Modding an HK AVR 2550

MatchASM · 31st January 2007, 10:09 PM

A friend of mine has a Harman/Kardon AVR 2550 and we're considering adding PSU capacitance and replacing the coupling capacitors with MKT/MKP type units.

There are a couple of questions I have with this amplifier:

- The transformer gets pretty warm; is that a matter of bad design?
- Each channel's own amplifier has a large number of electrolytic caps; I wonder why (I don't have a service manual to quickly look it up). I would expect one decoupling cap, and two power supply buffers, but what are the other caps doing on the PCB?

Also, any other suggestions for mods on this amp?

docfin · 3rd February 2007, 12:36 PM

Service manual for AVR-2550 available here: http://service-manuals.webs.io/

es44 · 3rd February 2007, 02:15 PM

MatchASM, if you need the service manual, you'll get it for free from me

Just PM me with a valid email address.

best regards
Ebbe

MatchASM · 5th February 2007, 11:13 PM

Quote:

Originally posted by es44
MatchASM, if you need the service manual, you'll get it for free from me
Just PM me with a valid email address.

best regards
Ebbe

I guess it's not possible to PM while under moderation?

I have a Gmail account with my nickname before the @.

Cal Weldon · 5th February 2007, 11:14 PM

You are now free to email.

MatchASM · 6th February 2007, 01:01 PM

Quote:

Originally posted by Cal Weldon
You are now free to email.

Thanks.

And Ebbe: thanks for the manual.

Now for some serious DIY-ing... :-D

es44 · 6th February 2007, 03:59 PM

You are very welcome

Hope you find the "rainbow" you're chasing

All the best
Ebbe

31st January 2007, 10:09 PM	#1
MatchASM diyAudio Member Join Date: Jan 2007	Modding an HK AVR 2550 A friend of mine has a Harman/Kardon AVR 2550 and we're considering adding PSU capacitance and replacing the coupling capacitors with MKT/MKP type units. There are a couple of questions I have with this amplifier: - The transformer gets pretty warm; is that a matter of bad design? - Each channel's own amplifier has a large number of electrolytic caps; I wonder why (I don't have a service manual to quickly look it up). I would expect one decoupling cap, and two power supply buffers, but what are the other caps doing on the PCB? Also, any other suggestions for mods on this amp?

5th February 2007, 11:14 PM	#5
Cal Weldon Speakerholic diyAudio Moderator Join Date: Jan 2004 Location: British Columbia	You are now free to email. __________________ Next stop: Margaritaville Some of Cal's stuff \| Cal Weldon Consulting

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3rd February 2007, 12:36 PM	#2
docfin Account Disabled Join Date: Apr 2006 Location: under the bridge	Service manual for AVR-2550 available here: http://service-manuals.webs.io/

3rd February 2007, 02:15 PM	#3
es44 diyAudio Member Join Date: Apr 2005 Location: Fredericia, DK	MatchASM, if you need the service manual, you'll get it for free from me Just PM me with a valid email address. best regards Ebbe

6th February 2007, 03:59 PM	#7
es44 diyAudio Member Join Date: Apr 2005 Location: Fredericia, DK	You are very welcome Hope you find the "rainbow" you're chasing All the best Ebbe