Help !! SMPS Repair

Bidya

New member
Hello Friends,
I am from India. I have a Hometheater Samsung HT-Z310 which is lying dead. Actually its SMPS (ORTP-616) has gone dead. I contacted the Service Center to CEO's Desk of Samsung India but they don't have any solution as the model has been discontinued. I tried to repair the SMPS board with the help of a electronic mechanic. On initial inspection it is found that the PWM IC FSDM0365 (it is wrongly mentioned as FSDM0356 in the schematic) was blown along with fuse and few diodes. Replaced all the faulty parts, IC FSDM0365 is not available anymore, so replaced with FSL136MR (as suggested in TI website), but still it is not working. We have checked all the secondary side and it is OK. The problem is in the primary side. Another IC i.e. KA5Q1265RF is also there which is also not available locally or online in India. I suppose it is OK. Can anybody suggest how it can be restored or any replacement available. The schematic is attached herewith, please look into it and help me to figure out the problem. Please note that the SMPS developed the problem due to heavy power fluctuations here.
 

Attachments

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P.S.RAJU

New member
Hello bidya
According to your attached file there are two smps transformer,in your supply,the small one is for standby power supply and the big one is for the power out put
amplifer,first you have to on the standby supply which gives 4.3 to 5volt after this supply is on this will switch on the 35 volts supply so it will be better if you
first on the standby supply, make some modification in the primary according to the available ic for the standby supply, i am an audio technician
 

Bidya

New member
Hello bidya
According to your attached file there are two smps transformer,in your supply,the small one is for standby power supply and the big one is for the power out put
amplifer,first you have to on the standby supply which gives 4.3 to 5volt after this supply is on this will switch on the 35 volts supply so it will be better if you
first on the standby supply, make some modification in the primary according to the available ic for the standby supply, i am an audio technician
Hello Sir, thanks for looking into my problem. I don't have much technical knowledge on electronics. I am trying to fix the problem with the help of a technician/mechanic. Can U please suggest what kind of modification will have to be done. The IC I am using instead of original FSDM0365 is FSL136MR. We have noticed that with FSL136MR the required current for Oscillation is not coming to the primary side of small transformer. Please help me.
 

P.S.RAJU

New member
Hello bidya
the ic fsl136 u r must be not the original one,the new ic may also be defective , one of my modification is ic no. viper 22 ,this will not fit
directly in your pcb you have to make wiring of sourse ,drain ,feed back ,vc,for this u should have good knowlage of smps
or,you can give the power supply to local techinician in mumbai electronic market,i know may places in mumbai ,
are u in the electronic field
 

Bidya

New member
Hello bidya
the ic fsl136 u r must be not the original one,the new ic may also be defective , one of my modification is ic no. viper 22 ,this will not fit
directly in your pcb you have to make wiring of sourse ,drain ,feed back ,vc,for this u should have good knowlage of smps
or,you can give the power supply to local techinician in mumbai electronic market,i know may places in mumbai ,
are u in the electronic field

Hello Mr.Raju, thank U. I am not from Mumbai nor in the electronic field. I am from Odisha living in a small town. But, I know the general technicalities of electronic components, so I can manage the IC U r recommending. Also the technician is there with me with which I am trying to fix the problem. So, there will be no problem if anything u will suggest to modify. By the way the IC FSL 136MR is original one of Fairchild Semiconductor purchased online from Element14 India. So, please suggest whatever possible for this, will try to follow correctly. Thanks again.
 

Bidya

New member
the problem is main power supplys or the standby, have 5.6v ref on sec or is dead

Here is the pic of SMPS Board. By the way I could not understand "have 5.6v ref on sec or is dead". I think u r trying to say if I don't get 5.6v in Secondary side the SMPS shall be considered as dead forever. Am I right or something else. Can U please elaborate.
IMG_2162.jpg
 

Bidya

New member
first of all need to work stb source.
QM1 provide vcc ic pin 3 whit power on..

The IC FSL136MR I am using is the equivalent one suggested by its manufacturer (Fairchild Semiconductor). I have the datasheet of both the ICs which are similar. But, why it is not able to produce the required voltage of through its vcc pin to start , we r not getting it right. However, the IC u r suggesting will match or not, or will have to replace both the power ICs to work ??
 

kanon

Member
stb you or not. 5.6V
before starting to replace ic
if you already commented stb ic biper22a Replace it with a very good replacement and easy to fit
 

Bidya

New member
first of all need to work stb source.
QM1 provide vcc ic pin 3 whit power on..

You were saying about QM1 Transistor of my SMPS, I couldn't get it right first time. Now, I can see the QM1 Transistor in the SMPS. Is it the powering on or standby location/source of the SMPS ?? Please guide.
 

Bidya

New member
you have not answered the secondary 5.6 v
as I can guide you if you do not answer the questions

Sorry Sir, I was out of my home for two days n this site was also having some problem in last three days or so, hence could not reply to your query. We have tested the SMPS again, but there is no secondary 5.6V. Also the vcc pin is getting -0.1V from QM1. So, what next ??
 

KX36

New member
To clarify the above discussion, the main secondary may have no output but there should (apparently, I haven't looked at schematic) be a standby supply separately.

Rather than confuse the matter further, is there any voltage on any of the secondary side capacitors?
 

Bidya

New member
To clarify the above discussion, the main secondary may have no output but there should (apparently, I haven't looked at schematic) be a standby supply separately.

Rather than confuse the matter further, is there any voltage on any of the secondary side capacitors?

Thank U Sir, giving a look into my problem. We have tested, there is no voltage in any of the capacitor of the secondary side. Actually there is no current reaching to the primary pins of both the transformers. There is required voltage in the main capacitors of primary side. Thereafter what is wrong we r not able to locate. Please see the schematic n pic I have posted and suggest what could be done.
 

KX36

New member
FIRST, REMEMBER THAT IT IS DANGEROUS TO PROBE THE PRIMARY SIDE CIRCUIT OF THE TRANSFORMERS WHILE IT'S PLUGGED IN. I ADVISE THAT YOU DON'T DO THIS YOURSELF IF YOU DON'T KNOW WHAT YOU'RE DOING.

OK, I don't think you've got a great chance of fixing this yourself and my advice would probably be to replace the unit. Here's a quick description of how I think it's supposed to start up.

1. CL5+6 charge through input rectifier (to what voltage depends on the input voltage selector or autodetector).
2. CM3 charges through ICM1's startup current source.
3. Once CM3 reaches the UVLO voltage of ICM1, ICM1 starts switching.C41,C1,C81,C11,C31,C51,C71 and C73 charge up and the ICM1/T2 flyback converter is essentially working. However the linear post-regulators are all switched off. The only output voltage from the lower output connector that should be on at this point is the +5.6V ("standby") rail.
4. CA3 should charge up and the upper circuit (T1) should turn on, including the +34.5V output

The soft power switch circuit to turn on the rest of the outputs:
5. The P/S output is held low by Q51 until CM6 and CM4 reach their voltage, at which time optocoupler PCM2 turns on, turning off Q51 and the P/S output goes high.
6. Presumably the P/ON connector goes to a front panel switch which connects it to P/S (or +5.6V standby). When the P/ON input goes high, the linear regulators etc turn on (U61 +5V, U81 +3.3V, U31 +12V, U21 +8V, unregulated -12V).

You have to work out where in the sequence it's not turning on or whether it's turning on then hitting a safety protection feature and turning off again.

Some datasheets for reader's reference:
http://pdf.datasheetarchive.com/datasheetsmain/Datasheets-11/DSA-216391.pdf
http://www.fairchildsemi.com/ds/FS/FSL136MR.pdf
 

Bidya

New member
FIRST, REMEMBER THAT IT IS DANGEROUS TO PROBE THE PRIMARY SIDE CIRCUIT OF THE TRANSFORMERS WHILE IT'S PLUGGED IN. I ADVISE THAT YOU DON'T DO THIS YOURSELF IF YOU DON'T KNOW WHAT YOU'RE DOING.

OK, I don't think you've got a great chance of fixing this yourself and my advice would probably be to replace the unit. Here's a quick description of how I think it's supposed to start up.

1. CL5+6 charge through input rectifier (to what voltage depends on the input voltage selector or autodetector).
2. CM3 charges through ICM1's startup current source.
3. Once CM3 reaches the UVLO voltage of ICM1, ICM1 starts switching.C41,C1,C81,C11,C31,C51,C71 and C73 charge up and the ICM1/T2 flyback converter is essentially working. However the linear post-regulators are all switched off. The only output voltage from the lower output connector that should be on at this point is the +5.6V ("standby") rail.
4. CA3 should charge up and the upper circuit (T1) should turn on, including the +34.5V output

The soft power switch circuit to turn on the rest of the outputs:
5. The P/S output is held low by Q51 until CM6 and CM4 reach their voltage, at which time optocoupler PCM2 turns on, turning off Q51 and the P/S output goes high.
6. Presumably the P/ON connector goes to a front panel switch which connects it to P/S (or +5.6V standby). When the P/ON input goes high, the linear regulators etc turn on (U61 +5V, U81 +3.3V, U31 +12V, U21 +8V, unregulated -12V).

You have to work out where in the sequence it's not turning on or whether it's turning on then hitting a safety protection feature and turning off again.

Some datasheets for reader's reference:
http://pdf.datasheetarchive.com/datasheetsmain/Datasheets-11/DSA-216391.pdf
http://www.fairchildsemi.com/ds/FS/FSL136MR.pdf

Thank U Sir for your safety concern and solution to my problem. I am not doing it myself but with the help of a technician, what I learn here, inform him n accordingly the SMPS is tested. The technician though knows the basic knowledge of SMPS, but does not know it in depth. Another thing, the SMPS is of Samsung Home Theater HT-Z310 which has been discontinued and the replacement is not available anymore, hence taking up the task to repair. Anyway, thanks again for the solution you have pointed out. Work on it tomorrow n post the result.
 
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