SX-780 recap list ?
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I did make a recap list for myself a few months ago. I can't remember where I put it. I don't know if you want my list because I used ALOT of WIMA film caps in it along with Nichicon KG as main cap and Nichicon UPW for the rest.
I'll look for it in case you still want it and no one chimed in.
I'll look for it in case you still want it and no one chimed in.
barkerd
Super Member
ccheath : thanks : can you pm me with that? I may be looking in the wrong places : but I am surprised NOT to find this info on the 780 as it was the single biggest selling model (I'm told) Pioneer ever made. I would also appreciate ANY advice/ opinions / on what works and doesn't. As a side-note : I am very pleased with this receiver , for old-school (efficient) speakers 45 watts is plenty in a normal room , and the styling , IMHO, is the penultimate of the "silver" series. While it doesnt have the wow factor of a 1980 I think it sounds sweet.
bisonguy
Active Member
I have attached a list of the caps I used to rebuild a 780 as a Christmas gift for my son-in-law. It doesn't have the corresponding Mouser numbers but I will look at my old orders and see if I have them. Hope this helps. Also note the discrepancies that I found between the manual and the actual caps I found on the original boards.
I am sorry I still couldn't find my list. I'm glad that bisonguy has the list that also list all the UPW series capacitors. Alot of capacitors I used were WIMA and they get pretty pricey compared to Nichicon UPW. But I am very happy with the result. But good caps I used for the mains were Nichicon KG Gold. They're fat but I manage to get it in just fine.
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barkerd
Super Member
Mods?
Maybe I should be pm'ing some of our well known members on this / but again : I am surprised at the relative small numbers of sx-780 diy threads given it's sales numbers / in any case does anybody have a list of mods for performance / reliability/ or sound reproduction that are worth incorporating when I am under the hood of this thing? (other than upgraded caps) / thanks in advance
PS : Bisonguy and ccheath : what sonic differences did you hear after the recap : or was this mostly a case of preventative medicine ? / also : I hear alot about the darlingtons ....but nothing on the cause of their demise when they go ( I'm asking because of their relative low price : should I be replacing them as preventative, or is it a case of abuse or other component failure which causes them to go?)
Maybe I should be pm'ing some of our well known members on this / but again : I am surprised at the relative small numbers of sx-780 diy threads given it's sales numbers / in any case does anybody have a list of mods for performance / reliability/ or sound reproduction that are worth incorporating when I am under the hood of this thing? (other than upgraded caps) / thanks in advance
PS : Bisonguy and ccheath : what sonic differences did you hear after the recap : or was this mostly a case of preventative medicine ? / also : I hear alot about the darlingtons ....but nothing on the cause of their demise when they go ( I'm asking because of their relative low price : should I be replacing them as preventative, or is it a case of abuse or other component failure which causes them to go?)
My main caps were dying (almost 1/2 rated capacity left in it) and I want it to be reliable so I decided a recap. When I recapped mine, I didn't want to change any sonics. I have been turning on and off my receiver after each determined set of caps and found the result:
Replaced all the caps outside the signal path: No difference.
Low Filter (also a coupling between preamp and main amp)
Replaced C227, C228 0.22/50 & C229, C230 2.2/50: Little noticeable difference
Preamp:
Replaced C207, C208 1/50: There is very noticeable difference.
Replaced C217, C218 4.7/50: There is very noticeable difference.
Loudness:
Changed from stock ceramics to WIMA film
C203, C204 330pf & C205, C206 0.022uf: Sounds smoother while ceramics sounded fuzzier.
The 2nd pic shows I removed the +/- pins (left the ground pins) from the cap board and soldered the wires directly to it in order to fit those fat Nichicon KG Gold which I determind to use.
The biggest difference is in the preamp. I can't remember whether C207, C208 or C217, C218 made the biggest difference. Initially I was a little bothered by it. It gets quieter where I have to turn the volume up a little more. The presence is reduced somewhat but not much. But knowing where the difference is (in case I decided to change it again), I decided to leave it be and see how I liked it. I grew into it and I really like it. I use the loudness quite often and I like the smoothness of it. I use this receiver as my bedside sleeper almost every single day. I actually found this receiver sounded more pleasing than my SA-7700 integrated amp. You may notice I used Nichicon UPW as I did on the rest of the circuit rather than WIMA for the phono preamp. WIMA was already breaking my bank plus I don't plan on using the phono in my bedside.
Edit: I almost forgot. While you in it, reflow the solder on those 3 power transistors (last pic). The heat of the transistors over the years caused the solder fatigue.
Replaced all the caps outside the signal path: No difference.
Low Filter (also a coupling between preamp and main amp)
Replaced C227, C228 0.22/50 & C229, C230 2.2/50: Little noticeable difference
Preamp:
Replaced C207, C208 1/50: There is very noticeable difference.
Replaced C217, C218 4.7/50: There is very noticeable difference.
Loudness:
Changed from stock ceramics to WIMA film
C203, C204 330pf & C205, C206 0.022uf: Sounds smoother while ceramics sounded fuzzier.
The 2nd pic shows I removed the +/- pins (left the ground pins) from the cap board and soldered the wires directly to it in order to fit those fat Nichicon KG Gold which I determind to use.
The biggest difference is in the preamp. I can't remember whether C207, C208 or C217, C218 made the biggest difference. Initially I was a little bothered by it. It gets quieter where I have to turn the volume up a little more. The presence is reduced somewhat but not much. But knowing where the difference is (in case I decided to change it again), I decided to leave it be and see how I liked it. I grew into it and I really like it. I use the loudness quite often and I like the smoothness of it. I use this receiver as my bedside sleeper almost every single day. I actually found this receiver sounded more pleasing than my SA-7700 integrated amp. You may notice I used Nichicon UPW as I did on the rest of the circuit rather than WIMA for the phono preamp. WIMA was already breaking my bank plus I don't plan on using the phono in my bedside.
Edit: I almost forgot. While you in it, reflow the solder on those 3 power transistors (last pic). The heat of the transistors over the years caused the solder fatigue.
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bisonguy
Active Member
You are most welcome. My handle came from my pre-retirement job as engineering manager for the Canadian Army Light Armoured Vehicles known as Bisons. I started with them as the vehicle engineer for their initial procurement in 1988 and retired in 2007 working in their life cycle management. Great job. Now my new hobby is old stereo gear, specifically Pioneer. My first good stereo was an SX-939 that I bought in Germany in 76.
In response to your question on the sound difference after re-cap I didn't pay particular attention to the before and after sound. My rationale was to take preventative action since it was a gift to my son-in-law. My daily machine now is an SX-1250. I have completely re-capped it except for the tuner. I hesitate to do the tuner just in case it will require adjustments when done that will need a trip to a tuner expert. As to the sound difference on the SX-1250 after re-cap I can't say. When I got it the flat amp board was split right through (don't know how that happened) and someone had tried to solder wires across the traces (lots of wires). It didn't work. After finding a replacement flat amp from a cannibalized 1250 I decided to do the re-cap as well. All I can say now is it sounds great hooked to a pair of HPM-100s. My main caps (22,000uF) are just beginning to leak, just barely noticeable, so that will be the next step.
barkerd
Super Member
thanks guys
thoughtful posts : thanks for the effort / if there was a way to catalogue threads by model number I think your work and thoughts should be stickied : along with some of the generic recapping threads this gives anybody with an SX 780 some solid info on what to do and what to expect (not to mention what to order / with Mouser's order import function its just a cut and paste exercise to get the whole thing done in minutes / cost as of today is approx $14 in caps ) I teach : so right after report cards I'll get on this (man I'd rather recap than do reports ; its gonna be hard to resist) :tears::tears:
Bisonguy : it never ceases to amaze me how much audio went via the px back in the day. ciao : I'll revisit this thread when I'm done .
thoughtful posts : thanks for the effort / if there was a way to catalogue threads by model number I think your work and thoughts should be stickied : along with some of the generic recapping threads this gives anybody with an SX 780 some solid info on what to do and what to expect (not to mention what to order / with Mouser's order import function its just a cut and paste exercise to get the whole thing done in minutes / cost as of today is approx $14 in caps ) I teach : so right after report cards I'll get on this (man I'd rather recap than do reports ; its gonna be hard to resist) :tears::tears:
Bisonguy : it never ceases to amaze me how much audio went via the px back in the day. ciao : I'll revisit this thread when I'm done .
AndresPlaza
Andres Esteban
Thanks for your advice ccheath!
I replaced the old main filter caps C501 - C502 (original 8000uF/50v) by 10,000uF/50v EPCOS. Distance between +/- original pins is 15mm and the new ones 9mm. I drilled new holes, with new caps in position pins were bent and they matched the +/- copper paths. No sweat! just solder them! Tested and no smoke!!!
So I went and replaced only the Preamp caps as follows:
- Preamp C207- C208 (orig 1uF/50v) by 1uF/63v
- Preamp C217 - C218 (orig 4.7 uF/25v) by 4.7/50V
Also, just in case, and following other threads advice:
- Resoldered Q25 2SD712 regulator transitor
Before closing the unit did:
- DC balance of power amplifers VR5(left channel) Pin9 & GND / VR6 (right channel) Pin6 & GND : about 8mV volt each with no speakers connected, volume at zero and aux (with no input connected), couldn't get 0mV. Tricky pots to adjust! Guess 8mV is a good value. :scratch2:
After that checked:
- DC speaker output voltage measured. Left the receiver on for 30 minutes with speakers not connected, selector in aux input and nothing connected, tone at mid position, no loudness, balance at center, vol at minimum. Used to digital meters connected to speaker outputs. Volatges measured:
left channel 9 mV , right channel 5 mV
My notes:
-It seems eveything is working fine. I believe it's even running cooler than before. Less heat dissipated. :tresbon:
-Changing those caps on the preamp section improved bass and treble quite a lot a lot! (You were right on the spot!) :yes:
-New filter caps (2x 10,000uF) somehow gave a better and clearer output, also no light trembling at high volume. :thmbsp:
-The only thing I'm not satisfied is the loudness section, perhaps should change caps also. There's little difference turning loudness on. It's there but not as impressive as I remember when the unit was new (32 years ago!!!
That's all for now. All comments, advices, remarks, will be greatly appreciated! Andy
Regards and thanks! Andy.
AndresPlaza
Andres Esteban
This may be of interest:
Today I replaced on my SX-780 the following caps Low Filter (also a coupling between preamp and main amp): C227, C228 0.22uF/50v & C229, C230 2.2uF/50v
Result: although the new caps had de proper values (checked them first), the qualty of the sound was changed, sounded raspy. Treble was incresed but as I've said now there was a "raspy qualty" I didn't like at all, so i decided to put back the original electrolytic caps (30+ years) which give a very mellow sound. So no improvement in replacing these caps. Don't know if it's a problem of capacitor brand... I used EPCOS. The same brand when I replaced
- Preamp C207- C208 (orig 1uF/50v) by 1uF/63v
- Preamp C217 - C218 (orig 4.7 uF/25v) by 4.7/50V
which gave an amazing improvement on the sound qualty.
After replacing caps DC balance of power amplifiers (VR5 and VR6) eas done!
... so... recapping all caps? Not necessarily a good idea! I think the correct procedure is to replace some caps, check sound and then decide if sound's improved or not.
Regards. Andy
Today I replaced on my SX-780 the following caps Low Filter (also a coupling between preamp and main amp): C227, C228 0.22uF/50v & C229, C230 2.2uF/50v
Result: although the new caps had de proper values (checked them first), the qualty of the sound was changed, sounded raspy. Treble was incresed but as I've said now there was a "raspy qualty" I didn't like at all, so i decided to put back the original electrolytic caps (30+ years) which give a very mellow sound. So no improvement in replacing these caps. Don't know if it's a problem of capacitor brand... I used EPCOS. The same brand when I replaced
- Preamp C207- C208 (orig 1uF/50v) by 1uF/63v
- Preamp C217 - C218 (orig 4.7 uF/25v) by 4.7/50V
which gave an amazing improvement on the sound qualty.
After replacing caps DC balance of power amplifiers (VR5 and VR6) eas done!
... so... recapping all caps? Not necessarily a good idea! I think the correct procedure is to replace some caps, check sound and then decide if sound's improved or not.
Regards. Andy
AndresPlaza
Andres Esteban
This may be of interest:
Today I replaced on my SX-780 the following caps Low Filter (also a coupling between preamp and main amp): C227, C228 0.22uF/50v & C229, C230 2.2uF/50v
Result: although the new caps had de proper values (checked them first), the qualty of the sound was changed, sounded raspy. Treble was incresed but as I've said now there was a "raspy qualty" I didn't like at all, so i decided to put back the original electrolytic caps (30+ years) which give a very mellow sound. So no improvement in replacing these caps. Don't know if it's a problem of capacitor brand... I used EPCOS. The same brand when I replaced
- Preamp C207- C208 (orig 1uF/50v) by 1uF/63v
- Preamp C217 - C218 (orig 4.7 uF/25v) by 4.7/50V
which gave an amazing improvement on the sound qualty.
After replacing caps DC balance of power amplifiers (VR5 and VR6) was done!
... so... recapping all caps? Not necessarily a good idea! I think the correct procedure is to replace some caps, check sound and then decide if sound's improved or not.
Regards. Andy
Wow, my posting was almost 3 years ago. I am still using my 780 as it was a few years ago. I also have another 780 that has not been recapped at all. I do notice the difference between the two. The original would sound more mellow and open while the recapped one sound cleaner and smoother (to me) but does sound a tad muted. The loudness gave plenty of boost for where I am using it. At least I did say if I was still bothered, I will still know where to change the caps to get the sound I like. I haven't done any change yet.
It's been 3 years since I posted it. I have learned since there are also other caps to consider. I have read that capacitors need to break-in to improve the sound(I won't debate on this subject, just merely pointing it out). Have you considered if you're going back to electrolytic in signal path, try Elna Silmic II, Nichicon FG, or KZ to name a few?
Recapping all caps? There are many views to this procedure. Your view of a correct procedure is your decision and there's nothing wrong with that. There is also another correct procedure when recapping is selecting the right cap when doing the full recap. As in my case with the use of WIMA films, they are good caps but I find them a tad muted compared to the originals but do sound very clean in my receiver. Eventually, I may experiment on my sx-880 (almost identical to the 780 circuitry) with the use of different caps to get it to sound right. But right now I am working on my Marantz 2385 & 2500 projects to work on, so it'll be quite a while before I even get to it.
It's been 3 years since I posted it. I have learned since there are also other caps to consider. I have read that capacitors need to break-in to improve the sound(I won't debate on this subject, just merely pointing it out). Have you considered if you're going back to electrolytic in signal path, try Elna Silmic II, Nichicon FG, or KZ to name a few?
Recapping all caps? There are many views to this procedure. Your view of a correct procedure is your decision and there's nothing wrong with that. There is also another correct procedure when recapping is selecting the right cap when doing the full recap. As in my case with the use of WIMA films, they are good caps but I find them a tad muted compared to the originals but do sound very clean in my receiver. Eventually, I may experiment on my sx-880 (almost identical to the 780 circuitry) with the use of different caps to get it to sound right. But right now I am working on my Marantz 2385 & 2500 projects to work on, so it'll be quite a while before I even get to it.
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I don't have time to do a deep analysis on this, but the 2.2 and .22 caps that sounded bad are part of a switched circuit and tone controls that will be quite sensitive to increases in contact resistance, so while the signal can pass through, it is entirely possible that the increased contact resistance (c229,r231?) can color the sound.
in other words deoxit and thoroughly clean those switches.
also any subsequent downstream electrolytic caps need to be changed at the same time.
also c213, c214 are also important. they seem to have escaped mention.
in other words deoxit and thoroughly clean those switches.
also any subsequent downstream electrolytic caps need to be changed at the same time.
also c213, c214 are also important. they seem to have escaped mention.
AndresPlaza
Andres Esteban
Hi Mark! In this post I'll also answer ccheath post #15:
Mark, the last caps you mentioned: C213 & C214 (1uF/50v) and C217 & C218 (4.7uF/25v) were the first ones to be changed (as suggested by ccheath), and the result was amazing!
Following downstream the signal path, the next electrolytics are C227 & C228 (0.22uF/50v) and C229 & C230 (2.2uF/50v) just after S6, the Low Filter. This filter in its OFF position puts both caps in parallel: C227 with C229 (left channel) and C228 with C230 (right channel). Combined capacitance is (0.22+2.2=2.42uF). As I've said before, with these new caps in place the sound was somehow raspy. Didn't like it at all. Perhaps I should try other brands (as ccheath suggested in #15).
Regarding your idea: "it is entirely possible that the increased contact resistance (c229,r231?) can color the sound" I agree, but the first thing I did was to deoxit the low filter switch (also bass and treble controls!!!). The raspy sound was on both channels. Therefore I put back the old original ones and sound came back to the normal "mellow" sound. So... bad new caps? Should try non electrolytic, or different brand?
Thanks in advance! Andy
AndresPlaza
Andres Esteban
As you've pointed out, the "break-in" issue is quite interesting. Many comments on several forums show this phenomena, sounds gets better after several days of continuous operation. I've been reading about capacitors' break-in time... well, there's some logic in that. Do you think I shoud have left the new ones in place (C227/C229 left channel and C228/C230 right channel) for some weeks to see if sound gets better? Or go for better brand than EPCOS as you suggested?
Thanks in advance. Andy
I took a closer look at the list and at least on the tuner card (so far) I ended up making quite a few additions.
Thus
Until I (or someone else) posts another list after a thorough vetting, the lists above, represent a starting point and not a finished product.
Thus
Until I (or someone else) posts another list after a thorough vetting, the lists above, represent a starting point and not a finished product.
Somebody got their notes crossed. For the sx-780, C213, C214 are shown as 47uf@6V on the specs. I am in the process of recapping an SX-780 and the C213, C214 are actually 47uf@10V on the board. There is probably no difference because it connects to the ground and a test location noted to be 0V dc.
