Sony PVM1454Q Monitor Repaired
The complaint of this Sony Monitor was no power.
I opened the cover and you can see the internal section in the below photo :
The main fuse was good. I then checked and scanned the power section and found the power IC STRM6523 was blown! The front part of the power IC came off. The good thing is the part number still can be seen if not I have to search for the exact schematic diagram to locate the part number.
Usually when a power IC have problem, one should check on the corresponding components. I found all other parts to be good except the Optoisolator IC with the part number of PC111. Since I can’t locate the part number in my place I replaced it with 4N37.
Once the power IC and the Optoisolator IC were fixed, the Monitor came back to life again.
This article was contributed by M.Reza from Iran.
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Humberto
June 3, 2015 at 1:50 am
Good repair M.Reza. Congratulations and keep up your good job.
Albert
June 3, 2015 at 2:23 am
Nice repair M.Reza. Since its a surveillance Monitor, if I'm correct, these are always usefull. And they do not take in too much space.
Normal older pc monitors I mostly disassemble for the components. For yesterday I got rid of an older but perfectly working Philips 17 inch color vga monitor. And only the tube I throw right away. I just do not have enough room to keep them all working. But the electronic monitor components are always usefull. Especially since all newer electronic boards have fewer components and more IC's.
Albert.
Robert Calk
June 3, 2015 at 2:56 am
Good job and nice repair, M. Reza.
reza
June 3, 2015 at 12:43 pm
hi Albert
thank u for your comment.
reza
June 3, 2015 at 12:44 pm
hello Albert
thank u for your nice comment.
MOHAMMED ALY
June 3, 2015 at 6:08 pm
CONGRATULATIONS SIR.
I AM A BEGINNER AND I HAVE A LITTLE QUESTION PLEASE, HOW CAN I CHECK THE OPTOISOLATOR?
reza
June 4, 2015 at 7:27 pm
hi mohammed aly
thank u for reading my article
go to this address: (How to test an optocoupler)
http://www.antimath.info/electro/how-to-test-an-optocoupler/
or search in to google.
Paris Azis
June 3, 2015 at 11:22 pm
Hello M.Reza,
Nice and interesting repair!
Anyway, I would like to bring to your attention the following:
The replacement optocoupler you used belongs to the “general purpose” family of optocouplers and this, although I noticed in its data sheet that it can be used in “feedback control” applications, encompasses drawbacks which the PC111 is free of.
In other words, the 4N37 can function perfectly in “on-off” switching of thyristors or triacs isolating the power circuitry from the controlling one.
On the other hand, the PC111 is especially designed for use in controlling the output voltages of S.M.P.Ss.
The most significant characteristic we need from the optocoupler to offer us in this application is that of the stability of the controlled-output voltage. This means that the linearity of the transfer characteristic of the optocoupler has to be as higher as possible, just because of the nature of the application.
Putting it more practically, “equal changes of current intensity through the infrared photodiode of the optocoupler, should result in equal changes in collector current through the phototransistor”. And this is not an easy task for all optocouplers to accomplish!
For example, if we test the stability of the output voltage of this power supply through the entire dynamic range of the input voltage for which the designer guarantees stable operation, it will be questionable if the replacement you used can satisfy this demand. This in turn means that in cases like this one there is always a danger for an unexpected and inexplicable second blow of the same power IC you already replaced, due to an oscillatory response of the new optocoupler to a sudden (or even slow!) change of the input line voltage as it tried to establish stabilization of the output voltage.
I would suggest you therefore to replace once again the optocoupler with the original spare part and in case that you either cannot find it in your domestic market or if you order it and until you install it, please connect a 100pF capacitor across the B-E terminals of the 4N37 (pins 5 and 6) you already installed. This is a simple but nevertheless a drastic countermeasure against any oscillatory tendency, applicable to all “general purpose” optocouplers.
Thank you for sharing this experience.
Best Regards
reza
June 4, 2015 at 7:24 pm
hi Paris Azis
thank u for tell me nice guidance.
Robert Calk
June 5, 2015 at 1:10 am
The emitter is Pin 4.
Parasuraman S
August 20, 2017 at 9:39 am
No idea, how I missed this article. Excellent informative explanation! (Thanks to Jestine Yong for providing the related links!)
Yogesh Panchal
June 4, 2015 at 12:28 am
Congratulations! and keep up sharing.
mahmoud_tajpour
June 5, 2015 at 3:46 am
hi dear Reza thanks for your best article iam very glad that my compatriot see it here.your truly M-tajpour from iran
Hicham
June 7, 2015 at 7:43 pm
Thank you Azis,
Your answer was fully usefull, keep up your nice interventions.
Paris Azis
September 1, 2015 at 2:30 am
Hello Hicham
Thanks for your good words and please excuse the delay to answer you as well.
Best Regards
Parasuraman S
August 20, 2017 at 9:39 am
Excellent article. Very informative!