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

playman 05-05-2019 04:11 PM

Harman Kardon AVR 270
 
I have a HK AVR 270 and only Zone 2 works on it.
Any one know on what PCB the Zones are located in the amp, and maybe by any chance know what might have broken?

Link to the service manual
https://elektrotanya.com/harman_kard.../download.html

madan1 05-05-2019 05:02 PM

Re: Harman Kardon AVR 270
 
Do the headphones work for Z1?

Also, have you tried to reset the unit?


p.s. Check SM page 162
If you are able to pass every source ( analog and digital ) through the zone2/pre-out output, than everything on the "smart" side works fine ( great news ).

playman 05-07-2019 01:01 PM

Re: Harman Kardon AVR 270
 
Quote:

Originally Posted by madan1 (Post 895025)
Do the headphones work for Z1?

Also, have you tried to reset the unit?


p.s. Check SM page 162
If you are able to pass every source ( analog and digital ) through the zone2/pre-out output, than everything on the "smart" side works fine ( great news ).

I'm waiting on my replacements parts for the SMPS board, will check that soon as I've replaced them.

playman 05-07-2019 02:50 PM

Re: Harman Kardon AVR 270
 
1 Attachment(s)
I was taking a better look at the CUP12457 board and noticed a smudge on it.
tested the Q2107 and belive it's broken, in the manual it's marked as
RT1P144C(PNP,SC-59,SISAHAYA
found the datasheet
https://pdf1.alldatasheet.com/datash.../RT1P144C.html
I can't find it for sale on either Mouser or farnell, any one know a suitable replacement for it?

madan1 05-07-2019 03:17 PM

Re: Harman Kardon AVR 270
 
https://www.aliexpress.com/item/50pc...884439063.html

playman 05-08-2019 01:22 PM

Re: Harman Kardon AVR 270
 
Thanks for that madan1 unfortunately I cant order it from aliexpress or alibaba as for some reason they started declining my card and i just spent almost 2 hours talking to their assistance witch got me nowhere, amazon ebay/paypal even google have no trouble with accepting my card.

Is there any other site or suitable replacement available.

R_J 05-08-2019 05:55 PM

Re: Harman Kardon AVR 270
 
A DTA114, should be the same, digikey DTA114EKAT146CT-ND What do you mean by broken? It will be hard to test with a meter due to the internal resistance, I doubt it is the cause of the problem

playman 05-09-2019 09:41 AM

Re: Harman Kardon AVR 270
 
Quote:

Originally Posted by R_J (Post 895585)
A DTA114, should be the same, digikey DTA114EKAT146CT-ND What do you mean by broken? It will be hard to test with a meter due to the internal resistance, I doubt it is the cause of the problem

Thanks for that, I noticed that R1 and R2 have the resistance of 10k in the DTA114, but the RT1P44 has the resistance of R1 10k and R2 47k, is that ok?

I thought it was broken because the Diode function on my meter gave me no readings and
Positive probe on collector gave me a reading of 6.05M ohm on both Base and emitter
Positive probe on Emitter gave me reading of 60k ohm on Base, same result with positive probe on Base.
And I managed somehow to break one of the leads :/ on the other one.

R_J 05-09-2019 09:56 AM

Re: Harman Kardon AVR 270
 
All similar https://www.digikey.com/products/en/...pre-biased/292

This should be better SMUN2114T1GOSCT-ND https://www.digikey.com/product-deta...SCT-ND/9087746

playman 05-09-2019 10:47 AM

Re: Harman Kardon AVR 270
 
Quote:

Originally Posted by R_J (Post 895677)

Thank you so much for that, putting in an order now.

P.S.
Did my readings say if it was bad or ok?

R_J 05-09-2019 11:22 AM

Re: Harman Kardon AVR 270
 
it is what is refered to as a digital transistor
Positive probe on collector gave me a reading of 6.05M ohm on both Base and emitter
This is what it should read (e-c, b-c open)
Positive probe on Emitter gave me reading of 60k ohm on Base, same result with positive probe on Base
47k +10k = 57k (very close to 60k which is correct
I would say it was good

playman 05-09-2019 11:25 AM

Re: Harman Kardon AVR 270
 
Quote:

Originally Posted by R_J (Post 895697)
it is what is refered to as a digital transistor
Positive probe on collector gave me a reading of 6.05M ohm on both Base and emitter
This is what it should read (e-c, b-c open)
Positive probe on Emitter gave me reading of 60k ohm on Base, same result with positive probe on Base
47k +10k = 57k (very close to 60k which is correct
I would say it was good

Allright thanks again :D

playman 05-15-2019 05:25 PM

Re: Harman Kardon AVR 270 - No power
 
4 Attachment(s)
I received the parts today and soldered them in.
Now it still won't power on, just like it did before I took it apart.
The orange power light turns white for a second then returns to orange.
I can hear a faint noise coming from the SMPS PCB, like it's trying to start but can't.
The noise seems to be coming from those two big black transformers or near them.
The Ceramic caps C984 and C983 were really dark so I replaced them, saw it somewhere that if those caps are gone the AVR would have the same symptom as I had/have.

Any one know what might be wrong?

R_J 05-15-2019 07:04 PM

Re: Harman Kardon AVR 270
 
You seem to be making it worse, In post one the zone 2 was working and your fault was with zone 1, and now nothing is working correct?
If the amp was working with zone 2, why would you change parts in the power supply? this makes no sense.

Did you just change the two 471/1kv caps in the power supply so far?

R_J 05-15-2019 08:38 PM

Re: Harman Kardon AVR 270
 
I think you have a short somewhere in the output section, with the amp off, check the resistance between +vcc and ground and -vcc and ground. If you don't have any shorts, Monitor the voltage on +vcc and then -vcc when you turn on the amp and see if you get +/- 50 volts
Did you have speakers connected to zone2 L&R and they were working?

playman 05-16-2019 10:55 AM

Re: Harman Kardon AVR 270
 
Quote:

Originally Posted by R_J (Post 896637)
You seem to be making it worse, In post one the zone 2 was working and your fault was with zone 1, and now nothing is working correct?
If the amp was working with zone 2, why would you change parts in the power supply? this makes no sense.

Did you just change the two 471/1kv caps in the power supply so far?

Hi, sorry, I guess I wasn't clear enough in my post, my bad.
The problem started at first with the zone problem, when I was checking it's settings out, it went to standby mode suddenly with a slight heat smell, after that it did not want to turn on again.
I was so sure that these caps were the problem since they looked burned, so I just asked about the zone problem here.
If I remember right, I heard some low crackling noises as I connected the speaker, just like it usually happens when you connect a speaker.
When I was putting it to gather I noticed that some of the large transistors on the large heatsink had been changed, and the repairman seems to have a little brute on the heatsink fan connector, as
the two pins were trough the PCB and ripped the connections under it, But I believe I've managed to repair it. The fan connection is located on the sound output board.

Yes I only changed the two 471/1kv caps.

I checked the VCC-/+ on the SMPS PCB the resistance started from 0.5k Ohm or so and just raised on both +and -, as if the DMM was charging it, stopped measuring at 2k Ohm
When I switched the Unit on the volts seemed to reach 50-55V + and -, just for a part of a second.

R_J 05-16-2019 11:16 AM

Re: Harman Kardon AVR 270
 
Your power supply is working ok, I suspect there is a fault in one of the amp output sections. place your meter probes on each speaker output terminal and turn on the amp, you should see 0 volts, if you see more than a couple volts on any of the speaker output terminals, that section has a fault, you will likely need to power of the amp between each speaker test as the amp will shut down.

playman 05-16-2019 04:35 PM

Re: Harman Kardon AVR 270
 
Quote:

Originally Posted by R_J (Post 896752)
Your power supply is working ok, I suspect there is a fault in one of the amp output sections. place your meter probes on each speaker output terminal and turn on the amp, you should see 0 volts, if you see more than a couple volts on any of the speaker output terminals, that section has a fault, you will likely need to power of the amp between each speaker test as the amp will shut down.

Just tested them, Front Right output gives me a reading of -22v (negative).
All the other outputs gave a reading of 0.5v or so.

R_J 05-16-2019 04:56 PM

Re: Harman Kardon AVR 270
 
Ok. you now know where the problem is, start by checking the 4, 0.47Ω ceramic resistors, then check the output transistors in the FR amp circuit. Also check the two 18Ω R631 & R636 resistors, You can compare your readings with one of the working channels if something looks off

playman 05-16-2019 05:43 PM

Re: Harman Kardon AVR 270
 
Quote:

Originally Posted by R_J (Post 896809)
Ok. you now know where the problem is, start by checking the 4, 0.47Ω ceramic resistors, then check the output transistors in the FR amp circuit. Also check the two 18Ω R631 & R636 resistors, You can compare your readings with one of the working channels if something looks off

R631 & R636? Don't you mean R632 & R637?
R631 & R636 are from the Center channel.
Any way those 4 18 Ohm are ok
R723 & R725 are open
Going to test the Trans now.


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