Jensen JE1907DC 12v RV TV

[Gorrillasnot]

Hello,

I was given a 19" Jensen JE1907DC TV. It came out of an RV and is powered by a 12v DC power brick.

When you press the power button the standby light goes from red to blue and the Jensen logo shows on the screen for a couple seconds then the TV turns back off and the standby light goes back to red.

The last pic shows the connectors where I measured voltages.
The readings I got @ the connector in the top left in standby and power on are
12v 12.2 - 12.2
12v 12.2 - 12.2
PWM 0 - 2.9
ON 0 3.2
GND

@ the connector at the bottom of the pic
NC 0 - 0
NC 0 - 0
CN2 1 - 0
PWM 0 - 3.2 (when pwr button first pressed) - 3.6 (when jensen logo is shown)
ON 0 - 2.9
GND
GND
12v 12.2 - 12.1
12v 12.2 - 12.1
GND
3.3v 3.3 - 3.3
GND
5v 0 - 4.8
GND

Unless I am missing something those voltages seem about right..what do you all think?
I don't see any obvious signs of any bulging or leaking caps on any of the boards.


thanks for any help

[nomoresonys]

Re: Jensen JE1907DC 12v RV TV

Did you do the flashlight test to see if you get any text at all on the screen like no signal, or menu when using the remote or buttons?

[Gorrillasnot]

Re: Jensen JE1907DC 12v RV TV

Did you do the flashlight test to see if you get any text at all on the screen like no signal, or menu when using the remote or buttons?

Thanks for the reply.
That's the first thing I tried even though it was a long shot..Normally when the flashlight test works is when a TV powers on and stays on but the screen goes black.
In my case the TV powers on, the standby light goes from red to blue, the Jensen logo appears, then the TV shuts itself off and the standby light goes back to red. Like its a psu issue or some type of protection circuit shutting down the TV right after the logo is displayed.

[nomoresonys]

Re: Jensen JE1907DC 12v RV TV

So not even a second of backlight? and you're sure the power brick is ok?

[nomoresonys]

Re: Jensen JE1907DC 12v RV TV

How do those 2 bluish top looking capacitors on the little white board look? hard to tell from the pic.

[Gorrillasnot]

Re: Jensen JE1907DC 12v RV TV

Not a 100% sure on the power brick..it is rated @ 12v 5A the closest thing I had to it was a 12v 2A and the TV had the same issue.

I don't see any bulging or leaking caps on any of the boards..I'll try to upload some better pics.
I also took the shielding/cover off the main board and took a pic.

thanks

[budm]

Re: Jensen JE1907DC 12v RV TV

Disconnect the cable that goes to the inverter board and see if the Power LED will stay on Blue or not.

[Gorrillasnot]

Re: Jensen JE1907DC 12v RV TV

Hi budm,

With the cable disconnected from the inverter the TV does the same thing.
Red standby light, press the pwr button and it turns blue, then about 8 seconds later the light turns back to red.

Would that mean the problem is likely with the main board or psu?
Probably the main board since the voltage readings on the psu seemed ok?

thanks

[nomoresonys]

Re: Jensen JE1907DC 12v RV TV

Probably need to try to force on the backlights, not sure how to do it for this one tho.

[budm]

Re: Jensen JE1907DC 12v RV TV

Hi budm,

With the cable disconnected from the inverter the TV does the same thing.
Red standby light, press the pwr button and it turns blue, then about 8 seconds later the light turns back to red.

Would that mean the problem is likely with the main board or psu?
Probably the main board since the voltage readings on the psu seemed ok?

thanks

I suspect main board at this point.
I see some 3-PIN Voltage regulator IC's on the main board that may be you should check them out.

[DXseekerMO]

Re: Jensen JE1907DC 12v RV TV

I have one of these Jensen 12V TV's with smashed CCFL's, and never thought I'd see another.

[Gorrillasnot]

Re: Jensen JE1907DC 12v RV TV

I suspect main board at this point.
I see some 3-PIN Voltage regulator IC's on the main board that may be you should check them out.

Testing the 3 legs on the bottom of each of the regulators from left to right I get the following results ( voltages measured after pressing the power button and when power light turns from red to blue).

1.
pin 1. .6v pin 2. 1.8v pin3. spike to 4.2v then settle at 2.9v

2.
pin 1. 0v pin 2. 3.2v pin3. 4.8v

3.
pin 1. 0v pin 2. 3.2v pin3. 4.8v

4.
pin 1. 0v pin 2. 3.2v pin3. 4.8v

5.
pin 1. 0v pin 2. 1.8v pin3. spike to 4.2v then settle at 3.5v

In the attached pics I numbered and circled in red the locations of the regulators I measured.

[redwire]

Re: Jensen JE1907DC 12v RV TV

I'm wondering if EEPROM settings aren't scrambled? They typically get loaded after the logo. It's just there might not be a hardware problem? Any "factory" reset" codes need the remote control and I could not find this Jensen model to suggest OP try them.

[Gorrillasnot]

Re: Jensen JE1907DC 12v RV TV

Should I try replacing the voltage regulator ICs in location 1 and 5 (see pics in post #12) since the voltage readings were different then the others?
If so which one's should I buy?

I'm wondering if EEPROM settings aren't scrambled? They typically get loaded after the logo. It's just there might not be a hardware problem? Any "factory" reset" codes need the remote control and I could not find this Jensen model to suggest OP try them.

I do have the original remote control but not sure how to reset a EEPROM.
There is a actual reset button on the PSU board which I have tried but it didn't fix the problem.


Happy Thanksgiving everyone

[budwich]

Re: Jensen JE1907DC 12v RV TV

you might want to try track down a new power brick. "5A" is a significant rating for a supply and if the system is unable to draw the appropriate amps (probably closer to 4) then it may be unable to run correctly.

Further, you can rig up a "simple" tester perhaps with some automotive bulbs (check their resistance before to ensure you aren't over drawing).

[budm]

Re: Jensen JE1907DC 12v RV TV

Budwich may be correct about 5A rating power supply after looking at that 12V regulated switching power supply board.

[Gorrillasnot]

Re: Jensen JE1907DC 12v RV TV

I have a spare power supply out of a PC that has a single 12v rail @ 37 amps.
Could I use it as a power source to test the TV with?

thanks

[budm]

Re: Jensen JE1907DC 12v RV TV

Yes.

[budwich]

Re: Jensen JE1907DC 12v RV TV

wow... that's power. It should be ok but check to see if there is some fusing somewhere that will protect things if they go "south".

further, if you have a "normal meter" (current rating for upto 10 amps), you might consider using it to see what current is being drawn.

[Gorrillasnot]

Re: Jensen JE1907DC 12v RV TV

Using the PC power supply the tv has the same problem.
Amp draw when the light is blue and jensen logo on screen and just before tv shuts itself off is around 6 amps.
Another thing is not every time, but sometimes when using the PC psu right before the tv shuts itself off I hear a fairly loud chattering sound coming from the tv's power board..