Pioneer SX-9 Where to start, if at all

weeber

Active Member
Just picked up a SX-9 receiver that I'm told doesn't work. No idea what's wrong. I haven't plugged it in yet. I did take the cover off and saw some nasty things. The two big capacitors are bulging at the top and it looks to be leaking out the bottom.

In theory, if I wanted to try and fix this, what are some things I need to consider?

First, my only electronics experience is building a nixie clock, which I had no problem with. I could perform all the tasks and tests, but only have very very basic grasps of the concepts involved, but I do enjoy a challenge.

Is this particular receiver to complicated to consider?

The capacitors are 15000uf 71v (at least that's what stamped on them). They seem expensive and I'm not sure I want to put in too much money.

Besides the obvious big capacitors that need replacing, what other components need to be checked before proceeding? That is before I plug it in. What do I need to do before plugging it in and then after?

I guess I'm asking where to start?

Oh, and I don't seem to be able to find a service manual, the closest I can find is for a SX-8.
 
It picked me. I picked up a set of cs99a speakers and the guy threw it in the deal. It's very ugly on the outside but on the inside still looks worth trying to revive.
 
Weeber:

Owner's manual available from HiFi Engine, service manual available from StereoManuals www.stereomanuals.com. The SX9 and brothers are not popular because they do not age well. the whole front (faceplate,buttons, sliders, doors, etc) is plastic that breaks very easy. Electronically the SX9 is a pretty good unit if working. When introduced this series was called "The Communications Series" often called "Champagne" by audiophiles based upon it's color. Actually good cosmetic examples of this series are pretty rare but it is hard to put together a "stack". I have managed to get some pretty good looking units. The SX9 is also not common in that it was primarily sold through military exchanges. If you want to evaluate this unit I would set up a dim bulb tester and see if it has any short problems. If it does not indicate problems in this area and fires up you then evaluate the reciever. It might surprise you - it is powerful. I have a real ugly SX8 in my shop which I use for testing other components. The best component of this series is the linear turntable PL-L800 and the A9 integrated amplifier. Strangely enough the RT707 was the reel to reel offering the year of introduction of this series. This series reminds me of a Corvette a friend of mine flipped (end over end) and blew off all the fiberglass body. The car was still functional but not steet legal. Powerful but looked like crap.
 
Okay, so I plugged it in, no fires, wires held all the smoke in, no unusual sounds or smells. All lights work and buttons all seem to function.

I hooked up some disposable speakers. Tuned in an AM station and look and behold it makes sounds! At least out of the left channel. Nothing out of the right.

Is there anything I can check without a manual? I'm still looking for a free version. Stereomanuals.com wants $22 which I'm not sure I want to commit to yet.

Maybe tonight I can post some pics. I know pics is the best way to get people to reply :)
 
Press all the switches and controls particularly the tape monitor switches, filters, and speaker switches see if you get the channel to come back.
 
Okay, so here are some pics:

Interestingly, when I tilted the unit up on its sides for the pics the sound cut out. Bad solder?

IMG_20140619_093949.jpg
Well here it is all lit up.

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The guts, nice transformer.

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Hard to see in this picture, but these caps are very pregnant looking. I'm hoping they have a litter of smaller caps for the rest of the machine.

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The underside of the caps. You can see stuff that has oozed out the bottom.

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The whole bottom. You can see some very warm areas on the bottom of one of the boards.

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Close up of the hot spots.

The only service manual I can find is a paper one for $22. I'll have work out a budget to see if I want to continue.
Can anyone guess at a total dollar figure to get this working? The big capacitors are 15000uf 71v, I'm guessing they will be more expensive than the smaller caps elsewhere.
I will test the transistors on the heatsinks according to a guide I found here: http://www.audiokarma.org/forums/showthread.php?t=43186&highlight=bipolar
 
Press all the switches and controls particularly the tape monitor switches, filters, and speaker switches see if you get the channel to come back.

Well, this seemed to get some more electrons flowing. Both channels now produce sound!

I don't want to run it too much though with those big capacitors all swollen on top and stuff leaking out the bottom.

Anyone know a good source for these? Any advice on changing them?
 
What are the dimensions for the large caps?

The best I can find so far are 18000uf 80v for $16.00. Mouser, but their screw terminal. 2.0 by 3.12 inches
 
2 inches is too big.

They're about 1.75 inches by about 4 inches.

They fit through holes in a bulkhead thingy, so they can be shorter or maybe a little taller, but not more that 1.75 inches fat.
 
i don't know anything about the different types of terminals. i see screw in type and snap in type? i just assumed there was a couple leads sticking out the bottom that were soldered to the board. i cant see how these ones are attached until i dissassemble it. the connections are covered by the plate with the holes in it that the capacitors stick out through.
 
That makes a difference. You might modify it to work, this could make it worth while to fix. Otherwise maybe not. I would try to make it fit so the next guy can fix it to original.
I'm sure another has done this before, but may not want to disclose the method due to the butchery performed. "Snap in" are solder posts, screws are threaded inserts with screws for ring terminals.

Look and see how the caps connect to the board.
 
So here are the caps removed. They are just held in by the Solders.

da2ury5y.jpg


They have 5 leads but it looks like only 2 do anything. The rest may be for mounting.

2yzejy5e.jpg


They have a number stamped on the top "23 CAH"

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I was thinking of using screw on type upside down with wires with ring terminals on one end and soldered to the board on the other end. Would this work?

Otherwise I could use snap in with just 2 leads (if the have the same spacing) and just make sure they're clamped in securely.

Sent from my Z10 using Tapatalk
 
Okay, I got some new big caps.

Panasonic 15000uf 80v. Fits right in no problems. Unit powers up and plays.

It seems one heat sink was getting hotter than the other so I thought I would check and adjust the DC balance and idle voltage.

Don't have a SX-9 service manual but apparently the adjustment procedure is the same as in the SX-8 manual (which I do have)

The first step was to adjust 6 pots labeled VR 1 through 6. Numbers 1 & 2 were set to the middle of their travel while 4 through 6 were to be turned all the was counterclockwise. Once this was done both heat sinks seemed to heat up equally (and what I feel was fairly quickly)
Next I checked the DC offset at the speaker terminals. The left channel was about 9mV, easily adjusted to 0 with VR1. However the right channel measured at about 190mV which I couldn't adjust much.

Now comes the part I can't figure out. The idle current has only 1 measurement point but the manual says for the right channel VR3 =56mV and VR5 =70mV. And at the measurement points I get 300 and something mV. I'm not sure how I should turn VR3 &5 to get these 2 voltages from one measurement point especially since both are already turned all the way counterclockwise?

I've included the adjustment procedure if anyone wants to take pity on me and help me out.

IMG_00000160.png

IMG_00000161.png
 
Slow down... please...

First some preliminaries:

DC balance will disappear at the speaker terminals if the (if present) protect relay opens up - because it is unhappy with the voltage.
Now while they say "across the speaker terminals", it is a GROUND based measurement with the black DMM lead connected to a bare metal chassis ground, which is usually where the black colored speaker terminals are (eventually) connected to. (In a roundabout way, the few millivolts of difference when the speakers are pumping out power are sometimes critical - but you won't see them in this situation).

Heat sinks getting blazing(ly) hot - I think you have a misunderstanding in how to connect the DMM for the idle current reading. It is NOT ground based. And it is a sequence. Best explained as such:

both vr3, vr5, vr4 and vr6 fully CCW

connect Red DMM lead to JP1(+)
connect black DMM lead to JP2(-)
set DMM range if necessary to 2 volts (maximum)
turn on unit
adjust vr3 to get an initial meter reading of 56mV or 0.056 volts
then
adjust vr5 to increase that meter reading to the final reading of 70mV or 0.070 volts
turn off unit

connect Red DMM lead to JP4(+)
connect black DMM lead to JP3(-)
set DMM range if necessary to 2 volts (maximum)
turn on unit
adjust vr4 to get an initial meter reading of 56mV or 0.056 volts
then
adjust vr6 to increase that meter reading to the final reading of 70mV or 0.070 volts
turn off unit
disconnect DMM leads

If I interpret things correctly, you got a manual from Rick at Stereomanuals.com?
If the adjustments above do not cure things, and we need to do repairs, either I need a good PRIVATE scan (I will PM you my email address - do not post the scans on the forum) of your manual to advise you, or I need another copy of the manual. I have searched for a manual also, and come up dry. I do not wish to "poach" on Rick's excellent work, but I'm not in a position to purchase a manual for everyone I assist.

If you wish to photocopy it, please keep the photocopies for your reference, and send me the original which I will then return to you when things are all working correctly. I need the best information possible if this is to succeed.
 
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Okay, that really clears things up. Thanks!

I don't have the manual yet. It's coming, but in the description it says it includes the adjustments for the SX-8. (a manual I found online for free). I think that is a typo, though, as I read the description on Ricks Site for the SX-8 and that said it has the adjustments for the SX-9.?

Anyway, I think I owe it to myself and this receiver to first get a better DMM with clips instead of probes and wait for the manual to show up.

When it does I'll take the measurements again, properly, and post the results.
 
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