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-   -   Harman Kardon AVR 270 (https://www.badcaps.net/forum/showthread.php?t=76451)

R_J 05-16-2019 05:57 PM

Re: Harman Kardon AVR 270
 
Yes, I scrolled up too far to the Center channel
If R723/725 are open transistor could be bad, also check the base resistors, R647/652, then work back checking the driver transistors and resistors. comparing same components to a working channel is helpfull sometimes

playman 05-16-2019 07:08 PM

Re: Harman Kardon AVR 270
 
My DCA55 says that there is a short between Collector and Emitter on Q652 trans.
The other two seem to be ok.
Will be testing rest of the stuff tomorrow.

playman 05-17-2019 06:54 PM

Re: Harman Kardon AVR 270
 
Just finished testing all the components in that channel.
Nothing out of the ordinary as I could notice, except for one Diode.
D582 measured 400kΩ and rising when positive probe was on cathode, other Diodes
did not do that, trans Q652 and the two resistors R723 and R725 are not installed.
Q882 and Q871 seemed ok.
I did not check the To-92 Transistors though.
Capacitors measured fine with the ESR meter, did not check the ceramic ones though.

R_J 05-17-2019 07:39 PM

Re: Harman Kardon AVR 270
 
You could lift one end of D582 to check it, Check the transistors like Q562, Q502, maybe they have some leakage.

playman 05-21-2019 10:25 AM

Re: Harman Kardon AVR 270
 
Quote:

Originally Posted by R_J (Post 896977)
You could lift one end of D582 to check it, Check the transistors like Q562, Q502, maybe they have some leakage.

D582 Looks ok.
Q562, Q502 looked ok also, I also checked the other remaining 6 and they also looked ok.

So I guess there is nothing left but to order the Q652 trans and the 0.47Ω resistors, plug them in and turn on the amp?

playman 06-04-2019 09:14 AM

Re: Harman Kardon AVR 270
 
I finally received my resistors today.
I decided to measure them just in case, They measured around 0.6Ω
they were supposed to be 0.47Ω.
Unfortunately my DMM only measures from 0.1Ω and up-to 60mΩ.
(not showing the extra decimal)

Is it ok for me to use them or should I order a new ones from some one else?

Ps
Is there any good way to know if they are M-Oxide films or just plain Carbon/metal film resistors?

R_J 06-04-2019 11:56 AM

Re: Harman Kardon AVR 270
 
The resistors are very low resistance so when you measured them you need to add your lead resistance, short your meter leads together, I bet the reading is ~.2Ω
What type of resistor did you order? I would'nt be too concerned, either type will work
Just a note:
Quote:

Unfortunately my DMM only measures from 0.1Ω and up-to 60mΩ.
mΩ usually refers to milli ohm, MΩ for meg ohm

playman 06-04-2019 12:53 PM

Re: Harman Kardon AVR 270
 
When I short it I get 0.1Ω reading
I bought this item.
https://www.ebay.co.uk/itm/30Pcs-2W-...frcectupt=true

sorry for that, I keep forgetting to capitalize letters when it is needed.

So I'll just plug them in and test the amp then.

playman 06-04-2019 03:23 PM

Re: Harman Kardon AVR 270
 
I've finished putting it to gather and all seems to work, I did reset it just in case.
Was able to listen to music on zone 1 with two speakers.
Now I just have to put it into the living room to test the 5.1 setup.
I did notice that the fans never turned on, even after running the amp on high volume for few minutes, did notice the heat sink getting hot, but not crazy hot.
Is there any way to test if the fans are working, besides taking them out and hooking them to another power source.

R_J 06-04-2019 03:51 PM

Re: Harman Kardon AVR 270
 
This is from the manual: It is normal for the fan to remain off at most normal volume levels.
I would think it will cut in after its been on for a while and runing at a high output.

playman 06-04-2019 03:58 PM

Re: Harman Kardon AVR 270
 
Quote:

Originally Posted by R_J (Post 899694)
This is from the manual: It is normal for the fan to remain off at most normal volume levels.
I would think it will cut in after its been on for a while and runing at a high output.

I read that also in the manual, just thought that they would turn on at that heat.
The amp should go into protect mode soon as it gets to hot right?

R_J 06-04-2019 04:05 PM

Re: Harman Kardon AVR 270
 
There are two test points you can short CN11 (FAN TEST) (page 170 of manual)

playman 06-04-2019 04:17 PM

Re: Harman Kardon AVR 270
 
The fans atleast work, guess there's nothing left but to place it into it's future home.

Thank you so much for your time and all the help, it's really appreciated!!.

playman 06-07-2019 04:41 PM

Re: Harman Kardon AVR 270
 
Update!
I connected everything last night and it ran just fine, except it was really hot, I barely could
hold my hand on top of the AVR and smelled heat/burning smell of it and noticed that neither of the fans were running.
So I quickly jumped for my table fan and cooled it down and had no trouble after that.
Until today....
I bought new HDMI cables and was starting to change things out and do cable management when the front right
channel started jumping in and out, like it was a bad cable/connection.
put another speaker on that channel with a new wire and it continued jumping in and out.
HDMI 1 is jumping in and out also.
When I turn it off it will turn on again x time later, if I turn it of then it will stay off.

Any idea what's wrong now?

R_J 06-07-2019 07:39 PM

Re: Harman Kardon AVR 270
 
Sounds like you still have a problem with the F.R. channel, maybe a poor solder connection somwhere if it does work but is intermitint. Did you check the voltage on the F.R. speaker after you repaired the channel? it should be close to 0 like the others.
If the amp turns on and off by itself when the hdmi cable is connected, it could be a poor connection on the hdmi plug on the board.
Check the voltage on D970 (k) and D980 (k), they should be logic high to turn on the fans, also check if the temp sensing ic (ic10) is connected

playman 06-08-2019 12:43 PM

Re: Harman Kardon AVR 270
 
Quote:

Originally Posted by R_J (Post 900142)
Sounds like you still have a problem with the F.R. channel, maybe a poor solder connection somwhere if it does work but is intermitint. Did you check the voltage on the F.R. speaker after you repaired the channel? it should be close to 0 like the others.

FR channel seems completely dead now, no sound coming from it.
Did check it's voltage right after the repair and it was similar to the other channels.
Did not notice any bad solder points in that channel, but could try and re-solder the channel.
The FR channel worked just fine it's first evening, it was not until they day after it started acting up.

My measurements on all channels
FR -1.5mv
FL 2.0mv
FHR -7.5mv
FHL -7.5
RR 0.4mv
RL -4.0mv
C -7.5mv

Quote:

Originally Posted by R_J (Post 900142)
If the amp turns on and off by itself when the hdmi cable is connected, it could be a poor connection on the hdmi plug on the board.

It has never turned off by itself, only turned on by itself, after few hours (didint time it)
Unplugged all the HDMI's today before I went out and when I came back home 1 or 2 hours later it was still off.
I was only using the HDMI 2-3-4 and 5 HDMI 1 was not connected when it turned itself on.
I had PS4 (off) Chromecast (On) Micro PC with Kodi installed (On) and the TV box (on) connected to it, not sure if any of them might have sent a signal to the AVR to turn on, or if the AVR allows to be woken up trough HDMI.

Quote:

Originally Posted by R_J (Post 900142)
Check the voltage on D970 (k) and D980 (k), they should be logic high to turn on the fans, also check if the temp sensing ic (ic10) is connected

D980 & D970 gave me 13.4mv (just probed it's left and right side, did not measure from the body, that's correct?)
The IC10 is connected, it's the one on the heatsink right?

Why do the AVR always have to be so hard to work on? lol

playman 06-11-2019 11:43 AM

Re: Harman Kardon AVR 270
 
I've resoldered the FR Channel and everything seems to be alright.
Did also drag the solder tip over the HDM1 contacts and haven't noticed any problem with it.
Would it be ok to short the fan test pins so the fans would just stay on, or would I have to fix some PC fan to the AVR instead?

R_J 06-11-2019 11:59 AM

Re: Harman Kardon AVR 270
 
Did you check the bias after repairing the FL channel? page 75 of manual
Have you check the voltage on the temp ic? BN10 should have +5 (3) gnd (2) and temp output voltage on (1) Check the output voltage then heat the ic with a heat gun a bit and see if the voltage changes
D970 would have a logic high to turn on the fan. I can't see that the amp should get that hot a low volume.
This amp has 2 fans correct?

playman 06-12-2019 10:09 AM

Re: Harman Kardon AVR 270
 
Did not check the bias, but have now and tuned them all to 25mv.
Pin 1 gave me 5.17v and did not change with the heating.
Pin 2 gave me 3v and raised as I heated it, I belive the amp went into protect mode as it raised over 4v. Could have been coincidence.
Yes the amp has one on the heatsink and 1 in the back.

playman 06-12-2019 10:14 AM

Re: Harman Kardon AVR 270
 
Did not check the bias, but have now and tuned them all to 25mv.
Pin 1 gave me 5.17v and did not change with the heating.
Pin 2 gave me 3v and raised as I heated it, I belive the amp went into protect mode as it raised over 4v. Could have been coincidence.
Yes the amp has one on the heatsink and 1 in the back.

EDIT:
checked now two times with the sensor loose from the heatsink and the amp turns off when I heat the sensor, but the fans never turn on though.


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