Acer AL2216W Dead

[a55bruce]

I have a dead (no light) Acer AL2216W with a DAC-19M009 power supply. I changed out the capacitors (still dead). I found 4 fuses (F100,F101,F102,F200) that check good. The big 120uF cap has 143VDC across it. What's next?
Thanks for the help.

[retiredcaps]

Re: Acer AL2216W Dead

The big 120uF cap has 143VDC across it. What's next?

143V DC is low. It should be 1.4* mains. Even at 110V mains, that is 110 * 1.4 = 154V DC. Is it at steady 143V DC?

Do you have secondary voltages like 5V DC on the connector to the logic card?

[a55bruce]

Re: Acer AL2216W Dead

My mistake, re-measured the cap, it's at 166VDC. There are no voltages present at the connector to the logic board

[retiredcaps]

Re: Acer AL2216W Dead

My mistake, re-measured the cap, it's at 166VDC. There are no voltages present at the connector to the logic board

1) Interesting. This is the 3rd no secondary voltage case to arrive in the last 2 days. AND this board looks like my non working CMV monitor as well.

2) When you say the fuses are good, do you mean they measure around 0.3 ohms?

3) Is that 8 pin IC in the upper right hand corner (2nd picture - backside) part number LM358 (that is what mine is)?

[a55bruce]

Re: Acer AL2216W Dead

2) The fuses do measure around 0.3 ohms.
3) The 8 pin IC is a LM393.

[retiredcaps]

Re: Acer AL2216W Dead

3) The 8 pin IC is a LM393.

My bad, I meant upper backside upper left corner near the AC plug. Mine is EA1532A which is a SMPS controller IC.

[a55bruce]

Re: Acer AL2216W Dead

Wow!
That is some hard to read lettering, badly faded. But, it looks like it says EA ?532A. I would think it's the same as yours.

[retiredcaps]

Re: Acer AL2216W Dead

Wow!
That is some hard to read lettering, badly faded. But, it looks like it says EA ?532A. I would think it's the same as yours.

1) Okay, it sounds like you have the same SMPS controller.

2) The datasheet for it is at

http://pdf1.alldatasheet.com/datashe.../TEA1532T.html

Download and look at the pinouts and page 5 figure 4 (typical applications).

3) Your problem might be the same as this thread going on right now at

https://www.badcaps.net/forum/showthread.php?t=9756

Start with post #6. Pay special attention to post #30 by PlainBill where he explains the SMPS walkthrough.

4) After you have read the above documents, we will probably be asking for voltages on the SMPS controller IC. From there, we can hopefully track down the problem.

5) If your board is like mine, the backside is not easy to get access to so you will have to find a way to ground the board to the chassis while measuring the backside.

[a55bruce]

Re: Acer AL2216W Dead

Still reading through the posts, while trying to understand the circuit, I did make some measurements. With black on the trace from the diode bridge negative pin.
1) 9.7V
6) .36V
8) 152V
All the other pins read zero.

[retiredcaps]

Re: Acer AL2216W Dead

Still reading through the posts, while trying to understand the circuit, I did make some measurements. With black on the trace from the diode bridge negative pin.
1) 9.7V
6) .36V
8) 152V
All the other pins read zero.

Okay, PlainBill is the real expert and I'm still learning this part of the board. PlainBill might smack me on the side of the head, but if you want to try some of my suggestions, look below.

1) with power off, test the dual diodes "in circuit" that are mounted on the heatsink just right of the SMPS transformer. These should be the 2 diodes that provide secondary voltages.

2) if those test good, then with power ON, measure the voltage at pin 2 (middle) on both dual diodes

[retiredcaps]

Re: Acer AL2216W Dead

1) 9.7V

Okay, I'm wading through the SMPS datasheet and on page 13, it says Vstart should be a minimum of 10.3V and a max of 11.7V with typical being 11V.

You measure 9.7V DC. So we are quite a bit short.

Now if you look back to figure 4 on page 5, traceback from pin 1 to the components on the diagram and take voltage measurements.

[retiredcaps]

Re: Acer AL2216W Dead

The service manual is at

http://www.nodevice.com/manual/newma.../get48311.html

but I don't have login. With schematics, it would help to know what leads to pin 1. There may be resistors in the path that are out of value?

[a55bruce]

Re: Acer AL2216W Dead

The diodes check OK, not shorted.
Not sure where to measure the voltages, center pin to center pin = 0V, from chassis ground to center pin, both=0V. Since the SMPS does not appear to running, those readings make sense to me.

I agree about the Vstart, I'll try to follow the circuit tomorrow..

[jetadm123]

Re: Acer AL2216W Dead

A few suggestions:

1) Check the FET, Q102? mounted on the heatsink next to the 120uf cap for shorts.

2) Part of the startup circuit consists of D107, above F100 (check for short) and R137-140 (check resistance, I think they are 0.2ohm each)

3) Interesting tidbit. Another forum member has the same power supply you do, except his has sound and belongs to a Viewsonic VX2235! Goes to show you that these supplies are not subject to a single manufacturer. And I won't go into the different versions of these supplies. This person might be helpful in determining voltage measurements on your PWM controller, since it looks like he's got partial power:

https://www.badcaps.net/forum/showthread.php?t=10985

[a55bruce]

Re: Acer AL2216W Dead

1) Check the FET, Q102? mounted on the heatsink next to the 120uf cap for shorts.
***Checks OK, no short between all pins, both directions

2) Part of the startup circuit consists of D107, above F100 (check for short) and R137-140 (check resistance, I think they are 0.2ohm each)
***D107 OK, all 4 resistors are good.

[retiredcaps]

Re: Acer AL2216W Dead

The service manual is at

I found a free version of the service manual at



I downloaded and looked through but couldn't find a schematic of this SMPS chip. So it looks like you will have to "buzz" out pin 1 and trace it back to the SMPS transformer.

I believe there should be at least a diode or zener diode feeding into pin 1.

[retiredcaps]

Re: Acer AL2216W Dead

Can we get a clear focused 2000x2000 resolution shot of the area outlined in red? This is the SMPS area and the SMPS transformer winding that provides the power.

[a55bruce]

Re: Acer AL2216W Dead

I found a free version of the service manual at



So it looks like you will have to "buzz" out pin 1 and trace it back to the SMPS transformer.
1.

Thanks for the link,
I've been trying to trace the pin 1 circuit, and have not been able to figure out where the 9.7VDC is coming from. There does not appear to be any AC coming from the transformer to generate the 9.7VDC I'm seeing on pin 1.

The circuit I have been able to trace out so far, resembles the one from FIG. 13 of the SMPS datasheet.

[a55bruce]

Re: Acer AL2216W Dead

Can we get a clear focused 2000x2000 resolution shot of the area outlined in red? This is the SMPS area and the SMPS transformer winding that provides the power.

Here's the picture....

[PlainBill]

Re: Acer AL2216W Dead

If you refer to the datasheet, the TEA1532T has a slightly unusual circuit design. It uses a design that improves efficiency by 'turning off' the startup supply when the power supply is running normally.

Pin 8 is tied to the low end of the transformer primary. That means when the power FET is turned off pin 8 should be at the same voltage as the main filter cap - typically 165 volts for 120VAC input. And it offers the option of monitoring the performance of the transformer and FET.

During startup, the voltage on pin 1 (Vcc) is generated by a current source in the controller. Once the SMPS is working the current source is turned off and Vcc is supplied by a tertiary winding on the SMPS transformer.

You reported Vcc is low. There are only a few reasons for that.

1. The rectified mains voltage (at pin 8) is too low. It should be at least 125 volts

2. The capacitor hooked to pin 1 is leaky

3. The diode from the tertiary winding is leaky.

4. The TEA1532 is defective.

You have already shown that 1 is not the problem. Remove the cap, if the problem persists, the cap is good, thus eliminating 2. Similarly, temporarily removing the diode will test if 3 is the cause.

Once you have eliminate the likely causes, the unlikely is the only thing remaining.

PlainBill