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.

[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.

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.

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.

[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

[nomoresonys]

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

Wonder if the firmware got messed up somehow?

[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.

[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.

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.

[nomoresonys]

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

Wonder if it's the NAND FLASH, one there, looks like they want almost as much as the whole board, well about half: https://www.ebay.com/itm/1pc-NAND-FL...UAAOSwM0ZbTrrQ

[nomoresonys]

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

Did you try freezing the nand flash, went back and read posts #26-33.

[NewAtThis]

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

Yes, I tried freezing the NAND FLASH. It made no difference. (If it were/is the problem, I am not skillful enough to replace it. The EEPROM, I think I would manage to replace.)

[nomoresonys]

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

Applying heat and cold don't always work, eeprom is worth a shot, cheaper than a whole board.

[NewAtThis]

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

Thank you, nomoresonys. I cannot find an EEPROM, however, and, as I mentioned in #50 posting, JVC is incredibly unhelpful.

[diif]

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

Thank you, nomoresonys. I cannot find an EEPROM, however, and, as I mentioned in #50 posting, JVC is incredibly unhelpful.

The only thing that's JVC is the screen printing on the front.
Is this your mainboard ? https://www.ebay.com/itm/JVC-3632-16...0/272421970166

[NewAtThis]

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

diif, No. My main board is different. Please, see attached photo.

[nomoresonys]

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

Whole board there for 60 bucks plus 8 something shipping, I didn't see any eeproms either, not sure if any other eeproms from slightly different models or screen sizes would work???: https://www.ebay.com/sch/i.html?_fro...3642-1302-0395

[NewAtThis]

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

Thank you, nomoresonys. I'll look into that.

[NewAtThis]

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

Update on Feb. 4, 2020: I got tired of waiting to find an EEPROM, so I just bought a new Main CB. Hopefully, it will fix the problem.

BTW, I asked two ebay sites, which say they'll repair the Main CB to get rid of the stuck-on-JVC-logo problem, what they'll do, but neither replied! Most state laws say that, not only do they have to tell a customer what they'll do and give an estimate, but they also have to return the defective part to the customer if asked to do so. Ebay offers no way to report this illegal behavior by some sellers, much less show any interest in enforcing proper behavior, in accordance with state laws.