SX-850 Restoration Record

[davros]

Latest update.

Replacing Q5 and on the Supply board did the trick. All my voltages have returned to normal on the power supply board.

Relay clicks in roughly 4 seconds.

After 15 min warm up I spent another 30 minutes obsessively working on Offset and Bias. Offset is now steady at .1mV on both channels. Bias is at 20.1mV on both channels.

I put her back together and spent 20 minutes on the radio with no issues.

Switching to Phono 1 is giving me some crackle and pop (both speakers), and going back to FM I lost the right channel.

I shut down and worked all the controls and levers and had right speaker back when I powered back on

Jiggling the stereo/mono switch seems to increase the popping on Phono.

I'm going to work the switches tomorrow, and if necessary I'll need to go back in to clean the switches further. I really gave it to those switches the first 2 times, so I'm hoping exercising them does the trick.

I also should have the new relay today, I may put it in and hit the controls again anyway.

I'm in the home stretch, and while not done, I can see the light at the end of the tunnel. I will continue reporting back, until it is running perfectly.

This has been time consuming, and for those following, its been a month long process.

I will also post a lessons learned, and a conclusion.

As this is my first Solid State rebuild, maybe I can part some of my meager knowledge on to someone who has been holding back from starting their own Pioneer.

I've certainly learned a large amount from the forums, and while it may have seemed I moved ahead without reply's at some times, its because my answers were found somewhere else on the forum.

 

[dlucy]

Congratulations!

 

[davros]

I changed the Relay, and popped the new relay in the old case. So much Better! Both channels are strong and the same volume, and both are dead silent without signal.

FM sounds amazing. I forgot how good that could sound! Wow!

As for Phono

I've got Static and popping coming out of the Left Speaker..

AWF-011 (Equalizer Board)
I changed Q1 and Q2 as they are the known troublemakers. Q 3,4,5,6 are all original.

Even with the phono inputs unplugged I get the noise in the left channel.

So change the 2SC1313 in Q's 3,4,5,6???

Could it be something else?

Some of the pops are pretty loud, I don't want to damage anything.....

 

[dlucy]

I've got Static and popping coming out of the Left Speaker..

AWF-011 (Equalizer Board)
I changed Q1 and Q2 as they are the known troublemakers. Q 3,4,5,6 are all original.

Even with the phono inputs unplugged I get the noise in the left channel.

So change the 2SC1313 in Q's 3,4,5,6???

If it only occurs when PHONO is selected, then I'd guess the 2SC1313's.



On the SX-850 that I did, I replaced the 2SA725's with KSA992's and replaced the 2SC1313's with KSC1845's.

 

[davros]

Due to the server outage and rollback we have lost some info.

Re-Update

I had decided one of the 2SC1313's had gone noisy and decided to replace all 4 (2 in each channel) I replaced them with the KSC1845 as per my parts list. These are backwards from the original transistors. The new are ECB, the old were BCE.

Upon start-up, I had dead silence on the Phono Inputs. Turning the volume up as high as I dared, there was still complete silence. The sound through the Phono is beyond what I could have hoped for!

During the weekend, I have now listened to FM for about an hour, and the Phono for about 6 Hours. The longest run-time was about 4 hours straight. Back was warm, but not worryingly so. Just enought that you could feel the gentle rise out of the vents.

No other issues have come up, and the performance on all counts is simply exceptional!

I have (or Had) the following..
Sansui 5000A (Unrestored)
Pioneer SX-650 (Unrestored)
Sony 5.1 Surround system (No Idea the model anymore, gone for years)
And I grew up with my Dads Sansui 5000X (Now a basket case in his attic, its my next project!)

This SX-850 Beats them all!
I really can't say how pleased I am at the outcome!

If you have followed this thread, and have never posted, or are hesitant to start you own project, Just do it!

The satisfaction of hearing what these are really capable of is worth it.
The increased reliability is worth it!
The fact that YOU can resurrect one of these beautiful machines and make them sing again is worth it!

Most of all, the help you can receive, by people who are really knowledgeable, and truly care about this hobby is Invaluable!

No doubt I will become a Subscriber, and no doubt I will continue to find these boards an unending treasure of information!

I will follow up with some personal thoughts and tips later, as well as what I used and found to be essential in my work.

 

[dlucy]

THe Sansui 5000 should be a good contender for best sound amongst all those. Set that as your next project.

 

[davros]

My Dads Sansui 5000X is next. He just sent it to me in the mail.

He's 70 now, and has more time than things to do. I hope to get it it back in top shape so he can enjoy it again.

It survived 45 years, 3 Sons, and 5 grand-kids, but the grand-kids did it in.

It's been in the attic for the last 5 years... He's been listening to a crappy Re-Pop AM/FM/Record player ever since.

 

[dlucy]

I'm pretty sure the 5000 is a cap-coupled design, so (in perfect, restored condition) it'll sound warmer than the direct-coupled SX-850 design.

 

[davros]

It is cap-coupled Doug. It's also a beast with the right speakers. My Dad, and this Sansui are the reason I'm love music at all!

I am finding though that the Sansui forum is not nearly as organized as the Pioneer board. No BOM's, no dedicated threads, and very scattered info.

For such a well loved receiver, I'm having to piece together a BOM, and figure a lot of it out for myself. I'll do what I can to correct that by posting my complete re-cap BOM.

 

[dlucy]

It is cap-coupled Doug. It's also a beast with the right speakers. My Dad, and this Sansui are the reason I'm love music at all!

I am finding though that the Sansui forum is not nearly as organized as the Pioneer board. No BOM's, no dedicated threads, and very scattered info.

For such a well loved receiver, I'm having to piece together a BOM, and figure a lot of it out for myself. I'll do what I can to correct that by posting my complete re-cap BOM.

Yep. Sometimes you have to be the trailblazer.

Keep in mind the schematic, the board's silkscreening, and the actual values sometimes vary. When I'm making my own BOM, I use spreadsheet columns for schematic values, as-found values, and the replacement parts' values that I'm ordering.

 

[Super Noob]

Due to the server outage and rollback we have lost some info.

Re-Update

I had decided one of the 2SC1313's had gone noisy and decided to replace all 4 (2 in each channel) I replaced them with the KSC1845 as per my parts list. These are backwards from the original transistors. The new are ECB, the old were BCE.

Upon start-up, I had dead silence on the Phono Inputs. Turning the volume up as high as I dared, there was still complete silence. The sound through the Phono is beyond what I could have hoped for!

During the weekend, I have now listened to FM for about an hour, and the Phono for about 6 Hours. The longest run-time was about 4 hours straight. Back was warm, but not worryingly so. Just enought that you could feel the gentle rise out of the vents.

No other issues have come up, and the performance on all counts is simply exceptional!

I have (or Had) the following..
Sansui 5000A (Unrestored)
Pioneer SX-650 (Unrestored)
Sony 5.1 Surround system (No Idea the model anymore, gone for years)
And I grew up with my Dads Sansui 5000X (Now a basket case in his attic, its my next project!)

This SX-850 Beats them all!
I really can't say how pleased I am at the outcome!

If you have followed this thread, and have never posted, or are hesitant to start you own project, Just do it!

The satisfaction of hearing what these are really capable of is worth it.
The increased reliability is worth it!
The fact that YOU can resurrect one of these beautiful machines and make them sing again is worth it!

Most of all, the help you can receive, by people who are really knowledgeable, and truly care about this hobby is Invaluable!

No doubt I will become a Subscriber, and no doubt I will continue to find these boards an unending treasure of information!

I will follow up with some personal thoughts and tips later, as well as what I used and found to be essential in my work.

Nice work... I too am a hobbyist and enjoy the process and results. One of my early rebuild was on the same set - SX850. It responded well to the rebuild. I really like this series.

They say 850 is where to start on this line. I rebuilt 750 and 1250 and was impressed as well. Believe the 650 as STK packs... which can be troublesome to replace when required. There are some interesting replacement boards that use discrete components for STK.

The right tools make all the difference as you have figured out. Thanks for sharing your journey.

 

[davros]

Thanks Super Noob, It was well worth the effort!

 

[davros]

So as promised, above are the items I felt were indispensable to my project.
1st is the Manual, BOM(Bill of Material) and Notes. The Manual is posted in the Digital Docs Forum. I had mine printed in color on 11x17 Paper. Cost a couple bucks at staples. INDISPENSABLE! Read it, and become familiar. You will use it!

next is a good MultiMeter. You don't need a fancy Fluke, but don't rely on a cheap Wally World job either. As for the cables I spent a little on the ends. The two probes have removable caps that just leave the Tip exposed. If not for them, I would have shorted the Amp board out a couple of times. Holding 2 Probes steady while looking at a meter is tough... The Clamp probes free up a hand when taking reading on you Power supply and Protection board.

Next the tools. With the exception of taking apart the body, I used these 3 tools exclusively. The green one is "Wire Forming"
Pliers. They come in many styles, and mine just have two perfectly round, slightly tapered prongs. They are perfect for grabbing wires, and twisting. They are round, so the will not nick the insulation. The other two are just small wire cutters and small needle nose pliers (The plyers are smooth in the bite area)

Soldering iron and Solder (Hard to skip this). I used a 60 Watt Weller that came with removable tips. I used the same tip the whole time, and 60 Watt was plenty enough heat without burning the board. The Solder is a 63/47 eutectic, and this was my first time using it. I thought it was far better than the cheap 60/40 roll I've been using for years.

Next up is DeOxit. It has been talked about endlessly. I won't waste time. Any questions check this out...
http://audiokarma.org/forums/index.php?threads/the-idiots-guide-to-using-deoxit-revisited.207005/

Last but not least is the DBT (Dim Bulb Tester) No One sells them, so you'll have to build your own. It's easy and posted all over the Forums and Internet. Basically the outlet is in series with the light bulb and switch. The light bulb will soak up all the Amps in case something is wrong in the amp. It will protect your outputs and Amp board.
Not using one is Russian Roulette with your Amp. I had no issues.... this time. If working properly, it will be bright for a second and go dim while your unit is on. If there is a problem it will get stay bright or get bright, depending on the circumstances. (I used a 60W Bulb)

Finally the unsung heroes... They are the rest of the people on the Forums who have done this many times before you. Some are Technicians who do this for a living, some a hobby. Others will do it just one time, just to restore a Family Heirloom.
Either way, pay attention, and read the posts in the 100's of other threads that talked about all of the problems you are going to have. Also pay note to the members that others treat as experts, they probably are. If you need help...Ask! It may take a few days but someone will chime in sooner or later. At the time of this post I just cracked 1000 views, people ARE watching...

Good Luck!

 

[Super Noob]

View attachment 1263422

So as promised, above are the items I felt were indispensable to my project.
1st is the Manual, BOM(Bill of Material) and Notes. The Manual is posted in the Digital Docs Forum. I had mine printed in color on 11x17 Paper. Cost a couple bucks at staples. INDISPENSABLE! Read it, and become familiar. You will use it!

next is a good MultiMeter. You don't need a fancy Fluke, but don't rely on a cheap Wally World job either. As for the cables I spent a little on the ends. The two probes have removable caps that just leave the Tip exposed. If not for them, I would have shorted the Amp board out a couple of times. Holding 2 Probes steady while looking at a meter is tough... The Clamp probes free up a hand when taking reading on you Power supply and Protection board.

Next the tools. With the exception of taking apart the body, I used these 3 tools exclusively. The green one is "Wire Forming"
Pliers. They come in many styles, and mine just have two perfectly round, slightly tapered prongs. They are perfect for grabbing wires, and twisting. They are round, so the will not nick the insulation. The other two are just small wire cutters and small needle nose pliers (The plyers are smooth in the bite area)

Soldering iron and Solder (Hard to skip this). I used a 60 Watt Weller that came with removable tips. I used the same tip the whole time, and 60 Watt was plenty enough heat without burning the board. The Solder is a 63/47 eutectic, and this was my first time using it. I thought it was far better than the cheap 60/40 roll I've been using for years.

Next up is DeOxit. It has been talked about endlessly. I won't waste time. Any questions check this out...
http://audiokarma.org/forums/index.php?threads/the-idiots-guide-to-using-deoxit-revisited.207005/

Last but not least is the DBT (Dim Bulb Tester) No One sells them, so you'll have to build your own. It's easy and posted all over the Forums and Internet. Basically the outlet is in series with the light bulb and switch. The light bulb will soak up all the Amps in case something is wrong in the amp. It will protect your outputs and Amp board.
Not using one is Russian Roulette with your Amp. I had no issues.... this time. If working properly, it will be bright for a second and go dim while your unit is on. If there is a problem it will get stay bright or get bright, depending on the circumstances. (I used a 60W Bulb)

Finally the unsung heroes... They are the rest of the people on the Forums who have done this many times before you. Some are Technicians who do this for a living, some a hobby. Others will do it just one time, just to restore a Family Heirloom.
Either way, pay attention, and read the posts in the 100's of other threads that talked about all of the problems you are going to have. Also pay note to the members that others treat as experts, they probably are. If you need help...Ask! It may take a few days but someone will chime in sooner or later. At the time of this post I just cracked 1000 views, people ARE watching...

Good Luck!

Agree with these items... but you forgot to mention your desoldering tool.

Wouldn’t be doing my projects without my Hakko desoldering gun. FR-301

 

[davros]

I was going to mention a de-soldering gun (Mines a Hakko) but as some people won't want to spend the coin on one just to do a single receiver, I left it out.

I have 4 Solid State projects I plan to do, so that's why I got one. If I only had the one to do I would have stuck it out with solder braid.

 

[pjf610]

Great job, I am about to start my recap of my SX850 but I do have a question, I used your replacement chart you had made my question is on the Protection Board AWM-062 Q7 has a 2SC1384 that is a to-92 package, you have for a replacement a KSC2690AYS that is a TO- 126 package is this a typo?? or did you replace that with the KSC2690AYS??

 

[davros]

MTF (Mark the Fixer) the resident Pioneer Guru has recommended a few of the transistors be replaced with larger package transistors due to heat dissipation.

There is also a transistor on the Power supply board (Q5) that is upsized to a larger package. they will fit nicely, but you need to completely get the solder out of the PCB holes or it wont fit.

As a note, I ordered many transistors I didn't need or use. They were usually pennies, and it was to save shipping costs and reorder hassles later.

I only replaced known troublemakers, recommended, and faulty transistors. Mostly the power supply, Phono (due to noise), and Amp board. The known troublemakers are (2SA725, 2SA726) replace every one you find no matter where it is. They are all bad or about to go bad (as per the local Guru's).

Good luck, its a lot of work, but it was worth every bit!

 

[dlucy]

There is also a transistor on the Power supply board (Q5) that is upsized to a larger package. they will fit nicely, but you need to completely get the solder out of the PCB holes or it wont fit.

Moving up sizes often requires use of a pin vise or just handheld small drill bit to enlarge the hole.

 

[pjf610]

Great guys and thanks for the feed back

 

[pjf610]

So My next question is do I need a heat sink??