Assessment/advice on a sx-727

[33&athird]

Out of curiousity, if the capacitors are replaced on the am/fm board, will it need a re-tune? I suspect it will, but since the capacitor values have drifted, along with the resistors over time, it may be off anyway. So, maybe the re-cap will bring it more into "stock":scratch2:.

Just now hooked up speakers to test the sound at no volume situation...when fully counter-clockwise, there is no audio, as expected. Maybe the reason I was hearing it was the other speakers I tried were more efficent?...either way, I don't think (at this time) that it's much of an issue, besides the volume pot needing to be cleaned. Tried it with headphones as well. Same result, and took out the pre-amp jumpers (while using the phones), and there was no sound at all, it was on the "spkr off" setting, if that makes any difference...

It's going to the bench offically, so I can leave it apart overnight without worry of cats and the like. I will determine the Power amp caps and whatever else ther is down there, as well as gain access to the pots and switches.

Speaking of, the "low-cut" switch cover (aluminum I belive) has become disconnected...it seems like a simple slide-on thing, but it refuses to stay on the shaft...maybe a dab of some sort of glue was used? the others are fine, and even if the faceplate comes off, it seems like they can stay on:scratch2:.

I'll keep updating as it happens:yes:. sorry progress is so slow, seems everything is around here:sigh:.

 

[markthefixer]

Out of curiousity, if the capacitors are replaced on the am/fm board, will it need a re-tune? I suspect it will, but since the capacitor values have drifted, along with the resistors over time, it may be off anyway. So, maybe the re-cap will bring it more into "stock":scratch2:.

Just now hooked up speakers to test the sound at no volume situation...when fully counter-clockwise, there is no audio, as expected. Maybe the reason I was hearing it was the other speakers I tried were more efficent?...either way, I don't think (at this time) that it's much of an issue, besides the volume pot needing to be cleaned. Tried it with headphones as well. Same result, and took out the pre-amp jumpers (while using the phones), and there was no sound at all, it was on the "spkr off" setting, if that makes any difference...

It's going to the bench offically, so I can leave it apart overnight without worry of cats and the like. I will determine the Power amp caps and whatever else ther is down there, as well as gain access to the pots and switches.

Speaking of, the "low-cut" switch cover (aluminum I belive) has become disconnected...it seems like a simple slide-on thing, but it refuses to stay on the shaft...maybe a dab of some sort of glue was used? the others are fine, and even if the faceplate comes off, it seems like they can stay on:scratch2:.

I'll keep updating as it happens:yes:. sorry progress is so slow, seems everything is around here:sigh:.

yes - tuner realignment, especially the detector and stereo decoder stages because these are doine "old school".

Everything comes off to pull a faceplate...

Be careful of small fragile things connected to the heatsink - they are irreplaceable, and the fragile leads LOVE to break off flush with the body of the component. IIAC the amp board and heatsink are an assembly mounted together and the heatsink has the chassis mountings.

 

[33&athird]

yes - tuner realignment, especially the detector and stereo decoder stages because these are doine "old school".

Everything comes off to pull a faceplate...

Be careful of small fragile things connected to the heatsink - they are irreplaceable, and the fragile leads LOVE to break off flush with the body of the component. IIAC the amp board and heatsink are an assembly mounted together and the heatsink has the chassis mountings.

Looking into it, I don't really have the parts I need for a re-alignment. What detremental effect could that have?, if its just the dial being slightly off perfect, I may live with it. It seems you need a signal generator, which I lack, as well as an am/fm generator, which I have, a eico 320 (I think), but i'm not too sure it's spot-on either.

The power amp section has been done. I located the carraige screws, and the whole assembly came out with a little effort and a bit of stress (to me, not the board). All the caps are pretty much manual-correct...some higher voltage ratings though.

Got all the knobs and switch covers off the faceplate, and labeled them for later. However, the tuning knob has allen screws. From what I found its a 1.5mm (according to ccheath in another topic)...I want to make sure this is correct, as it seems like it would be very easy to strip it out. Unfortunately the manual says nothing about these screws.

While i'm waiting for the Deoxit/faderlube to come, i'm going to try to clean up the chassis, soldering iron, faceplate, and case. I assume there are topics about cleaning the faceplates (as I recall)...and the wood case as i've read has solid walnut laminate, so a general wood cleaner should work on that. I may try a test patch to make sure though. If all goes well this will turn out great...here's hoping :yes:.

EDIT: tried a .050 allen wrench (the equivilent of a 1.5mm is .0506"), and it didn't work at all, its too small. The next size up in the pack was too large, i'm going to have to dig out some of our other ones. Trying to be carful, as these are very small screws, and easy to strip, being allen screws and such. (why not just use small flatheads :scratch2

 

[fastbike]

Well gee

I know you're the Magic Wizard of Pioneer, but I was able to clean up the volume and balance pots on my SX-727 without pulling any boards. Thus I am SURE about what I say.

To get at the pots, you WILL have to "remove" boards MECHANICALLY - BUT they are MADE to stay electrically connected and slide out. The decorative front panel comes off, showing the chassis front panel where they are held by screws and threaded nuts on the pot shafts.

That will give you access (probably - unless additional plates come off) to the OPEN wafer connection area of the pot.

The X2X series were built like tanks.

I have an 828 open on the bench right now, thus I am SURE of what I say.

 

[33&athird]

I know you're the Magic Wizard of Pioneer, but I was able to clean up the volume and balance pots on my SX-727 without pulling any boards. Thus I am SURE about what I say.

Not that I doubt it, but I would really love to know how...Looking at it I can't see a way:scratch2:

Though, at least in my case, I have to pull it to check the caps anyhow, so it was/is unavoidable. Wouldn't mind figuring it out for future reference, since i'm sure i'll have to re-do most everything long down the road.

 

[markthefixer]

I know you're the Magic Wizard of Pioneer, but I was able to clean up the volume and balance pots on my SX-727 without pulling any boards. Thus I am SURE about what I say.

Well, then the 727 and 828 are different, the 727 is a gap in my experience as of yet, only the 424, 525, 626 and 828 have been eyeballed.

The 828 audio board is very wide, shrouding access badly.

From the manual it isn't clear as how to access the pot behind the chassis panel, a description would be welcome, and as a bonus, pictures would benefit many people, in perpetuity.

 

[33&athird]

Well, then the 727 and 828 are different, the 727 is a gap in my experience as of yet, only the 424, 525, 626 and 828 have been eyeballed.

The 828 audio board is very wide, shrouding access badly.

From the manual it is NOT apparent as how to access the pot behind the chassis panel, a decription would be welcome, and as a bonus, pictures would benefit many people, in perpetuity.

:yes:, getting to them is an issue, the 828 and 727 are really quite similar, from what i'm looking at, you could get to the pots, but it would be bending over backwards...especially for the ones in the middle of the amp. I would say if you've seen the 525 and 828, you can estimate the 727...it really is just a beefed up 525 (really all I have to compare to). I can get some pictures up, although I couldn't point out how to access them. The part I can't think up is actually getting the fluid into the casing:scratch2:

Either way, if a recap is in order, that board gets pulled (it would seem).

 

[33&athird]

First off, sorry it's taking so long...

Second...finally got the faceplate off, and am met up with this;

Seems like I need to undo the washers and nuts holding the pots on, and then undo certain screws around them. I want to make sure this is correct, since it seems at this point one wrong move could really mess with key components.

The other thing is: can this unit still be turned upside down? I think I may have to put spacers under it due to the radio indicator being exposed now.:scratch2:

As it seems, this is the last board to have caps...so i'll have the list up in its entirely tommorow. The deoxit came today, so i'll do that as well, and may do a brief test afterwards. I haven't gotten a good look at the pots...is there an easy Deoxit point, or am I going to have to do the drilling buisness I hear about once in a while...I certainly hope to avoid that.

Oh, on another note; I now belive these are built better than tanks...seriously, this thing is a beast...can only imagine how the sx-1980 is:yes:.

 

[markthefixer]

Yes, washers mainly, but some screws might be holding things together that are deeper and don't need removing yet... ymmv

Stand it on it's side, power xfmr down - it will be somewhat stable, a wide piece of plywood with countersunk screw holes matching the bonnet's holes will turn the side into a very stable foot. (that's how I do it, plus I have a lazy susan turntable I set it on)

NO pots need drilling, the area where the leads enter is wide open, might have to heat and bend a deoxit straw into a "J", put a wire through the straw b4 heating to keep the channel open.

They get easier to work on as the models advanced x2x > x3x > x50 > x80 and so on... less overbuilt, sometimes better access.

 

[33&athird]

Hey, the cap list is belived to be complete, however...

There is a unit called the "AF board", appears like this is where all the potentiometers and switches are. The serivce manual says the board should be "AWK-010"...But on mine, the board says "ANP-059-0". The additional service manual update they released only mentioned the protection board change, nothing about a different "AF" board. I guess I shouldn't care since all the caps have been visually checked. Seems like the "updated" board has more caps than the service manuals version, I don't get it . For the list you said you needed the "flavor" of capacitor...this is easy if the caps are manual-correct, how would I check if they aren't realted...i'm not really seeing "cea" or "cssa" expressly written...

I'll double check everything again, make sure I have the right format for the list and report back.

In the meantime, I may attempt a Deoxit/Faderlube fix. I'll read up on it...seems easy enough, put some in, move the wiper, let dry, then re-lube. Switches should be the same method:scratch2:.

Edit; more fun...it seems like it would be somewhat easy to get to the pots if the large metal plate was removed from around the pots and on top of the switches. However, none of the screws on the piece of metal want to move...at all. I think I can still get to the pots with a little manuvering. For the switches can I just inject it into the back of the unit...or somewhere else?. Sigh, I know it will all be worth it, but this likes to throw something at every turn.

 

[markthefixer]

Yes, washers mainly, but some screws might be holding things together that are deeper and don't need removing yet... ymmv

Stand it on it's side, power xfmr down - it will be somewhat stable, a wide piece of plywood with countersunk screw holes matching the bonnet's holes will turn the side into a very stable foot. (that's how I do it, plus I have a lazy susan turntable I set it on)

NO pots need drilling, the area where the leads enter is wide open, might have to heat and bend a deoxit straw into a "J", put a wire through the straw b4 heating to keep the channel open.

They get easier to work on as the models advanced x2x > x3x > x50 > x80 and so on... less overbuilt, sometimes better access.

uhhhhh ^^^^^^


the contacts in the switches are very close to their solder connections, that's where to find cracks or crannies to spray into. Use a rag to catch over spray and runoff.

 

[33&athird]

uhhhhh ^^^^^^

...ah man, sorry I missed that:sigh:

Cap list coming next post...got the paper next to me.

 

[33&athird]

Hey, I was entering the cap list, and have a few questions: for one, the CEA and CSSA caps as the manual mentioned are still a mystery, and I don't know how to read that from the physical cap. The other thing is the component numbers...i'm having a heck of a time matching what I wrote down to the numbers from the manual...any advice there, or should I just match as best I can...especially on the boards that have more caps than the manual says so:scratch2:.

I'll keep writing the list in word, and then post it here.

 

[markthefixer]

Hey, I was entering the cap list, and have a few questions: for one, the CEA and CSSA caps as the manual mentioned are still a mystery, and I don't know how to read that from the physical cap. The other thing is the component numbers...i'm having a heck of a time matching what I wrote down to the numbers from the manual...any advice there, or should I just match as best I can...especially on the boards that have more caps than the manual says so:scratch2:.

I'll keep writing the list in word, and then post it here.

this might help? don't know if I posted this before on this thread - several cap threads going at once....

http://www.audiokarma.org/forums/showpost.php?p=3012505&postcount=11

the cssa's are usually a sky or powder blue, tha NL's are orange and the tantalum (csza) caps look like gumdrops - rounded construction, not aluminum cans.

 

[33&athird]

this might help? don't know if I posted this before on this thread - several cap threads going at once....

http://www.audiokarma.org/forums/showpost.php?p=3012505&postcount=11

the cssa's are usually a sky or powder blue, tha NL's are orange and the tantalum (csza) caps look like gumdrops - rounded construction, not aluminum cans.

Nope, I may have seen it on another topic, but not thought about it much. It helped alot, I saved a copy for future reference. Seems the only "css" ones are the powder blue sanyo ones...the only ones without make markers, just the values. All the Elna and nippon chemi-con ones are well-marked and "ce" types...All the ones for recap are "A" as well, except for the larger ones due to terminal type. Very interesting system.

Any way, i've been putting it off:

Posting here would have been a bit cumbersome...so the attachment is a word (97 oddly enough) document with the list...if you need it in another format, a different place, or more information i'll fix it right up, I don't want to make it any harder than it is or needs to be.

> another note; earlier in the topic, the non-polarized aluminum sanyo caps came up, and you recommened replacing them with a film cap...would any film cap work? if so, i'll pick up a couple in the order.

Also, how do you keep track of so many repair topics? My mind is boggeled at the one i'm working on:scratch2:.

Edit; for one, the inital de-oxiting is done, but i'm going to wait for the caps before I put it back together, since that faceplate means buisness...not fun at all to take apart, tons of washers :sigh:

Oh! and happy holidays...hope you got a nice break from things!

 

[markthefixer]

Ok, I've got the doc onboard and will try to get it back, finished, by the end of the weekend.

PM me your email addy so I can return it and you can post it (my posting space is getting squeezed).

RE: keeping things straight - different models / different problems / different mental "associations" for recall.

film caps - stacked metalized poly film Panasonic ECQ or Cornell Dubilier DSF.

 

[Rockmore]

Are you going to replace those "little powder blue" caps that look like electrolycts with film caps ? If so, what films?

I have two also. Can not match them up to the schematic.

Mine state M309 Sanyo 1/25.

 

[33&athird]

Are you going to replace those "little powder blue" caps that look like electrolycts with film caps ? If so, what films?

I have two also. Can not match them up to the schematic.

Mine state M309 Sanyo 1/25.

Uh...i'll have to check the list again

Those are a form of electrolytic that are solid aluminum. Typically in old pioneers they are sanyo caps, with, as you noticed, weird markings for a capacitor. The ones mentioned earlier in the topic are sanyo, but are non-polarized, and used on the protection board, which some units lack. The way sanyo marked them is, in your case 1/25, or 1uF at 25volts. I belive the rest are polarized, just not the standard electrolytic. In the manual they will be listed as CSSA, where most caps are marked as CEA...these are just standards, and indicate different caps.

I'll try to find them in the list, but I'll have to swap computers...maybe markthefixer will have it off the top of his head:yes:.

 

[Maddart]

When you get the cap list I'd be intrested in it as i have a 727 next in the pile to rebuild.

 

[33&athird]

When you get the cap list I'd be intrested in it as i have a 727 next in the pile to rebuild.

Alright, later today or tommorow i'll send it out or attach it here, if mark doesn't mind, since the mouser list is the most helpful I belive. If you just need to know what it may have, the word attachment on up the page is a visual of what my unit had...though they differ. I'll try to get it up sooner than later:yes:.