Proton Int Amp 1 channel intermittent

GMiller

I've got a 20+ yr old Proton D540 integrated amp that I scrimped and saved to purchase back in college, and has served me well. Unfortunately over the past couple of months the left channel has intermittently gone silent. It is worse when the amp is cool, seems to go away when the amp has been used for a while. I use it in an area of the house where it is used infrequently. It also gets better when I smack the lid a la Arthur Fonzarelli. I have opened the cover, inspected the interior goods, and have used canned air to blow out any accumulated dust. All the connections appear fine, I don't see any fx on circuit boards or the like.

When the problem first started I called a local electronic repair shop and enquired about repairs. I was told it would be cost prohibitive, just buy a new receiver. I don't want that.

Anybody have a troubleshooting path I can follow?

Cheers!
Greg

George Grand

Do a search on a product called DeOxit. I'd say you need a can of that before you need a technician.

scootchu

Two things come to mind when you say you have to give it a smack. Cracked printed circuit board or a bad solder joint. I would try to find a schematic for it and and trace the suspect channel.

dcmeigs

What he said.

You can often prove the cracked circuit board theory by flexing the board while it is playing. Use something non conducting like a pencil eraser to put force on the board to get it to flex.

lakesailor

good comments so far...I would check (wiggle actually) each and every button/control bar/knob (whatever is being used) on your amp.

I recently got a pre. amp back from the repair tech that had this same problem. They checked everything and found nothing. Finally by fluke I discovered the cause.

The tone defeat switch. You need to wiggle it otherwise you could have all kinds of problems with the sound output (i.e. cutting out; intermittent, etc,etc) obviosuly this button is either dirty; has a bad conenction or needs to be replaced. Fortunately I don't use my tone controls anyways and can still get by.

Good luck

GMiller

Great suggestions all around. I was unable to reliably duplicate the problem with judicious pressure using a pencil eraser, and couldn't see appreciable problems on the PC board, so I followed Mr. Grand's advice and cleaned all contacts using DeOxit. Have no difficulties now.

Lake Sailor, where do you sail? We sail the Pamlico Sound and Pamlico and Neuse Rivers.

raymondrza

GMiller wrote: »

so I followed Mr. Grand's advice and cleaned all contacts using DeOxit. Have no difficulties now.

I have the same issue with my proton aa-1150....but i'm unsure about the DeOxit and contact cleaning process....what specifically do you clean? the entire underside of the circuit board etc... i don't have an output knob ....so what to clean seems daunting at the moment. The radioshack near me has the Deoxit kit with the Gold spray, but i do not want to cause havock. Any pointers? Please !

Thanks,
Mark

treitz3

Unplug the unit. Take the cover off. Take the Caig DeOxit and install the red "straw" looking thing to get a direct spray. Direct spray all electrical contact points, RCA connections and the electrical contact points of movable switches, knobs and buttons. Anything that moves, such as a volume knob, move all the way up and down (after spraying of course) about 20-30 times to loosen any foreign substance that may have built up over time. Be careful not to completely douse the area with the product.

When you are done with this, wait for about twenty to thirty minutes and do the same thing, this time using the Caig Gold. Wait about an hour [or more] for everything to completely dry. If the problem persists, repeat process.

You may find that after this is done, a scratchy "noise" may still be present on let's say the volume knob. Instead of repeating the entire procedure again, just concentrate on the electrical connections of the volume pot.

Neskahi

Some amps have solid wire on the back of the RCA jacks that attach to a circuit board.
If the jacks are not mounted rock solid it can push on the assembly every time you plug
or unplug the jack, weakening the solder joint at the circuit board. Those jacks are a good
place to start wiggling.

Gooligool

I have the exact same amplifier, and for some time I had the exact same problem.
It is the input switches on the front of the amp that is not getting enough contact
on the cantact surfaces. The switches are very tiny and sensible. You can try and
open the cover, and spray them with contact spray and then give them a good
"exercise". I remember doing that once or twice, but the problem came back after
some time. Then I opened the switches up and polished the contact surfaces by hand
(you have to be handy and very careful).
The amp has been flawless ever since.
Hope this will help you, because its a good amp otherwise.