Pioneer SX-737 overloading???

Hi folks - I'm new to your Forum and this is my first post.

I am the original owner of a Pioneer SX-737 receiver.

It seems that the inputs from tape, CD and phono all seem to be overloading the amp a bit. Under-recorded or low level music sounds fine. However, if it's not, then it seems to be too strong going into the inputs and the sound seems slightly distorted.

The output from the LCD TV (which is variable) sounds fine.
FM & AM seems OK too.

Is there some way that these circuits drift over time (30 + years) and is there a pot (or pots) inside that I can turn down the input level from these other fixed level external sources?

Thanks.

First try deoxiting the contacts and pots, aftr 30 years it will need it, then faderlube the pots....

IF that doesn't do it, (and it probably will) then we read the power supply voltages with a DMM.

markthefixer said:

First try deoxiting the contacts and pots, aftr 30 years it will need it, then faderlube the pots....

IF that doesn't do it, (and it probably will) then we read the power supply voltages with a DMM.

Click to expand...

Mark-
I'm not a techie so your jargon is lost on me.

What is "deoxiting", "DMM" and "faderlube the pots"???

The front panel volume and balance controls are all clean - no static or noise whatsoever.

Thanks.

duraflex said:

Mark-
I'm not a techie so your jargon is lost on me.

What is "deoxiting", "DMM" and "faderlube the pots"???

The front panel volume and balance controls are all clean - no static or noise whatsoever.

Thanks.

Click to expand...

Deoxit is a chemical (Caig Dexoit D5 for example) that deoxidizes things, specifically electronics. It also cleans out the original lubrication, which is why you should put faderlube back where you cleaned with deoxit.
DMM is digital multimeter

There are many previous threads about those operations available through the search function.

Deoxit is (usually) a spray can of an effective contact cleaner,that chemically loosens the sulphate type corrosion that forms in switches and controls after many years of exposure to the stuff we breathe. Then we operate the daylights out the switches and controls to scrub the loosened corrosion away.

Since the switches and pots are usually sealed from the front to keep coffee, pop etc out of them, the nooks and crannies to spray into to get deoxit to the actual contacts are from the inside. Sometimes there is some disassembly required to get to the more deeply buried switches etc...

Faderlube is also a spray can, of lubricant, to ensure continued long life from your rotatonal type controls.

DMM = Digital Multi Meter = A voltmeter, ohmmeter (with diode test!!) and ammeter (at the least, there are other desirable measurements) rolled into one package with a digital readout. really cheap ones can be found for 10 bucks, effective ones for our purposes can be found for 30 (radio shack ) and then up to 200 to 400 for quality professional instruments designed to take extreme abuse.

Years ago I had given up on vintage equipment repair, because I had never found an effective cleaner (and I had LOOKED!!). I had equipment (including an SX-636) that was malfunctioning ONLY because of the corroded controls, that I had kept for sentimental reasons, but had no expectation of ever working again due to the unavailability of uncorroded replacement controls.

THEN I heard of, and tried, Deoxit. Within days I had everything cleaned and working. I was in HEAVEN!!

We have seen COUNTLESS examples of deoxit resurrection on this board, and deoxiting is now the de-facto first step in just about every repair... It REALLY prevents us from chasing ghost symptoms.

Deoxit (D5) and faderlube (F5) are available at Guitar Center, Fry's and quite a few mail (web) order houses. Generally they go for 10 bucks a can, but a can will last quite a while when used but not over used (less than 1 second bursts gets more than enough in )...

Pay good attention to the switches. I have 2 737s, both needed attention on the switches.
I see the input sensitivity is only 150 mv. I guess it's possible that your sources are too hot, but that doesn't explain the turntable. Make sure the loudness is off unless listening at low volumes.

Thanks to markthefixer, sir.byrd and shel-e-bean for the detailed info in layman's terms.

Now I have a clear idea of what to do.

Much appreciated.