Did you do any work on the protection board yet? The relay kick in time is a bit on the short side, 4 to 7 is supposedly the norm, but I like to see at least 5 seconds to ensure the startup surge is fully dissipated.and the voltages are stabilized.
Pioneer SX-737 Re-Cap
- Thread starter Young46
- Start date
Yes, all boards have been rebuilt. I did not replace the relay (should I) yet or the main caps. How do the voltage readings look?
If they are within 5-10% OK. This is based on different wall voltages today vs. 1974-76. If the relay contacts are pitted badly, then yes. otherwise no. Main caps, based on age, yes. But test for AC ripple. Post results and we'll give you a yes or no.
The relay works based on voltages from the protection board. It does what the board tells it to and no more. So if it's working ok, and the contacts aren't pitted, just take a piece of paper and fold it over and soak it in DeOxit, then insert the paper between the contacts, manually close them and pull the paper thru one direction only until the paper comes out clean. Use a new piec of paper each time. Let the DeOxit work on the contacts about 15 minutes between the 1st and 2nd piece.
The relay works based on voltages from the protection board. It does what the board tells it to and no more. So if it's working ok, and the contacts aren't pitted, just take a piece of paper and fold it over and soak it in DeOxit, then insert the paper between the contacts, manually close them and pull the paper thru one direction only until the paper comes out clean. Use a new piec of paper each time. Let the DeOxit work on the contacts about 15 minutes between the 1st and 2nd piece.
Looking at the service manual, the voltage readings I got look good (within 5-10%). I checked the relay activation time after startup and it was 3.18 seconds by my trusty stopwatch on the iPhone. I tried getting the guts of the relay out of the housing and it would not budge. I did not want to break it. Is there a method for removing it that I don't know about?
I played it for 3 hours and 20 minutes while I was doing a cleaning and de-ox on a Sansui 2000 a friend gave me. I played the radio for about 30 minutes the CD player for about 34 minutes and the tape player for the remainder of the time. I started out at low volume and worked it up to just over three clicks as it warmed up. No hiccups! It sounded great!
The main caps never felt warm and the area around the heat sink was just barely warm. I do not have a clue how to test for AC ripple. Any help in this area is appreciated.
Thanks!
I played it for 3 hours and 20 minutes while I was doing a cleaning and de-ox on a Sansui 2000 a friend gave me. I played the radio for about 30 minutes the CD player for about 34 minutes and the tape player for the remainder of the time. I started out at low volume and worked it up to just over three clicks as it warmed up. No hiccups! It sounded great!
The main caps never felt warm and the area around the heat sink was just barely warm. I do not have a clue how to test for AC ripple. Any help in this area is appreciated.
Thanks!
Based on your last post, you can probably hold offon the mains for a while. Just keep an eye on them and if they start warming up on their own, replace them. Otherwise let her rip! Check the bias using the spkr connections. (red to red and black to black, volume down, tone controls centered and selector to AUX. Measure voltage to stay below 25mv)
Larry
Larry
hoggwild89
Active Member
Shit-storm going to happen but I MUST say....You CERTAINLY CAN un-wrap wire-wraps... You just need to solder them beck when your done 
and the "special tool" really isnt that special. It just wraps the wire tightly around the post.
I have often had suspect noise and intermittents in various devices caused by oxidation beneath the wrapped wire. When in doubt... SOLDER.
and the "special tool" really isnt that special. It just wraps the wire tightly around the post.
I have often had suspect noise and intermittents in various devices caused by oxidation beneath the wrapped wire. When in doubt... SOLDER.
Y
Thanks, I appreciate the information.Shit-storm going to happen but I MUST say....You CERTAINLY CAN un-wrap wire-wraps... You just need to solder them beck when your done
and the "special tool" really isnt that special. It just wraps the wire tightly around the post.
I have often had suspect noise and intermittents in various devices caused by oxidation beneath the wrapped wire. When in doubt... SOLDER.
Y
Well, just as everything seemed to be working fine I get the same old problem with the relay cutting out. I have not been able to complete the work because of other things going on but yesterday I soldered the diode to the pins on the protection board and put the wires back into the wire looms and buttoned it back up. It played fine for about an hour on lower volume. I put on some Rare Earth and turned the volume up slowly and just before I got to 10 o'clock it cut out. Dial it back down and it cuts back on around 9 o'clock. Crap!
Sure enough! A transistor was in wrong on the protection board. I reinstalled it and it volumes up fine now. I played it at fairly low volume for about an hour and then cranked it up slowly to 12 o'clock ( way louder than I will ever play it) for about 5 minutes. No hiccups! It's a beautiful thing! Thank you so much! Again, thanks to all who responded and helped me in this rebuild! I could not have done it without your support.
Hello you guys, I just signed up on here today because Google brought me here from looking up a SX-737 my friend gave me. He bought it new when he graduated high school around 1974. Thanks for this post. I just got through reading the whole thread and got a lot to reread and try to understand. So far all I have done is replaced a chewed up power cord and done some vacuum cleaning of inside. I'm not new to electronics but bad rusty. I turned 41 yesterday and was one of the last classes to go through electronics at the local community college back in the early 90s. Shortly after they did away with that degree all together. Mostly my dealings with electronics have been from Ham radio. (KE5KBG) This is my first attempt at trying to get an old receiver going. After replacing the power cord and flipping the on toggle I get nothing. All fuses are checking good and I'm getting power but nothing happening. Going to try using some of this good info you guys provided.
THANKS
ROBERT JACKSON
THANKS
ROBERT JACKSON
Aaron99
Active Member
Welcome Robert,
I would recommend you start a new thread with your SX-737. Many here will help as much as they can to get you going. Also, post some pictures of the Pioneer....
I'll do that thanksWelcome Robert,
I would recommend you start a new thread with your SX-737. Many here will help as much as they can to get you going. Also, post some pictures of the Pioneer....
Spenser; The LY2F-DC24 is the sub if the LY4F-DC24 is unavailable. I normally change cases on these (new guts in the old case ) and it fits tightly, but it fits. I've put the LY4F in a 1010, a 939, and the 737 with no problems. And this goes back to 2010 with the 1010.
Here's the O-FISH-UL WORD on RELAYS for the x3x series of PIONEER Receivers from POST #30 of this thread...
http://audiokarma.org/forums/index....x-1010-939-838-et-al-relay-replacement.150439
----------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
4pdt chassis mount using upper ears 24v 653-LY4F-DC24 MOUSER.COM stock level 14 @ $11.61
or a substitute:
dpdt chassis mount using upper ears 24v 653-LY2F-DC24 MOUSER.COM stock level 51 @ $ 6.55
being chassis mount, conversion from double connected 4pdt to dpdt contacts is easy
Here's the O-FISH-UL WORD on RELAYS for the x3x series of PIONEER Receivers from POST #30 of this thread...
http://audiokarma.org/forums/index....x-1010-939-838-et-al-relay-replacement.150439
----------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
4pdt chassis mount using upper ears 24v 653-LY4F-DC24 MOUSER.COM stock level 14 @ $11.61
or a substitute:
dpdt chassis mount using upper ears 24v 653-LY2F-DC24 MOUSER.COM stock level 51 @ $ 6.55
being chassis mount, conversion from double connected 4pdt to dpdt contacts is easy
Last edited:
NOTE ON RELAY REPLACEMENT! The LY4F-DC24 WAS RE-DESIGNED and is too LARGE for any of the units listed in post 37. THE GO TO RELAY is Now the LY2F-DC24.
Unfortunately I ordered the LY4F. and discovered it was too large. Luckily the old one is still working ok. Good to know the correct part number now. Thanks!
