KDF-E42A12U, new bulb, still failed !!

[time2innov8]

3 days ago there was a noticeable 'popping' sound heard from my Sony 42 inch DLP television, following which the display went blank and the diagnostic sequence (as I discovered) of 3 blinking led's was displayed. A search on the internet pointed to a possible short on a power circuit board. As the display was off the first step was to source a replacement bulb; I subsequently found a replacement on ebay for £105 inclusive of next day delivery.
The bulb was duly delivered and I carried out the relatively straighforward task of replacing it within the existing holder (the centre column on the failed bulb was completed detached from the main bulb housing, the other wire remained connected) . Expecting there to be a no more problems I switched on the power to the television only to be to greeting with a 2 blink sequence of the diagnostic led. Being involved in electronics I took the decision to remove the television back and investigate further. No obvious signs of damage were present on any of the visible circuit boards, the only destructive testing carried out involved confirming the correct operation of the fan using a seperate 12v dc power supply.

Other posts related to a 2 blink sequence indicated a possible problem associated with the lamp cover switch. I carried out the following further tests; observing the diagnostic led with
1) the bulb holder removed
2) the lamp cover removed
There was no change to the diagnostic indication with either of these tests.

Where do I go from here??
I have sourced the service manual online for $19 which does not sem not bad.

Has any one else experienced a similar problem?

Is the bulb failure always associated with a corresponding noticeable "popping" sound? Or has some other fault occured which has resulted in the bulb "blowing" ?

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time2innov8

[time2innov8]

The diagnostic led doesn't lie !!!

You always learn by your mistakes!

I took the decision to download the manual for the television by paying $5 online. After confirming that the 2 blink sequence relates to the lamp I identified on the diagrams the components involved in the lamp detection circuit. There are two pcb's involved (T1 - lamp door switch and T2 - lamp position switch) which both provide a short circuit if the correct condition is being met. Initially I looped the connectors with wires to bypass the pcb's, switched on the television and it worked !!!
By a process of elimination it was identified that the T2 switch was not being detected, something was wrong with the lamp position. Although I had pushed the lamp assembly in several times and assumed it was correct (it locked into place) I used my hand to move the holder in a downwards movement so that the holder was near the bottom of the chassis (previously it was raised up). I subsequently switched on the television and it worked correctly - just goes to show you should never overlook the obvious.

In order to get the manual I paid for a 30 day subscription at the respective website, if any one wants a manual I can see if it is available, just send a pm.

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time2innov8

[jimmyboy1]

Hi time2innov8,

I don`t know why do you pay for the manuals there are freely available. just a good search on the net would have found you a good manual for free. Check this out as well very good manual;

Installation Guide

[time2innov8]

jimmyboy1,

I agree that I could have found good manuals but an exhaustive and time consuming search did not find the manual for my television which was required to identify the circuit boards in the bulb circuitry. Only after examining all the options did I decide to pay for the manual, (There was no responses on avforums to my initial post), and then only after finding the most cost effective method. (The same manual was available on other sites at a higher price, on at least one site it was five times the price I paid). Looking back I should not have required to make references to the manual but hindsight is a great thing!

time2innov8

[jimmyboy1]

Hi time2innov8,

Hope the video would have helped you in placing the bulb. Hows your Tv going Many new movies to come have you watched HArry Potter, great movie man. Bye Tc