Jensen JE1907DC 12v RV TV

[budwich]

Re: Jensen JE1907DC 12v RV TV

Ah... interesting. That amp draw would suggest an issue with the tv as it does appear to be over even the "regular power supply" capabilities.

Did you try the "disconnect the inverter" test that you did earlier to see if the power supply made a difference in the outcome.

You might have to try some other "disconnect test" to see what happens especially if you can get the backlighting to come on.

you need to post a picture showing how everything is connected up so people perhaps can make further suggestions.

[Gorrillasnot]

Re: Jensen JE1907DC 12v RV TV

Using the PC power supply with the inverter unplugged from the white board at the top (location circled in pic) the TV still shuts itself off, and the amp draw is 1.38.

Is there a way to bypass the mainboard and trick the backlights to come on to see if the problem is indeed with the mainboard?

thanks

[budwich]

Re: Jensen JE1907DC 12v RV TV

On some tv designs, unplugging the main board from the power supply and having everything else connected can / may turn on the back lights with no picture displayed. You might get lucky. Again monitor the current. It would appear from your previous test with the lower current draw with the inverter unplugged that perhaps there is an issue with the inverter and / or lighting. Not sure whether this set has "tube" or "led" back lights.

Further, with respect to your previous test, you might find out more by looking at some of the pins signal / voltages that are labelled... things like PS-on, BL-err, etc. Might give you more ideas.

[R_J]

Re: Jensen JE1907DC 12v RV TV

It would seem that if you can see the jensen logo on the screen, the backlights are working, If only the backlights are failing, usually the tv would stay working and you could see an image using a flashlight. This fault seems to be with the main board and likely the eeprom
You could try freezing the eeprom and see if the tv works longer.
You need to freeze the eeprom before you apply power not after.

[Gorrillasnot]

Re: Jensen JE1907DC 12v RV TV

budwich,
I tried unplugging the mainboard and I don't get even a standby light. I'm never that lucky lol
Also I tried looking for markings like you suggest, but the only things labeled that I could find are @ the plugs on the white board near the top of the TV (measurements in 1st post).

R_J,
Tried freeze spraying the eeprom and still get the same problem. TV still shuts itself off right after the Jensen logo is displayed.

In post #12 I measured the voltages of the voltage regulators on the mainboard as budm suggested and 3 out of the 5 I could find had the same voltages but 2 were different.
Are those 2 regulating something different or do you think they are faulty and need replaced?

thanks

[budwich]

Re: Jensen JE1907DC 12v RV TV

with the main board unplugged, you might have to "force on" the power supply by providing that appropriate signal (ps-on or otherwise). People use a resistor and pick up a feed from one of the pins that outputs 5v.

If you are successful, you then can see if the backlighting is fully functional (and stay on) and further, you can monitor the current again to see if it is ranging higher or not.

[R_J]

Re: Jensen JE1907DC 12v RV TV

In post #12 I measured the voltages of the voltage regulators on the mainboard as budm suggested and 3 out of the 5 I could find had the same voltages but 2 were different.
Are those 2 regulating something different or do you think they are faulty and need replaced?

If you don't have the schematic you would need to post the regulator's number and what voltage it has on all legs, IE in, ground (or adjust) and output. They are very likley different

[nomoresonys]

Re: Jensen JE1907DC 12v RV TV

Some testing of a samsung. https://www.youtube.com/watch?v=ocqn...0Fk_YPqYREoqD-

[Gorrillasnot]

Re: Jensen JE1907DC 12v RV TV

Not sure what else to do I decided to try heating the various boards with my cheap paint stripper type heat gun.

Tried all of the boards 1 by 1 and it made no difference.

Then I tried heating the board with the power switch and the TV started turning on and off on its own..I tried a little longer and heated the board up a good bit and the TV stayed on for several seconds then started turning on/off again after it cooled.

I noticed that there are resistors on the button board and it's probably 1 of those that are bad.

Thinking I could just unplug the board with the buttons and the TV would work by using the remote..nope TV still shuts itself off (now looping on and off).

my questions are
1. Is the power button board required for the TV to work properly?
2. What value resistors do I need? ( I have an assorment of 1/4w resistors bought off of ebay)

thanks

[nomoresonys]

Re: Jensen JE1907DC 12v RV TV

Test the resistors.

[R_J]

Re: Jensen JE1907DC 12v RV TV

The tv should operate without the button board, and the remote should still operate it as the remote sensor is not on this board

[Gorrillasnot]

Re: Jensen JE1907DC 12v RV TV

Using the resistor color code calculator on digikey I determined the values as R923 910 ohm, R924 2k, R925 3.9k, R927 3.9k, and R921 2k.

I tested the resistors out of circuit and they were ok.

I then went ahead and replaced them with a new 1k, 2k, 4k, 4k, and 2k. but it didn't fix the problem.

I tried unhooking the button board and it still has the same problem.. When I plug the TV in the standby automatically turns blue then the Jenen logo flashes on screen, then the TV shuts off, and then the cycle starts over again (by itself..the remote didn't do anything) .

I plugged the button board back in and let it dangle away from the TV to isolate it, then began heating it with my heat gun and after it gets pretty hot the TV will stay on. Remove the heat and the board cools and starts the on/off cycle again.

I fluxed and touched a bit of solder to every pin on the board and it didn't help.

I looked on ebay and there isn't any replacement button boards for this TV available.

Not sure what else to try?

thanks

[budwich]

Re: Jensen JE1907DC 12v RV TV

post some good pictures of the front AND back of the board. Further, it would appear that the board has only a 4 pin connector. Start measuring various combinations of pins (look at the board tracks to try to understand what / how it is connected) along with presses of buttons, especially the power button to see if you can find some understanding about its operation (ie. certain resistance when not pressed, certain resistance when pressed, etc).

[budm]

Re: Jensen JE1907DC 12v RV TV

Leave the switch board disconnected and then check the resistance between the two switch contact pins to see if any of them show resistance reading, it should not since they are normally open contact switch.

[Gorrillasnot]

Re: Jensen JE1907DC 12v RV TV

My cheap meter shows a 1 and then 0s when pressing the buttons.
I think they are ok.

If the board is somehow faulty, but required for the TV to work could I add up the values of all the resistors on the button board then hook them to the button board connector to trick the TV into thinking the board was still hooked up and then use the remote to try to power on the TV?

[budm]

Re: Jensen JE1907DC 12v RV TV

The switches are N.O. (Normally Open) so those resistors are not switched in until the button is pushed.
What Ohm scale did you use?
We still need to see the bottom side of the board.

[Gorrillasnot]

Re: Jensen JE1907DC 12v RV TV

I believe the setting I used was 20k ohm.

Thinking maybe the wires in the cable going to the button board could be shorted I tried disconnecting the cable where it plugs into the main board and it made no difference.

The button board cable has 4 wires. a blue, black, white, and light red.
On/Off voltages read blue .05 spike to 2.8 then back to .05, black gnd, white 3.2, light red 0..not sure if all that is normal or not.

I have read that this make/model TV was known to have main board problems and I'm guessing that is probably my problem as well, but why would heating the button board make the tv stay on? especially if the resistors aren't active unless a button is pushed...I don't get it.

thanks

btw in the pic the gummy looking residue on the pcb I think is from my heat gun assault..also please forgive my ugly solder ..i'm a noob

[budwich]

Re: Jensen JE1907DC 12v RV TV

I don't think that type of testing is what is needed (yet). As suggested, you need to check resistance values which is done with the board disconnected and reading those values at the connector NOT the switches.

Further, if I "see" that picture correctly, the only pins that are "used" are the middle ones as the two "outside/end" end ones appear to have no connection... but you can verify that. IF that is true, measure the resistance across those two pins, then start pressing buttons and see what happens thereafter.

Still further, a "quick look" at the way it is laid out, it would appear that the buttons act as some form of "resistance ladder" and probably means the system is always looking for some form of resistance to determine what button was pressed. It is quite likely that the board has to be in place for the tv to function... my guess though.

[R_J]

Re: Jensen JE1907DC 12v RV TV

That white goo looks like what's left of the connector, will you still be able to connect it to the cable?

[Gorrillasnot]

Re: Jensen JE1907DC 12v RV TV

Further, if I "see" that picture correctly, the only pins that are "used" are the middle ones as the two "outside/end" end ones appear to have no connection... but you can verify that. IF that is true, measure the resistance across those two pins, then start pressing buttons and see what happens thereafter.

the only combination of pins that showed a reading on my meter was the bottom 2 as shown in the pic. Meter shows 1 when power button is not pressed and fluctuated between 8 and 10ish with the power button pressed.
Pressing any other buttons or trying the meter on any other combination of pins showed a 1 on the meter.

That white goo looks like what's left of the connector, will you still be able to connect it to the cable?

That white glob on the bottom of the board is glue. The connector is still in good condition.

not sure what else to try at this point?

thanks