Question about Sony STR-DE675 Receiver

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Sony STR-DE535 This amp uses the MP1620 and MN2488 complementary pair. There is a diode included in the package between the collector and emitter. I tried fitting an external diode across the pins but it doesn't work... I think the biasing characteristics of these transistors are pretty different to conventional output devices, so you will have to use the originals. If your amp includes the upc2581V then replace the 220uF/10volts caps around these chips as they cause all the problems by drying up and producing spikes or overvoltage. This may blow the outputs. I'm still working on this amp as I write this note. I found Q651 and Q655 shorted (due to the spikes) but still no joy. It's only a Pro-Logic amp - worth bugger all, but the customer loves it and will pay top dollar to get it fixed. Hopefully tomorrow will be a better day.... RPG

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Sony STR D865 5.1 channel receiver blows the 6.3 Amp 125 Volts fuses that send power to the MN2488 & MP1620. Tested with an ohm meter and there is zero resistance between the collector and emitter on both...


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.

Mar 02, 2017 | Audio Players & Recorders

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I am facing a problem with a SONY amplifier, model STR-DE185. On its screen is written the word ''PROTECT''. I have checked the transistors MN 2488 and MP1620 and are OK. Could anyone tell me what else...


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.

Apr 20, 2010 | Sony Audio Players & Recorders

1 Answer

My STR-DE835 receiver will not stay powered on


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

Nov 16, 2009 | Sony STR-DE835 Receiver

1 Answer

What fuses does the sony str-de535 need


I beleive it is a 6.3amp gma. It will be printed on the circuit board next to the fuse holder and on the fuse itself. If it is open(blown) you probably will need to replace a set of the output transisters (mp1620 and mn2488). DO NOT use a slow-blow fuse this will cause more damage to your receiver.

Oct 21, 2009 | Sony STR-DE535 Receiver

1 Answer

When I power the reciever on all i hear is a click noise and it does nothing else.


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!

Oct 21, 2009 | Sony STR-DE485 Receiver

1 Answer

Sony reciver blows the fuse when i turn it on


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

Oct 16, 2009 | Sony Audio Players & Recorders

1 Answer

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


Ed,

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

Feb 22, 2009 | Sony STR-DE935

1 Answer

What type of fuse does the sony stereo receiver model number STR-DE597 have.


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)

Jan 24, 2009 | Audio Players & Recorders

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