Project: SX-950

[Super Noob]

Tone Amp...... look at the Tantalum caps that you removed, if you still have them. There should be two .22uf, six 2.2uf, and two 10uf Tantalum caps.

Thanks Meg... I am very methodical with my process. 1) verify polarity matches board, 2) verify cap uF and voltage. There were six (6) 10uf tants that were pulled off that board.

 

[Super Noob]

Good work, nice to see that you used/spent the extra $ for film caps as much as possible.
I see you re-used the old Toshiba output devices. I blew mine a few times, we used to crank it when we were young, so if you plan to play it loud or with low ohm speakers, you might want to upgrade to MJ21193,4 devices as they are much more powerful. They were not available when I did my upgrade, so I used the earlier MJ15003,4 devices, they have held up well over the years.

RCS16 - I like your posts. The STK solution looks great. I have Fisher 2010 headed my way... going to buy your boards off ebay (as I suspect the STK-0080 are toast).

Typically don't wholesale the larger transistors especially the original T03 outputs... I just pull them and re-paste them with Wakefield paste.

 

[1MEGΩ]

Thanks Meg... I am very methodical with my process. 1) verify polarity matches board, 2) verify cap uF and voltage. There were six (6) 10uf tants that were pulled off that board.

Well then Pioneer made a change on the tone amp board at some point in time.

 

[Super Noob]

Well then Pioneer made a change on the tone amp board at some point in time.

Not Really... respectfully.

 

[1MEGΩ]

Not Really... respectfully

I just recapped one and removed six 2.2uf caps C13, C14, C15, C16, C23 and C24. All Tantalums.
Look at your own reply #10 where you even show them in the list.

 

[Super Noob]

My unit dates March 1976. I pulled the list of other posts. The schematic shows 2.2 but the board and cap list in the service manual shows 10 uF.

Agree that something changed... when was your unit made?

 

[1MEGΩ]

My unit was made April 1977.

 

[whaleoil]

I have a SX1050 that needs this treatment, I'm assuming this list is almost identical???

 

[Super Noob]

I have a SX1050 that needs this treatment, I'm assuming this list is almost identical???

Okay... I recommend a couple of things.

1) Pull the schematic off of high-fi engine (you will need to to set the bias and offset anyways)
2) Update the spreadsheet by confirming from the board parts list in the schematic.
3) or Google SX-1050 parts list and you should find something that gets you close.
4) 850 and 950 very similar... the 1050 has a toroidal transformer and is a step up more similar but not quite like SX-1250
5) Recommend a desoldering gun = that is the secret to doing this quickly and not mucking up pads.
6) Build a dim bulb tester, get a good soldering iron, & cheap component tester.
7) Buy some good solider = recommend .8mm
8) Take you time and read, then read some more. It is not hard if you are not in a rush.

http://audiokarma.org/forums/index.php?threads/sx-1050-parts-list-advice.648399/

Good luck.

 

[whaleoil]

thanks

 

[AZstone]

EQ Amp:
C1: 1uF 25v CSSA / WIMA 1uF 63v
C2: 1uF 25v CSSA / WIMA 1uF 63v
C7: 330uF 6.8v CEA / Panasonic 330uF 16v (FM Series)
C8: 330uF 6.8v CEA / Panasonic 330uF 16v (FM Series)
C11: 3.3uF 25v CEANL / WIMA 3.3uF 50v
C12: 3.3uF 25v CEANL / WIMA 3.3uF 50v
C17 100uF 35v CEA / Panasonic 100uF / 50v (FM Series)
C18 220uF 25v CEA / Panasonic 220uF / 35v (FM Series)

HFE Gain Matched 992s = all transistors replaced on this board.

Before:

Thank you for documenting this process so thoroughly. I want to start with this portion in my SX-950 as the phono stage isn't working. As I'm looking these parts up on Mouser there seems to be a wait of ~19 weeks on a few of the parts.
505-MKS2C041001F00JA specifically. Also, my EQ board is labeled AWF-011B which doesn't match with the service manual exactly. Have you run into any of those? Thanks again.

 

[Super Noob]

https://www.mouser.com/ProductDetail/WIMA/MKS2C041001F00JI00?qs=sGAEpiMZZMv1cc3ydrPrF7l45uRd9dVhbjKpnl7gdJA=

There are typically alternate parts that will work fine. Take some time and reconcile the caps on the list with your unit, or you will likely be making multiple orders.

You can mark each cap with a marker after you verify / cross off list. Sometimes there will be changes during production - but the verification process will ensure you have the parts on hand prior to starting.

 

[rcs16]

Try this one for a 505-MKS2C041001F00JA sub

80-F612JT105J100R
or 505-MKS2C041001FJI00 as said above.

 

[tarior]

An LY series relay will snap right in to the old relay case. Oddly, a new MY series won't.

 

[AZstone]

https://www.mouser.com/ProductDetail/WIMA/MKS2C041001F00JI00?qs=sGAEpiMZZMv1cc3ydrPrF7l45uRd9dVhbjKpnl7gdJA=

There are typically alternate parts that will work fine. Take some time and reconcile the caps on the list with your unit, or you will likely be making multiple orders.

You can mark each cap with a marker after you verify / cross off list. Sometimes there will be changes during production - but the verification process will ensure you have the parts on hand prior to starting.

That was great advice, thank you. I made my list and it coincides pretty closely to the one you posted earlier on the thread. Thank you for putting all of that together.

 

[AZstone]

https://www.mouser.com/ProductDetail/WIMA/MKS2C041001F00JI00?qs=sGAEpiMZZMv1cc3ydrPrF7l45uRd9dVhbjKpnl7gdJA=

There are typically alternate parts that will work fine. Take some time and reconcile the caps on the list with your unit, or you will likely be making multiple orders.

You can mark each cap with a marker after you verify / cross off list. Sometimes there will be changes during production - but the verification process will ensure you have the parts on hand prior to starting.

My parts finally came and I was able to re-cap and replace transistors on the EQ board following all of the instructions here and on youtube. Now I'm getting a signal through the phono 2 (signal is there for phono 1 also, but I have to hold in the phono 1 selector button I'll worry about that on a different day) which is a huge improvement over what I had before (nothing). The frustration now is that even though I can hear the music I'm playing on my turntable, I am having to turn the volume up quite a bit louder than with the tuner to get the same level and I'm hearing what I would describe as a constant whoosh sound even with the turntable off and disconnected. I'm sure this has happened to someone else before, right?... I'm reading what I can find and hopefully I'll be able to get it ironed out.

Edit: Only happens when I have selected the phono 1 / phono 2 inputs, so I assume it has to do with the components I changed out today.

 

[MIJ_Pioneer]

My parts finally came and I was able to re-cap and replace transistors on the EQ board following all of the instructions here and on youtube. Now I'm getting a signal through the phono 2 (signal is there for phono 1 also, but I have to hold in the phono 1 selector button I'll worry about that on a different day) which is a huge improvement over what I had before (nothing). The frustration now is that even though I can hear the music I'm playing on my turntable, I am having to turn the volume up quite a bit louder than with the tuner to get the same level and I'm hearing what I would describe as a constant whoosh sound even with the turntable off and disconnected. I'm sure this has happened to someone else before, right?... I'm reading what I can find and hopefully I'll be able to get it ironed out.

Edit: Only happens when I have selected the phono 1 / phono 2 inputs, so I assume it has to do with the components I changed out today.

The tuner on my 650 is way louder than the phono for me too, but it goes into distortion sooner. Have you tried hooking up the turntable to another reciever/phono preamp to compare?

 

[tarior]

The tuner on my 650 is way louder than the phono for me too, but it goes into distortion sooner. Have you tried hooking up the turntable to another reciever/phono preamp to compare?

That's pretty normal. A moving magnet cartridge is a fairly low level signal when compared to a strong FM station that is being driven to the max.

 

[AZstone]

The tuner on my 650 is way louder than the phono for me too, but it goes into distortion sooner. Have you tried hooking up the turntable to another reciever/phono preamp to compare?

I just did this afternoon and had the same problem as with the other turntable. I decided to look at the selector switches to see if it would function better after some serious Deoxit, and nothing changed. When I carefully opened the lid to the switch assembly I noticed that the little gold conductor bars had been spread somehow and were touching each other. I removed them and carefully tried to form them back to original. The function buttons don't seem to work completely unless I hold them in, but the majority of the noise from earlier is gone. New adventure, I guess.

 

[PioneerPro]

My Pioneer SX-950 restoration is almost complete. I am waiting on a couple of Capacitors on backorder and I am having just one issue.

My problem is this one new Output Transistor on the Power Supply Board is getting overly hot in a short period of time. This only happens when the receiver is on FM mode and it heats to 142 degrees in just 1 minute. The 3 other new Output Transistors on this board are just fine. Anyone have any idea?

The two Capacitors with Red Marker on top have not been changed and are on backorder.