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I have a Hitachi 53SDX01B (DP06) that has convergence issues. I replaced both STK392-110 IC's with STK394-160's. I also replaced rk50, rk58. Reinstalled board. Convergence issue was still there and now the top and bottom of the picture curved towards the center. Removed board, found rk62 was burnt (I don't think it was before but not 100% sure), replaced it, reinstalled board. Same 2 problems still there. I've checked for voltage on pins 4 and 5 (actually checked it at jumpers on board) and everything is good. I'm starting to think I've got bad chips as I got them from Ebay (seller claims to be Sanyo dealer and has 100% positive feedback). Does anybody have an idea of what to do next? Is there a way to check the IC's? I'm stumped here, I need help. Thanks.


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Read the convergence thread again carefully. You have to check the resistors with the chips out and yokes disconnected. If you missed a resistor, you very well could have damaged a chip. You could also have other problems such as a bad convegence generator module (DCU). Check the dc offset on the inputs to the ICs with the ICs removed. If you have a scope, look at the waveforms and see if they change with changes in the convergence adjustments.

You may or may not have gotten bad parts. I do not trust vendors other than the ones I listed. If one of them is selling on Ebay, then they would be fine, but otherwise, just spend the money to get the right parts from the right source. Please list the seller so that others will have the info if you think you got bad OR good parts.
 

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You can build a test jig and feed in some signals and test the output with a scope. The test setup is usually in most of the spec sheets from Sanyo. Otherwise you can verify that the signals from the DCU are correct. If they are and you verify all the related parts are OK (resistors, etc) it is easiest to use the set itself. If everything else is ok, and you still have problems or blow resistors or fuses, you can assume the parts are bad.

I would just start over, buy parts from a known reliable supplier and check everything suggested.
 
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Thanks for the responses lcaillo. I don't have access to a scope and wouldn't know how to use it anyways. :sad: So I guess I'll get some more chips ordered. In the meantime I'll desolder one side of all the associated resistors to make sure. In fact, for no more than what they cost, I might run down to radioshack and replace them all just to be on the safe side. Are the radioshack brand resistors worth a dang or should I make a trip to the electronics store (45 minutes away) and get NTE brand?



PS- Sorry if I have a lot of newb questions, I know just enough about electronics to get myself in to trouble, but I'm learning (and having fun to). :T
 

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As long as the resistors are the correct resistance, tolerance, power value, and type, it does not matter which brand you use. Be sure that they are metal film and not carbon type.

Please be sure to use a reliable supplier. If you buy the Hitachi kit for your set, it should have the resistors that you need.
 
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I desoldered all 12 associated resistors. All checked out good. So, I went to take the IC's off the board. After desoldering I had to pry a little bit with a flat screw driver to get them off the heat sink, the Arctic Silver thermal compound is extremely sticky. Anyways, the cover came off of one of them. I don't know if this confirms that they are cheap copies or not, but I decided to post a couple of pics for everyone to see.
 

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Make sure that you do not use too much heat sink compound. There should only be enough to fill the gaps where there is no metal to metal contact. A common mistake is to use too much.

The issue of copies or counterfeit chips is a bit of a mystery. I believe that there are not only copies of many chips (mostly 392 series) but also batches of rejects that get into the secondary and black markets. Think about it. Why would some vendors be able to sell chips for a third or less than others. It is not like the more reliable vendors don't know where to buy them or buy small quantities. In fact it is usually just the opposite. Just stick to the distributors that I list or check them out if you use another. The experience of many service shops and techs goes into the decisions about where we by parts.
 
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I'm convinced the chips were bad. I ordered STK392-110's (I know, I know) from Bdent, replaced all the associated 1 watt resistors, installed the board and we're back up and running. I still need to fine tune the convergence but atleast it's fixed. Let this be a lesson for everybody. DON'T ORDER CHIPS FROM EBAY!!!

Anyways, thanks for all your help lcaillo, I really appreciate it.



Bartstop
 
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