Blaupunkt 32" LCD TV / Monitor repair : " No  Signal " issue - Page 1
Forum section: electronics / repair

author: Vince
author_rank: Super Contributor
timestamp: January 29, 2021, 11:47:43 pm
content: Hi all,A colleague just handed me today this 8 year old defective TV / monitor for me to have a look at : Blaupunkt model B32FA112BK / BLA-32Only a quick look to see if I can find something simple and cheap... if not, in the trash. Well, he allowed me to keep it so I can salvage the board and ditch the rest...I know ZERO about TV / monitors, never had to work on one. So I thought I would ask for some help...Story : TV is 8 years old. Used by his son strictly as a monitor, to connect to his game console.Kid said that the monitor would lose picture after a while. Then he would turn it off, and power it up again and often the picture would come back, and then disappear again after a little while playing the console.Well, that was a year ago at least, then he left the TV alone.Today, a year later : what I find is that the TV powers up, and I can navigate the menus. So the PSU and digital stuff must be working I guess.When navigating the menus, the picture is just fine, zero issue, so the LCD panel iself is fine (branded Samsung LT A320AP33 )The problem I found is that when I connect a signal to the VGA input (kid I guess used HDMI for his console ?? But I have only VGA stuff here sorry), I get no picture, just a " No signal " error message on the screen. Yes, I did select 10 times the VGA input in the menus... but to no available.The VGA connector likely saw zero use in the entire life of the monitor, so unlikely to be a cracked joint on the connector pins. Checked anyway, all joints are just fine, like new. Those on the two HDMI inputs are too.So I guess the problem must be that it fails to display ANY signal, whatever the input you use... so the connectors and their joints are ruled out. It must be a problem with whatever circuitry is in charge of switching from one source to the other.Problem : from what I can see, there is no external switch for me to probe / investigate.. as you can see on the pictures, it's an extremely integrated design : single board design (a small one at that) and a single chip design : A BGA chip hiding under its glued heatsink, surrounded by a Winbond DD3 SDRAM chip and a Winbond 32Mbits Flash serial chip, and that's about it !All the traces coming from the various input connectors, go straight into the mysterious BGA chip... That chip then contains both the MCU and the analog stuff to handle all the inputs, and also drives the LCD panel itself, via 5 twisted pairs. So, somehow the processor and display part of it still work fine since the menus work fine... but the input multiplexer stuff is kaput.Well that's my conclusion from knowing nothing about these things, and spending an hour on it.What do you think, am I right ?Is that a common / plausible fault, in which case it's not repairable ?Or maybe with some luck, it's a power supply problem ? Maybe the input stuff in that BGA chip uses its own dedicated power supply rail, and it's faulty ? That would be too good to be true. I couldn't find a service manual for this device, so don't know any detail about the design of this thing.Power supply wise, there is the mains switching PSU, then on the secondary side, there is another local small 8 pin switch mode step down converter, ref. FR9886.Maybe there are a few dodgy solder balls under the BGA, and I could try reflowing it ? Nothing to lose so.... But my shitty hot air station will never manage to heat up that big chip, especially with its heat sink mounted on it ! So no joy.So basically, from what I see, I would say the BGA chip is faulty and there is nothing I can do about it, so the TV is good for scrap.What do you people say, you there, no, YOU... the one on the left, third trow, who knows these things inside out ! Tell me your thoughts please !Hopeless as I fear, or still hope for a faulty local power supply or some random tiny passive component surrounding that BGA chip ?I could use the markings and labels on the PCB to see if I can find a schematic for it ? Or maybe buy the whole board altogether ? Maybe it was used in many different TV, various brands, and is easy to find and affordable... who knows.Regards,Vince

author: Vince
author_rank: Super Contributor
timestamp: January 30, 2021, 02:25:49 pm
content: OK, that's the end for this TV, RIP...I tried to identify the board to see what info I could find about it. Gave the silk screen markings a try : " TP.MSD309.BP75 ".Good pick ! Google instantlyfound me images of boards that look just like mine.Following links on the interweb from there, looks like this board was used in at least one other brand : " AKAI ".Looks like it also was mated to different kinds of screens. Looks also like the Winbond serial flash contains the firmware for the MCU (no wonder why it takes ages to power up then...), and that you can buy preprogrammed such chips.. in many different versions, for about 15 Euros.The board itself is hard to find. Could only find a handful of ads, all used / salvaged board, none new. Most of these rare ads were sold out. Found only 2 on ebay that actually were current, none in France. One in the UK the other in Italy. About 55 Euros the board. However none of them correspond exactly to my board. Same H/W of course but then you have a sticky label on the board that gives additional parameters, a long string of characters encrypting I guess the various options of the firmware. None of the boards for sale match the one I have, sot it's just too risky to buy something and then have to cross fingers that the variations in the F/W won't actually matter all that much in practice.Maybe it would work, maybe not. Maybe it would not work and then I could buy a new serial flash if I can find one matching mine. But more cost, more uncertainty...So it's probably still fixable, technically... just not in the budget that the owner envisaged for this old TV. If things don't go well, costs could easily spiral well over 100 Euros, which he won't pay for, nor should he. This TV is nothing special and has no sentimental value to him.He just gave it to me in case there was a quick and easy fix like a blown fuse or dodgy solder joints or blown electrolytic caps.. something easy obvious cheap and straightforward to repair. We are hardly in this scenario sadly...Given that its fate was now set in stone, had nothing to lose so tried heating the BGA cheap with my crappy under powered hot air station. I was certain it had zero hope of actually being to reflow a big BGA, with a heat sink glued on it to boost. So I was simply intended to heat the joints a bit, see if that made any difference. What I did not expect, is that crappy as it is, my station somehow quickly desoldered that BGA ?!Oops... it's dead now. Can't reball it now.. and have never done it. Chip is completey toast anyway... the plastic case even melted/liquified in one place... ah well. Anyway, good to know that even a crappy station has enough horsepower to solder rather large BGA chips.Would need to get some practice on smaller sized BGA first though, from scrap boards...Anyway. This board is now toast for good.Best this TV can do now, is offer its board to me. Will grow my collection of scrap boards, can never hurt.The Samsung screen itself is perfectly good so maybe there is a market for it, will have to check. Maybe I can get 50 Euros out of it, can't hurt.Anyway, that was my first TV repair... attempt. I was not expecting to find so little electronics in there. Small single board, single chip design.. even though the TV is not that recent, from early 2013.

author: shakalnokturn
author_rank: Super Contributor
timestamp: January 30, 2021, 07:55:35 pm
content: I have a very similar piece of unholy crap I've been trying to save from a corrupt firmware, mine is a 26" Saba branded one.Unfortunately I haven't been able to find a compatible FW and reading the original (sometimes bootable) SPI flash and rewriting to a new SPI body hasn't given the wanted results.As for BGA it really does take some practice and a underside PCB preheat is very strongly recommended.

author: Vince
author_rank: Super Contributor
timestamp: January 30, 2021, 08:25:42 pm
content: Quote from: shakalnokturn on January 30, 2021, 07:55:35 pmThat got me thinking... I am stupid ! I could just get any version of that board, whatever the firmware, and then just swap the F/W chip ! It's just an 8 pin SMD package, piece of cake ! But... it's still gambling as I don't know for sure if the firmware chip is the only difference between the various boards for sale. If it doesn't work, I will have to swallow the cost , no way. Anyway, no regret : even if I could find a board with 100% same markings on it.. it still would be well above 50 Euros including shipping, and it's way more than the owner is willing to invest.But, might be an option for another TV or monitor one day, where there might be more budget and incentive to fix the device.QuoteYeah I thought of that, but gave up that idea because there were lots of minuscule SMD passives under the BGA, which no doubt would have been flying all over the lab had I dared to take a hot air station to them... Well or maybe set the station to only 150°C or something, to be sure the solder would not melt. Yes... that will be for next time.I prefer to learn on hopeless junk first, so I can save successfully more desirable devices later...

author: perieanuo
author_rank: Frequent Contributor
timestamp: February 01, 2021, 03:57:17 pm
content: hi,first, be sure you 'force' the vga videocard to some accepted resolution&frequency for that monitor, don't expect the old stuff to correctly negotiate this.if that's acquired, move to check the video signal paths, maybe you find just some simple h or vsync problem like a broken inductance/resistor/capacitorusually no signal implies no hsync 'seen' by the monitor

author: Vince
author_rank: Super Contributor
timestamp: February 01, 2021, 05:24:01 pm
content: Hi Perieanuo,Thanks for the advice, however as I said in my previous message... the TV is toast now, so nothing to repair anymore....As explained previously, I don't think the problem had t do with the VGA input. The TV fails to display any signal no matter the input.Didn't know the video card had to "negotiate" to be able to display something on a screen. My 25 year old CRT monitor displays anything the card throw at it. Might not look pretty, but it will show some kind of a picture...If a 2014 monitor can't display something that a 25 year old monitor can... well there is something wrong !If the problem was restricted to the VGA input, then yes I would investigated in this direction. No sync signal is indeed much more probable than any "negociating" going on. That said, even then, it would still probably lead to the faulty BGA CPU because there are no passives in the path. All the signal traces go straight into the BGA. No bad joints on the connector, no physical damage no cut traces no nothing... board is sparkling new. Signals go straight into the CPU so... there is not much to blame other than CPU itself sadly.Extremely integrated / minimalist design indeed...

author: perieanuo
author_rank: Frequent Contributor
timestamp: February 03, 2021, 10:32:25 am
content: the video card can negotiate/report his accepted resolution+refresh rates with the monitor, but old monitor are not implementing thishttps://www.extron.com/article/uedid

author: Rasz
author_rank: Super Contributor
timestamp: February 03, 2021, 02:59:59 pm
content: you can buy universal LCD controller boars on ebay starting at $10 with free shipping. Just read the panel model and make sure to ask sellers if its compatible/if they have ready made cable for it.

author: Vince
author_rank: Super Contributor
timestamp: February 03, 2021, 04:20:58 pm
content: Really ? Wow, thanks for the info, very interesting indeed !At 10 bucks it would be a viable option. Will investigate...The sticker on the screen is below. Says it's a Samsung LTA320AP33 but also says LTA320AP33 L03.Not sure if the " L03 " bit is important or not as far as the controller board is concerned ?!...