sx-1010 developed Crackling & Popping Sound overnight

[GITAY'ND]

hey everyone

i have this sx-1010 that i bought on ebay 2 years ago.
had an sx-737 before it , sold it an upgraded to the sx-1010.
i have 2 pair's of hpm-60 & i uselly hear with 1 pair (they are different positioned).
also a tube tuner , The-Fisher kr-60.

so that's my system & let me tell u , it's sounds amazing !!!

sx1010 has a "monster" tone control that can push +15db for bass and\or treble (4 knobs).
the hpm's are bass'y & treble'y and very clear and crisp and also have a tone control that can push up.
not many systems sounds as big and real like it , not for that price ...
i bought all of those components after hours of reading here ,
your revives on the sx1010 & hpm60 & the fisher tube tuner convinced me , and u were right ...
all my of friends and family are amazed by it

i am an engineering student , study all they long while listening to the tuner, tv also connected to it.
so i use it all day long , morning til midnight every day , it's making my life so much better.
i don't have much , choose to buy the system over a new pc ,totally worth it ...

as u can imagine am connected to my sx-1010 like if it was my son...

2 days ago it started having crackling & popping sound from the speakers , only from the left side.
it's an loud crackles too , that can damage the speakers.

it's on both a or b speakers ,
it happens even when i removed the jumpers (pre-amp to amp on the back side) ,
it happens even when i disconnected all input's (tube tuner . pc ) .
it happens even when i press and un-press all the buttons & levers .

something is probably wrong with the left amp board ...

i want to fix this , can u guy's help me to figure what and who ?
i read post's of members re-capping & re-building an i have always wanted to that too,
guess now am kind'a forced to, so maybe it's for best...

 

[zebulon1]

Don't power it up any more. Take the bonnet off. Four screws and snap an image of the amp boards. They are the boards vertical and mounted in front of the heatsinks.
Let's see if its original.

 

[GITAY'ND]

it's original , bought it in is original box , it was new allmost new.
i removed the wooden case and it was 100% clean from dust .

 

[jeffpaletz]

Have you been running it with that towel covering the heat vents on the back top?

 

[dr*audio]

First you need a sacrificial set of speakers, or put a 100 Ohm resistor in series with each speaker to protect it.
Next buy a can of freeze spray and spray a tiny amount, using the snorkel, on each transistor on the left channel board. The one that causes the noise to increase or decrease when you spray it, is bad, replace it.

 

[larryderouin]

The 2sc1451 transistors in the amp are the #1 suspect for the symptoms the OP has with the 1010. #2 suspects are the 2sa726 and 2sa725's thru out the unit. I'd replace the 1451's 1st, and retest. Replacement is the KSC3503DS or DSTU. Either one.

Larry

 

[zebulon1]

The 2SC1451's can take out the big outputs. Even if you can identify the noisy transistor - follow Larry's advice. The boards are old and in need of attention. Good time to repasted the outputs take care of the phono board.

 

[dr*audio]

Whatever transistors you do replace, do the same thing to the other channel. Pioneer had a reputation for using some crappy transistors that become noisy with time.

 

[GITAY'ND]

thx for all of your help guys !

Larry , i will order the replacement transistors and replace them first,
can u plz be more specific about the replacement name's for 1451 & 726/725 and were can i buy them ?
also who many should i order ?
also, any other common problematic parts ?

dr*audio , once i replace the part's above , if it doesn't solve it ill know where to look next.
and ill will change symmetrically

 

[larryderouin]

Type in the transistor numbers i listed earlier @ mouser. You'll need 4 ksc3503's and about 24 ksa992's. Reason being you'll need to match Q1-Q2, and replace Q3 on each amp board, then the rest of them are scattered thruout the rest of the signal boards. Get the SERVICE MANUAL and go thru the parts list and verify each and every transistor. If the manual says 2sa726 or 725 and there is a 2sa763 in there, leave it alone. This was a later replacement that doesn't have the tendency to go noisy.

You have 2 amp boards. 2 of 1451's and 3 of the 725/726 for each amp board. (I'm not looking at the schematic right now and going off the top of my head.)

 

[Overundr1]

Good info, common issue in this series. Be very careful with the two diodes attached to the heat sinks (the ones with the white fabric covers as the leads are fragile and if bent can and do break off the diode which although repairable is a real pita. When you reinstall them to the heatsink do not over tighten them or they will crack. Also, given how short the wires are coming through the chassis to those driver boards you may consider removing the back receiver panel to allow easier access to the boards. Others may have a better option here though

 

[zebulon1]

I am on a run of 1010's. For some reason three have been getting the go through. I really love these sets but they are more difficult to access than most Pioneers. The Amp boards are the worst of it. Rebuilding the boards requires:
Detach the STV diodes from the heatsinks. Be very careful of these.
Lifting the heatsinks out.
Removing the outputs.
Removing the boards mounts.
Removing the cover from the Phono EQ.
And like "Overundr1" removing the back cover.
I never removed the back plate but it sounds like a good idea. I think loosening it up and keeping it connected might help access (desoldering is needed to completely remove the back plate). The back plate has a front cover that can be removed and that maybe enough to get the advantage on the back of the amp boards.
I cover everything that's not getting loosened or removed with rags and masking tape to protect the finish and components. It's easy to scratch and damage other parts with the heavy heatsinks, soldering iron, and other tools.
And most of all, like "Overundur1" said and we should of mentioned earlier; Protect the STV diodes as stated in the above post!

 

[Overundr1]

The unit I am restoring at the moment was worked on in the past. Whoever did 'that' repair used ecg and ge outputs and made it easy on themselves by cutting the wiring off the output boards as well as i don't have a clue nte transistors in the protection board, grrrrr. Moral of the story, try not to cut any wires to get at components, take your time and look at the assemblies and do it once, do it right
When in doubt ask.

 

[GITAY'ND]

thanks everyone !!!

your posts really help, i know exactly what to do (and what not to do) .

i ordered the parts and ill post pictures of the work on my sx-1010 when ill start.

 

[GITAY'ND]

good news everyone !!!

i finally got the time to fix my sx-1010, with your very helpful guidelines i replaced 3 "2sa726" to "ksa992fbu" & 2 "2SC1451" to "ksc3503" in each amp board.
i matched Q1 & Q2 ( 4 matched in total ).

it solved the problem !
no more Crackling & Popping Sounds

didn't took any pictures because it didn't look so great at first ,
i took out the heat sink & the amp board mounts but didn't want to detach any wires.
had to pull out the old transistors & insert the new while fighting the heat sink that was always in the way .
bad lighting, bad tools, bad working position, i tell you it didn't look so good, i worked like an amateur .
but i didn't damage anything and i got the job done so overall am very happy with the result .

and let me tell you, i almost cried when i heard it play again after all that time ...
my wife hugged me, she noticed the excitement , she was excited too.
she said she missed it so much, she picked the first song and started dancing
she always saying that the music sounds better with this system , "like a night club"...

very happy day for us and its all thanks to you .

thank you all for your comments and info !!!

you guys make it possible for anybody to fix their own gear, adding lot more fun to the hobby,

saving others hundreds of dollars and making man like me to be more appreciated by their wife

larry , you saved my sx-1010 , in my book you are the greatest .

zebulon , your words were very helpful ,Overundr yours too.

 

[bando281]

I'm glad you got it running; the 1010 is a nice, nice, NICE sounding receiver.

 

[markthefixer]

You don't fight the heat sink, you regrease the output transistors, which involves removing the power output transistors from the heat sink - which will free up the board considerably. Of course you document the heck out of things before disassembly.

Still, congratulations on your success.

 

[GITAY'ND]

mark, i tried to avoid any complication.
its my first time with that kind of work, i just needed to fix the problem not to service the receiver.

i got the receiver in mint condition , it sounds perfect with no issues so ... (in its original box with no sign of use)

i think i damaged the transistors ( one of those i changed ) with my high gain tube radio.
the tube tuner sounds better in high gain & also naturally has better "signal to noise" ratio ...
it didn't have any distortion sounds, it was higher then the pc but smooth, the extra pressure must have broke it.
i tuned its volume down to the same level as my pc ( both act as inputs to the sx1010).

i want to take the opportunity to say that the "the fisher km-60" tube tuner sounds amazing !!!
it sound clearer & more realistic then my pc,
i have a 400$ professional sound card on my pc playing over 10mb\sec songs and still the tuner sounds better.
down at the radio station they make 1,000,000$ sound and the only way to get it perfectly is with a tube tuner.
when they play vinyl records ...
its like the speakers not working any more & there is an open portal to another damnation on the wall.
nothing sounds like that !

in case you wanna know , my antenna is a ~100 feet (~40 meter )copper wire wrapped around a ~30 feet high tree (~12 meter).
i have an "antenna tree"

 

[zebulon1]

I would love to see a picture of that! (Tree antenna)

 

[GITAY'ND]

its not very easy to see , but you can see some of my "antenna tree".
first ill show my original sx1010 antenna