Question about Sony STR-DE935

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Hi, on my Sony STR-DE935, Fuse #801 keeps blowing.Is it caused by a shorted bridge rectifier or one of the voltagr regulators, or am I looking in the wrong direction? Thanks, Ed Knight

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  • wirelessvent Feb 23, 2009

    Hi Johnwdarts,

    Thank you for the information as you were correct in saying that the problem could be on of the MP1620 or MN2488 transistors. After doing a continuity check on these components, I found one of the MP1620 transistors to be shorted! It has been many years since I have done bench work and it was fun solving this problem with you advice.

    Thanks again,

    Ed

  • Anonymous Mar 21, 2014

    My fuse keeps blowing some lights work except main lights don't

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Ed,

It could be one of those but most likely it is a set of shorted output transistors. MP1620 MN2488 in most sony receivers.

Posted on Feb 22, 2009

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1 Answer

Hi. I have a samsung le32. It won't turn on and keeps blowing the internal fuse on the power supply board.


Sir it indicate that there is a shorted part, common parts are the regulator and the bridge type rectifier try to check this part or replace them or you can contact a service technician to do it for you and save you from stress good day and best regards.

Sep 11, 2011 | Televison & Video

1 Answer

Turn on the unit the 120v 6amp fuse blows right away


Hi,
This is an indication that you have a short on 1. Power cord - even low of chances but still to be checked. 2. Rectifier Diode 3. Transformer 4. Voltage regulator IC/transistor 5. Main filter Capacitor.

This is not DIY and can't be fixed without some test instrument so I've advice you to look a technician to isolate the shorted parts.
Hope it may help you.
Thanks for using Fixya. JDVillanueva

Feb 06, 2011 | Sony STR-DG520 Receiver

3 Answers

No Display, no sound- not working, showing dead. But input Power is ok. Picture tube filamment not getting power. model sony KV-2192M3


Hello
Check the input fuse first. If it is blown, there will be some short inside the power regulator circuit. Usually Sony sets uses STR regulated power supply. You can see this STR, and Ic, screwed onto a heatsink. Replace it with a same type and number. Before replacing the STR, check the diodes used in that section for damage, mainlu zener diodes. They might get shorted along the blowing of the STR. Check that section throughly before resoldering the new STR.
If any further assistance you needs, get me through Fixya. Ok.

Nov 27, 2010 | Sony FD Trinitron WEGA KV-21CL10 21" TV

1 Answer

In my tv fuse is blowing off immediately


Hello
If fuse blows off immediately, i means that there is a short circuit occured in your telivision. This can mainly due to some diodes or regulators inside your tv. An overvoltage, spikes, ie [sudden high rise and go low], in the supply votage in your home, could damage power supply regulator components inside your tv.
All Sony Tvs has high accuracy power regulating systems inside. It is an onboard assembly, usually take 1/4th of the area of the TV. In older Sony TVs, this section was built in with use of transistors of different types. But your tv is not so old, so its power supply system is built with an STR, an Ic meant only for power regulations. Normally it willb numbered STR S6707, STR S6703 etc; according th the working voltage of the main board, and screen size of the TV.
This STR may get shorted due to power fluctuations, or any other reasons. A I mentioned above this is an Ic look like small squuare biscut of about an inch in square, and will be black in colour.
The rectified main power supply is given to it via an SMPS transformer [Swiched Mode Transformer], and the Ic will swictch it on and off at the rate of sbout 25KHz or more, and this transformeres secondary voltage is used to power up the other part of the ciiruit board.
If the fuse is blowing as soon as the set is switched on, this Ic will be faulty [Shorted inside]. If you put an another fuse, it also will blow up due to short. It is not good to play with power supply system by doing this as it may harm to other components also.
You have done it I thinks. Here in India, we gets 220VAC as home power supply. Sony TVs used here have a fuse rateing of 250V 3.5Amps. If your household supply system voltage is also this you must put only this rated fuse. If it is 110 or 120VAC, the fuse rating may differ; and will go upto 6 to7 Amps. More than this rated fuse should not be used.
You just do one thing. Just open the back cover of the TV, locate the power regulator section, and chech whether any main rectifier diodes for leak. There may four of them. In some sony Tvs, rectifier stalks are used. Check it for leak. If thery are all good, measure the resistance across the main filter capacitor with a multimeter set in Ohms range. If the STR said above is short, the meter will give full scale deflection. Unsoder the STR and pick it out after loosing its fixing screws to the heat sink. Again check the resistance accross the main filter capacitor. It must sho a low deflection or no deflection at all. Never replace the STR with a new one as there may be some other faulty components in that section. Usually when STR fails, there are some Zener diodes, Wire wound resistor etc will also gets shrted. If you replce the STR before checking them for fault, the STR you puts in will get shorted as you swich on the set. It will take just 1/100 part of a second.
So check all the components related with power regulator system, and then only repace the regulator. Caution: Keep chlidren away from you while you open the tv. Never touch any part of the circuit board while power supply is there. Plug out from the wall socket each time you touch the printed circuit board. As your Tv screen size is 32", an approximate of 25KVDC [15,000VDC], will be present at the first anode of the picture tube while it is working. It is too dagerous to contact.
If you haven't through knoledge, skill and patience, never try to repair it. If you knows to follow its schematic digram, buy one book and follow the circuit.
Keep an adult beside you as you try to repair your set, as a precaution.
If you have any doubt, report to Fixya, they will give me alert. Ok

Oct 20, 2010 | Sony FD Trinitron WEGA KV-32FS120 32" TV

1 Answer

Have a Sony STR-DE635 that keeps blowing the 2 8 amp fuses in the power supply. disconnected all speakers and powered up with same result. Checked bridge rectifier and (2) 10000 uf caps all are good


Have you checked the rails to ground for shorts. Get hold of a variac as it does make things a lot easier.

Sound like you might have some shorted output devices.

Hope this helps
Thanks for using FixYa

Aug 18, 2010 | Sony STR-DE835 Receiver

1 Answer

I got to replace 2 fuses from a sound board of a reciever Sony STR-DE935 but I lost the old one and now I don't Know how many Amp and volts should I buy to replace it .where I can get it?


If its the sound board both fuses are the same. but if they blew you may have a bigger problem like output transistors shorted. But try replacing fuses first if they blow again thats your problem. Good luck

Jun 02, 2010 | Sony STR-DE935

1 Answer

Blows fuse


If the line fuse keeps blowing fuses when the unit is plugged into AC, then there is a short in the Primary side of the power supply, usually the bridge recifiters or a shorted Diode rectifier or power regulator.

Dec 15, 2009 | Televison & Video

1 Answer

Fuse keep blowing off


If the fuse keeps blowing, that is an indication that something has failed and is drawing too much current. Most likely it could be a problem with the power supply, such as a shorted rectifier diode or voltage regulator. Another possibility could be a shorted audio output module. Unfortunately, you'll have to take it to a repair center to be serviced.

Please let me know if I can help you further.

Good luck!

- Jim

Feb 01, 2008 | Sony STR-DE345 Receiver

2 Answers

Fuse keeps blowing


NEVER EVER replace a fuse and think that va fuse will blow all by itself. The fuses are there to protect the set from catching on fire incase theres a short inside the set. Now in some cases an intermittant short can work after you replace the fuse but if its burnt black or brownish, theres a short inside the set in one of the circuits. always use a 100 watt light bulb across a blown fuse if your not sure if there is a short. if there is, the light will absorb the short and glow bright. if there is no short the bulb will glow bright , then go down very dim. you could have a main power supply problem, such as shorted bridge rectifyers,shorted main b+ capacitor, Hot could be shorted, or the Vertical or audio output IC could be shorted

Sep 06, 2006 | Panasonic CT-32SX12 32" TV

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