Harman Kardon AVR 3700 / 370 Repair - Turns Off After 14 Seconds
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- Опубликовано: 4 июн 2018
- A common issue with Harman Kardon's AVR 3700 series receivers. This video shows you how to fix it. You are expected to have moderate electronics repair skills. If you've never worked on electronics before it is recommended that you do not attempt to repair these devices yourself.
Bought this receiver a year ago on eBay for just $80, fixed it , and recently found another on eBay for the same price. Used it in this video to demonstrate how to repair them.
The service manual and schematics for this receiver can be found here: arisux.com/upload/uploads%5Cse...
If you don't want to repair this yourself, you can send us your old power supply and we will repair it for a flat $50 fee, plus shipping.
Our website: arisux.com/
This video applies to the following receivers:
Harman Kardon AVR 3700
Harman Kardon AVR 370
Harman Kardon AVR 2700
Harman Kardon AVR 270 
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I had exactly the same problem in the same AVR model. I wore gloves and followed your video but soldering the caps under the board as suggested in another answer and was much easier, I have to say my AVR was completely dirty and I cleaned it deeply. It works perfectly ever since! I can not tell you how much appreciate the knowledge you share in the video, because even when the replacement is not that hard, knowing exactly what to replace is the real important thing to know and understand, Congrats and Thanks!
Thank you so much for your knowledge and this fix. I picked up my AVR3700 in mint condition at ( of all places) Goodwill for $20! It worked fine for a month then started shutting down but would come back to life in a couple minutes. This timing kept getting shorter until it was 12 seconds , then I saw your video and my burnt , and I mean burnt, caps. Replaced them last night and its been running just fine ever since! Thanks again!!
My reciever would shutdown like yours sometimes, most of the time it just froze on startup. Thx to your video I diagnosed the 2 5600uf6.3v Acon caps on same board as bad (slight bulge). Replaced with 2 Panasonic FM series caps from Amazon and I'm back in business. Thanks!
This 100% worked for me. I went with the 2kv capacitor to prevent issues in the future. You guys are badass!
Thanks! Glad to hear it!
Ri5ux, thank you!!! Problem was exactly the same and is now resolved.
Thank you so much for the video. I would have, probably, only replaced C984 (cracked and discolored) with the same part and in the same position again. Now, thanks to you, I now have 3kV capasitors (both C983 and C984 replaced) mounted on the signal side of the PCB, away from the heat generating MOSFETs. Again, thanks a lot from Sweden for this video.
Thank you mate, I have brought the same unit without knowing it was having the same issue who sold to me did not informed me either. I just dis exactly the same fix like you have shown here, ghis post saved me without trashing the unit.😀 again thank you again for saving my day 👍.
Wonderful and very useful video's.
Thanks a ton ! I have an AVR 2700 and replaced the caps but it blew a fuse shortly thereafter , Noticed a blown MOSFET so I replaced both 11N80C3 mosfets for higher rated 17N80C3 type . Works great now !
Thanks for the video.
I paid Aussie $60 and bought a couple of 3Kv 370 pF caps for Aussie 3.20 on the way home. Like someone else said, I pushed them away from the Mosfets and resistors. Booyah I have a working amp.
Thanks so much!
OMG you nailed it, both of my caps were black and cracked, would of been really hard to diagnose without this video, they are very hidden, I put the new ones under the pc board, there is a ton of room there plus they will be cooler there further from the MOSFETS and heat sink... thanks AGAIN :-)
Absolutely hard to diagnose, It took me an entire day to figure it out the first time since they're so hidden. That's where I put the caps on the last one I repaired (under the board). It's a good spot! Glad I could be of help!
Thank thank thank thank you so much! Just repaired my 370 following your Video, in my amp, only one capacitor was broken, ( C984 ) -50V side , and I've soldered C984 and C983 in the PCB side so far from hot mosfet.
I hope that, in this way it can be live more time.
Great job friend!
Glad to help! Always nice to save a good piece of technology from the trash!
Friend thank you i have almost put in the trash my hk avr 3700 your solution works like a charm, have a happy new year, greetings from Colombia.
Good to hear it was saved!
just fixed mine 30 min ago, the same t capacitors blown, fixed with 2usd worth of ebay parts, 471k 2kv buttons :)
works perfect.
thanx mate!
Thank you so much. I had the some problem. I changed the two capacitors and now it works perfct. :-) great!!!!!!!
I have an AVR 370 and the issue I am facing for quite some time is that after power-on, the AVR is struck up at the Startup screen for about 5 minutes (with source and volume level displayed). After that, the AVR boots up and functions. Also, the AVR gets hanged frequently if I try to access folders when playing music from USB drive or connecting to network. Is this due to any problem on the power supply board?
Thank you!!! I just fixed mine the same way. I put the capacitors on the underside of the PCB. Having the capacitors sit next to a heat sink on the top side doesn't seem to help longevity.
@Buyshop SP, this is interesting. I have a 3700 and just had this problem happen yesterday. I just replaced the two 471 capacitors and the problem still remains. To note, after clicking the power on, mine returns to the sleep state almost immediately, we're talking about like half a second. At first, like 2 days ago, the problem first started as a shutdown when the audio signal would increase with amplitude, like during an explosion in a movie. Not talking like loud volume; it was at around -30 dB on the nob.
Hi, One of them has exploded. it was black. I changed the 2 capacitors as described with 2kv 471 ones. The problem is still the same after power on. What can it be now ?
I have AVR 150, when I try to switch on, it switch on for a second and then the power on light keeps flashing . It would not switch on. It would be appreciated if you would give me some advice in this regard.
Hello, I have the AVR 370 model and it can not be turned on when turned on, the button and knob glow white and then goes out, what could be the problem?
If I disconnect the tape near the wifi it works normally
I have same receiver harman avr 3700 while updating firmware through usb not complete and systems totally down can you please help me for this issue how to communicate through RS232 port
any idea as to why my 3700 avr 7.1? volume outputs are low when using HDMI inputs . THis just started so the sound is very low even turned up to its notmal safe operating range. after about 2 min of use with very low volume the AVR shuts down but the orange sleep mode light on front is still lit. iv tried all hdmi inputs as well as sterio and optical it does the same thing. I love my AVR any help would be great mine is a 2012 model owned since new it has been a great machine i really hope to get it working again.
Thank you... I've bought it new and for the last year it's been giving me problems
No problem, glad to be of help!
Hello! I have same symptoms on AVR-7500 with big transformer inside. I checked transistors but it all Ok. I changed all capacitor to new on mainboard but it was not help. Can you give me advice where else to looking for ? Or can you help me using viber or other message software(I can turn camera on to show) ?
Thank you so much 😁 very helpfull 👍 thx man
I have that receiver but my model is ADS C270 and it's not getting any power what part of the state are you in do you receive shipment that you can work on.
I have a HK AVR 325 receiver with the same problem, it will power up for a couple of seconds, then back into standby. A murky world of mystery was entered, as I opened it up and looked for anything obvious (bulging caps, fried fuses, smoked resistors, etc.) but everything looked "normal". It's still here, collecting cobwebs, but am always open to suggestions?
Very thank you. You are amazing. I bought with this problem and i repair. it works well :D
Absolutely! Glad to be of help :)
Ri5ux Thank You :)
It worked! What a pain in the ass to do, but it worked. Thanks!!!
Can you tell me input voltage and output voltage of this transformers? This is the harman kardon Avr on 240 model. (UL VER :CLT 5J 033 zu. Trans. sub)
my avr 370 became not responds or slow respond while use remote and no sound out from speaker. whats the problem ?
Thank you
No. I have an AVR 525. For unknown reason its off in a few second and its in stand by. What is it?. Please
Great video! having the exact same problem with my AVR, but i am a bit unsure what kind of capacitor i need to order. Could you give me the specs so that i don't order the wrong one?
You need 471K ceramic capacitors with a voltage rating of 2KV or more.
How much pF should they be ?
Hello
I also have problems with my receiver if you help me .....
Harman Kardon AVR 3000 - Turns Off After 5-7 Seconds
Hi,i watch your video fixing h/k avr3700 I have the same problem i bought it in 2015 can i send it to you to get it fixed thank you.
AVR270 here. It wouldn't boot anymore but would still stay in standby. I went and replaced the two caps with 470 pF 2KV ones. However now the damn thing won't even turn on the power LED. I can hear a faint buzz from the power supply when I plug it in but no other signs of life. What I did differently was removed the top PCB (containing the HDMI ports) in order to get to the far screw on the PSU but I made sure to align the pins and plug the flex cables back in.
Hi. Thanks for a great video. I have a HK AVR5500 with exactly the same problem of powering off after some four (4) seconds. Could the same remedy help?
The AVR5500 uses a transformer as its power source instead of a switch mode power supply. This method won't work. It sounds like your receiver may have a shorted transistor on one of the output channels. You'll have to check all of them.
My Harman Kardon AVR 25 II just developed this problem. Is it transformer based or will changing out those capacitors work on mine?
The AVR 25ii is transformer based, this video does not apply to it. The transformer may be bad, it is about 24 years old, but it's hard to tell without seeing it. Honestly, unless you want it as a collectors item, it's probably not worth fixing. I'd recommend finding a newer receiver, that one was introduced in 1994. Just my opinion.
How can I reset my avr 370 pls tell me @Ri5ux
Same problem, I changed the two little ones, now it works but I don't have sound anymore
I have AVR 445 with the dame problem, do you think the capacitors id the problem ? regards
The AVR 445 is very different internally from this receiver. This receiver uses a switch mode power supply and the AVR 445 uses a transformer. Sorry, but that could not possibly be the issue with the 445.
Hi, thanks for the video, but how the heck did you unscrew the heat sink from the second FET that is hidden beside the small vertical board? no way to get access to the screw head ! you jumped straight to "I sucked the heat sink" , I've been struggling to get the screw out for 2 hours already.
I finally managed to unscrew the ****ing screw, I had to drill in the board in front of it very carefully. The amateur who designed this had a hole in the board planned, but the hole is too small and not aligned properly to the screw head, so there is no way to unscrew it unless you drill in the board. Plus they used crazy glue on the screw just to make your life more difficult. They may have corrected this on some boards versions but mine took a good 3 hours just to get the screw out.
Hi, sorry about that. That's my bad, I should have specified. I will add a notation in the video. The best way is to desolder the MOSFETs and heatsink from the board and pull it all up in one piece. and replace the entire assembly later. I learned this later on, but yes, I completely agree... terrible design.
To be honest what I did the first time is absolutely not the correct way, but what I did was align the screwdriver with the hole and gradually bend the risen board until I had enough of a grip to turn the screw. Smaller radius flathead screwdriver with a long handle works best. It can damage the risen board if you push too far, so I don't recommend it.
Only for future reference, I faced the same problem and solved in 2 different ways with out removing the heat disipator, one for each cap:
The one that is below the screw clear where the cable is screwed, The cap can be accesed with small tweezers lock the cap while you heat the soldering and pull it out. Then replace it in the same way using the tweezers.
For the second cap, remove it as the other one but you may find to put it back in the same place too hard, the easiest way is soldering it on the down side of the board, you will get the same result. You may want to solder both caps in this way.
Hi there! Awsome guide ty for this. When u bought those kompacitor did you search for kompacitor recievers or how u found them?
Thanks Peter Sweden
I salvaged mine from other boards, but if you search "2kv 471 capacitor", you'll find them.
@@ri5ux435 ty very much sir
I have a Harman Kardon AVR151 with similar issue. It will go to protection mode if the power button is pushed. The red indicator mode would switch to white for a couple seconds (with short hissis sound was heard) but turned back to red, and blinking. I lifted the ampli up should there should be something stuck inside the board, and powered it up again. Now it went back to normal (with long hissis sound was heard). I listened to the music for a couple hours. Turned it off (plugged it out) but when plugged it in back, the same situation happened. Again I shook the ampli for a couple second, and it was on again.
This routine happened a couple times and I have a feeling that the problem is not that serious. Can you tell me what is happening here?
It definitely sounds like you have a loose connection somewhere, whether it be on the power supply PCB or a wire plug. Without seeing it myself, it's very difficult to pin down and diagnose something like this. If you're interested in a little bit of experimentation, I would try opening it up, and while you have fairly thick insulated gloves on, lightly wiggle components like ICs or inductors until something changes.
Thank you for replying, after browsing in youtube, it seems I am not the only one. Here is a video of the exact problem: ruclips.net/video/hycrfPY2qAM/видео.html.
Upon checking on the comments section there are also a lot of people with this problem. Is this probably a factory's fault?
Thank you so much! Just repaired my 370 following your Video. It solved the issue with a shutdown after 14 seconds, but now I can´t get any sound out of it. Neither from amplified output nor pre-amped. Any idea?
Everything else is working fine. Including HDMI in- and output, graphical setup and so on.
Glad it helped you out! If I recall correctly, this can happen if your power supply is not providing the -50V and 50V rails. Make sure you have the amp board plugged into the power supply, if it is, be sure to test for output voltage on those rails.
@@ri5ux435 I checked it, all the connections were correct but as you said, I didn´t get the -+50V. I´ll check the mosfets next.
@@mio4mio Check the continuity between the -50V, 50V rails and ground. What values are they at? Check on the output of the rail and trace it back to the MOSFETs as well. It is possible that the inductor the MOSFETs are switching is bad, but is not very likely.
I have the HK 1650 and it appears the message "protected" and tunrns off. Do you think is the same trouble?
I´m on my own, some technican told me that was unfixable, but I don´t trust them :)
It's more likely a short in the amp side of things, but no it should definitely be repairable. Not necessarily easy to do though.
I am use Harman avr 270 but when on sound test not come but hdmi display ok and vol settings operation is very slow
My problem is most likely similar.
It started off as being problems with the on/off button on the front. Sometimes, it would just turn off the interface, but then turn on again after about two seconds, where the surround settings would have been changed to five speakers (I only have two speakers). Or sometimes, pressing the on/off button on the front would make the interface go off in about 2 seconds, where it would just turn back on. This has changed now:
After months with the situation mentioned above, the light in the interface and the volume button randomly turns on/off rapidly after a pop in the speakers (after having being turned on in about a minute) followed by loud noises from the speakers, which makes you wonder if the roof of your house is being scraped off. I have now completely stopped using the stereo, as it seems useless in its current state.
The situation might be a little bit different now though (after a week of random explosions from the speakers and sounds of large pieces of metal collapsing). It seems as the stereo completely turns off (except the light in the on/off button - it stays white) after about 30 seconds, and then turns on again after perhaps 30 seconds (it's a guess). The loud noises do not seem to be there anymore. But when it randomly turns off, the connection to my computer is gone after it turns on again - where I will need to completely take the stereo off of power to make it reconnect to my device.
It's a Harman/Kardon AVR 155 (looks quite different on the inside from yours).
I'm not really seeking help - just letting my frustration out, but if anyone has tips, I'll gladly read them.
Sounds like multiple issues. I've heard of similar issues to the loud noises being caused by a faulty HDMI port or cable. Intermittent connections here cause screeching sounds. As far as the power issue, you might be lucky enough to just have a faulty power button. You could try replacing it if you have the soldering skills to do so.
How long would one need to leave the device disconnected from power for the capacitors to discharge themselves and become safe to handle?
Some power supplies can take weeks or months to self dissipate. Some just a few minutes. It's hard to say for sure. I'd use a multimeter to check them for voltage. This is typically why I just carefully remove the power supply and use a resistor to discharge the caps
I just purchased a brand new in the box avr 2700 this week, ( yess in 2021 for a 2012 avr ).
Everything work great but if i listen a movie it shutdown/sleep after around of 1h . I put it ON again and will go in sleep in hour. Do you think it can be the same problem ?
It definitely sounds like it's related to one of the issues mentioned here. I would try jumping the fan override connector inside of the unit to get more air moving through it.
@@ri5ux435 ohh ! seem legit, i take a look and never see the fan run yet. The amp did not seem really hot but i will try this !
Thank you for the answer my friend !
@@pnzrwgn You're welcome, and yes, you're right. The fan rarely turns on, even when hot.
Mine has this exact problem, I have the same model (AVR370) however Mine was purchased in New Zealand so is 240v. The inside looks different to the one in the video and it does not have those small capacitors you replaced, two major differences i can see from a little comparison i did is the two capacitors you discharged in the video in the same place on my build there is only one that is twice the height (Probably the 240v thing?) there is no 2nd one. The 2nd diffrence is on the right hand side of the heat sink on the power board instead of nothing there like on your model mine has a box with a plug running back to the left of the heat sink into a socket right next to the closest large brown capacitor (to the heat sink). Any ideas what on my version might need looking into?
I helped someone with the 240V variant, it is the same issues, but the capacitors are in a different position. They are still next to the mosfets, hidden behind the heatsink. I can't remember specifically, but I believe you still need to remove the mosfets and heatsinks to get to them.
@@ri5ux435 Oh cool thanks heaps for the reply!, I had a closer look with a 1200 lumen torch after your rely and found them, they are both cracked. One silly question, would they still be 471k 1kv ones? I haven't pulled them out yet to see.
@@adamcomrie5957 I would recommend 2kv instead of 1kv, mine is still going on 3 years after the repair with 2kv caps. Other than that, yes 471 rated.
Awesome video, great to see people repair instead of buying new!
I've got a avr270 which switches off extremely random, could this be the same/similar issue?
It does sound like a similar issue actually. I had one that started out doing that once every 30min or so, and it ended up increasing to 5m, then 30s, and finally it wouldn't turn on at all and had a flashing standby light.
@@ri5ux435 mine has been doing it since 2 years, but sometimes it plays for hours without issues, sometimes is switches off almost immediately.
If you say this still could be the same issue I will try your repair.
I'm not that great with a soldering iron, so if it sounds like a different problem I'll rather take it to an expert.
@@666bamn Unless it increases in frequency, it's probably a different issue. May be heat related, the fans don't always kick in when they need to on these models. I forced mine on all the time.
@@ri5ux435 thanks for trying to help!
I do have extra fans cooling the Amp as it is in a cabinet.
Is the heating up quick after startup? Because sometimes it switches off within seconds after booting up.
And I can switch it on almost directly again, and then it may play for hours without issues
@@666bamn That is quite odd. Probably not heat related in that case. That's going to be a difficult issue to diagnose without hands-on diagnosing it. When it shuts off, does the light pulse or flash at all? Even momentarily or is it just solid off?
I followed your video and it worked like a charm! ... For about a week. Now the damn thing won't even power on. Orange light is still on when power is connected, but it doesn't respond to any button press. Any idea what could be going on here?
That's a new one. I haven't seen that problem yet. Quite possibly an amplifier failure, but if I recall correctly the system will at least try to power on for 8s and shut back off if that were the case. There are some signal pins on a ribbon cable coming from the amp used to assert error signals to the logic board. You should be able to find those pins using the schematic for the receiver. If you cover those pins on the ribbon cable with scotch tape and re-insert it, you the receiver will ignore the errors and attempt to power on (but may not actually produce sound).
@@ri5ux435 I don't think I've ever facepalmed this hard. Turns out I didn't push one of the pins all the way in during my original work, so it was only barely connected and must have gotten loose when I moved the receiver around at some point. It's working just fine. Thanks for your response though! And kudos for the video :)
I have an HK3770, standby light is on but amp won't power on.
PLS Ri5ux HELP ME!! i have the avr 161 recieiver,and short after powering on it goes to sleep mode.it have also a smps.but it little different as your smps in your video.i have buy this reciever to repair it like you shown on your video.but its diferent.can you pls advise me?please.you are my last hope.
Here is the service manual to your receiver: arisux.com/upload/uploads/service-manuals/harman-kardon_avr161_avr230_sm.pdf
The power supply likely has the same issue, you'll just need to locate your capacitors. Page 176 is the schematic for your power supply. I believe the capacitors you should be looking at are labeled C911 and C905. They should be nearby the switching MOSFETs.
Thank you sooo much for this video !
Just replaced C984 and C983 in my 370 but the funny thing is the amp still switch off exactly after 14 seconds :-)
Do you think something can damage them (C984/983) or are any other capacitors still damaged ? Thank you for your help...
It's a result of the -50V and 50V rails not being present. You can try testing without the two capacitors. If the issue is still present, the MOSFETs next to those two capacitors may have failed. If you have a multimeter, while the unit is off, try testing for continuity across any of the MOSFET's 3 pins, if you have any continuity across the pins, the MOSFETs are shorted and will need to be replaced.
@@ri5ux435 I just checked both options. Same problem without capacitors ( 14 seconds - off) and the MOSFETs are fine. Checked with a multimeter.... hmmm? If you have any others ideas.... thank you :-)
I was hoping to hear the amp voice on the tonight new year's party but bad luck :-)))
Happy New Year!
@@Pawel_GP If you check both the -50V and 50V rails, are you missing just one or both when you try turning it on?
@@ri5ux435 I checked ... It's -54V and 54V
One more observation. When I plug in the headphones everything is fine.
@@Pawel_GP I would check for shorts in your amplifier. Start with checking continuity between the speaker outputs and ground.
Works with a 470 pF 3000 VAC/VDC 5 mm capacitor or is it to high?
That will work perfectly. I use a 3KV capacitor on one of mine as well now.
Thanks!!
I have the same model, the problem with mine is that the fan does not turn on which causes the AVR to overheat and shuts down after a few hours of use. please i really need help with this problem
There is an internal header near the rear of the amplifier board where the fan speed can be overridden with a jumper.
Anyone knows if i can use 470pf 5kv capacitor? I have 471 1kv right now. Unfortunatly the only one i can get is 470pf 5kv.
As long as the farad rating is the same, you can use any voltage rating above the original. I recommend 2kV, but 5kV will also work.
Hello my friend, I have the same model 3700, my amp doesn't go off after 14 seconds, it goes on playing for about an hour and then I turn it on again and it goes for about the same time and so on, do you think changing the capacitores will fix the problem? Thank you for your help.
If I understand correctly, it shuts off after about an hour, but you can turn it back on again and use it for approximately another hour? If yes, the issue will get worse over time, so you should replace capacitors C918, C921, and C943. You should also bridge the "FAN Test" header with solder to force the fan to run at max speed all the time. It will be louder, but will prevent the issue from occurring again.
@@ri5ux435 Yes, that is exactly the problem, and I thank you so much for your promt answer, I will follow your instructions and fix it. I thank you again. Best wishes for the new year.
@@romulosantos8019 You're welcome, glad to help. If it persists, feel free to ask for more assistance!
Yes my friend that is exactly the problem, I will follow your instructions before it gets any worse. Thank you very much for your fast reply, very much appreciated. Have a great New Year.
@@ri5ux435
I'm sorry , just one more question are those capacitors located in the same section that you worked on in the video?
This seems to be a common issue. I have an AVR-7200 that does the same thing. It's been sitting on my closet floor for the last 10 years or so.
Indeed so . . . my HK AVR series has become a magnificent cobewb collector. It powers up for a second or two, then shuts down into standby mode. Quite a few similar descriptions appear with a google search.
nice
Most of the Harman Kardan AVR receivers having problems after 1 year. Why aren't installing quality components in the Products?
Hi, I have the same issue with my AVR 370 device, shut down few seconds after start, but not permanently (sometimes it doesn't shut down instantly but after 30mn, 1hr use,...), do you think it is the same root cause (2Kv capacitors)?
If yes, I would like to replace them, but I can't find any vendor providing them (DEBB33D471KN2A from Murata), seems they stopped the production. I'm not an expert... I found a website (digikey) where they propose a substitute (CK45-B3DD471KYNNA from TDK), do you think it would match? thanks for your video, really helpful!
It is very possibly those capacitors, it could also be C918, C921. When it shuts down, can you turn it back on immediately? If you do, does it shut down quicker the next time?
Also, you don't need to have the orignal brand/model of capacitors. Any 470pf 2KV ceramic capacitors will work.
@@ri5ux435 You're right this is the scenario : we start watching a movie, and at a time the device shuts down suddenly, with a loud noise. I turn it back on and it shut down again quite immediately...
Is it the same issue you described in you post?
@@kadlin791 Yes, that is caused by the receiver overheating. C918, C921, and C943 are bad. If you replace them it will resolve it, but you also need to find the "FAN Test" header on the amplifier board and short the terminals together. This sets the fan at max speed, which isn't terribly loud, but it will prevent further issues.
Should work on the avr-2700
Can I use 470pf 3kv
Yes that is perfectly acceptable
Sadly, that great Video came a way to late for me. But next time I can repair it on my own instead of spending 100 € for repair. I really love that Receiver but sometimes it drives me crazy >.
Sounds to me like the channel was somehow blown without shorting the output transistor on that channel. Most of the time they fail shorted and it causes the receiver to shutdown. Not sure though, it could be preamp side. Could be a couple different causes.
My amplifier comes on protection mode and if i remove the power cable which goes to the amplifier board its getting switched on all the MOSFETs seems to be good the jig -vcc grnd +vcc
Please any hints
Sounds like a similar issue to that in the video. Is it the same model? If not, which model is it? Check for resistance across VCC- GND and VCC+ and post your results.
Thank you for your reply. The model is AVR 370/230
@@MuhammadArif-lh7oh Which is it? The 370 or 230? Those are completely different models with completely different ages.
@@ri5ux435 Hey, I have a problem similar to Muhammad. My AVR 3700's 471 Caps were bad and I replaced them, but when I turn on the unit light goes from solid standby orange to white for less than a second and turns back orange, same as before. When I disconnect my amplifier board (CN20) I can turn on the unit and all connected components appear functional, The unit is stable and remains on. I've done what
Eivind suggested with the 1k resistors and verified that all the 5 volt outputs are reading properly and that the amplifier output voltage is working (I think). The voltages on CN20 are as follows: V[VCC(+50V)-VCC(-50V)]= 54.4 V, V[VCC(+50V)-GDND]= 27.1V, V[VCC(-50V)-GDND]= -27.27 V. Does this look right? If so, where should I start on my amplifier board? Thanks!
If anyone is experiencing an issue where the power light is flashing orange and won't turn on, I have the fix for that too. It is caused by excessive heat damaging the following capacitors on the power supply: C918, C921, C943. Replacing them will fix the issue, but it will happen again unless the overheating issue is resolved as well. In order to fully resolve it, find the "FAN Test" plug on the amplifier board, and bridge it. This will force the fans to run at full speed, and it will be louder than usual, but it prevents further damage. It's hardly audible if you have it in a cabinet or further away anyhow. Very solid receiver after these issues are taken care of.
i have no amber light no power at all on my harman kardon 3700 any help would be appreciated thank you for the video hope you can help me
@@frankserrano6665 I would check the standby circuitry. There is an IC that handles it with the part number OB2358AP. It's the closest 8 pin IC to the smallest blue taped transformer on the power supply PCB. If this IC is bad, you will have no standby power, or fluctuating power. If this IC is good, it could simply be a blown fuse. If the fuse is blown, there is likely a bad mosfet and capacitor on the main switching circuit.
I tried to replace the C918,C921 and C943 electrolyte capacitors on the Power supply board with no luck. The power LED is still blinking orange. I also changed the two 470pf ceramic capacitors. Do you got any other suggestions? (What makes the led blink orange and how is the power supply turned on ) 🤔
@@eivindamundsen7090 There is another scenario in which the power LED may flash. You may have bad solder connections on your standby circuitry. I would apply fresh solder to the joints on IC OB2358AP and the inductor/transformer directly next to C918.
@@ri5ux435After scratching my head for 10 hours I found the issue to be somewhere in the standby circuit. I get ~ 4.80V on the ST+5 pin and but asson as I pull .5 to 1mA the voltage drops to 0 and rises again to around 3,5v before it drops again. If I apply ~13v to pin 7 of IC92 (ICE2B365) i get the 5V up running and i can enable the 50V (-25 0 +25) "supply". (so both the 5v and 50v circuits works ) I just ordered a few OB2358L (IC91) and KA431SAMF2 (IC96). I suspect there is an issue with the OB2358L ic or maybe a bad connection (internally ) at the primary side of the TF91 transformer/inductor. But I will try to resolder the IC and the transformer/inductor.. Thanks for your reply! :)
Btw: it's super easy to replace the 470pf capacitors with a tweezer without removing the Mosfets/heatsink.
completing my comment: when the receiver was ok, before the problem (and changing the capacitors) , i was at another room. Receiver was on , and working. i think i heard a loudy sound, and then it was off , and with this problem of exploded capacitor.
Check the mosfets next to the capacitors. It is likely they are shorted.
Thank you very much for answer! I sent the receiver to an assistance, and told them what you said. They told me it can be the mosfets. I m waiting for them , and probably tomorrow i will have a position.
@@buyshopsp5375 Sounds good, be sure to let me know what they find out!
Hi, assistance said nothing wrong with mosfets. i found the service manual and sent to him. He said that he thinks power suply is ok. That service manual could be usefull to repair the power suply only.
He thinks the problem is with the hdmi board. I don t have ideia. I think i will try to send it to a Harman authorized. (I m in Brazil). What do you think? Can be the board that has all the hdmi ports?
This can be a usefull information too: First when i saw it turning off itself, i reseted the receiver. But it seems it was ok. it turns on at FM radio normaly.
@@buyshopsp5375 Which capacitor exploded specifically? One on the power supply, amplifier board, or logic board? If you could provided the component ID number, that would help too. Also the service manual provides schematics for the amplifier and power supply boards. I think it also provides the schematics for the logic, but cant remember off the top of my head.