Pioneer SX-838 Left Channel Issues

Smack2k

Member
My Pioneer SX-838 Receiver that I restored about a year ago has been giving me issues with the left channel. No matter what Speaker set I choose (A, B, C), the left channel goes in and out or gets static. its driving me crazy as I want this thing to sound as good as it did before this started happening...

What can I do to fix this? Anything in particular I need to look for?

I really appreciate the help
 
Have you worked all the switches and buttons when the issue arises?
Remove the jumpers in back and use an RCA patch cord to swap the amp channels. See/hear if the issue moves to the other channel.
Left pre amp to the right main amp.
Right pre amp to the left main amp.
 
I can give that a shot....

As for the switches and buttons, I have worked them and what usually gets it working, is turning the volume up to a higher level....just cant keep it at that volume, although I'd love to.
 
My relay part number reference post from MTF:
Note:
Some info/Part Numbers maybe obsolete.

Pioneer receiver replacement relay reference guide

edit: note -
the MY series relays have the PCB PIN coil connections in a line with the contact connections
the LY series relays have WIDER pcb pin coil connection spacing than the contact connections!!!
Thus unless special provisions are made for the wider coil connections, the MYx-02 and LYx-0 won't interchange

condensed version:
----------start of: There aren't any relays in these models----------
models:
SX-424, SX-525, SX-626
SX-434, SX-535, SX-636
SX-450, SX-550, xxxxxxx
!!!!!!!!!!, SX-580, SX-680
or looking at it sideways, SAME models:
SX-424, SX-434, SX-450, !!!!!!!!!!
SX-525, SX-535, SX-550, SX-580
SX-626, SX-636, xxxxxxx, SX-680

!!!!!!!!!! = no such model
xxxxxxx = has a pc board mounted relay

----------end of: There aren't any relays in these models----------

----------start of: these models use ONE chassis mounted protection relay:------------------

models:
SX-727 SX-737 xxxxxxx
SX-828 SX-838 SX-850
!!!!!!!!!! SX-939 SX-950
!!!!!!!!!! SX-1010


dpdt chassis mount using upper ears 24v 653-LY2F-DC24 MOUSER.COM stock level 51 @ $ 6.55

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
to mount this relay use standoffs (mouser.com parts numbers) 15mm M-F aluminum,
need two per side for 30mm: 728-FM2110-3005-A due to the ears being on TOP instead of on the bottom!!

stainless preferred standoff from mouser 15mm (need two per side): 728-FM2110-3005-SS
728-FM2110-3005-A is 4.5mm od 3mm x 0.5 thread 15mm male female aluminum 0.63 /100: 0.43
728-FM2110-3005-SS is 4.5mm od 3mm x 0.5 thread 15mm male female stainless steel 1.07 /100: 0.74
728-FM1262-3005-A is 4.5mm od 3mm x 0.5 thread 15mm female female aluminum 0.59 /100: 0.40
728-FM1262-3005-SS is 4.5mm od 3mm x 0.5 thread 15mm female female stainless steel 0.97 /100: 0.67
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
----------end of: these models use ONE chassis mounted protection relay:------------------

----------start of: these models use ONE PCB mount protection relay per unit:------------------

SX-650
SX-750
SA-7800
4pdt pcb mount 24v 653-MY4-02-DC24 MOUSER.COM stock level 82 @ $7.24



SX-1050
(the SX-1050 is a rare use of this particular relay,
but because it has a second chassis mount soft start relay
it is listed twice, once in this post, because only 3 models use it.)
4pdt pcb mount 48v 653-MY4-02-DC48 MOUSER.COM stock level 38 @ $8.11


----------end of: these models use ONE PCB mount protection relay per unit:------------------



--------- start of: these models have TWO relays each ---------------------------

---------------------------start of SX- x50 model series-------------------------------------------------

SX-1050 #1: asr-20 protect relay pcb mount 48 v 653-MY4-02-DC48 (pcb mount pins)
SX-1050 #2: asr-015 soft start relay chassis mounted 653-LY1F-DC48 (solder tabs)
why is this soft start relay different than the original? answer:
a visual chassis inspection reveals a dpdt and that WOULD be a type ly2f relay that uses 48v, which doesn't exist,
there IS a ly2f type relay available, BUT it's available ONLY in a 24v coil!!
luckily 24v is available on awr-104 board if you want to convert it to the 24v, using the 653-LY2F-DC24
otherwise the ly1f type is available in both 24v or 48v (why convert to 24v when a 48v is available?)
all 3 (653-LY1F-DC48, 653-LY1F-DC24, 653-LY2F-DC24) are stocked in 40+ quan under $7.00


SX-1250 #1: asr-10 protect relay pcb mount 24 v 653-MY4-02-DC24
SX-1250 #2: asr-015 soft start relay chassis mounted use 653-LY1F-DC48
why is this soft start relay different than the original? answer:
a visual chassis inspection reveals a dpdt and that WOULD be a type ly2f relay that uses 48v, which doesn't exist,
there IS a ly2f type relay available, BUT it's available ONLY in a 24v coil!!
luckily 24v is available on awr-107 board if you want to convert it to the 24v, using the 653-LY2F-DC24
otherwise the ly1f type is available in both 24v or 48v (why convert to 24v when a 48v is available?)
all 3 (653-LY1F-DC48, 653-LY1F-DC24, 653-LY2F-DC24) are stocked in 40+ quan under $7.00

------------------------------end of SX- x50 model series ----------------------------------------------
------------------------------start of SX- x80 model series ---------------------------------------------
start of convenient but confusing rehash:
SX-580 has no relay
SX-680 has no relay
SX-780 (for protect) 4pdt pcb mount 653-my4-02-dc48
SX-880 (for protect) 4pdt pcb mount 653-my4-02-dc48
SX-980 (for protect) DPDT pcb mount 653-my2-02-dc48
end of convenient but confusing rehash.


The sx-1080, SX-1280 & SX-1980 each use two relays, both are PC board mounted:

note #1:
these last three models (1080,1280,1980) use the same PCB mount soft start relay: 653-LY1-0-DC48 (hmmm: 4/20/16 edit: look for LY1F-DC48??)
this is the preferred relay if you can find it,
otherwise use a 653-ly1-0-dc24 and modify circuitry to run on 24v
this is possible on the sx-1080 and sx-1980 BUT NOT on the 1280,
because I suspect the 1280's 24v supply is weak.

note #2:
these last three models (1080,1280,1980) use the same PCB mount protect relay: 653-my2-02-dc48

thus:
x80 models that have two relays, one protect, one soft start:

SX-1080 #1 (for protect) DPDT pcb mount 653-my2-02-dc48
SX-1080 #2 (soft start) 653-LY1-0-DC48, (4/20/16 edit: LY1F-DC48??)
the pcb pattern will NOT support adapting in a 48v LY2 type relay.!!!
if 653-LY1-0-DC48 not available, there's 24v @ plenty of current available at AWR-152 C23 + for a 653-LY1-0-DC24,
remove AWM-120 R12 (2.2k 2w) and run a wire from the pad/hole connected to the relay through the chassis to AWR-152 C23 +

-------
SX-1280 #1 (for protect) DPDT pcb mount 653-my2-02-dc48
SX-1280 #2 (soft start) LY1-0-DC48 (4/20/16 edit: LY1F-DC48??) note there is NO mouser.com 653- prefix!! this is a rare relay) so use: 653-LY2-0-DC48
the pcb pattern WILL support an LY2 relay, and my board was factory drilled for it.

(it's better to use a 48v relay here, as the the 24v power supply is made by a "doubler",
and the 24v (653-ly1-0-dc24 & 653-ly2-0-dc24) relays MIGHT be too much of a load for the doubler circuit)
edit; you CAN use 24v relays by changing the sx-1280's AWR-157 R22, from 2.2k @2 Watts recalculates to 1.7k and 3+ watts
BUT you will be pulling 3.2 watts (instead of 1.6 watts ) from the power supply and throwing away 2.3 watts (instead of 0.8 watt) as heat in the new resistor.

-------
SX-1980 (for protect) DPDT pcb mount 653-my2-02-dc48
SX-1980 (soft start) 653-LY1-0-DC48 (4/20/16 edit: LY1F-DC48??)
if not available, there's 24v @ plenty of current available for a 653-LY1-0-DC24
the pcb pattern will NOT support adapting in a 48v LY2 type relay.
ALSO: WATCH YOUR HEIGHT - THE TOP OF THE RELAY IS VERY CLOSE TO THE BOTTOM COVER!!


------------------------------end of SX- x80 series ---------------------------------------------

--------- end of: these models have TWO relays each ---------------------------

Some of the protection relays in higher power units had factory mounted magnets on the outside case near the contacts
This was to suppress DC plasma arcs when interrupting 30v + DC faults.
I have removed the magnets from the old tape (good stuff - high quality and still lasts) and superglued them to the new cases.
Tape (most modern tape) generally gets gooey after a few years, unless specially formulated (and expensive - like kapton tape)
I NEVER use any tape for "permanent" fixes.

and as a LAST resort when having to replace a chassis mount relay that formerly had ears (The "F" in the part number),
with a more generally available relay WITHOUT ear type mounts, I use two angle brackets attached to the relay sides by superglue.
(the LYxF type relays listed in this post have the "ears" for the chassis mount.)
A "secret": superglue has lousy shear (twist) strength - so make SURE that the angle brackets are properly positioned,
otherwise when tightening down the second bracket - the misalignment will translate to shear force and POP OFF!! (lol)....
(LY1F-DC48??)


edit LY 4F removed, LY2F works.
 
With him working the switches and turning up the volume, this is indicative of dirty switches. The 838,939, and 1010 ALL have the same type switches for speakers, and functions. These have a tendency to get dirty faster than any thing I've seen. I have to clean my 939 yearly. I would advise to pull off the top cover locate ALL switches, spritz ALL of them with DeOxit D5 then exercise 40-50 times smartly. Then spritz each with FADERLUBE F5 and do it all again. You can switch hands/fingers as needed. Do all the pots at the same time.
 
Larry, just a thought:
It's about time we started evaluating caig's preserv-it
Perhaps your 939 can serve as test case?
You've established cycle / lifetime data, we could see how much preserv-it extends the time.
 
Hmmmm. Not a bad idea.. You buying???:D:D (Just kidding Mark). I'll get some and we'll see how it pans out. Might be just the thing for old carbon pots on my FISHER Tube gear too.

Note to Mark; preserv-it is now called DeOxit SHIELD. Just ordered a can.

Larry
 
Last edited:
I have an SX-838 that suffered from the same issue. On mine it was those black selector switches lined up just below the tuner scale window.
The most troublesome were the 2 Phono, FM, Aux, and Loudness switches. When I first got it, when switching between FM and Phono one channel would get scratchy and drop out. I don't recall whether it was left or right, but I think it was the left. The switches were a bugger to get at.

Mark, told me how to take about 6" of thin strand insulated wire and strip the copper core out of the insulation. Flare the end of your Deoxit straw, insert the gutted insulation and you then have a flexible straw extension for your Deoxit. To get at those switches, remove the front face of the receiver. There should be little slot openings around each switch, can't remember if they are on the sides or above and below, but thread your straw extension into those little openings and then do the normal spraying and working the switches in/out several times.

Since then I've even taken the remaining strand of copper and spiral wound it around the straw extension which allows it to be curved and bent to be used in hard to get at locations.

Not saying this is the problem with your 838, but it was on mine.
That straw extension trick has saved me a lot of time on many other units - brilliant idea Mark, thanks.
 
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