Hello everyone, I am trying to rebuild my SX-737 with new capacitors. However, many of the BOM list's which I see on audiokarma for the sx-737 have certain parts which are obsolete. I was curious if anyone had an upgraded BOM list for the sx-737 which does NOT have any obsolete parts? Any help in this matter would be greatly appreciated!
Pioneer SX-737 upgraded BOM list
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You can use the parts in this thread. The 7730 and 737 are esentially the same. Project 7730 (SX-737)
mjward1157
New Member
Hoping someone can answer this basic question before I order some parts. I recently purchased a Sx-737 as well and have read most of the recent posts regarding the parts bom list for replacing capacitors, transistors, and such. One thing I immediately noticed was that when looking at the replacement parts for the tuner board (haven’t looked at others yet) several of the electrolytic capacitors are replaced with film capacitors. So I’m assuming that polarity is not an issue it wanted to confirm? Thanks.
Film capacitors are bipolar, so you don't have to worry about plus or minus pin.
"Film capacitors are made out of two pieces of plastic film covered with metallic electrodes, wound into a cylindrical shaped winding, with terminals attached, and then encapsulated. In general, film capacitors are not polarized, so the two terminals are interchangeable. There are two different types of plastic film capacitors, made with two different electrode configurations"
https://en.wikipedia.org/wiki/Film_capacitorhttps://en.wikipedia.org/wiki/Film_capacitor
"Film capacitors are made out of two pieces of plastic film covered with metallic electrodes, wound into a cylindrical shaped winding, with terminals attached, and then encapsulated. In general, film capacitors are not polarized, so the two terminals are interchangeable. There are two different types of plastic film capacitors, made with two different electrode configurations"
https://en.wikipedia.org/wiki/Film_capacitorhttps://en.wikipedia.org/wiki/Film_capacitor
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mjward1157
New Member
mjward1157
New Member
Probably should have asked my friends question better. I was wondering though if it was ok to use a film (non polarized) capacitor in a board where the original part was a electrolyte (polarized) capacitor. I assumed so since that is what others posted as replacements parts but wanted someone to verify. Thanks again.
If you have some time, you can try to find some answers here in my step by step SX-737 rebuild Thread
https://audiokarma.org/forums/index...-rebuild-on-a-sx-737-done-by-a-newbie.985597/
The tuner part starts here.
https://audiokarma.org/forums/index...sx-737-done-by-a-newbie.985597/#post-15363109
https://audiokarma.org/forums/index...-rebuild-on-a-sx-737-done-by-a-newbie.985597/
The tuner part starts here.
https://audiokarma.org/forums/index...sx-737-done-by-a-newbie.985597/#post-15363109
mjward1157
New Member
Thanks. I had already printed it out and that partly led to my question. For example, in it you said that C38,C39, and C40 were all replaced with film capacitors but the OEM parts are electrolytic capacitors (blue Sanyo). Not fully understanding circuit boards, I was just trying to confirm that it was ok to replace polarized electrolytic capacitors with non polarized film capacitors. I assume since you did it and it worked was ok, but didn’t understand why that works. Might be above my ability to understand though.
The modern film capacitors for values below 1µf are always better than the old caps in that position.
That's an old post regarding the SX-1080 but I think it gives you the best advice from @markthefixer.
Rules of thumb:
2.0 µF and lower should be non-polarized film caps.
cea 2µf and above should be UPW
csza 2µF and above should be UKL
https://audiokarma.org/forums/index...n-board-lessons-learned.959973/#post-14792433
That's an old post regarding the SX-1080 but I think it gives you the best advice from @markthefixer.
Rules of thumb:
2.0 µF and lower should be non-polarized film caps.
cea 2µf and above should be UPW
csza 2µF and above should be UKL
https://audiokarma.org/forums/index...n-board-lessons-learned.959973/#post-14792433
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mjward1157
New Member
Great. Thank you.
electrolytic capacitors are a compromise to fit that much capacitance in a reasonably sized package.
the compromise in this case is the chemistry and polarity business inside of it.
film caps have been getting better at stuffing more capacity into a space that can fit in our electronics.
film caps tend to last, frankly, forever.
electrolytic capacitors tend to dry out and fail.
that's it in a nutshell.
the UKL thing is a type of lower noise (electronic leakage) electrolytic capacitor. film caps are already low noise / electronic leakage.
the compromise in this case is the chemistry and polarity business inside of it.
film caps have been getting better at stuffing more capacity into a space that can fit in our electronics.
film caps tend to last, frankly, forever.
electrolytic capacitors tend to dry out and fail.
that's it in a nutshell.
the UKL thing is a type of lower noise (electronic leakage) electrolytic capacitor. film caps are already low noise / electronic leakage.
mjward1157
New Member
Appreciate the insight. Another question…i also read a post where someone used The Nichicon UPM series of electrolytic capacitors in lieu of the UPW. When I attempted to order some parts from Mouser, I noticed that one particular capacitor was Out of Stock until perhaps later this year. Can someone comment on whether that is acceptable to use the UPM series instead. I did compare data sheets and they seem the same except for perhaps the size?
for our purposes they are interchangeable.
Things are different for the electromagnetic hell of switching (digital high efficiency ) power supplies. But we don't care....
Things are different for the electromagnetic hell of switching (digital high efficiency ) power supplies. But we don't care....
UPM's tend to slightly larger than the UPW's but, as Marks said for our purposes they are interchangeable. I took a screen shot excerpt of a UPW 4.7uf 50v Datasheet. Up at the top of most all NICHICON Datasheets for Caps, they show 2-3 options for size or less or more capacity (leakage, impedance, etc.) Those options are in the same Immediate family of caps.
