Wednesday, September 29, 2010

LG 50PC3D with negative image on screen after replacing YPPD-J015C on 6870QYC104C

Yesterday an email from a customer arrived and it said:: 

Dear Coppell TV Repair,
we purchased part # YPPD-J015B from your company through PayPal.
The item arrived and is defective.  Please advise how we may return this part to you for exchange or refund. 

Thank you.

Since we sell J015C and not J15B and since the mix-up of a J015C and J016B is deadly, my first guess was that they had installed J015C as a replacement of J015B and, sure enough, it would have lasted a very short time.
I wrote back explaining that we pay premium for our J015C components (and we really do!) and that we haven't had a defective one in a very long time (and indeed we haven't!) and that perhaps they confused J015B with J015C. This is a common mistake which is the reason why in the listing for the YPPD-J015C sale we have multiple warnings about the need to use C versions for both IPM modules on the sustain board.

Here's the response:
You are most certainly NOT correct in your assumptions.  The part you sent us was NOT NEW. As soon as we received it my technician pointed out that there were imprints from the screws where it was formerly fitted and pinholes on the back of the silicone seal.
I told him to go ahead and use it because we had previously bought parts from your company with no problems.
The TV did not fail as you presume but has a negative video.
I do not dispute the experience of your company or the satisfaction of your clients.  In the pas I was also a satisfied client.  However, I resent your implications that we dot not know what we are doing here. we have been successfully servicing TV's here for the past 22 years and like Coppell TV we are highly trusted and respected.
I am telling you that the part you sold us is defective and would like your cooperation to return it for exchange or refund.
Now, I am posting the response without any changes. This way you can see that someone with 22 years of experience (and, frankly, that's more than  us!) claims the part we sold them was used and defective.
 You draw your conclusions and decide if you want to purchase from us. You were warned!

For the curious minds I'd like to point out that the sustain IPMs are NOT involved in forming the color of the picture on the display. They are responsible for the high-voltage impulses that power each individual row on the plasma, but NOT with the color.
Any defect in the sustain IPM will affect typically the brightness of the entire row, in fact the entire screen.

Other parts on the board, however - and they are, of course, related to the IPM - are responsible for using the color information to 1) control the IPM timing and 2) dispatch that information to the sustain buffers.

At the moment I will not say which are those components. I will only say that they go bad often when J015C shorts and need to be checked when J015C is replaced. (BTW this also confirms customer was right about my initial guess being incorrect; they had clearly used J015C and they had observed a common problem with a failed J015C).

What has happened at the end? Well they asked for a refund or replacement and they got a refund since a replacement would not have had an effect. Since they've been in the business for 22 years and they knew the part was defective (and we knew it wasn't) we kindly asked them to send it back. In order to avoid similar conversations in future we asked them to use a different vendor. As I said we pay top dollars for those parts and believe it or not there's a shortage of components - even at the high prices we pay - and a great supply of customers.

We also predicted they will observe the same result with the next IC they use.

Now that I think about it, we didn't play it in the best possible way. We weren't quite service-oriented and instead of helping them solve their actual problem we got ambitious of proving they weren't right.

Then again what was their actual problem? It depends on where you look at it.

To me it all started with "The item arrived and is defective."
Here's my two cents: if you're a customer and you buy from supposedly respectable source (e.g. top-rated seller with a long history and lots of positive reviews) do not jump to conclusions if things don't go as you expect. 

Try "I am having a problem, can you help me please?".

I'll be the first to admit the advice applies at 100% for yours truly.

Follow-up on October 6 2010: The J015C unit did arrive last night. I was impatient to test so I stayed late , put it on a board and, sure enough, it was working. So much for jumping into conclusions!

Thursday, September 16, 2010

How to test power supply R0804-0901 from Polaroid FLM-3232 / Polaroid FLM-323B

Since we repair those power supplies (contact us for repair if you need yours repaired!) I am often asked how can it be tested if it works.

"My Polaroid just died and after some research I found that it's usually the power supply and then I found your blog and learned that CoppellTVRepair repairs it. I opened up the TV, looked at the board and I indeed have R0804-0901. There are no swollen caps or broken elements that I see...I want to use your service, but I want to know I actually need it before I pay."

That's a fair statement. To start with, only about half the time it's the power supply that goes bad. The other half it's the main board and , at least for the time being, we can't help with that...with more than the helpful information I already posted a while ago about cross-referencing main boards from Polaroid and Memorex.

So it makes a lot of sense to test the power board instead of assuming it is dead.

And here is how:

The R0804-0901 is extremely simple in regards to operation and outputs. Unlike most TV power supplies its only standby circuit produces 24V and those can be measured at any time - on or off - at connector CN3, where the first three pins are ground, the second three are +24V and the last one is used to turn on the secondary power source for the back lights:

I measure the voltage by simply feeding power to the supply and sticking the meter probes in the connector:

Most of the time, if you have 24 volts there, your power supply is good.

Now if you want to be sure that everything works, then you also need to test the secondary output, which is at connector CN2 across the board.
It is even simpler as it has 5 pins ground and 5 pins 24 volts (separate from the first ones!):

In order to do that, though, you need to turn that circuit on, which is done by connecting the PS_ON pin on the first connector (look above) to the primary +24V through a resistor. 
Anywhere 1 kOhm to 10 kOhm should do.

On the picture below I had used a simple cable from another TV to allow me to easily connect the lowest pin to some of the ones above it through a resistor.
You will likely not have such a cable handy...but then again you only care about this test if your TV powers on and off, has sound, but there is no back light.

Monday, September 13, 2010

Samsung LN-S4041D LNS4041D shuts down intermittently

Well I'm back from Europe and overloaded with work!

This post is for a trivial problem with the BN44-00134A power supply used in some Samsung LCD TVs.

Just yesterday came across a LN-S4041D TV unit. It was brought in for service with complains for intermittent shutdowns after working for a while.

Sounds familiar - many TVs would do that, very often due to puffed capacitors in their power supply boards.
(of course it is not always the case; remember, nothing is ever certain, so the next time you call a service technician please spare their day and tell them the problem you see and not what you think is causing it!)

So anyway, after taking the back off and looking at the power board this is what I saw:

An even closer look at the upper right corner revealed the following:

Did you notice the two puffed caps? They are a little harder to see on the image - I am an electronics and software engineer, after all, not a photographer - but if you know they are there you will see them even on this image.

Puffed caps like that are usually connected in parallel and usually have the same value.

In this case they were both 1000 uF / 10V .

When replacing puffed caps it is usually best to use the same value for their capacity (1000 uF in this case) and always safer to use same or, better yet, higher value for their rated voltage.

Another important property of the electrolytic capacitors is the upper temperature range they can work on. On most boards these days this is 105 degrees Celsius and I recommend using the same or higher value.

Replacing those two with a pair of 1000 uF / 16V / 105 degrees fixes the set and will keep it running for a long long time.

Maybe happily ever after.