Proscan 32LB30Q PWR ON red LED to blue flashes 7x to solid &no display

I recently acquired a Proscan 32LB30Q that when plugged in the red LED comes on and I hear a relay click in the middle back.

When I press the power button, I hear the speakers make a brief low volume static noise that goes silent and then the previously red LED flashes blue seven times and then stays solid blue with nothing other than a blank black screen the whole time.

When I cleaned the system... I did notice what looked like discoloration above and maybe on two of the transformers (top two) on the CCFL power supply or maybe is called an inverter board more accurately.  I didn't notice any leaking or bulging caps or burn marks anywhere else.

Any questions, comments and/or suggestions regarding where to start?

Edit (added images):

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Motherboard:

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Power Board:

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T-Con Board:

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Thanks in advance!

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Replace the main board.

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I used the PROSCAN 32LB30QD MAIN BOARD 0708060138 B.ZRAT3C-1 7355 which is a different version of the board. This board still worked and the unit appears to be functional again. I will test the inputs next.

https://www.ebay.com/itm/PROSCAN-32LB30Q...

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@jafinch78 this “did notice what looked like discoloration  “ could be an issue with your LED power board. You want to go ahead and post some good pictures of all of your boards with your question. Use this guide Adding images to an existing question for that. It will allow us to see what you see. You will have to have a multimeter to see if your power board as the voltages that are required to run your TV. There is not to much information about your Proscan so we will have to rely on your troubleshooting skills.

UPDATE 08/11/2018

here is the schematic for your power supply. Different revision but it will still give you the same ouputs etc.

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No schematic seems to be available for your main board B.ZRAT3C-5

@jafinch78 check the jumper CN4 on B.ZRAT3C-5 8374 and see if it is on 5V or 12V. Any chance this could have been switched. Yours looks like it is at 12V try to switch it to 5V. Keep your fingers crossed and see what you get.

UPDATE 08/12/2018

Looks like the T-con board runs kind of hot. Check the fuse to make sure you got continuity as well as power when your TV is on. Check to make sure it is just the thermal pad that is crooked and that there are not issues with the processor

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According to your T-con board your display panel is a T315XWO2 VL Here is the datasheet for that. You may need it later on Microsoft Word - T315XW02_VL_v0_4_0118_Final.doc

Interestingly enough the T-Con board as well as the Inverter V266-001 are identical to a Sony KDL-32L4000 I am going to check if the Sony manual will give us more information.

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Thanks for the prompt reply. I just uploaded some images and had already created a Replacement Guide though left generic as replacing the inverter board, though may be LED’s need to be replaced however I am thinking is a CFL LCD system and one or two of the transformers for the inverter board is bad and thinking you are correct in line with the transformers power supply circuit on the CFL board needs to be checked). I think there is a fault protection circuit on those transformers that can be jumpered to bypass if only one and doesn’t look bad in regards to the image quality. Otherwise will be replacing the transformers or the whole inverter board. Hopefully, the photos shed more light into the details regarding and we can demonstrate on ifixit the work through. Right, I tried adding the “Proscan Television” as a “Device” also so the image will be present and able to be selected versus just generic “Television”.

Looking forward to your thoughts.

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Re-uploaded the images since I just realized they uploaded with errors.

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The voltages from the power supply board were all in specification: 5V +/- .1V and 24V +/- .4V.

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Okay so your TV uses CCFL's and this could be an inverter board issue, but your connector with the BL_On will be of imporatnce. That is actually what turns our back light on. If you do not get a signal, your invert will not work. Do not just wildly repalce parts. That usually leads to a whole bunch of confusion. Focus on the connectors and make sure you have the exact output as it is listed. Post some "clear" images of all of those.

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@jafinch78 just noticed something but it is hard to see. Post some good pictures of your power board.....

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There should be some surface mounted transistors on the inverter board that may be shorted. These will be small black squares with 2 regular pins and a short cut off one in the center (attached to the back/tab). Check these for a short. You may get lucky and only need to replace one or more of these.

Dan

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I'm wondering if I can find a schematic to determine what the values should be. Maybe contacting the manufacturer is something I can do next and add to the repair guide also or this post too?

I'm guessing the transistors are some sort of power regulator or logic and should read 12V, 5V or 3.3V though am not sure. So with the transistor, think like they're a diode and test to verify correct directional function? Is this able to be performed in circuit?

Maybe a resistance test to verify resistance isn't less than say 30 ohms?

Thanks for the feedback.

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Oh, wait... finding the datasheet for the component would be a way to find what the values should be in regards to being in specification.

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I'm thinking too (now you have me thinking more) that I can find where the output voltage rail is and use a power supply to supplement to see if the CFL works.

I'll test the transformers and regulators off and see if I notice anything first. Then on startup and see what the values are and compare to see which looks off. I see two and maybe three transformers that look like they have magic smoke lampblack on the case. :-)

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The continuity tests for the transistors as diodes seems in specification. Nothing out of the ordinary.

The transformers all had zero resistance at the test points.

Something is triggering that board to shut off at the transformers since I don't measure any voltage on the transistors or transformers where the voltages are all ~24V coming into the board with a 4.0V on the top brown wire and a red wire below that is 0.0V. I am guessing this is some sort of signaling to not power on? Reads above the pins as MOD-SEL, PWM and BLON. Where the black as GRD and the other RED are VDD.

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Can you elaborate more on what I am supposed to be seeing on these inverter board transistors? I am not sure exactly now.

I am getting strange readings on the transistors (Q102, Q104, Q105, Q107) where there is no output value (back or center cut pin part), though the input and adjust pin values are 24.4V other than U901 which reads a input of 24.4V and adjust of 11.8V PWR ON.

PWR OFF U901 pins read 0V input and 2.4V adjust.

Q101, 103, 106 & 108 read 0.00V on all pins PWR ON or PWR OFF.

The capacitors C172, C166 & C164 read 24.4V. C162, C176 & C174 read 0.0V.

The transistors on the main board seem correct where the adjust pins are grounded, the inputs are 4.9V and the outputs are 3.0V.

I'm starting to suspect the inverter board again.

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