Pioneer Sx-1010: Newbie audiophile needs guidance

larryderouin said:

Is the clunk coming from the speakers or the 1010? Go back and triple check the oritentation of the legs on the transistors you installed. Remember the board drawings are backward (from the solder side, not the component side.). This threw me for a while when i did mine back in '10. Try tightening down the mounting bolts on the transformer.

Click to expand...

The CLUNK was without any speakers attached with volume all the way down.

As for the transistors, I put them in based on the top side of the boards themselves. I plugged the Emitter legs into the hole closest to the arrow side, the base into the hole closest to the bar line and the collector into the hole closet the last one. I see that the schematic is from the solder side. I only used that for the locations, not for the orientations. ALL the orientations were based on the printing on the top side of the board. Even for the Caps. I plugged the positive sides into the holes closest to the "+".
I checked the power supply board and the printed top side board graphics match the orientations (mirrored, whatever) from the service manual.

I do not think it was the power board, protection board, or any of the boards I changed out caps and transitors now. I tested and ran the unit after each board and everything WAS working until that last time I took out the amp board and replaced two transistors I had forgotten. I am not even getting past the 5 4 3 2 1 CLICK for the protection circuit anymore. IT blows fuses the mOMENT I turn it on.

Will the 40watt bulb at least tell me if there is a short before moving on to the 100watt? I also have a 60 watt and a 53 watt standing by. I will get a 100 watt later

I also replaced the power cable with a newer one just in case the short was there.

What is the big round soft orangish things that looks like a big saucer like capacitor between one leg of the power plugs and the main fuse? Is that a "soft fuse" that i have heard of? I put a DMM across it and I get a chime so It DOES have continuity.

Transformer arrived. Spliced in the new one. I stripped the ends of the existing wires from the boards and stripped ends of the transformer leads. I tinned the ends and soldered the ends together, matching up the colors on each side. THEN I wrapped each joint in heat wrap to cover the splice. Should be good right?

ANyhow. NO GO

Still pops the two 6amp fuses. The one inside the automotive fuse holder turns black inside. The one inside the main fuse holder just kinda melts a little.

Is that a clue?

I am using 1, 3, and 6 amp. Glass ones. from Mouser. the 6s go in the outside main holder and inside the automotive style one I bought at radio shack. The 3 is on the rectifier board and the 1s are next to it.

I am about to give up. What next? Should I reorder all the transistors and caps and start again?

Ok. I give up. I think I will just order new transitors for the power supply board and protection board, and maybe a new speaker switch, even though it looks brand new. Something blew up, somewhere that must be causing this short.

While I am at it I think I might replace that resistor to the ground and that round saucer thing attached between the power input and the main fuse.

BEFORE you order any parts it is best to post a list of the parts you are going to replace so the list of parts can be vetted. This will safe time/money/headaches, etc and will allow others to assist in the replacement process. Please read up on prior posts on this amp as it will lead to a positive result rather than frustration..

rowingcoach said:

Ok. I give up. I think I will just order new transitors for the power supply board and protection board, and maybe a new speaker switch, even though it looks brand new. Something blew up, somewhere that must be causing this short.

While I am at it I think I might replace that resistor to the ground and that round saucer thing attached between the power input and the main fuse.

Click to expand...

rowingcoach, please just give this project the time it deserves. Don't get in a hurry, the guys around here will help, just be patient.

We're all rooting for ya, bro.

Stop, take a breath, and summarize for yourself and us what was done.

Which boards got capacitors? Transistors?

You successfully powered up before starting work? Or did it have problems?

Did you successfully power up between different boards? Is it the amp boards when this started?

only A REVERSED main capacitor or shorted (or told to turn full on by a bad amp driver board) power transistors will blow the main fuse.

I thing the thread eliminates the reversed main capacitor, but I can't take all the time to analyze the thread, thus the summary, with pertinent questions.

What part of the Chicago are are you in, rowingcoach?

AC, We got you covered. I have been were you are now! This is a journey, enjoy it. The biggest reason I love repairing these sets is "It's a puzzle". Not to MTF or a few others, they have it mastered. Helping us Noobes is the next step for them. We need to double check and triple check every thing we do to the sets. It is always something we did and in most cases it's visual, you can see it!!!! A transistor or cap in backwards, outputs in the wrong positions. The large filter caps? Did you mess with them? The lighting circuit runs on AC, did you mess with that? Pinch any wires when reassembling the tone control boards back into the front panel?
I have to get my 1010 out for craxx6969. If it helps I'll take pictures.

I am in CHicago, Proper. I live on North side in Edgewater, I work in Hyde Park. Both are CHicago addresses. The sx-1010 is on my workbench at work.


I did things in this order

Power Supply Board

1. replaced the caps
2. replaced the transistors
3. replaced the resistors
4. powered on the unit. It worked.

Tone Board

1. recapped
2. new transistors
3. powered unit up. It worked

Cleaned and DeOx'ed the push buttons and knobs. Lubed the pots with faderlube.

Muting Assembly

1. New caps and transistors

Powered up unit. Worked.

Phono preAmp

1. Transistors and Caps

Powered up Unit. Worked.

Power Amp Board Left.

1. Replaced all caps, all but one set of transistors and q7, and the pots
2. powered up and worked

Power Amp Board Right.

1. Replaced all caps, all but one set of transistors and q7, and the pots
2. powered up and worked

Tried to set the Bias and Offset. Could not get a good reading on Left Board. Something was open or grounded and the numbers kept going all over the place. See the earlier thread describing this.

Removed Left Board again. Replaced two more transistors that I forgot the first time. still have not replaced q7

Turned on.... and BOOM. Blowing fuses.

Figured that the problem was that board I just worked on. I had not touched anything else. Noticed that there was some crusty crust the color and consistency of dried up CocaCola down the back side of that board. Scraped it off carefully with a flat screwdriver. Cleaned it up with compressed air and alcohol. Looks much better.

Still blew the fuses.

Zeb sent me a replacement board. I installed it with MORE new Transistors except Q7. Also replaced ALL the transistors again except Q7 on the other board to match. Rechecked the orientation of them as I replaced them.

Installed new Main Filter Caps with new bleeder resistors. Put a new automotive type fuse holder in place of the fuse with prongs.

This time had a Dim Bulb Tester with a 40wat bulb. Bulb lights up.

Thought maybe the short was in the power cable. Replaced it with another known to be good cable

Thought maybe that the bulb was too underpowered. The local hardware store no longer sells anything higher than 60 watt. Tried turning on unit WITHOUT a DBT. BOOM. More fuses blow up.

Replaced the Transformer outright.

Went to other side of CHicago, found a HOme Depot that sells 100 and 150 watt bulbs.

Thought maybe I ordered the wrong bleeder resistors. Took them off and put on the bypass caps I bought in place of them.

100 bulb lights up fully. never dims.

I have just finished checking the installation of the caps and transistors against the Data sheets from Mouser to make sure I had all the orientations correct. The power board and main AMP boards are all correct. The protection board is next, but just looking at it I can see that all the transistors I replaced look correct Left to Right ECB.

Here are some shots of where I am now. Does anything look out of place?

and another batch

Ok, have patience with me, it will take a while to digest those EXCELLENT and concise posts.

IF everything turns out to look ok, the next step is to investigate WHY the power amp sections are turning on the output transistors hard enough to blow the main fuses.

That is what we are doing over in the craxx6969 thread.

He removed the power transistors and insulated the empty sockets, so that faulty power amplifier boards can be trouble shot.

I will take one flying leap, and say that the initial position of the IDLE CURRENT trim pots VR2 (470 or 500 ohms) in the center of the power amplifier boards is critical, at one extreme of rotation (single turn) there is minimum idle current, but at the OTHER extreme the idle current is way too high, it may be possible this is the problem.

The key is to use an ohmmeter and read across the installed trim pot, and turn the adjustment so that the ohmmeter reads zero ohms between the lone terminal (one end) and the two terminals (the OTHER end and the sliding tap) that are connected together on the larger "blobby" foil.

This is something that's easy to check. Thus my premature answer before analyzing the posts and photographs.

edit - the photo of the amp board with the yellow wires soldered on, (not the other with the blue wire wraps) looks like the trim pot is full clockwise - which would be 500 ohms and baaaaaddddd..... it COULD be as simple as that!!

markthefixer said:

edit - the photo of the amp board with the yellow wires soldered on, (not the other with the blue wire wraps) looks like the trim pot is full clockwise - which would be 500 ohms and baaaaaddddd..... it COULD be as simple as that!!

Click to expand...

Just tried it again connected to the DBT with both the idle pots turned both ways all the way up and all the way down. Made no difference in the DBT.

I just looked up Bensonville! You are closer than Ikea and by Ohare International Airport? WOW. If this turns out to be a major pain in the ass maybe I will have to come drop it off ;-) Do you own a shop?

Man, this is getting good. Hang in there rowingcoach.

By the time I am finished I will have the NEWEST and MOST BESTEST SX-1010 on the planet! I can prolly feed a small country with what I would likely be able to fetch for it on EvilBay. Which I wont do. Just saying. I was looking before I got this one and bid on one there that had been restored that went for over $600. I think I might have at least that into this one by the time I am done. I should have just bought that one! OH well. hindsight. At least when I am finished I will be able to say "i did it!" AND "I can recap and rebuild pretty much any amp!"

RC,

Mark will walk you through this with positive results and you will have the pleasure of saying I DID IT MYSELF. Mark is probably on a 6-12 month backlog so I would wait for him to get to this one. He is working on a project for omri that is a time cruncher. Check out my thread for his comments....

Patience is a virture when working on these units..

rowingcoach said:

Just tried it again connected to the DBT with both the idle pots turned both ways all the way up and all the way down. Made no difference in the DBT.

I just looked up Bensonville! You are closer than Ikea and by Ohare International Airport? WOW. If this turns out to be a major pain in the ass maybe I will have to come drop it off ;-) Do you own a shop?

Click to expand...

Could the problem be the volume knob? Like... maybe something inside it is shorting and causeing the volume to be ALL the way up? And because the trim pots have not been set yet that the fuses are blowing up right away?

How can I bypass the volume pot or disable it so that I can do a test power up at ZERO volume with the DBT?

UUUUHHHHHGGGGG (say it like Charlie Brown)


So I was reading another MTF troubleshooting post about the sx-1010. It is one that I have read a couple times. It reminded me that the main filter caps had the negative and positive lines reversed on one of the caps. I checked against the caps I cut out and there it was!

I had the leads to the main filter caps REVERSED. I had the Orange wires connected to the positive side!

I reversed them and tested on the DBT and no change. There is still a short somewhere.

NOTE: The original incident with the short happened BEFORE I even touched or replaced the Main filter caps.

Could I have "fixed" the original problem, which may have been a short in the left poweramp board and then created ANOTHER one that resulted in my Output Transistors blowing?

RC,

I would not replace or do anymore work to the unit until Mark finishes his project for omri. He can walk you through the jungle and come out smelling like a rose.. And yes, if you put the main filters in incorrectly and did not use a dbt when you fired up, there could be additional damage. Shorts are a PITA, crossed wires, loose wires, one wire touching another. Did you take any photos before you started the project as those are one of the most valuable assests you can have, saves lots of headaches.

Have patience young RC.. all things will work out..

JT

rowingcoach said:

UUUUHHHHHGGGGG


So I was reading another MTF troubleshooting post about the sx-1010. It is one that I have read a couple times. It reminded me that the main filter caps had the negative and positive lines reversed on one of the caps. I checked against the caps I cut out and there it was!

I had the leads to the main filter caps REVERSED. I had the Orange wires connected to the positive side!

I reversed them and tested on the DBT and no change. There is still a short somewhere.

NOTE: The original incident with the short happened BEFORE I even touched or replaced the Main filter caps.

Could I have "fixed" the original problem, which may have been a short in the left poweramp board and then created ANOTHER one that resulted in my Output Transistors blowing?

Click to expand...

That's what I get for not starting at the basics and assuming...

cascading changes (UNPOSTED work) only obfuscates the problems.

so it still blows main fuses.

I hate to say it, but I must:

remove the 8 output transistors and insulate the sockets.

we will get to the point where we KNOW the amp boards are being fed properly and will behave themselves when they are allowed to play with the output transistors.

Sorry - but you kicked me into "trust nothing, check EVERYTHING" mode...

once they are out and the sockets insulated, bring it up on the DBT and see if it dims.

IF it dims, read the voltages (DC AND AC) across the terminals of the two big caps.
Then repeat the readings with the black dmm lead connected to a bare metal chassis ground.
insulate the red probe - all but the tiniest portion of the tip, make an exposed mm look big...

Then read the DC voltages on the awr-054 board, pins 6 - 15 (pins 1-5 just have ac on them)
please make it easy on me, and list what the voltages are SUPPOSED to be.
there are plenty of awr-054 board posts/threads from me to guide you instead of me finding and duplicating those posts.