Pioneer sa-9800 with slight mains hum?

Hi there - noob here so please be gentle

I have a problem with my sa9800 - owned for 29 years never missed a beat but rarely us3d never driven hard by any means.

not used her for about 2 maybe 3 weeks and decided to listen to some tunes last night when i notice a faint mains hum on both channels.

things i have checked out so far, not apparent with pre power jumpers removed, even with volume on high or max still the same but no indication of anything on the readout everything else works as it should just a noticable hum with headphones no bad with speakers but im just one of those unfortunate people that when i notice it i cant ignore it until its gone!!!
changed the power cable changed plug sockets even took the amp to a friends with the same result.

also i noticed with no source selected obviously with vol on high if i twist the bass knob to max its like i can hear it being changed lol crazy but thats the case, also noticed one of the transformers seems a little more buzzy but so minor only because i know the amp so well nobody else would ever notice.

im ok with taking the cover off and i have a DMM but not massive on electronics but please any help would be fantastic.

many thanks oh im from the uk too.

hi again sorry dont mean to bump this post rather an update:

seems the hum changes slighty when playing with the treble bass and tone switch
as well as the mode switch could be nothing but thorght id mention it :thmbsp:
thanks

Mostly the gurus help troubleshoot these types of problems and they keep late hours. You can, in the mean time, search previous posts concerning this hum issue by google'ing for example "Hum in my pioneer: Audiokarma". This will produce links to hum problems others experienced. The exercise will warm you up to the possible procedures required to fix this very nice set.

Its good you noticed this change in your set. If it turns out AC is present where DC is only allowed, you may of saved your set.

You should leave the set off until otherwise stated.

pioneer-nut said:

Hi there - noob here so please be gentle

things i have checked out so far, not apparent with pre power jumpers removed, even with volume on high or max .

Click to expand...

Just want to make sure I understand you correctly. With the Pre-Out/ Main-In jumpers pulled, the hum goes away? Do you have any other source with a variable output that you could plug into the Main-In jacks...other preamp, portable discman with a minijack to RCA adapter, iPod with same adapter?

If so, try that hookup and see if the hum is present again. Also, if you have any other power amp with the same sort of setup, you could try using the 9900 Pre-Out into the other amp and see if the hum transfers to the other amp. This would isolate the issue to the preamp section of your 9900.

With them separated, does the one transformer buzz the same and or get hot still?

pioneer-nut said:

also i noticed with no source selected obviously with vol on high if i twist the bass knob to max its like i can hear it being changed lol crazy but thats the case, also noticed one of the transformers seems a little more buzzy but so minor only because i know the amp so well nobody else would ever notice.
.

Click to expand...

Sounds like preamp section issues, but more troubleshooting will narrow it down. Like Zeb stated, I wouldn't go using it a whole lot til you can troubleshoot properly. Some things you can do powered off and unplugged are to check grounding wires, transformer bolts/screws to ensure they are tight, clean your switches and pots with deoxit/Faderlube...

Welcome!! You're in the right spot. But have patience, answers are not instant. Sometimes I can have a latency of several days, depending upon how life intrudes.

All good stuff above. Id say swap the AC plug "polarity" in the socket (they are made to do that) but with all the moving around you did with it, odds are you already did that inadvertently.

If not cured, then we'll check the supply voltages for the preamp. Caps could be getting old and letting hum through the regulators.

Try all inputs including the tape 1 and tape 2 play, and use short shorting plugs at the input you are checking to differentiate between internal noise or pickup from an external source.

Then see if ANY other front panel controls (like volume, balance, tone off/on etc) affect it, and how.

And YES, the tone controls WILL modify the hum if it is getting in before that part of the signal chain.

hi guys and many thanks for the replys, i used my galaxy phone ( mini jack out in this order )

phone mini jack out to phono power amp in then pre out to aux and had sound no problem, no hum/buzz im certain.

maybe the transformer is fine im just thinking it sounds a little more buzzy may or may not be the case.

with vol on high you get the usual bg slight hiss vol on low the hum is still present, its very faint but noticable.

treble and bass as well as model selector have an effect on thr hum for what they do but still there.

again id like to thank evertone for their inputs.7

pioneer-nut said:

hi guys and many thanks for the replys, i used my galaxy phone ( mini jack out in this order )

phone mini jack out to phono power amp in then pre out to aux and had sound no problem, no hum/buzz im certain.

Click to expand...

Why did you send the phone output to the phono input?

You also had an RCA cable from the Pre-Out jacks to the Aux jacks?

What was plugged into the Main-In jacks????

When trying to determine whether the issue lies in the Power amp circuitry or the Preamp circuitry, the jumpers connecting the two are removed. So what I was suggesting, maybe poorly worded, was to use a different preamp whose output was plugged into the 9800's Main In jacks. You don't want any signal being processed in the 9800 and then sent out the Pre-out jacks at all.

So, if your phone is the only other preamp device you have, connection is phone to Main-in. Make sure the 9800 power switch is off and all other switches set to neutral/out and the volume knob is zero. Really, the only switch needed for this test is the speaker selector. Make sure your phone volume is zero, then turn the 9800 on. Is there any hum with no volume on the phone?

Cue up a song on your phone and start slowly increasing the volume. Do you start getting the hum? You should start to hear whatever song you cued up as the volume on your phone is increased.

If there's no hum present, the problem likely lies in the preamp circuitry of your 9800 because all of that was bypassed during this test. You were just running the 9800 as a power amp, your phone was being used as a signal source/preamp. If the hum is present with this setup, it might be narrowed down to the filter caps, grounding issue, or something else in the power supply and/or main amplifier boards. It could also be interference from fluorescent lights being amplified, too many on the house circuit that the 9800 is plugged into. It could also be that your phone just has too little output signal (ideally you'd be using a dedicated preamp for this test). Do you have access to one, or do you have a CD player with a headphone jack that has its own volume knob?

If there was no hum with the first test of the power amp portion of the 9800, if you have any other integrated or dedicated power amp, or could get your hands on one from a friend, test the preamp section of the 9800.

Connections would be:

Source (CD, Tuner, Tape...whatever you have) plugged into the corresponding input jack on the 9800. 9800 Pre-Out to the other amplifier Main-in or Input if it's a dedicated amp. Speakers hooked up to that other amp.

Power up with 9800 volume knob set at zero. Source selector switch engaged for whatever jack you decided to use. Is there hum? Start source music and slowly turn up the volume knob of the 9800. Does the hum become audible if it wasn't before? Does it change at all? Now try your balance switch, full left and right. Is the hum present only on one side? Balance to neutral. Tone control knobs. Again, does it change?

If there is no hum with this setup, the problem likely lies in either the power supply or the main amp boards. If there is hum with this setup, and there was also hum when testing the power amp circuitry, it's likely a power supply issue because that's the only common circuitry in the two tests (filter caps would be a likely culprit).

Oh, and feel free to type a few more words and proper punctuation in your explanations of what you're doing during the testing. It's not like this is twitter or anything.

hi john, when you say main in jacks what are refering to xactly?

sorry for my lack of understanding, anyway i carried out the task as follows:
sony discman to sa9800 aux in then pre out to another amp i had laying around aux in and increased the volume as you said with no hum detected just the usual hissy bzz sound you hear like interference.

PM me anytime thank you again ans sorry for the bad spelling

pioneer-nut said:

hi john, when you say main in jacks what are refering to xactly?

Click to expand...

On the back of your SA-9800, there's a bank of inputs/outputs (Phono1,2, Tuner, Aux, Tape1,2)

Then, there are two more pairs of jacks off by themselves connected by bare metal thick jumper wires that make a "u-shape" if you pull them out. These jacks should be labeled Preamp Out Main Amp In (or something to that effect), and should also have L and R channel labels.

These are the "u" jumpers you want to remove to separate the pre-amplifier section of your 9800 from the power amp section.

Though the pic is of my SA-8500II, and the location of them will be different on your 9800, the green arrow in the pic points to what you should be looking for on your amp.

Once you find them on your amp, follow the directions I posted above. The other amp you're talking about will need this same set of jacks to be of use. If it doesn't have them, you really won't be able to check the preamp section as I've described. If you need further clarification of the procedure just ask, but your discman should be plugged directly into the jacks labeled "Power Amp In". So, looking at the pic, you'd remove those silver jumper "u"s, and plug your discman into the pair on the right side of the arrow for L and R channels. None of the other RCA jacks should have anything plugged into them.

Ahh i see now ☺

so i need to plug the phone into power amp in then pre out yo aux on other amp with speakers on to check for hum right?
Sorry to be a pain john - im sure 'll get it right one day

The phone into the power amp in jack will help determine if the hum is in the Power Supply or Power Amp Boards. It removes the preamp section of your 9800 completely from the troubleshooting equation. Nothing should be plugged into any other RCA jack on your 9800 during this test. Nor should your 9800 be plugged into anything else. The pic shows what I'm talking about.

The fact that you said the tone controls affect the sound of the hum makes me think the problem lies in the preamp section. So, testing the power amp and NOT getting any hum is what we want.

You don't want to hook the preamp out jack to another amp's Aux/Tuner/Tape input jack because you'll be "doubly preamping" the signal. You would send the Preamp Out to another power amplifier's Power Amp In jack. The RCA cable just acts like a long, flexible version of those solid metal jumpers because the signal has to go further to a separate chassis.

Try to think of this as separate components. A receiver consists of a Tuner, a Preamp, and a Power Amp all in one chassis. An Integrated Amp like your SA-9800 combines the separate Preamp and Power Amp into one chassis with a common power supply. You need to add a separate Tuner to listen to AM/FM when you have an integrated amp vs. a receiver. "Separates" takes these three components and puts them into 3 separate chassis, each with it's own power supply and each dedicated to only doing its assigned task (tuning FM/AM signals, amplifying the signal to levels the power amp can use, powering the speakers...)

By removing the jumper "u"s you're taking your Integrated Amp and separating the functions it performs. They're still in the same chassis using the same power supply, but they're not "talking" to each other. For instance, lets say you needed a 500W power amp to drive some really inefficient speakers. You could purchase just a power amp, and still use your SA-9800 as a preamp/source selector. You'd simply remove the metal jumpers, use RCA cables to connect the Preamp Out to the new, more powerful Amplifier inputs, connect your speakers to the new amplifier, and listen.

ok right i followed that through and can confirm no immidiate hum, well i have to place my ear right on the dustcap of the speaker driver and theres the very very slightest of what i think is a mains hum.
same for the headphones the 'hum' is very very faint but there but so much more faint than when the jumpers are in place!
strange one this is - goiny back to when you mentioned florecent lighting, i live in a flat with thise lights outside my door and on the main exterior of the building may be nothing but you got me thinking.

One important thing not mentioned yet is to deoxit any/all pots and switches. Thins can be a bit tricky and will require partial disassembly to do it correctly. Also, I am assuming the amp has never been recapped? As MTF mentioned, the EL caps will certainly be drying out and can cause this to happen. You mentioned "flat" so I am guessing you are not in the United States? You did mention "mains hum" though and if it is a 60HZ hum (US) then it can be a grounding issue inside the amp. Or, as previously mentioned too, there is something on the power line/circuit that is generating this hum. Try and turn off everything in your "flat" especially anything with a motor and check it.

ive never cleaned out the switches so could i use some cheapo electrical switch cleaner or does it have to be the caig deoxit product?
secondly i already switched off everything else in the flat from the main fuse box and left only the plug sockets on but switched everything else off even the fridge lol.
any other suggestions on how i may be able to find out the cause of this dammed hum?
oh and before i forget thorght id also mention that i tried the amp in my friends flat with the same result :sigh:
And yes im from the uk.

"cheapo" (any) cleaner leaves clean corrosion.

deoxit has cleaner, but it also has something that loosens the bond between the corrosion and the metal, making it easier to scrub off the corrosion by contact friction.
The corrosion is sulphates, not oxides.

as for the hum, I'm still trying to decipher everything above.

There was no specific mention of testing each set of source jacks with shorting plugs to see if the hum pickup is internal or external.

That means simply: get two short circuit male rca plugs
plug power cord into wall
connect speakers
be sur pre-out / amp in jumpers cleaned and in place
NOTHING else connected to amp
turn on

put shorting plugs into phono 1, select phono 1, turn up volume, stick ear into speaker, be sure both channels are humming and are they humming equally?
repeat all (plugs, select, volume, listen) for phono 2
repeat all (plugs, select, volume, listen) for aux
repeat all (plugs, select, volume, listen) for tuner
repeat all (plugs, select, volume, listen) for tape 1 play jacks
repeat all (plugs, select, volume, listen) for tape 2 play jacks

edit - I don't know where to get caig deoxit D5 (red can) across the pond....

i use servisol super 10 ..it works well. maplin should have it ..if not ebay is the place ..

Hi MTF, i dont have shorting plugs so is there a cheap inexpencive way to make some or will i have to buy some?
i know for a fact none of my flat mates will have any :sigh:

if you have an old working rca cable you could cut the ends off leaving an inch of wire and twist the wires together .

ok great i'll try that ☺ many thanks

Well i tried that as you said MTF and still the same im afraid.
But i would like to say im very greatful for all the input ive received so far, it means alot that there are other people dedicated to this stuff best forum ever ☺

so.....what next lol.