[TechAssist] Re: Semiconductor purchasing question
- From: "al m" <ampm@xxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Thu, 6 Oct 2005 08:54:53 -0400
Check the resistance on the pin and see if there is any difference from a
good one and a bad one. I got some STR53041's and they ran very hot. I
checked one with one out of a Zenith TV that was running cool and there was
a difference.
Al Marquardt
ampm@xxxxxxx
Al Marquardt Electronic Repair
206 W Main
Girardville Pa. 17935
----- Original Message -----
From: <MDileo0000@xxxxxxx>
To: <techassist@xxxxxxxxxxxxx>
Sent: Thursday, October 06, 2005 8:20 AM
Subject: [TechAssist] Re: Semiconductor purchasing question
> Bill,
> No doubt that there are inferior parts, but your problem in this case may
> be
> due to board contamination between the pins. I ran into a similar
> situation
> more than once while servicing Zeniths using that IC. I had a lot of these
> sets
> to repair as they came from several hotel/motels at the time. The problem
> was
> being caused by solder flux residue and cleaning the area with acetone
> using
> a toothbrush resolved it.
>
> I now clean out the pin area whenever any IC is changed.
>
>
> Dominic DiLeo
> Atlantic TV
> Freeport, Maine
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
> In a message dated 10/6/2005 6:09:18 AM Eastern Daylight Time,
> premtech@xxxxxxxxxxxxxx writes:
> Group,
> I had a Panasonic 27" in for repair today, with a not uncommon 3" high pic
> across the screen. Found three caps behind the vertical heat shield and
> the
> vertical IC LA7838 at fault. Replaced these and still had the problem.
> Traced
> and tested for about a half hour more and replaced the IC again, still
> same
> problem. At this point I'm fuming, going over the print, retesting up the
> circuit, ESR testing caps that I had done at least twice and looking for
> any clue as
> to why the IC looked as though it had failed.
> Finally I tried a third IC and to my surprise the pic was restored. I
> looked
> at the packaging and found that these three ICs were purchased from
> Tritronics and they didn't appear to be the cheap TT Chinese knock-offs.
> I'm at least
> intelligent enough to knowingly avoid those. In fact, I noted that I had
> paid
> almost nine bucks a piece for these.
> So, I went to order some things from Tritronics this evening and searched
> the
> LA7838 on their site. It came-up with several brands all using the LA7838
> and all of them a different price, ranging from a couple of bucks to
> eleven plus
> dollars a piece. So what denotes a knock-off from an original Sanyo made
> component when all you have is the price to go by?? None of the brands
> listed
> were Sanyo and most of them showed each of the brand part numbers, Hitachi
> and
> Toshiba for example, identifying it as a LA7838 or OEM part. It's
> probably how
> I ordered the last ones - middle of the road price or manufacturer number.
> This makes a about four times in the last month I've had to replace a
> component because it was a failure right out of the box.
> I'll be calling Tritronics tomorrow but this seems like an epidemic that
> obviously could be cured at the supplier's end. Besides, I just hate
> wasting
> money on such a small margin repair as this one.
> Anyone else had a similar problems lately with Tritronics parts?
> Bill
> William Rayburn, CET
> Premium Technologies
> PO Box 442
> Long Beach, WA. 98631
> 360-642-4993
>
>
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