Re: Memorex MLT3221 - No Power
I can do that, but out of curiosity, does this board have a 5v reg? If not how is it developed?
I can do that, but out of curiosity, does this board have a 5v reg? If not how is it developed?
-
-
Re: Memorex MLT3221 - No Power
Can anyone tell me what R56 value should be? It's located just to the right of EC7, one of the famed failure caps.Last edited by johnnieboy2; 10-16-2011, 07:56 PM.Comment
-
Re: Memorex MLT3221 - No Power
This is a switching mode power supply (actually two of them on one board). Regulation is accomplished by the interaction between a TL431A voltage reference, an opto-isolator, and the SMPS controller IC. In very general terms the SMPS controller pumps energy into the primary of a transformer, the secondary voltage is rectified and filtered, and the voltage reference instructs the smps controller to vary the amount of energy dumped into the primary based on the how closely the filtered voltage matches the design voltage.
While it sounds (and is) complicated the entire arrangement can provide over 200 watts of well regulated (within 1%) power at more than 80% efficiency from a package about the size of a cigar box. By comparison, 30 years ago I workec for a company that built 200 watt linear power supplies. They were 18" x 8" x 8" and less than 33% efficient.
PlainBillFor a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.
Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.Comment
-
Re: Memorex MLT3221 - No Power
Thanks for explaining that.Comment
-
Re: Memorex MLT3221 - No Power
I've ordered a set of caps for the P/S board, 16 in all...will update when installed and tested. If this doesn't do it then it's
!!! And in case of failure...anyone looking for components off this thing?, Let me know. 
Comment
-
Re: Memorex MLT3221 - No Power
As you know, your 5V DC standby voltage is most likely your problem. With that being said, the problem rests on the power board. There are only a few components that make up the 5VDC. I dont have a schematic, and I'd give my left pinky toe for one, but I think the PWM might have something to do with the standby 5V. Check to see if that main chip, near the main output connector, has 13 volts on one of the pins. I can't remember what pin it was. I'm gonna try to find a thread with more info to help out.The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS
Comment
-
Re: Memorex MLT3221 - No Power
Your input is most appreciated. I really don't like the 'shotgun' approach I'm using but without a schematic and lack of Digital TV experience it's that or the junk pile.
That said, what would be the conclusion if I have or don't have the 13v?Last edited by johnnieboy2; 10-26-2011, 06:14 AM.Comment
-
Re: Memorex MLT3221 - No Power
Troubleshooting the standby power supply is rather straightforward. Dgtech is suggesting you check the power supply pin for the SMPS controller. Googling the part number and datasheet should lead you to the datasheet, which will identify the proper pins. If Vcc is missing, it suggests a problem with a bleeder resistor or the rectified mains supply. If it is low and steady, it suggests a bad SMPS controller. If it is pulsing, it suggests a short on the output or a bad startup cap.
PlainBillFor a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.
Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.Comment
-
Re: Memorex MLT3221 - No Power
All I got was some low levels of pulsating voltages, millivolt range. Definitely replacing those startup caps when I get them. Short on the output, can you elaborate, what part... another board?
Last edited by johnnieboy2; 10-26-2011, 01:21 PM.Comment
-
For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.
Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.Comment
-
-
Re: Memorex MLT3221 - No Power
If that's the pinout for IC8 then what voltave do you have on you pin 13 VCC?The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS
Comment
-
Re: Memorex MLT3221 - No Power
Well, since you were nice enough to provide good pictures, I'll return the favor.
These identifications are tentative; if you supply the part number of the first three I an confirm them.
Blue circle - PFC Controller.
Yellow circles - Standby and Main SMPS controllers
Orange circle - Inverter controller.
Red circle - unknown, but possibly a 'power good' sensor.
PlainBillAttached FilesFor a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.
Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.Comment
-
-
Re: Memorex MLT3221 - No Power
Gosh, I need a microscope! Best I can tell...
blue...very hard to read, guesstimate...ST (?) C2747 or CZ747
yellow...top one in pic is 78074 and STM4410A
yellow...6675A (Extremely hard to read accurately)
orange...SG3525AN
Red...D78F9222CXLast edited by johnnieboy2; 10-26-2011, 09:06 PM.Comment
-
Re: Memorex MLT3221 - No Power
I guess I was wrong to think that chip was the main PWM for this power supply. I could not find any schematic to go by. How would I identify this as the main PWM in this circuit (for furture ref.)?The strong-minded rise to the challenge of their goals,the weak-minded BECOME HATERS
Comment
-
Re: Memorex MLT3221 - No Power
Aww, crap!!! It looks like I was wrong. I'm going to have to look over this again. One of the ICs I identified as an SMPS controller is a power FET, the other isn't identifiable, both are on the cold side of the power supply. The one I thought was an inverter controller
is an SMPS controller. No, it's worse than that. The SG3525AN is definitely the controller for the high voltage (inverter) output. And the SMPS controller must be on the hot side of the power supply
PlainBillLast edited by PlainBill; 10-27-2011, 07:27 AM.For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.
Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.Comment
-
Re: Memorex MLT3221 - No Power
OK, time to regroup. After looking this over carefully, I missed a LOT of clues, and misidentified the function of some components.
IC2 (six pin IC up from the IC I circled in blue) is probably the SMPS controller. What is it's part number (yes, time to get a magnifying glass).
The IC circled in blue is almost certainly the PFC controller; we aren't going to sweat the identification.
PlainBillFor a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.
Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.Comment
-
Re: Memorex MLT3221 - No Power
IC2 (six pin IC up from the IC I circled in blue) is probably the SMPS controller. What is it's part number (yes, time to get a magnifying glass).
number on this is...62739Comment
-
For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.
Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.Comment
-
Vizio e601i-A3 - Has Sound and Display, But No Backlight - Bad Power Supply Board or Bad LED Bulbs ?I was given this TV from my great uncle. He said it just wouldn't turn on one day out of nowhere, replaced the TV, and gave it to me to possibly fix and use for myself.
Upon bringing it home and plugging it up, it showed a standby light.
I powered it on and without a flashlight, the display showed the "V" but the lighting is very dim, but visible.
The screen seems to blackout and stay black, but with a flashlight I can see the display.
With my Playstation 4 connected via HDMI, and running a game I can hear sound.
Assuming... -
Hi all!
I'm trying to troubleshoot a Microsoft Surface Pro (5th gen) model 1796 that won't power on. Motherboard model is M1007506-015. My priority is retrieving data, but the SSD is integrated so it looks like if I can't repair it it'll need to go to a data recovery company. I've done a little basic board repair before, but nothing this advanced until now. So please forgive my ignorance in advance. 😅
I found the boardview for this laptop in the forums here, and am able to open it on my PC with FlexBV.
https://www.badcaps.net/forum/troubl...-hardware-devi... -
Hi all,
TL;DR - this laptop is driving me nuts with the oddball power-related behaviors. Appreciate any insight you can provide!
I'm experiencing a power issue on an Asus Probook P5440UF-XB74. Although I've worked with electronics and computers for decades, this is my first attempt at getting into motherboard-level component troubleshooting. Any help the community can provide is greatly appreciated!
A few weeks ago I was using the laptop (on battery power) for a Zoom meeting. The battery was running very low (long meeting) but I wasn't worried about... -
I have wanting to do this project for quite sometime now and I finally found a switching power supply that will work on this desoldering gun station ZD-915 that the original switching power supply took a shit and just was not worth trying to fix it because this switching power is not quite big enough to handle the heater element and the vacuum pump
One note when I tested the switching power supply and the voltage control board I noticed that this desoldering gun heat up much faster than the original switching power supply which I was really surprised by to the point that I might buy... -
This specification for the HP Pavilion Power Pavilion Power 15-cb009nl Notebook can be useful for upgrading or repairing a laptop that is not working. As a community we are working through our specifications to add valuable data like the Pavilion Power 15-cb009nl boardview and Pavilion Power 15-cb009nl schematic. Our users have donated over 1 million documents which are being added to the site. This page will be updated soon with additional information. Alternatively you can request additional help from our users directly on the relevant badcaps forum. Please note that we offer no warranties that...09-06-2024, 05:59 AM
Comment