Harman Kardon AVR 141 Protect Mode

[Asterix]

Hi,

I have recently myself a Harman Kardon AVR 141 amplifier.
I bought it not knowing if it worked so i dont have any warranty.
It also makes me a free man to learn and fix it!

The issue with it is it keeps getting into protect mode and returning to standby.
i have found some information telling me it might be a short in the speaker output or a thermal security by the device.
So far i have been able to find the service manual and i have shorted 1 thermal sensor because i read this in another forum.
Both weren't able to help me here.
I also found a clip where a guy replaced one of the transistors. He was able to measure them by resistance.
I found this very hard to tell. Because i measured them and some of them were around 298 and some of them were around 667
But i didnt found a dead short as he showed in his video.

I also found it hard troubleshooting because the amplifier turns back to stand by so you cant measure voltages.
Wich would mean i have to measure each component by its own. Wich is really difficult.
I also visually controlled the jacks and connections there were no things off.

Do anyone happen to know wich part to replace? or maybe some tips for diagnosing?


P.s. I am from the netherlands so my apoligies for any language difficulties.
P.p.s. Service manual i have used: https://drive.google.com/file/d/1tCMPQW_tcZt-2hEX7KpLX5rvUZ_CFtEN/view?usp=sharing

[ambrosia heart]

There are several approaches to know what type of protection is .  When you turn amp. on ,
(1)turn off immediately~~~over-current 
(2)turn off 2-3 seconds~~~DC at speaker terminal. 
(3)turn off immediately with very very hot transistors~~~thermal 

See photo.

When measure CE,BE & BC resistances, "unplug" the amp. Jot down values for comparison.  Measure ALL transistors.

When measure voltage, plug the amp.
In normal condition, zero voltage at these
points.

[Asterix]

Hi!

Thank you for your reply.
Considdering your description it would be an over current.

Myself i checked everything once again.
And found a broken transistor : "SK D2389 98 P"
My local electronics store is closed until tomorrow,
and i didnt have another one on stock.
So i will let you know tomorrow!

Thanks for your reply tho if it doenst turn out to be the transistor i will let it know either!

[ambrosia heart]

See photo

[Asterix]

Hi!

Okay so i read your message a bit too late.
I went to the store and got myself a transistor.
Soldered it in and still it stuck in protect mode.
Then i read your reply and checked the condensators in line.
I wrote it down and attached a picture of it.
I hope you are able to help me.
I did find one wich stated Open Line.
I have already desoldered that one so i will get a new one tomorrow.
But the other condensators also gave some weird measurements.
Do i have to replace these? or only the one wich stated open line?
By the way i have found a post from someone fixing it.
Are you the source of the blog?
https://jestineyong.com/a-sound-video-amplifier-with-protect-on-display-repaired-model-avr142-230-harman-kardon/

Regards,

[ambrosia heart]

According  to attached  photo, only 1 channel blew.
How to troubleshoot, see pm. 
If money is not  an issue, replace them ALL.
If money is an issue,    measure resistance  on board.
Large  different from  marked value, take it out to measure.
Measure capacitance if you want or replace it.
Newly bought one can be faulty again if installed for testing
never use it.  Remember to replace transistors  in pair.
Read service manual p.82 C-CH.
See photo.

[ambrosia heart]

Forget to tell you...... see photo.

[Asterix]

Hi!

Okay so i have been quit busy today.
I replaced everything u said.
It still turns into protect mode. I think it is taking a bit longer for it to turn into protect mode
But it still wont play.
Is there someone who can help me?

[Asterix]

Hi,

I replaced everything.
However it won't work.
I have been reading your messages once more.
It takes 2-3 seconds before it turns of.
Before it was straight away no 2-3 seconds.
That means dc at speaker terminals.
Can you help me a bit more? I have been measuring the transistors
Some of them are around 300 Ohm and some of them are open line one sided.
Can you tell me what measurement i should expect?
I have been comparisong measurements of the transistors they are somewhat the same.
The problem right now still exists. I did check the plugs at the back and there is no short.

Can you please provide with me with the information?
It bothers me that i am missing something and i can't figure it out at the moment.

[ambrosia heart]

"It takes 2-3 seconds before it turns of.
Before it was straight away no 2-3 seconds.
That means dc at speaker terminals."

Yes check 2 points to classify which type of protect.

Don‘t panic.
Don‘t worry.  Step by step troubleshoot your amp.
See photos.
If bias adjust(1) performed go to type protect(2).
After measure 2 points voltage, go to unbalnced (3).
If voltage unbalanced, troubleshoot(3).
If voltage balanced or fixed go to protect work (4).
See x point (5) and measure(6).
Troubleshooting steps see pm

This is a second hand amp.   You don‘t know  if the preceding end user change or remove any components from circuit board.  Or you don‘t know  if the end-user try to call somebody to repair or repair by himself.  This leads to difficulty. Be patient. Detailed troubleshooting steps will send to you later.

[Asterix]

Hye There!

I also replied to your messages but i dont know if you received them yet.

I measured the following:
P_Fail: 3.27V
Protect mode 1mv

However i also tried checking the transistors once again and i had desoldered a couple.
Before i did that the amplifier still would go in protect mode.
Now it doesnt. It stays on!
Yess! I thought i fixed for a second but now i dont have any sound on my speakers.
Can you help me fix this as well?
Things i tried:
-FM Tuner
-Speaker terminals
-Adjusting volume
-Checked my wires
-Used an ipod as source on DVD in
-Used an ipod as source on CD in
-Tried the speakers on another stereo

I hope to hear from you soon!

[Asterix]

Hi!

I got your message today!
I wasn't able to find the speaker relay as you did describe.
Can you tell me what i should look for
Attached to this will be the pictures of the inside

[ambrosia heart]

protect problem leave aside. This protection must come from middle point voltage >0.
After you removed power transistors, unbalanced voltage cannot flow from voltage amp section to speaker terminal
via 2 power transistors. Hence no dc protect detected.
Voltage amp section must be checked. I have already told you via pm. (go to protect work (4))

adjusting volume
There comes no sound on my speakers, also no buss noise when on FM
I did here a light tick sound in my left speaker when i changed sources.

First you need to isolate the problem. Detailed steps see photo.
No measurement required , just a task of wires connection . Tell me the results.
Remember before wire connection,reset the amp and see if mute is present on front panel.
If digital board problem confirmed ,you need to measure ALL working voltages on digital board.
Remember to take clear photos of those circled connectors and post them. I need to know what words are written on this board.
Detailed trobleshooting steps will send to you on monday via pm.
If ALL working voltage are OK, you need an oscilloscope to diagnose chips involved on this board.

I have read your amp schematics ALL. No speaker relays and speaker drive circuit in your amp.

[Asterix]

Hi man!

I dont know what to do?
U keep suggesting a lot of things  wich are helpful.
but right now i need to find the fault.
I need to know what to check and what is supposed to be the good result.

I uploaded the pictures to a google drive folder.
See: https://drive.google.com/drive/folders/16rW6bULfdLF0TTlfCeWF9hyxuv0qeOrh?usp=sharing

I hope to hear from you soon!

[ambrosia heart]

I dont know what to do?
See photo last post told you.
(a)Select 6/8 channel input on front panel.
(b)Connect sound source to 6/8 input via CD/DVD/Blu ray player/iPod/smart phone. 
(c)If 6/8 input used C&SR, speakers connected to C&SR.
(d)play music disc and tell me if sound heard!
(e)test FL , SL& FR and repeat (a)-(d). One channel no sound
due to transistors removed.
I want to isolate the problem.
Just do it.  If harman amp has a debug mode, I could have
entered this mode. It does not have a debug mode, however.
Trust me and do (a)-(e) , tell me the result.
This helps me to save time in repairing.
If you don‘t do those steps, I don‘t know which part of circuit
is faulty. Repair will end here.

 Despite just connecting wire, it is
a powerful step to isolate a problem.  In Hong Kong, no any
tech. knows how to repair even authorized service or Apliu
street.  Harman will replace the digital board only.  Not  just
harman, onkyo/denon/yamaha/pioneer/marantz/krell and
rotel do the same thing due to company policy.

In Hong Kong, I also teach hifi users to repair their gears.
They will follow my instructions without any doubt.  Why?
If they know how to repair, no need to ask for help. 

[Asterix]

Hello,

First off i asked for help.
Help does not mean just suggesting a couple of things to prove how great you are.
Besides in Hong Kong they also sell sewage oil to each other.


Over here we are social to each other and solve problems.
Not just to prove to someone how great i am.
So i appreciate your help but if you just want to show off i would like to ask someone else for help over here?
Besides all, i asked you to tell me what to measure and what is considered good or bad.
This way we can actually find out what is faulty.

So as a reply to you.
a. i already tried this you know it doenst work. See your DM.
b.Same as A
C.
D. These arent the fault considered the fact i tried multiple sources as you know.
E. i asked you already what you want me to measure and what should be a good result.

As i told you i already completed this steps.
and send you the pictures as you requested.
Considering this i wonder if you are really capable of repairing such a device?
Or are you just another chinese show off who lives in a appartment made of recycled paper and thinks he can repair something?
If you are not a show off and actually are able to repair such a device as this and are capable of teaching.
I would like to hear in your next reply.

Have a nice evening!

[ambrosia heart]

(1)Look what you did:
Things i tried:
-FM Tuner
-Speaker terminals
-Adjusting volume
-Checked my wires
-Used an ipod as source on DVD inthe
-Used an ipod as source on CD in
-Tried the speakers on another stereo

Asking this question let me know what level you are at.(low level)
Anyone who have experience in repairing a digital board will immediately know what's wrong
with the amp. They will do my steps at once or enter debug mode to see what's wrong in order
to isolate the audio path .

(2) Over here we are social to each other and solve problems.
Not just to prove to someone how great i am.
So i appreciate your help but if you just want to show off i would like to ask someone else for help over here?

Ok, you are right. Let them help you!!! Do you think they will tell you how to troubleshoot a digital board with the technique of signal tracing?  Too simple, sometimes naive. Digital board is the most difficult part in an av amp. Not only hardware, but also software affect an av amp if it works properly.  In order to make a completely diagnose, correct waveforms (amplitude
, frequecy , ACK,CS,  SDATA,  SCLK, adress transient signal analysis .......) are needed. I2S and micom path signals are needed to be measured which involve at least 5 chips in harman av-amp.


(3)Considering this i wonder if you are really capable of repairing such a device?
Or are you just another chinese show off who lives in a appartment made of recycled paper and thinks he can repair something? 
If you think I am these people, why you follow my steps to repair over-current protection.
Are you a dumb-ass??? Will these people have an ability to tell you how a circuit work?
Before you write something on a post, use you brain, genius.

(4)If you are not a show off and actually are able to repair such a device as this and are capable of teaching.

Why still no sound??? I won't tell you and reply this post anymore, ha ha.
Before I leave this post, I tell you what...... Never makes someone able to help you angry and follow their steps to do.
Why? If you are so tanlented, why you ask for help? 
Remember one thing, genius, if your av amp knowledge is at low level, just SHUT UP and
LISTEN .

Originally, you have 90% to completely fix this amp if I tell you the
signal flow and how micom communicates the audio decoders. Now the chance for you to fix
this amp is of course ZERO. If you know the technique of fixing this amp, I    dare to tell you
fixing onkyo/denon/yamaha/pioneer/marantz is not a problem. 

Believe it or not, in here, able to troubleshoot a digital board and know how it work no more than
5%.

AH, one more thing, tell harman service dept. to repair the amp, you can fix it.
What will they do first? Of course the steps I written here.
I hope somebody can help you, genius. 

Ambrosia Heart.

[Asterix]

Hi!

I wonder how it is possible that such a genius as you are not able to write a social reply to my question.
If i ask you ask you a question i ask for an answer.
I didnt ask you to tell me how great you are.

The reply you posted will be public over here.
I think it will be very clear to me and other people that when things get tough.
You get going!

I appreciate the life lesson you teached me!
There are indeed stupid people around the world.

Regards