Harman Kardon PM665 Integrated Amplifier - Adjustments and Demo
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- เผยแพร่เมื่อ 5 ก.ย. 2024
- Harman Kardon PM665 integrated amplifier was built in between 1985-1986. It has dual transformer power supply design and 100Wx2 output power rating. This amp has been in the storage for a long time and needs services. This video shows how to adjust DC balance and bias of power amplifier.
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That flashing LED at startup indicates it is going through its startup routine. As soon as all the electrical settles down and checks out okay it turns on the system.
It's a good thing.
Just helped me bias my PM-665VXI!!
Thanks
I always liked the clean look of this generation of HK gear but the reviews about performance are mixed - bad and good.
Excellent video !
They're clueless. HP amps are high current and great sounding amps . They sound better than most amps today .
Great Amp and great Job!... What's that song?
Great video! What's that track you mixed in?
The flashing LED at startup indicates it is going through its startup routine, but I hear "boom" on the speakers when it stops flashing. I do not have it on my other amplifiers. Is it a failure or just a feature?
I believe it was the production flaw of the amplifier. There is "click" noise when the speaker relay out of the protection mode. Mine has the same problem. You can try to replace the speaker relay and see if the problem improves.
@@VintageAudioFan I have 4 HK amplifiers and all of them have the same feature.All of them 5-6 sec after powering on,give ,,poof,, sound on one speaker.The reason for that is high DC offset(over 400 mV).I agree with you when you say ,,it was the production flaw of the amplifier,,.
Can you help me diagnose what the problem is with my amp? I have a HK PM665 Vxi and the left channel is very quiet while the right is not. Is there a reason for this?
Yes. But my suggestion is to isolate the problem first before going to the next step. You can hooked up a functional power amp to HK PM665's pre-out (in rear panel) to test the the preamp section working condition. If the sound works fine, then the problem is in the power amp section. The other option is hooking up a functional pre-amp to PM665's Main-In to test the power amp's working condition. If it sounds fine, then the problem is in the pre-amp section. Let me know the result and I will guide you to the next step.
@@VintageAudioFan Main Amp works and the Pre out works fine when i plug them in. They sound good no crackle.
Good. The next step is check the source switch and the volume control. Sometime the bad contact in the signal path can cause the sound output problem. I suggest using Deoxit (electrical contact cleaner) clean all the switches (specially SW4 Mute switch) and controls to ensure all contacts work properly. The third step is check pre-amp circuit board if the second step doesn't help. I noticed that there are few coupling capacitors including C507(10/16V) and C517(47/16V) in the Tone Control circuit of PM665 VXI plus C901(0.1/50V) and C909(0.22/50V) in the Loudness circuit. These coupling capacitors are the main reason cause the weak output of output. You can replace them if you don't know how to check them. If all above methods don't work, then you need an experienced tech. fix for you. Hope this information helps.
@@VintageAudioFan Awesome man thanks for the help!
Hello, i know what is a bias tune, but don't know much about the DC adjust, what is all about please ? (sorry for my poor english, i'm French)
Here is the simplest explanation which I got it from the website: "DC offset (or DC balance) is a concept employed when dealing with electrical components, most notably audio equipment. These components send audio signals using alternating current (AC), by which the signal reverses direction regularly. If the signal does not spend an equal amount of time traveling in both directions, however, the resulting imbalance is referred to as DC offset. A high level of DC offset can damage electrical components and degrade signal quality." That is why it needs to be adjusted close to 0V.
@@VintageAudioFan it seems the offset on these HK amps can fluctuate from 0mv to -10mv to 10mv. I'm told it's okay?
@@sellsubz Yes. It will be fine.
What loudspeakers are those?Can't see the logo.
Paradigm Titan speakers.
How onkyo receiver 616 fix no sound and no network
There are so many possibilities could cause the receiver not working: (1) Defective power supply (2) Speaker relay in protection mode (3) Power amp has short circuit....etc. I suggest to have an experienced tech. to check it out and fix for you.
Ampifire and wd 40 is not suitable