What role do the main filter caps play in the SX-1250?

[vitalsigns65]

I was wondering why am I hearing such a difference since R&R of these components for the better? The old ones I should mention were not showing any signs of wear so it isn't like they failed. What is it exactly that they do?

 

[Hyperion]

The Main Filter Caps are there to smooth the output from the rectifiers which in turn is fed from the mains transformer.

Aging main filter caps can cause undesirable effects, such as too much current pulled from the supply when the amp is not playing (leakage). Not enough current delivery under load (High ESR / Low capacitance). Hum modulation on the supply lines (both of the above).

All of which will significantly affect the fidelity of anything you are listening to - the audible differences being most apparent in the lower frequency ranges (Bass).

If you notice a significant difference now, when just the Main Filter Caps have been changed - then they were WELL overdue for replacement. You should have all the remaining electrolytic caps changed sooner rather than later - if this has not been done already.

Nice Receiver - look after it.

 

[vitalsigns65]

Thanks for that John. Under the big, round, looks like a small birthday cake device is a board and the fuses are there.... those big axial caps are next to go.Is this the power supply board? This part of the receiver has the potential to reek havoc if it fails. Am I on the right track?- Jim

 

[Hyperion]

Thanks for that John. Under the big, round, looks like a small birthday cake device is a board and the fuses are there.... those big axial caps are next to go.Is this the power supply board?

Not familiar with the inside of an SX-1250, that fuse board, does it have any components other than fuses on it like capacitors & transistors - if it does then that is quite likely the regulated PSU board, if not then its just the fuse distribution board. Also when you say "...those big axial caps are next to go" do you mean the biggest caps in the receiver? as these are unlikely to be axial (one connection each end) - more likely to be radial (connections at one end only).

This part of the receiver has the potential to reek havoc if it fails. Am I on the right track?- Jim

Yes you are absolutely on the right track, everything depends on the PSU (wherever it is in the SX-1250 ) giving out the right voltages, reliably, and even when under stress.

Just one point though, those Main PSU caps we have been talking about - unless yours are visibly leaking some goo from anywhere near their terminals or ore otherwise damaged (dented?) I wouldn't necessarily change them BEFORE any of the others, i.e. the smaller ones. I usually leave the main caps until last UNLESS they have goo or damage - or give me other symptoms which would make this a prudent measure.

Chime in anyone, I am running on vapour regarding SX-1250 innards

 

[markthefixer]

The board with caps and fuses is power rectification and storage for the regulated power supply, which is one of the four removable boards on the top side rear of the unit.

The big transformer in the center, and the 4 big caps around it, are the specific power that is used to push the speakers, the amplifiers control this power, but the amplifiers themselves (and everything else really) are run off of this other regulated power, with only the driver and power output sections using the "speaker power" which is capable of delivering far more current (amperes) than the regulated power supplies (look at the size difference in the caps).

These regulated supplies, and the boards they power with their signal coupling and control circuits including capacitors have a far greater effect upon the sound, as they shape it.

 

[vitalsigns65]

Thanks to all who offered their wisdom on this. Here's where I am at with this SX-1250. I have the four main caps replaced, all the switches and pots thoroughly cleaned and lubed, and all is well. The tuner is very good and blows away my G-8000 tuner but that piece needs an alignment(whole other topic) Back to SX-1250.. I intend to try and replace all the elect. caps board by board starting with the four that flank the main filter caps. Two driver boards, one stabilizer board, and one protection board. The reason I want to begin with those is that they unplug and R&R of those boards is a no brainer, a good warm up for whats to come down the road for unless I am mistaken the others will require some disconnection of wire to remove them and get them benched so I can comfortably remove the old elect. caps and install new ones. Never did this before but I have done some electrical assy. in the past and I believe I can do this. Markthefixer hello and please allow me to say your words here have been a tremendous help, and thanks!:thmbsp:
Should I be taking out each board and replacing every cap that I see on that board are they all electrolytic or are some of a different type that can stay ? Don't want to fix it if it isn't broken. What besides e caps should I do while it's there in front of me?

 

[vitalsigns65]

When the time comes to de-solder the old caps should I expect to find them glued as well? Gently pry them off? Re-glue the new ones? Thanks- Jim

 

[vitalsigns65]

This board concerns me. Is this the one that if it blows I'll finally get that skylight I always wanted in my den?:scratch2:
I see e caps, tantalums, and resistors- do em all and let God sort em out?

 

[markthefixer]

All of your questions can be answered by reading this forum for a while, they all have been covered. LOTS of guys have done 1250's here. There are parts lists.. might only cover the 4 boards, maybe more - like the signal sections...

NEVER EVER NEVER EVER NEVER EVER UNDO THE WIRE WRAPS!!!!!!!!!!!

In rare circumstances I occasionally desolder a PIN from the board for slack...

But we ALL manage to do all those front boards (all of em actually) without disconnection. They were MADE with slack in their connections for removal as modules.

RT(F)M - the exploded drawing tells much... if you don't HAVE a downloaded hi res pdf manual - ASK -

I stand the unit on it's side, on a lazy susan turntable, unstable units get cross brace feet connected through the bonnet screw holes.

big caps were glued to boards. for production wave soldering. thus NO glue needed.

electrolytics dry out - replace them
solid aluminum caps short out just like tantalums, usually more slowly
tantalum caps - short out spectacularly

It's the little caps that dry out first and screw up the sound.

replace resistors?????????/ unh unh unless toast...

some known troublemaker transistors get preemptively replaced.

power supplies cook transistors and caps to death. To-220's have metal that turns black. that = replace!!

plus if these terms are gibberish to you, you are gonna get yourself in trouble replacing caps willy nilly:
cea ceb ceanl cssa csza - again read the manual - LOOKING for these - then either find my "rule of thumb" for caps or find and read the "tuning fork" thread. these are cap types: UPW UKL ECQ.


You have pretty much marked yourself (to me) by going after the LAST caps that are usually done if necessary in a receiver... the big expensive ones with the largest moisture reserve... I'm gonna have to watch you close, and you are gonna cost me a LOT of work, time, sweat and repetition of things I have posted in the recent past. AND I'm currently elbow deep and halfway through a sx-1250 on the bench. Power, power amps and protection all squared away. The rest by the end of the week or end of weekend - depending upon AK Pioneer Forum traffic...

I do acknowledge that the search feature sucks, and slows down the gathering of knowledge. Maybe that's why the new gung ho guys want it handed to them on a plate, instead of hitting the buffet table.

My objection is not the questions, questions are better than blowups or do-overs, but when the answers are already in type it can be a bit offputting to do repetitions so frequently.

 

[vitalsigns65]

Thanks Mark. Going to read those suggested by you. I spend hours reading, looking, reading, and so on... It's sometimes a mess and finding information can be a challenge, the way it's structured. As far as replacing the main filter caps first, not sure why I chose to do that.... Big and staring me right in the face maybe and due to their importance in the path and not wanting to clean up a mess if they vented...live n learn, guess. I won't push the receiver past 10 oclock and my paradigm 100 v2. are efficient enough that I will save long n loud sessions for after I have covered more ground with bringing this piece up to date. Thanks again for your guidance. Be well, Jim:ntwrthy:

 

[markthefixer]

<snip> Thanks again for your guidance and that hubris for which you are so famous for... made me smile- Be well, Jim:ntwrthy:

Hubris
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Look up hubris in Wiktionary, the free dictionary.

Hubris (also hybris; pronounced /ˈhjuːbrɪs/ due to the hypercorrection of the Greek spelling due to the incorrect transcription of /u/ for /ὕ/) means extreme haughtiness or arrogance. Hubris often indicates being out of touch with reality and overestimating one's own competence or capabilities, especially for people in positions of power.

:scratch2:

are you sure that you wanted to use the word hubris?

start of edit - this was posted on 12-11,two days later, and is copied here to show we have reached a mutual understanding and respect and that all is well. We made nice before this below was posted.

I have been sitting here for hours reading multiple posts from markthefixer and one thing that's become painfully obvious to me is that I made a unsuitable remark in an earlier post. The word I used to describe markthefixer was "hubris"- I clearly was insulted when the truth was told to me regarding being too lazy to put more work into my searches regarding acquiring basic knowledge that was already in print. Well, Mark, please accept my sincere apology for looking a gift horse in the mouth, so to speak. Hope that this will help clean my face at an embarrassing moment for sure! Sincerely, the big mouth Jim

All is long forgiven, evidenced by the flow of information.

I guess that my style of information dump can sometimes be misinterpreted by the uninitiated(to this forum) and unsuspecting... gotta work on that, to remember to be gentle with the new folks, until they are ready to "drink from the fire hose".

***** end of edit , to show that we have arrived at a mutual respect, and forgo any members thinking there bad feelings. ****

If you are sure, then I ask the rest of AK, have I slipped into the definition of hubris:

extreme haughtiness or arrogance. Hubris often indicates being out of touch with reality and overestimating one's own competence or capabilities, especially for people in positions of power.

I ask this as a genuine request for feedback, to see if I have slipped or am starting to slip into this very objectionable territory and am in need of some attitude-ectomy. :sigh:

Audiokarma, all audio, no attitude.

 

[Blue Shadow]

Mark, as a frequent reader of your posts, I applaud your efforts and agree 100% with what you have said in almost every instance when someone seemed "to want it handed to them instead of browsing the buffet" as you say. Your attitude is never over the top as the only instance I did not agree was when someone went too far with an attitude and you continued to assist. Keep up the great work.

 

[vitalsigns65]

One needs only to read MTF post to mine and it's glaring and obvious to which remarks I have remarked.

 

[vitalsigns65]

So today I went looking for a caps list here and what I found was really great. It was all there in front of me courtesy of an AK member who obviously spent considerable time and effort compiling this list for the benefit of others. Thank you to the author, IDK who. So.... copy and paste to Mouser and lo and behold my order for 70 some odd electrolytic capacitors is on its way. Very excited because I love my gear like the rest of us do and a little apprehensive of my ability to ID each one and install each one properly. Any pointers?
awprint:

 

[Japetus]

I ask this as a genuine request for feedback, to see if I have slipped or am starting to slip into this very objectionable territory and am in need of some attitude-ectomy. :sigh:

Hi Mark,

you also helped me a lot with your posts, and you asked the rest of AK'ers, so I felt the need to aswer. If it is still of your interest:

Yes, I am here only since a short time. But I have read many many posts of you from back 2005 up to now in only the last 3 months, so I think I have a quite good impression on how things developed.
The impression I got from you by reading all these posts, is I surely believe you mean 'genuine request' as it is.
So here's my genuine view:
On matters of objectivity concerning analysis of the problem and advice your score is flawless, also in this thread.
On matters of common courtesy the tone gained a little bit of austerity recently (yes, I got this feeling - step down on me...).

This is no reason by far for any 'some attitude-ectomy', IMO.

I hope you go on as you did.

OK, I'm done, just one voice.

Frank

 

[markthefixer]

I might be a bit burned out lately, and have allowed postings to get grumpy and testy. Sometimes I just get frustrated when I have trouble putting the concepts in my head down on paper easily and succinctly. Or finding and using applicable quotes from time past...

The list is courtesy of KingBubba and myself. He started accumulating everything I published on the sx-1250 including my innovation - the BOM lists I made to avoid "alphabet soup errors.." in component ordering a while back, and we went back and forth a bit with revisions getting it up to date. If you backtrack my posting history, few are the days that I have spent less than several hours a day researching and posting answers to questions here, and steering various tests and repairs. In other words, lots of time? that's me... don't take my word for it, look and ask around... I can close my eyes and see Pioneer stuff, although I always check the service manual - when I don't it bites me....

Out of stock parts still keep me jumping in the various lists I have published as older lists are resurrected. Also I have LEARNED stuff since doing a particular list, which is why I ask people to post the list before using it, so I can go over it with a fresh eye and new experience, adding in appropriate changes.

Like why CEA type UPW/UHE caps and CEANL, CSSA, CSZA type UKL caps ? UKL is usually 2x as much $$ (only a few cents so pfffft), but they are low electrical leakage, and Pioneer USED equivalent caps (CEANL) to make the amp quieter in certain sensitive spots. I did a high end amp years back with all UPW caps, and it was slightly noisier afterward - bothering me, leading to extensive research, eventually I found the Pioneer tuning fork info, figured a few things out, used different caps (UKL,ECQ) in one channel as a test and got a marked improvement in performance... instant convert....

The list should be in the format:
power supply stabilizer ok
awr-106 c1 220 80 cea 220 100 647-UPW2A221MHD
awr-106 c2 220 80 cea 220 100 647-UPW2A221MHD
awr-106 C5 47 35 cea 47 35 647-UPW1V470MED 0.17
awr-106 C6 47 35 cea 47 35 647-UPW1V470MED 0.17
awr-106 C7 22 50 cea 22 50 647-UPW1H220MDD
awr-106 C8 22 50 cea 22 50 647-UPW1H220MDD

the awr-106 is the board, and tha hi-res service manual will point you at C1 c2 etc.. locations, as well as the fact that there are uf and voltage printed on each cap. And each cap type comes in stock number marked bags.
cea's are nichicon UPW and UHE, but there may be special cases like these:

power amp left ok
awh-048l C2 10 16 ceanl 10 50 647-UKL1H100KDDANA 0.23
awh-048l C5 220 16 ceanl 220 16 647-UKL1C221KPDANA 0.36
awh-048l C11 0.22 10 csza 0.22 250 667-ECQ-E2224KF
awh-048l C15 470 80 ACH-038 470 100 647-UHE2A471MHD
awh-048l C16 470 80 ACH-038 470 100 647-UHE2A471MHD

where low (electrical) leakage UKL caps or stacked film ECQ caps are used.

This is why I stress reading some stuff ahead of time - I can yammer on and on about these lists, but there has to be a point where you have read all this stuff, and when the mental connections are made, going: " OHHHHH , I GET IT, these are more than parts lists - they're ROAD MAPS to replacement/upgrades" for those that SEE the connections, and how the information refers back to the service manual.

 

[CDFixer]

Mark, I have no problem with your posts. All the forums have folks asking the same questions over and over, it does get tiring when especially when the answer is in a "sticky" at the top of the forum. Several times I have clamped my teeth shut to answer a question, since I have to do the search that should have been done. That all being said. Some of the folks trying to do this stuff may not have the knowledge to know what to search for until they get some questions answered. Using a search engine (especially AKs) when you really don't know what question to ask is daunting.

 

[merrylander]

Mark, I think the gentleman simply used the wrong word, I would hardly use it in a description of your work.

BTW as a simlple note, and diodes are often used in AC circuits as dimmers, without a cap to charge and discharge repeatedly all you get off a single diode is pulsating DC, hard to distinguish from AC but a nice clue to open caps in these power circuits.

 

[Hyperion]

Mark, you share your intellectual property more generously than anybody else I can think of on AK.

I am sure other tech's like you, get fed up with repeating the same answers to questions from dumbheads like me, it's just the nature of the beast.

Keep up the good work :thmbsp:

 

[MarkNC]

Mark, before starting my first-ever recaps/refurbishings (SX-880, 1080 finished, and soon 1050), I pored over multiple threads of yours and learned all kinds of things about capacitor selections, to the point that I felt very comfortable making my own substitution decisions when Mouser/DK are/were backordered. You're not just a "fixer", you're an educator to those wanting to be educated.Too many folks, it seems, just jump in w/o doing their homework first. It's highly understandable that that would be frustrating, and if anything, you've been a paragon of patience.

Best regards,
Mark E.