohm resistor would draw .5A; close enough for Government work.

While it is POSSIBLE running the supply without load would damage it, that wouldn't be my first guess.

PlainBill

[PlainBill]

Re: HP w2007 PTB-1773 - Where to start?

Darn!

[EGuevarae]

Re: HP w2007 PTB-1773 - Where to start?

A switching mode power supply (SMPS, the type of supply we are dealing with here) requires a load to work properly. Without a load, I would expect them to produce some output, but voltages could be off and regulation would be poor.

As a rule of thumb the load should be between 10% and 110% of rated output current. Since the inverter draws very little current when the backlights are off AND the regulator circuitry ties into the 5V supply, we would load that. A few monitor supplies that I remember were rated at 3A. A 10 ohm resistor would draw .5A; close enough for Government work.

While it is POSSIBLE running the supply without load would damage it, that wouldn't be my first guess.

PlainBill

Well, that's more or less what I wanted to tell, just I didn't have the knowledge to tell it that way.
Thanks, Bill!

[maverick530]

Re: HP w2007 PTB-1773 - Where to start?

Ok, I resoldered CVcc (C807) and it looks better, and also one of the legs of the IC that looked like it needed more solder, but it hasn't changed anything. I still get oscillation on pin 1 from 9.4v to 10.5v.

At what point should I desolder the joint between the power side of the board and the inverter side again? Is that worth trying again?

I'm at a loss as to what else to try. If anybody is willing to look at it, I'll send it to them free of charge.

[ventzel]

Re: HP w2007 PTB-1773 - Where to start?

Try to change optocoupler (I802) and TL431(I803) and check all smd resistors near I803 and all resistor connected betwen optocoupler and TEA1530 pin 4. I have the same problem and it was optocoupler defect. When power suply is ok you'll have 1.5V in emitor of optocoupler.

[jiGSaw]

Re: HP w2007 PTB-1773 - Where to start?

#1 - 0.77 v
#2 - See Attached. Is this detailed view better?
#3 - The writing on the IC is upside down in the attached picture. Does that mean pin 1 is the top right pin? If so, I should also be checking across pin 1 +(Vcc) and pin 2 - (GND) instead of 1 & 3 right?

i have found a solution and i am currently using that monitor now...if u look at the board u will see a diode D905..REPLACE THAT DIODE...it worked for me hope it works for u..i have a HPw1907 and i used the diode form a HP W17e which has almost the same circuits

[traveler_15]

Re: HP w2007 PTB-1773 - Where to start?

does anyone have a trick to get this monitor apart as there are no apparent screws other then the base.. thanks for any insite

[retiredcaps]

Re: HP w2007 PTB-1773 - Where to start?

If this is similar to the w2207 (which I have taken apart) be very CAREFUL. The "keyboard" aka front panels buttons are attached. In addition, the panel is connected by a very thin and fragile cable. Do NOT pull the without checking.

This isn't the same model, but see

http://www.youtube.com/watch?v=Ul5LhuCT1y8

for a general idea on how to pry apart these monitors.

does anyone have a trick to get this monitor apart as there are no apparent screws other then the base.. thanks for any insite

[maverick530]

Re: HP w2007 PTB-1773 - Where to start?

does anyone have a trick to get this monitor apart as there are no apparent screws other then the base.. thanks for any insite

First time I tried to open this monitor it took me 2 hours, for the very same reason. So to save you some time, I'll tell you how to do it:

Once the base is unscrewed and all visible screws from the back are removed, start with the monitor facing you-- so you're looking right at the screen. Then pry away the the backing (it snaps off). Start with the top left corner, so you don't have to mess with the power button or the controls on the bottom right. Don't be afraid to use a bit of force, that was my problem, I never used enough of it because I didn't want to hurt it.

This monitor has a natural groove between the backing and the front, that is the groove you pry into. Hope this helps, sorry I don't have pics.

[Bobhoskin]

Re: HP w2007 PTB-1773 - Where to start?

Hi to all, I'm Cindy from Italy,
I will say sorry for my not perfect english,
time passed for this thread, I will keep it open a while if you can help me .....i've the same identical Powersupply PTB-1773,

Here I post the same photos maverich made... to help remember




Reading all pages of this thread, I report same test made by Maverick530, and same results... then I desolder even a leg of 2 diodes and test (D803, D804), on one side I see a value, the other nothing ....they are ok!....?

I go now to buy the 4 capacitors that are around the TEA1530AT (for sure this is a 1530AT, I will post a macro photo of it soon) plus other 3 small cap near the 16 pin chip.
1x_ 82uF 35v
2x_ 1uF 50v
1x_ 2.2uF 50v
other 3x_ 2.2uF 50v

I've tested the optocoupler like ventzel suggest, following this guide
http://www.antimath.info/electro/how...n-optocoupler/
But I don't have a regulating power supply to increase o decrase voltage, so I test with some 1,5v battery, some with more power and some less... all seems to work properly.
Ventzel also says he changed TL431 (I803) , but mine have another code on it A67FL.... another version?
there is a way to test this piece? i803 on board.

any other suggestion?

Now, thank you to this great forum, I hope I can help in some way.
I go buy capacitors...
see soon

Cindy