JVC JLC42BC3000 screen froze on "JVC" logo.

[NewAtThis]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

Well, RJ and nomoresonys were right. The "stuck-on-JVC-logo" problem returned, after 3 weeks of the TV turning on normally. So, the two caps I replaced that fixed the problem were a symptom, not the root cause of the problem. (They are still good, but the TV is not turning on normally.)

I called JVC and asked whether I could download either the original firmware or an update, but the man with whom I spoke was of no help. I asked to talk with a technical/service person, but he refused to let me do that! He said that they do not offer any advice over the phone. So much for ever buying another JVC product ever again -- I own 3 JVC TVs, 1 DVD player, and 1 VCR. It is hard to believe that a manufacturer would not have at least the original firmware available to owners of its TVs.

Does anybody know whether I can download the firmware from somewhere? Or, if that is not possible, whether I could buy a new EEPROM? I have tried a few suggested links, but none worked. I could find EEPROMs for the JVC JLC42BC3002, but not for the BC3000.

Incidentally, the cold/hot test on the EEPROM did not help the TV to turn on. I could only get it to turn on after 1 - 6 disconnect/connect from the AC outlet, but not by any other means. Also, all voltages and capacitances are as I had reported earlier in this forum.

[NewAtThis]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

budm, Thank you for all the links/references. I am slowly reading, and learning a lot. Grateful.

[NewAtThis]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

First, I think that RJ and nomoresonys are probably correct. Although I know very little about TVs, I do know about computers. It appears to me that the "stuck-on-JVC-logo" problem is very similar to a computer getting stuck at bootup. In the latter case, it is almost always a problem with the BIOS (e.g., the order of bootup devices getting changed, or a peripheral device is no longer recognized, etc. It is seldom a hardware problem on the motherboard, although that is also possible). Since the EEPROM/Firmware of the TV plays the role of the BIOS on computers, the suggestions by RJ and nomoresonys make a lot of sense to me. If (or when!) the problem recurs, I'll focus on that.

Now, back to answering budm's questions/suggestions on PSU caps. I had measured the capacitances (in circuit) of as many of those as I could before doing anything with the main CB. The attached pdf file (so that the Table will preserve its format and be more readable) shows what I found.

If anybody sees something weird, please, let me know.

[nomoresonys]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

Wonder if the firmware got messed up somehow?

[R_J]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

Being that this is basically a Vizio, I wonder if its not an eeprom issue

[NewAtThis]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

budm, thank you. I gave a detailed reply to your suggestions, but, after I clicked "Post Quick Reply", the website asked me to sign-in again, and all the text was gone! I'll reconstruct it later, hopefully late tonight. I'll make sure I write it on my computer first, and then cut-and-paste. I didn't know the website would do that.

[budm]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

Pin 1 (VRB_B) is the backlights brightness control signal from the main board, it will vary with the Backlights level setting.
Power supply board:
C208, 209, 210 are filter cap for the 5.2VSB power supply.
C203, 203, 20? are filter caps for switched 12V power supply.
You may want to check the ESR and the capacitance of all those caps.

[NewAtThis]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

Thank you budm & RJ for the VERY helpful responses.

Next time I remove the TV back cover, I'll "practice" removing the small ribbon cable. Fortunately, I managed to replace the CE1 and CE22 caps w/o disconnecting or breaking it!

Indeed, the labels I read on D201 and D202 could be incorrect. The letters/numbers are very faint and, worse yet, the caps in front of them do not allow direct viewing. I used a flash light and even a dentist's mirror to get those. A photo of D201 and D202 shows nothing useful. I'll search online for the labels w/o the "1" and see what comes up. budm's answers already put me on the right track.

Although my TV now turns on and off normally, after replacing the CE1 and CE22 caps on the main CB, I am still suspicious that the real, ultimate cause of the "stuck-on-JVC-logo" problem may be something else, such as wrong voltage(s) sent from the PSU to the main CB. So, I measured the voltages at the 14 pins of the cable that goes from the PSU to the main CB. Here is what I found (incidentally, the voltages are the same at both ends of the cable, so the cable itself is OK):

(Please, see attached pdf file, which preserves formatting.)

Does anybody know what the correct voltage at Pin 1 should be while the TV is on and working normally? (All other voltages seem OK to me.)

Thank again for any help. I AM learning...

[budm]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

[R_J]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

I think you have an extra 1 in the diode number It could be:
MBRF20U65CT
MBRF10U60CT
To unlock the small cable, slide the white lock in the direction of the yellow arrow but not too far, that will unlock the flat cable and it can be removed.

[budm]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

https://www.shopjimmy.com/vizio-0500...t-inverter.htm
Looks to be your power supply board.
Q201 () is the power MOSFET, it is used as a switch to provide switched 12V when PS-ON control signal from maia board is present.
D201 is the common Cathode diode, it is used for providing switched 12V.
D202 is the common Cathode diode, it is used for providing 5.2 VSB.
Look at the bottom of the board and you can easily see how those parts are connected and for what they are for if you have basic knowledge of electronics.
Are you 100% sure that the P/N you see on the diode is correct? Can you take good clear pictures?
MBRF 10U160CT
MBRF 20U165CT
Example of MBRF diode:

[NewAtThis]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

Thank you, budm. I will when I have the opportunity to open the TV up again.

I have difficulty identifying the three components that are attached to the relatively large heat sink on the upper right quadrant of the PSU (please, see photo). I copied their labels and tried to identify them by searching online. They are:

Q201: 1615AU FQPF 13N06L. Online search found this to be a MOSFET.
D201: MBRF 10U160CT 122. Online search yielded nothing!
D202: MBRF 20U165CT 104 Online search yielded nothing!

If somebody could tell me what these are and what they do, I'll be grateful. I am trying to learn.

The 3 pins of Q201 have voltages 12.28, 13.15, and 14.47, but I am not experienced enough to tell which pin is the Source, which the Drain, and which the Gate.

Similarly, I cannot tell which pin is the Base, which the Emitter, and which the Collector for D201 and D202. (I assume that they are diodes, because JVC uses the symbol D for such.)

I measure strange voltages relative to the metal back of the TV for D201 and D202.

For D201: Pin 1: -0.06V, Pin 2: 13.15V, Pin 3: -0.06.
However, the voltage between Pins 1-2 is 2.8 - 3.2 V (i.e., it varies!), and that between Pins 2-3 is 2.6 - 3.4V (also variable). I feel lost.

For D202: Pin 1: -0.05V, Pin 2: 2.27V, Pin 3: -0.05V.
The voltage between Pins 1-2 is 5.30 V (steady), and that between Pins 2-3 is 5.33V (steady).

Thank you in advance for any help with this.

[budm]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

They are filter caps for the 5V and the 12V power suppliers, you should check the caps on the power supply board too.
According to post #4
F1= is for 5V power supply
F2= is for 12V power supply

[NewAtThis]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

Well, since I did not know how to disconnect that little ribbon cable (see last posting), but I wanted to try to fix the "stuck at JVC logo" problem, I carefully turned the main CB upside down and rested it on a soft foam slab. (I had tried all the things recommended on this site, but nothing made the TV turn on normally. However, I had noticed that the capacitances of CE1 and CE22 on the main CB were unsteady with no power applied to the TV. I was aware that one cannot measure capacitance reliably while the cap is in circuit, but I thought I would give it a shot, since nothing else worked.) I replaced those 2 caps (it was hard to remove the old solder!). Beginner's luck: The TV turns on and off like a charm!!

Does anybody know what those caps are doing and why, if one or both are bad, the "stuck on JVC logo" problem will occur?

On the attached photo, the CE1 cap is circled. The CE22 is just to its left. Their nominal values are 220 uF/16V and 220uF/25V.

[NewAtThis]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

Thank you RJ. No, it's another connector. I'll post a photo as you suggest. Hm, I uploaded the photo, it tells me it's an attachment, but I do not see it here as part of my message! I'll click "submit" and see if it shows up. If it does not, I'll try to figure out what I am doing wrong. Sorry for my ignorance. I am really new to all this.

[R_J]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

Post a picture by clicking on go advanced, then click the paper clip next to the smiley face, browse to your picture, click upload
Is this the connector? Tilt the black lever, remove the cable.

[NewAtThis]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

I have recently discovered this old but very helpful discussion. I hope that somebody more knowledgeable than me is still watching! I want to remove the main CB from the TV, which has the "stuck on JVC logo" problem. I have figured out how to disconnect all cables from the board, except one, a tiny ribbon cable, second from the bottom on the left side of the CB, as one looks at it from the back of the TV. The connector on the CB has a black part (the one farthest from the cable), which seems permanently attached to the CB, and a white part (the one closest to the cable). I thought that the white part is a plug that I could pull straight out, but I do not see how it can separate from the black part of the connector. Should it? Or should I pull the tiny ribbon cable itself out of the connector?? I want to post a photo, but I do not yet know how to do it.

Thank you in advance for any help.

[dc8frate]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

Thanks for this thread. I found the bad NAND chip using the freeze spray method and then I just cut to the chase, and sent the board to Ableman tv in Vancouver and they replaced the chip and updated the firmware. It works great, and I didn't have to buy a programmer for a one time job etc.

[RADIOTRON]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

Have you able to fix this issue???? I have the same issue now.

[fzabkar]

Re: JVC JLC42BC3000 screen froze on "JVC" logo.

I'm confident that the NAND flash IC is the problem, but I don't have much experience in repairing flat panel TVs, so I'm hoping that someone will provide a second opinion.

That said, if you decide to replace the chip, then you will need a chip reader/programmer to read it and copy it. The following article shows you what might be involved:

https://cdn.badcaps-static.com/pdfs/...c21b9c088a.pdf

It might be worth considering a different brand of NAND as a replacement (eg Samsung, Intel, Micron), but you will need to ensure that it is compatible.