PIONEER SX-255R RECEIVER AMPLIFIER REPAIR.

PIONEER SX-255R RECEIVER AMPLIFIER REPAIR.

[@t-rodshader9593]

almost everytime I find one of those pioneer amps like that, the amps always go, I usually get the ones with the separate board/heatsink/transistors, people always has those and they weren't bad sounding amplifiers, they were just troublesome when they started dropping resistors and transistors, I've had some experience with those and can definitely say the rail to speaker is one of the most common issues because of the shorted transistors, Ive had them also blow a resistor and produce half wave, and I've seen them backfeeding and fry half the transistors and resistors in the preamp section, have fun, lol. BTW I like your channel and appreciate someone like myself and my fellow people who get into this stuff and actually takes the time to try and share it, you do a great job, and you share alot of things I try to share with people and you are a good teacher and have good advice

[@MikeRR142]

Really appreciate how you explain your thought process and walk thru it step by step. It’s educational and entertaining at the same time!

[@Finite-Tuning]

Never be weary of a 60+ min video, if that is what it takes then I will sit and watch/listen! Whomever dreamed up the 10 Minuit video rule is not me or anything even remotely close, I love the hour long videos! Take your time and tell/show your story; nothing is better then that! It takes what it takes, however long does not matter, not to me at least. As always, thank you for making these vids.

[@viewer54322]

Agreed

[@jeromeclarke4141]

From Suriname 2019 December 6 well done ,,i have a SX 205 that was out,,now i have it on after repiring but there is no sound ,i am 64 years of age and love this work .

[@Darryl603]

Nice job cleaning up that transformer. Thanks for explaining how the schematic translates to how the circuit works. That was very helpful. Thanks again for sharing. My stereo's a little more complicated than that pioneer though lol

[@SuperBoobaloo]

Just discovered your channel. Loving your vids. Keep it up.

[@MrMac5150]

Love these type of videos, would like to see them daily.. Thumbs Up-.

[@shamuutube]

Thank you this video helps me out a lot.

[@telephonelineman]

I just picked up this 255R receiver at a hospice thrift shop for $ 32.00. I hooked up to my speakers and powered it up and It works great. I had my fingers crossed buying it secondhand without trying it out. My Pioneer vsx 504s has a problem with it's output driver. A scratchy static sound after a few minutes. Now to get it fixed.

[@johnpartridge7052]

Very interesting and great job 👍

[@saarike]

Very nice and informative. Thanks!

[@JustFun-iz9rf]

Love the trouble shooting. Thanks

[@bundylovess]

Grate video mate big thumbs up

[@Insane92]

My sx-255r would power off by itself and the display lights would not light up while powered on. I noticed when I would move the power cord inside the receiver and it would turn off and then turn back on. I then realized I had to solder the positive and negative power pins on the motherboard. Did that and it works just fine. No more shutting off by itself issues.

[@saarike]

Nice video!

[@redfelipe6565]

Well done, thank you. Like.

[@aaroncarlson5637]

How can i hook a pioneer m970 amplifier to a newer receiver or avr..the m970 got that cable strip that plugs into the partner preamp cx970 you have any suggestions

[@mortenrolsing7137]

Nice video, thanks :-) Subscribed, hopefully for more troubleshooting videos. Greatings from Denmark. Morten

[@The_Active_Region]

Thanks, I will have more vids..

[@mortenrolsing7137]

:-)

[@MichaelBeeny]

With all those issues, I was amazed that you did not have DC on your speaker outputs.

[@2010stoof]

I have had this receiver since new and not had any issues. But good to know there's videos like this to repair it!! I can't seem to get the cover off mine. Got the rear lifted enough to blow it out from time to time Is there a trick to getting the cover off from the front display facing? I unscrewed the 4 screws jn the back and the 2 on the side. Am I missing some? And now after watching this very technical video I know feel foolish about asking how to open the cover. But I seriously can't get it to separate from the face where it tucks in there.

[@p8051a]

Great video! I'm in the process of repairing the exact same model and I noticed pretty similar damages. In my case the ceramic transistor pack was also open (along with the output transistors which were shorted) and I'm now waiting for a replacement power resistor. Have you ever attempted to place a piece of wire instead of that 0.33Ω resistor just to briefly check if the dead channel comes back? I could certainly wait for the replacement part and do it properly but I was just wondering if it was safe to do so for a short period of time (seconds)..

[@slimjim119]

cool well done

[@annafan83]

Thank you for this video :-)

[@louistonshepherd6438]

annafan83

[@sonny1980]

Can I use regular alcohol to clean it? My own has distortion on one side of the speaker. Thanks

[@janakapriyadarshana5835]

What is the formal coding layer on the top of tracing?

[@TECHNOGEEK20000]

I have a question and hopefully I can get an answer. I have a pioneer sx-251r that the am/fm tuner does not function. It will act like its working but all I get is a popping noise when I try to tune in anything. Bad chip(s) maybe? Also it always thinks it does have a signal as the stereo and tuned lights are constantly illuminated so another clue that I think it may be a logic issue but I dont know. Tried to locate the service manual for it but for that model I cannot seem to find anything and no youtube videos show up when I search for this model. Any advice is GREATLY appreciated. Receiver works great otherwise just cant use the radio. I would love to get this working if anyone knows anything that can help me. Thanks!

[@preppersintent]

Right around the 23 min mark,Wow my computer would have taken 30 seconds to reload the lost page...lolol!

[@jimbo3431]

What kind of cord do I need to connect my iphone to the phone jack port?

[@LifeSized101]

Found ya / subscribed AND There might be a fix for my SONY DA1200ES . The LEFT FRONT channel faintly works . A 100 watt x 7.1 AV receiver though

[@lajson]

Good vid kev, very clear and explanatory. It's a way to learn good trubbel shooting! I have one little question kev. I have a denon PMA-700V which is a very nice amp but after I changed the main filter caps and powered on it developed some " magic Smoke" on the lef channel preamp section. When I later tested the amp with variac then one resistor and one transistor got very hot. Do you think I should change the whole preamp section or just the ones which are getting hot? I would love to fix this amp because it has lovely sound and it's very musical.

[@The_Active_Region]

The ones may be getting hot from something else wrong with the pre amp. You will have to probe the circuit for shorts of diodes and transistors etc.

[@lajson]

Thanks Kev, I'll do probe those transistors, one more thing, could you do some vid about how to properly measure power output on power amps with oscilloscope and how to calculate the real output power?

[@The_Active_Region]

I don't have all the right equipment to make that calculation accurate. You can always do ohms law math to get you close.

[@coreyfellows9420]

Hey fellah, I have a handful of equipment needing minor repairs.. What are your rates?

[@UbaidKhan-xt7dt]

I have Pioneer vsx-425 left channel not clear how to find the bad resistor or etc ....

[@simon_a_s]

Love your videos! I have recently started to troubleshoot some amps with various faults so these instructive vids helps alot. Have one question though, one amp I'm dealing with - a car audio amp; Alpine 3544 keeps bugging me. When I opened it I saw 2x diodes burnt from the board (large 3A rectifiers across the power line), one had cracked from heat I guess. I changed the diodes and checked all transistors for shorts but there's nothing obvious. When I'm starting up the amp, it turns on with a current draw of about 1,2A then, after like half a second the current draw rises with 2A/sec until my power supply goes into CC. What could be the possible cause for that "slow" rise?

[@The_Active_Region]

+Simon A S sounds like a bad fet or fets. They could be latching up due to a bad fet or surrounding conponent.

[@The_Active_Region]

The diodes maybe burnt from a reverse polarity hookup and may have damaged other stuff as well.

[@simon_a_s]

All the high power transistors are BJTs. I checked them today, in circuit they were showing shorts between base-emitter - both ways (NPN-power section). When I took them out they read ok. All the big caps ECR ok as well. The audio side all transistors read normal in circuit when testing PN junctions. Found a loose connection on a small poly cap going to some comparitive IC. Haven't come any further though. I tested the transformer windings, and resistance is very low, like 0,3ohms and on two of the windings the meter don't detect any inductance, only resistance. Dunno if that's supposed to be like that... Thanks for the reply!

[@The_Active_Region]

When you found a short before you pulled the parts out and the parts were ok. Make sure you test to see where the short was from and that it is supposed to read that.

[@simon_a_s]

I've been doing some more troubleshooting and with the resoldered cap going into the upc494C (which apparently is the PWM IC), the amp does light up. However it's still drawing a massive amount of current. I tried setting my bench supply to 12,8V @ 2A and it drops to 7V with CC limiting, I poked around checking for components that are heating up and the dual rectifier diodes are getting really hot. Measured almost 120V p-p spikes with my scope on the center pin and if you turn up the current limiting even more to about 3 amps there's audible noise coming from the large transformer coil. Perhaps there is a short on the audio output side anyway? I'll desolder the transistors there tomorrow =/ Again thanks for the advise.

[@MrMac5150]

Kevin Question. If after you put in the so so transistor, if after test, loaded signals are the same running even with the same peak to peak voltages, why order a special transistor, why not just leave in the close beta value one you used for testing. if so close you would never hear the difference. Please correct me if I am wrong

[@The_Active_Region]

The part did not cross exact. I could leave this in but the voltages and gains are not an exact match. You always want to send work out with same crossed parts as the original. If not its kind of hack. It can be noted that it will work and you can get away with it, but I wouldn't want to see the unit on my bench again due to a future failure.

[@jeffharker6851]

I have a pioneer sx-255r receiver amplifier that I turn and on the display it shows the word "turning" for a few seconds and then a radio station is displayed for a few seconds and fine it flashes "no power". What is my problem and how do I repair it?

[@ElTexMexAlex]

Nice video, but where did you connect your function generator probes?

[@davodduncan]

GREAT VIDEO , HOW DO YOU UNDO THE RIBON CONNECTIONS FROM C BOARD , I AM STRUGGLING . THANKS DAVID

[@The_Active_Region]

I don't remember disconnecting any ribbon cables on this unit. I just unscrewed the back panel and some other screws and the whole amp board folded out of the amp. I would assume they would need to be un clipped and pulled out or un soldered depending on the type of ribbon connection.

[@roymcalister1878]

I have one that will not change from tuner to CD to radio etc. Any ideas?

[@runneryg]

MY PIONEER WILL NOT POWER ON AFTER I HAD A CAC POWERED FROM MY LAPTOP TO THE AMP HAD IT FULL BLAST AND THERE WAS THIS BURUNG SMELL. WHERE TO START? I CHECKED THE FUSE ONSAID AND ON THE PLUG NEEDED CHANGING STILL DID NOT POWER UP.

[@entoletao]

what model is that microscope you use ??

[@speedysteve9121]

My sx251r is not turning on. Any ideas?

[@williamwong5627]

Wonder why there was water damage? Having a beer on the top cover of the amp.

[@ianfelix2139]

its not so simple to fix but what power amp u work on

[@arjunperneti2968]

Bro Im using same amplifier the problem is if i increasing sound it will turn off how to solve it plz

[@rameshkadagala2831]

I have pioneer VSX 323k 5.1 av receiver it's power on incially audio coming excellent but after 5 minutes audio gradually down and all channels noise disturbance & missing sounds no audio what can I do please kindly help me. Thank you

[@mdzacharias]

I cringed when you went to the emitter resistor with that scope probe. The grounded collar was within a couple millimeters of the amp output. Been burned that way myself. Brrr.

[@jhunenriquez8551]

Hi Kev, l have an Sherwood A/V DSP Pro-Logic Receiver RV-7050R. The Right Channel does not working, what parts need to be replace? How much it will cost?

[@The_Active_Region]

Email my channel Email for repair inquiries.

[@leoncaudill7914]

Kev31779 I have a pioneer sx 680 that hymns really bad and it doesn't seem to select different outputs like aux and phono whats the best option

[@Lickemstick]

Dare I ask? What would be your favorite brand of Receiver? Thoughts on Denon or, say Yamaha?

[@The_Active_Region]

+Jeremy Schoonover Both are pretty good brands in my book. I own both and it is hard to say. Depends on price range and what it can deliver. If i had to pick I would choose a nice Yamaha.

[@Lickemstick]

Kev31779 Thanks for the timely get-back and the information my friend. You do great work.

[@The_Active_Region]

Thanks

[@MrBlokc]

my sx-255r powers on but the lights don't come on. what do I need to do

[@coreyfellows9420]

Likely just a bulb or something easy

[@alanarmstrong2323]

I have an optimis recieved that looks just like this

[@Electrolab28Ag]

Good trouble shooting. Not too much of a rabbit hole.

[@Acidtool0]

I'm not seeing your email for contacting for repair anywhere. Would you mind shooting me a link please?

[@The_Active_Region]

[e-mail]

[@ianhua3823]

Alpine Mrv-1505

[@PurpleDreki]

Plant stand...omg.

[@PhuckHue2]

receiver with open vents at the top used as a plant stand? owner needs all electronics removed from his house

[@The_Active_Region]

Yes bad idea. It was a trash pick I think.

[@peterjmcgee4680]

Can we move on with it already

[@The_Active_Region]

Relax. Use the timeline scrubber.

[@MrTopsoil911]

Ur vol on ur vids too low

[@olivierrakotonyrina3855]

vous pouvez me donner un shemas d'un amplificateur de puissance de 20 watts

[@peterjmcgee4680]

tell the truth Pioneer has become a big pile of crap because they no longer make equipment that is worth buying it's such a cheap garbage that and they charge so much for it that it's not worth buying and the way it's built it's built to fail and we live in a by and throwaway world that at the time the stuff wines up in the landfill because they want too much money to repair it for just the same reason it's too hard to work on because you can't access the bottom and they designed it that way so nobody wants to work on it so they can take some of the people throw it away and I forced to buy a new one