Hello all, I looking for grey beards. Or white. Or none at all. Actually, I could use someone to bounce my problem off so I might figure it out an learn something along the way, and have a trail so anyone else who want's to tackle this, can. There seems to be no googleable info on this which I find quite remarkable.
This is my first post ever about anything like this, so please bear with me. I'm just kinda at my wits end and would like to solve this problem. I've never received any formal education with electronics, they didn't offer where I went to school, so please continue to bear with me.
I have learned what I know from fixing the world around me and reading books, this website and youtube. I have some pretty big holes on my understanding of certain things. This may very well be the case here. I'm hoping to get a better understanding of this circuit, and long answers are perfectly fine with me. I'm not really looking for a career in repairing tv's, I just hate to see so much waste due to a couple of faulty components.
I know this post isn't really design, it's repair, but maybe somebody may have schematics or experience with this board to shed a little insight on what some little devices are. I am having a very tough time finding schematics for the inverters of a TV I'm attempting to repair. Or any information, for that matter, on the parts that are failing. I have a service manual for the TV but the inverter(s) section doesn't have any detail. Just that it's an inverter and the silly crap to troubleshoot and swap out boards.
After following what the service manual suggests and not finding a remedy, I decided to try and repair the inverters. To do this, I'll need to
understand the circuit a little better.
There are four inverter boards. Master, slave1, slave2 slave3. It appears the master and slave 2, are a channel and, slave 1 and slave 3, are the second. Im having trouble with this second channel. After switching the boards out and it failing (such an annoyance as these boards are really expensive, and failed cause I'm a twat) I measured everything I could on all boards to see if I could swap these regulatorishy looking things. I managed to find some predicable behaviour using the diode check on my meter. Since i have two sets of these boards, you'd think I could use parts from one to the other. No dice. I'd like to be able to find these parts as I'm pretty sure they're failing, but can't figure out what the part is. I am pretty certain these parts are the offending bits, a bit intuition, a bit hours and hours of probing.
There are four different variations of these regulator looking things across all these boards. I have purchased one master board and then bought a whole set of inverted thinking that the worst case scenario is that I'd be able to swap parts from the boards. This doesn't seem to be the case.
None of the part numbers I google turn up anything, or turn up a bunch a datasheet listing that lead to 'datasheet not found'.
*I do love that I don't have to go through a big old paper directory, but really, these datasheet catalogs get pretty annoying. It;s so rare they ever turn up with your desired info and you usually waste a good few minutes and a few pages before they tell you they have no idea what you or they are talking about. I digress. *
All four variations contain 'D606' just below the heatsink tab. I thought they were maybe a + and - until the second round of board which all use exactly the same IC. The branding on the chip looks like its trying to be 'AP' in a handwritten signature style. Im not sure it says AP even, I've never seen this brand before.
The codes on each chip are as follows,
BA7S1X
BA7N12
These are from the stock boards.
The first replacement 'master' came with
BA7K1L in each location. Replacing this board managed to allow the CCLF's to light for a several seconds so more work was required.
I purchased a whole set of boards and foolishly swapped the board I assumed was pooched. I know, stupid. Never again.
The next set of boards had a completely different code prefix all together.
BH6449. These also have the 'AP' D606 with the BH6449, but all of these IC's appear to be identical.
They have 5 pins with the centre internally connected to the heatsink. For two of these devices, this is connected to ground and the other two i think maybe + and -. I think. I didn't think to measure the working channel until writing this. I can do this because the master/slave channel will allow the backlight to remain on for a couple of seconds.
I assumed and still assume that the circuit on all these boards will be practically identical. I can't imagine why the different FL tubes would need a different inverter. I don't however, know if the boards master/slave2 and slave3/slave4 are two circuits, or four.
Well, I've swapped the boards and I'm still not able to get this second channel to not blow it's fuses.
The boards are:
VIT70035.50, Master Q28, Q29, Q30, Q31
VIT70035.51, slave 1 Q213, Q214, Q215, Q216,
VIT70035.52, slave 2 Q313, Q314, Q315, Q316
VIT70035.53. slave 3 Q413, Q414, Q415, Q416
The master board has a OZ9928 - Dual CCFL inverter controller and a couple of AS324m soic opamps, and 1 as393 soic comparator. there seem to a number of sot diodes, transistors and whatever else fits in that package.
Maybe these are dual channel mosfets? Maybe they're some boutique regulators? Is there a different way in which I should approach this?
Any help would be great. These inverters seem to be in a lot of different TV's and I think the internet and the environment would benefit from this information being discussed.
Apologize if this was a bit long winded. I'm just trying to supply all the relevant info.
Cheers,
Joel
Home
Help
Search
Login
Register
