Carver PM 1.5 making small crackling noise in quiet parts of music -I just bought it what are the first things to check would anyone be able to help

I finally took the plunge and picked up a carver pm 1.5 on ebay for cheap which got delivered today and it sounds awesome with my magnepans-better than the class a 100w monoblocks I was using but it has a small crackle in quiet passages but only does it when music is playing no sound when on standby. What are the first things I should check-clean etc? I have never owned one so I'm not sure what to look for
 
Check the earthing, put isolating ground caps, the SMPS in your computer may not agree with the Carver power supply, which were kind of different.

Some Carver supplies had a triac arrangement, they were not pure linear or SMPS, and the switching frequency may be causing harmonics with your computer SMPS.

Try changing the output level off your computer, too low can cause the amp to go into over gain territory.
There are controls for the computer OS, which I set to full, and use the playback program to control the volume, the amp is generally left at about 50% output.

Check it with another source, maybe FM radio, or even cell phone or tape.

Oh, and do a general service, spray the selector switches and so on.
And maybe this was a known fault, look on this and other forums.
And do use it a week or so, let the capacitors reform, maybe the problem will go away.
 
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I agree, if the above does not work.

Carver sets were different, not every repair man can fix them, requires training and experience.
Particularly the power supplies, some were called 'magnetic field power amplifier'.
Most technicians are not familiar with them, and I do not think many were sold in Australia, and the unit must be old, which is another set of problems.

There is a member here, 'anatech' (Chris), who did warranty service for Carver in Canada.
Wait for him to post, or pm him, he is quite helpful.
 
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turk 182

Member
2012-10-26 3:03 pm
so just what sort of amps where used before?
keep in mind that a Pm 1.5 has balanced inputs and without knowing just how you've connected things it could well be from the input not being properly terminated...or dirty input jacks...as most of these amps saw PA system duty road dirt and touring and worked hard i.e. wacked with massive amouts of front end gain it's possible the input stage may need some TLC.
 
Get hold of a schematic, check the voltages at various points in the circuit, that may give a clue.
And yes, it could be a stupid thing like bad terminals.
But buying a piece of hard used equipment for home use may not be a wise decision.

And apologies, 'Anatech' is an administrator here on this forum, and has decades of audio equipment experience. He is not an ordinary member, and has a deep understanding of Carver equipment, backed up with practical experience, as he was a (or the) warranty provider for Carver in Canada, as I mentioned earlier.