Sony resistor values?

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most of the time in a sony receiver, when the output transistors are shorted and blowing the fuse, it doesn't take any more than replacing the outputs and fuse then you should be good to go. They don't usually require any resistors or other components to be replaced.

Transistor Problem


To replace the power transistors ( MN2488 and MP1620 )

• you need to have a technique in soldering.

( much faster is cut the transistors pins , but be careful only for

professional serviceman )


click on the link below:


Soldering Guide

After taking out the burnt transistors:

• get a multimeter and measure the DC voltages present on

each amplifier output stage ( center of the two resistors in series ).

• • it should be no more than 0.7 V, if it s, remove those pair of power

transistors and test again for output voltages.


the negative probe

of the multimeter to the chassis of the unit.


• Do not connect new power transistors yet.

you may need to power it without it.


Until you sure that the unit powers up and have some/other channel

working to prevent further transistors and components failure.





But if there are still more than 0.7 v on some of the outputs


• Check for VAS circuits and Differential Input Stages



Let me know how you make out with the inspection.

It is a good chance you will find something.


hope this helps, thanks for using Fixya!

The capicitors in the unit are charged. Replacing the output transistor(s) is not a task for a novist. Capicitors, resistors, driver transistors and sometime preamp chips can also be bad as well. If all the bad components are not replaced the parts you replace could blow out again.

Hi and welcome to FixYa,

Initially, the displayed message "PROTECT" is as it implies, the STR-DE185 has gone into auto-protect mode. The built-in auto diagnostics has sensed a fault and kicked in to prevent further damage to the Sony unit. In most instances, this is brought about by a faulty speaker (should be 8~16 ohms), loose/disconnected speaker wiring, strands of speaker wires inadvertently touching its opposite, overheated, ventilation holes covered, played with the volume level high for an extended period of time or a localized fault in the internal electronics of the amp circuitry.

Offhand, since DIY (do-it-yourself) repair is being done and assuming that you are comfortable working with electronic components & circuitry, use of a DVM/VOM, a soldering iron/station and safe practices with electrically powered devices, access to a Service Manual or at the very least, a schematic diagram would be a necessity.

1. consider doing a RESET. Turn off the STR-DE185, press and hold the POWER button for 5 seconds or more or till "INITIAL" message is displayed. This would force the Sony to revert to factory defaults removing any glitches, errors in settings & configurations, presets, memories and user preferences;
2. check if relays RY781 - to 783 are engaging;
3. check pin 8 of IC901 (should be 5.6V);
4. check protect switch Q784 to 786;
5. check overload detectors Q705 & Q706;
6. check that the MN2488 and MP1620 are not leaky
   

Good luck and thank you for asking FixYa.

Most likely bad output transistors and a couple of resistors. mp1620 and mn2488 are the part #s for the transistors. If you take it to a repair shop you are looking at spending $100-$130

Check the main fuse if it is open (blown) it will probably need output transistors MP1620 MN2488, if not it may need the main power transformer.

DO NOT use a slow-blow fuse this will cause more damage to the receiver!

The fuse opens due to a short circuit in the receiver most often it is a set of output transistors. mp1620 mn2488 are common in sonys

Ed,

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

The main and I think only fuse is a gma 6.3v fast blow.

DO NOT Use a slow blow fuse it will cause more damage to your receiver!!! If it opened once it will probably open again.

Odds are a set of output transistors are shorted (MP1620 and a MN2488)