700G no backlights

[PlainBill]

Re: 700G no backlights

You are easily excited...

Pin 8 reads .33 off, about 4 seconds after turning on it drops down to around .002 and then goes back up to .33 and remains when lcd goes into standby.
Pin 9 reads .03 off, about 4 seconds after turning on it jumps up to as high as 1.74 (did it several times) then drops back down to .03 and remains there.

Is that using the capacitor and with the DMM on the 20V AC range?

PlainBill

[sceva]

Re: 700G no backlights

I can tell that is not what you expected, so I did it again. The meter is set the same as when testing the MOSFETs. Same results. I attached a pic of my tester in case I did not get your instructions right.

I am packing for vacation to the mountains in the morning, so if you don't hear back from me for a week or so, don't worry! If you do get back tonight I will try and check...

[PlainBill]

Re: 700G no backlights

I can tell that is not what you expected, so I did it again. The meter is set the same as when testing the MOSFETs. Same results. I attached a pic of my tester in case I did not get your instructions right.

I am packing for vacation to the mountains in the morning, so if you don't hear back from me for a week or so, don't worry! If you do get back tonight I will try and check...

You learn very well, Grasshopper. While I'm not absolutely sure that your DMM is ''fast" enough to read that frequency, I'd have to say evidence is pointing to a defective BIT3193. If you want to be super secure before ordering one, I've sketched a 'peak voltage adapter' that will determine the peak voltage pins 8 and 9 of the BIT9139 reach.

PlainBill

[sceva]

Re: 700G no backlights

Back from vacation. If you like the outdoors and mountains, I would recommend Glacier National Park - beautiful, great weather, lots of wildlife!

I had a spare BIT3193g on another board and swapped it out. Now jumping directly to U301/2 I see:
1 = 0v with lcd off and on
2 = 0v, then when turn it on it will go to .03v, then back to 0v
3 = 14.5v, when turn on it goes to 17.3v
4 = 14v, on goes to 16.5v
5-8 = 10v off, up to 13v when on
So I am finally getting power to 5-8, but lost voltage on #2

Checking pins 8 and 9 on U303 I get the same .03v as on pin #2 on U301/2.
Pin #5 on U303 is Timer, and goes to 4v. #15 is ISEN, which says open load situation if less than 1.3v, and I read about .5v when on.

[sceva]

Re: 700G no backlights

I found some BIT3193g's online for under $10. I will update after receiving and testing them.

[sceva]

Re: 700G no backlights

Tried the new BIT3193 and got the same results as the previous one I swapped out... I am officially retiring this one to the re-use pile. Thanks to everyone for the help, and I have three more BIT3193's if anyone needs one. Just pm me and I will send them out.

I do have an increased interest in an oscilloscope after this thread, but will have to do some more reading as I know nothing about them, other than they can be helpful in diagnosing where the problems are. I have a search set up on craigslist but not many in my area at the moment.