Denon PMA-750 static

108.235.157.25

Posted on April 25, 2016 at 16:52:42

MannyE
Audiophile

Posts: 2088
Location: Miami Beach
Joined: March 4, 2001

I was really excited to have picked up a Denon PMA-750 for 25 bucks a couple of weeks ago. It sounded really good and was making beautiful music with my (also thrift) $10 RS-225 speakers. Until today.

I made the mistake of touching it and attaching an additional turntable as well as a CD player into the mix and as soon as I started trying out the different settings, the phono and tuner buttons developed heavy static.

It seems like I may have disturbed the well developed dust and rust and gotten all the switches dirty.... I'm thinking.

What is the generally accepted reason for static in these units? It's not static "above" the music, it's the music itself coming in and out. If I bang on it, the static changes... gets worse or lessens. Once it went away completely for a moment, but then came back.

Would it be safe to wash it out with some denatured alcohol to get all the nasties out of the switches? The same way I dipped an iphone into a glass of the stuff to dry it out? I figured with a soft brush and a squeeze bottle I could get the thing clean as a whistle. Yes? No?

Hide full thread outline!

RE: Denon PMA-750 static

Awe-d-o-file

08:29:19 04/27/16

RE: Denon PMA-750 static

MannyE

17:07:48 04/27/16

RE: Denon PMA-750 static

Jonesy

07:34:59 04/26/16

3

...

Show full thread outline!

RE: Denon PMA-750 static

Awe-d-o-file

08:29:19 04/27/16

RE: Denon PMA-750 static

MannyE

17:07:48 04/27/16

RE: Denon PMA-750 static

Jonesy

07:34:59 04/26/16

3

RE: Denon PMA-750 static

MannyE

12:22:55 04/26/16

2

RE: Denon PMA-750 static

Jonesy

12:39:17 04/26/16

RE: Denon PMA-750 static

MannyE

19:18:22 04/26/16

RE: Denon PMA-750 static, posted on April 26, 2016 at 07:34:59

Jonesy
Audiophile

Posts: 3156
Location: Winnipeg, Manitoba
Joined: September 1, 2005
Contributor
Since: March 1, 2018

I've had good results with MG Chemicals zero residue contact cleaner. Spray can with long thin plastic tube gets into hard to reach places. Adjustable pressure spray is also nice. I always surround the swith or pot with some wadded paper towel so the spray doesn't get on everything else. Some inmates like to use deoxit. Could do an Asylum search to see recommended cleaners.

Nice purchase by the way!

Jonesy

"I know just enough to get into trouble. But not enough to get out of it."

RE: Denon PMA-750 static, posted on April 26, 2016 at 12:22:55

MannyE
Audiophile

Posts: 2088
Location: Miami Beach
Joined: March 4, 2001

Thanks! I used to use a lot of MG Chem stuff to clean up flux after soldering components onto a board, but recently I find that alcohol does a decent job, so I don't have any of the MG on hand. But I'll give it a shot.

Actually, last night a crazy loud buzz started coming from it so I dropped it off at the local Denon repair shop. It sounded so nice when it worked that for the 50 buck diagnostic fee and I guess up to another 100 bucks to repair/recap and what have you, it's totally worth $175 (150 + 25 to buy) to get it back to 100%.

RE: Denon PMA-750 static, posted on April 26, 2016 at 12:39:17
Jonesy Audiophile Posts: 3156 Location: Winnipeg, Manitoba Joined: September 1, 2005 Contributor Since: March 1, 2018	Good idea. Sometimes taking it in saves lots of time and grief. Hope it works out for you! Cheers! Jonesy "I know just enough to get into trouble. But not enough to get out of it."

RE: Denon PMA-750 static, posted on April 26, 2016 at 19:18:22
MannyE Audiophile Posts: 2088 Location: Miami Beach Joined: March 4, 2001	I will report the good or bad news as it comes.

RE: Denon PMA-750 static, posted on April 27, 2016 at 08:29:19
Awe-d-o-file Dealer Posts: 21037 Location: 50 miles west of DC Joined: January 10, 2004	Those are more problematic switches in my experience than the rotary rec out switch below. Open it and clean the contacts. Look at what someone did with the same issue. ET ET "If at first you don't succeed, keep on sucking till you do suck seed" - Curly Howard 1936

RE: Denon PMA-750 static, posted on April 27, 2016 at 17:07:48
MannyE Audiophile Posts: 2088 Location: Miami Beach Joined: March 4, 2001	Ha! I wonder if that worked? Considering the actual switch is about 8 inches behind the button!

Amp/Preamp Asylum

Denon PMA-750 static

108.235.157.25