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Thanks for the insight guys.
But now I am (more) confused about what a cap under a heat sink looks like.
The removing it without taking the heat sink off part is bewildering me.

Any pics?

Thanks
Small electrolytic capacitors under the overhang of the heat siinks. Most of what you are probably used to looking for are capacitors in the 1000 to 3300 uf range. The ones I've had causing problems similar to yours will be 100uf @ 35v. These will be much smaller in physical size, but still the same type as the other ones you've seen.

Make sense now?
 

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Discussion Starter #82
Yes, thanks...i understand.
I was thrown off by talk of how are they are to get at and replace.
My mind's eye saw caps the smaller than a letter on a page of a book residing UNDERNEATH the heat sinks.
 

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Yes, thanks...i understand.
I was thrown off by talk of how are they are to get at and replace.
My mind's eye saw caps the smaller than a letter on a page of a book residing UNDERNEATH the heat sinks.
LOL,,,and also remember polarity, those small caps are harder to see the markings. The small ones still blow up if polarity is reversed. I did it a couple weeks ago, and had my face over the thing when it blew. Electrolyte doesn't feel good on the face when its hot......
 

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Discussion Starter #84 (Edited)
Well i changed out all the e-caps in PS1 but am still getting the same ol' same old.

I was able to test the old e-caps and the new e-caps with the Blue ESR meter as well as the Peak Atlas Esr70 (which gives you both esr and capacitance). All the old e-caps read within specs.

Being that i had no way of testing DA replacing the caps was the next logical step but it seems the e-caps on the power supply was not the cause of this problem.

Im not sure if i should stay on the power supply or start looking for problems on the sustains.
I'll have to read up on ceramic dsc caps and see if they suffer from DA or high ESR as well.
 

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Hello KYBOSH,
I have learned much from reading through your experience in repairing your 60" Hitachi. Good luck on getting it going again. I am trying to repair a 50" that was given me and I have replaced the CAPS on the power supply. My SDR-U has 2 burned chips that need replaced. The http://fixnex.ecrater.com/ link in one of your earlier posts gives me a "no such seller" when I click on it. Do you have current contact information for the guy that respired your board or know someone else that does the repair? Thanks for all the good info!

bluecatfish
 

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Discussion Starter #86
Hello KYBOSH,
I have learned much from reading through your experience in repairing your 60" Hitachi. Good luck on getting it going again. I am trying to repair a 50" that was given me and I have replaced the CAPS on the power supply. My SDR-U has 2 burned chips that need replaced. The http://fixnex.ecrater.com/ link in one of your earlier posts gives me a "no such seller" when I click on it. Do you have current contact information for the guy that respired your board or know someone else that does the repair? Thanks for all the good info!

bluecatfish
PM Sent.
Hope it helps.
 

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Discussion Starter #87
Okay folks, I'm back on the case!

I found myself with a little free time so I decided to give this problem another go. The last major thing I did was to replace ALL the caps in the power supply. Even though they all tested good I was concerned about the potential for dielectric absorbtion, aka battery effect which was first mentioned by Leonard. Changing the caps had no real affect on the symptoms but now they can be ruled out.

Yesterday I started by observing the symptoms again. When the TV is first plugged in the PS activates and quickly deactivates. This is marked with a CLICK .... 2 second pause...CLICK (Powerup-Powerdown). The main power light does not give any flashing error code and stays solid blue. Pressing the power button has no effect on the power supply but the light will go from ready (blue) to standby (red/orange) if the power button is pressed for ~5 seconds.

Back in post #59 I detailed how I used a Hitachi technical document to test the power supply by forcing it to produce voltages. Back when I first tested it I was not getting any voltages on certain pins. After desoldering components, testing them and resoldering them the board miraculously came back to life and I was able to get the TV working again (with a few tricks).

Its pretty clear to me know that there was a faulty/failing component or possible a dry solder joint on the board. My tinkering with the board got it working for a short time but it was destined to fail again and has. I retested the PS by forcing voltage generation and everything checked out except the PS is not generating any Vs or Va voltages. In the short 2 seconds the PS activate the voltages for Vs and Va stays flat at 0v.

The PS seems to cutoff as a circuit protection measure. I have scanned the PWB and all parts for burns, cracks and other defects but don't see anything suspicious. I have not checked for dry solder joints yet as I just read up on them but I will.

I am going to pull the PS again and go hunting for defective components. From my reading, since the caps are all new, the primary suspect will be an IC. If its a voltage regulator I will have to test them with the TV Powerup which I did not do before (only tested for shorts).

This will be my first time testing ICs (any IC) and hope I won't have a problem testing them with the PS in protection mode. Testing the voltage regulators attached to the heat sinks will be very tricky because everything is packed in pretty tight and Im not sure of the best way to do it.

If you guys have any tips on testing the ICs I'm happy to hear them.
 

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Discussion Starter #88 (Edited)
Re: Hitachi P60X901 (60" not 50") led flashes 2 times (not 3)

Today when I was spot checking ICs one of me MOSFETS exploded.
I'm not really sure why because at the time I wasn't doing a thing.

It was on the primary side.

I had the board jumpered to produce voltages as described earlier.
The board was on the tv and connected properly.
I was honestly just checking voltages here and there.

A few minutes before the MOSFET popped I was checking a nearby photocoupler (in pink) and got a VERY large spark. Took me completely by surprise! All the other photocouplers have very low voltages across them so the spark was totally unexpected. I unplugged the TV and looked over everything but didnt see anything wrong.

After I plugged the TV back up the MOSFET exploded. :crying:
 

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A FET popping in the primary of a PS usually indicates a timing problem where it is being turned on too long and overheating. Most commonly would be an open resistor or cap. Could also be a controlling IC or a failure in the feedback loop.
 

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Discussion Starter #90
Just my luck ... none of the scenarios would have been the root of the original problem :duh:
 

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Your "luck" is not really that unusual. Not everything is a simple symptom-repair relationship. That is why troubleshooting is an important skill in electronics repair, along with knowledge of how various circuits operate. There are many predictable repairs when there are systematic problems like are common in these sets, but there are also many more random failures that occur.
 

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Discussion Starter #92
Well said Leonard...

You mentioned the latest incident could have been a "timing problem where it is being turned on too long and overheating." I'm confused about that part. It was only one for less than an hour when all this developed. Can having the back open and no fan have caused that in less than an hour? Even when it wasn't sending power to any other board (everything disconnected)?
 

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A FET in a switching power supply is used to switch the current on and off through the primary windings of the transformer at a high rate. The rate and or the pulse width are modulated to control the current in the secondary. Usually the rate is in the tens to hundreds of kHz. If you have a timing problem that turns the FET on for too long on each pulse, it can blow almost immediately. It would have to be running close to normally to be affected by heat sinking or ventilation.
 

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Discussion Starter #94
Okay folks, here's an update/conclusion to my journey of getting the P60 working again.
After blowing that FET while testing the function of the PSU I began to realized that this particular component level repair was going to be out of my league.
I simply did not (do not) know enough about how each component works with one another to do a good job at troubleshooting.
If it were a simpler/smaller set with more documentation on it I may have had a chance but as that FET showed I could actually do more damage than good.

So I took to the net again in search of a replacement Power Supply for this TV.
Initially my searches came up dry as usual but after taking a look at the board again I noticed some other numbers aside from the part number given by Hitachi US (HA02001).

Namely a part number on a sticker which read MPF7714A.



So I search this part number with Google.
The first hit was a ShopJimmy link and sure enough it was out of stock.
But I noticed that there were several links in CHINESE so I clicked on them and was surprised to see this power supply available out of China.
Even though the website was entirely in Chinese that Google Translator did a very good job converting everything to english for me.
The site the power supply was on is called Taoboa which is apparently the Chinese version of eBay.

(日立专卖)全新原装日立等离子P60X101C大电源板MPF7714A

Only problem is there is no real way for people outside of China to buy on Taobao directly.
They dont use our credit card system or Paypal and that speaks nothing of the language barrier even if they did. What I had to do is find a Taobao agent who acted as English speaking buyer's agent.
For a percentage they purchase the item on Taobao and ship the item to you.
You usually pay them via Paypal each step of the way.
I found a Taobao agent who charged me about 8% of the power supply's price.
You can search ebay for a Taobao agent as there seems to be a lot of them.

After I sent them my paypal payment they ordered the item from the seller and it was sent to their location. They then packaged it to my specifications, weighed it and sent me a quote for shipping.
I choose EMS (Basically Global Express Mail International + Insurance) and it ran me another $60 or so and it was delivered in 7 days flat.

The reason I am telling you guys this is to let you know that even though you cannot find a power supply, buffer or sustain for your TV here in the US, the Chinese market is awash with them.
The model numbers of the TVs might be slightly different but the internals are all the same.
For instance my P60X901 is known as a P60X101C in the Chinese market.
If I look up items for that sku number I found almost every component imaginable for this tv in brand new condition.
They are almost impossible to find here in the US.

So you have options other than looking for IC chips or used components.
If anyone needs more details about my experiences ordering from Taobao feel free to ask.
In all I paid $215 ($147 for a new power supply, $55 postage to the US plus the $12 agent's commission).
If ShopJimmy had the USED one it stock it would have been $190 shipped.

So today my PSU came in the mail.








Just as the Taobao listing described it was brand new in box. At least I could not tell any difference...

I sat it side by side with the original PSU and it was a perfect match.... no noticeable variations.



So I placed the new PSU into its place...






And fired the P60 up. First thing I noticed (other than the absence of an explosion :) ) was the PDP actually initialized/powered up along with the fan. It then cut out after a few seconds (power save mode).

I hooked my Apple TV to an HDMI port and the picture came right on.



Everything worked as it should. I was actually surprised that I did not have to do any adjustments to the little knobs (the name escapes me right now) on the power supply as I read that replacing power supplies and sustains would require a bit of tuning.

So now I am happy that I turned my 200 lb. doorstop into a working TV again.
Even though I upgraded to a Samsung I really love this TV.
Unfortunately is so big its going to sit right there in my garage until I figure out what to do with it.
Really have no need to another large TV that's not superflat. :(

Maybe this is an opportunity to build a new cabinet...





Anyway, in all I spent $86 replacing all the capacitors on the old power supply, $75 on getting the IC chips on my SDR-Buffers replaced and $215 on a new power supply. That's $375 spent and over a year in waiting but invaluable experience gained. :T

I want to give special thanks Leonard (lcaillo) and Jim (74f100) for your invaluable and patient guidance. This forum is THE BEST.
 

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Discussion Starter #95
Man...it feels like yesterday when I was repairing this TV.
Wanted to checkin and let you guys know this TV is still alive and well.
Since then I have repaired a few other TVs adding more and more testing tools to my arsenal along the way.
I look back with regret that I wasn't able to figure this one out on a component level but there were a lot of lessons learned with this one.
 
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