Being new to vintage audio (mostly JBL monitors and a few Pioneer & Sansui receivers) I’ve recently come across AudioKarma.org in numerous Google searches. Clearly this is the place for all things audio.
So I’ve registered as of today.
I have a tech question in which I’m hoping to get some assistance or advice:
I recently picked up a Pioneer SX-1000td that was ‘thrown in’ along with the beautiful pair of JBL L19’s that I was buying. The seller didn’t recall there being any problems with this receiver, and it’s appearance is mint; however upon attempting to power it up, I got nothing.
I quickly realized that there was no fuse in the voltage selector. Hindsight now tells me that there was a reason for that. After replacing the fuse with a low amp fuse (2 amps or so) then powering up, there was a very brief buzz in my speakers….then the fuse blew.
I opened it up and there are no signs of abuse, corrosion, dust or visual signs of blown or melted components. I sniffed around and could only smell signs of the burnt fuse.
This receiver is in nearly mint visual condition. I’d really like to get it working, but not being an electrical guru, I have no idea as to where to start to test the components.
Here are some more details:
The voltage selector was set at 110v. I’m getting approx. 124v from the wall. My other options on the selector are 117v and 130v (IIRC).
Also, although it appears to be original, the power cord is brown without a non-polarized plug. It looks like a lamp cord. I’ve never seen a non-polarized brown power cord on any audio equipment newer than the 50’s. Is this the oem cord?

Is anybody familiar with this fuse blowing problem?
Is this a sign of a fried power supply, incorrectly set voltage selector leading to a fried power supply (or just a blown fuse), failure of another non-replaceable component; or is there a chance that it’s something repairable - something that I should check?
This looks like a really nice receiver of a quality that you don’t see anymore. I’d really like to get it fired up.
Thanks,
J.P.

Jptl,

Welcome to AudioKarma. You are correct in your statement that this is a site filled with great information and a lot of VERY helpful people. Have you looked at the Pioneer data base to see if the service manual is available? There are several here who will be able to direct you in a very methodical manner to effeciently troubleshoot your issue. If I try to help you - we may get there, but it would not be so methodical.

Please apply a little patience help won't be long.

Good luck-

Thanks Lux Man,
I did look at the Pioneer db, however I didn't realize that there was a reference to the availability of service manuals. All I can see is a db with years produced, wattage, cost, tube/no tube, etc. But I don't see any reference to service manuals. Am I missing something?
Re: advice/suggestions on this issue, I'll hold tight and hopefully somebody can chime in.

When he said database, he was referring to the generic collection of stickys that stay on the top of the pioneer audio forum list. One of them has directions to over a gig of scanned service manuals. The 1000 is among them, schematic only...

There's only ONE fuse in the 1000, so it could be anything, so you need to make a dim bulb tester, and we try to figure out the difference between the low voltage from the dim bulb, and the even lower voltage at the short.

It could be a shorted rectifier or cap in the power supply, or a bigger internal fault.

Look up dim bulb tester, it will be inserted inline, like a fuse, an incandescent lightbulb (20w, 40w, 60w,100w???) is subsitiuted somehow, and it will limit the current through the receiver and the short, and thus additional damage while the unit is powered up as the short is searched for.

You need a DMM. And soldering/desoldering equipment....

I can follow what you're saying, and I have soldering equip. and desoldering braids, but no DMM (don't even know what it is...I'm assuming that it's a meter w/capabilities beyond a basic ohm meter... I know I don't have one).
Shucks.

I can follow what you're saying, and I have soldering equip. and desoldering braids, but no DMM (don't even know what it is...I'm assuming that it's a meter w/capabilities beyond a basic ohm meter... I know I don't have one).
Shucks.

Not shucks, GET one...

Digital Multi Meter volts (ac/dc, down to millivolts on both) , ohms, amps (ac/dc), *** >>>diode test<<< manditory ****

study this:
http://en.wikipedia.org/wiki/Multimeter
to get an idea.... (I'm dead serious)

why a diode test:
http://www.audiokarma.org/forums/showthread.php?t=43186&highlight=bipolar

The later (than yours) model Pioneer receivers had multiple internal fuses which makes localizing the fault a lot easier, but ces't la vie....

Mark,
Thanks for staying with me on this. Your advice is keeping me from stashing this receiver on a shelf in the basement until the day comes when I've somehow learned electronics in my sleep:boring:
If I can mess with this using your guidance, at least I can say I tried.
OK, so I didn't figure the obvious...Digital Multi Meter. I'd always called a DMM an ohm meter. Anyway, I have a good analog meter, one decent DMM and one 'budget' DMM. I've read EchoWars' tutorial on testing a diode.
Now to confirm that my meter has a diode test function: I have a "Check" setting with an arrow icon (as in the top image - without the "a" & "k") next to it.
Assuming that my DMM has the diode test function, do I start testing diodes, or is my next step to educate myself about the dim bulb test?http://www.kpsec.freeuk.com/images/diocon.gif

Educate and make a dim bulb tester, to use it....
It's also called a "poor man's variac".

here are a few links:
http://www.audiokarma.org/forums/showpost.php?p=1733644&postcount=14
probably the master link:
http://audiokarma.org/forums/showthread.php?t=41523
thread about the trials and tribulations of building one:
http://www.audiokarma.org/forums/showthread.php?t=126934
another picture of one:
http://www.audiokarma.org/forums/showpost.php?p=1247628&postcount=42



The diodes are a low probability failure item, the main caps are the highest, with the power outputs somewhere in between.

Have you had the unit open yet? If not open it up and look for the main capacitors, they will be probably be about the size and shape of a can of tomato paste. They could have vented their contents or be significantly bulging. It is worth a look.

You could test the diodes while waiting to go get parts... there will be six on the power supply board, and they COULD be two different sizes..

Can you post some pictures, of the top and bottom of the chassis, and email me higher res versions I can modify and return to you, pointing to things?

Thanks Mark,
I took a look, and don't see anything black, bulging, popped or melted - top or bottom.
However I see one component that seems questionable: The white porcelain rect. component with Japanese writing on it connected to the cap(?). The other has Western numerals/characters: 5W 0.7Ω. The one with the Japanese writing has significant white powder resembling confectioner's sugar on the underside (see pic #11 & #12 for component; see pic. #10 for location).

Also there are large solders at misc. places w/in the circuitry (see last two pics) I'm not used to seeing hand solders like this. I'm guessing factory, but maybe not??
Attached are general pics of the unit in the following order:
Top - full view; top closeups
Bottom - full view; bottom closeups
The remaining four are as follows:
White porcelain component w/powder; Solder at lower chassis - power line in; Solder at lower front right corner.

I have the unit on my bench opened up w/my camera standing by, should you need any more/closer pics. Also I can upload & link to a site that I maintain for higher res. images if need be.

This isn't going to be easy. The boards are screw mounted and hiding their components. There are NO foil layout drawings or component identification drawings to help me to communicate to you which to test. There are no identifications of even WHAT wire goes off the board WHERE...

Let's HOPE it's a simple problem, otherwise it's off to the shop on this one.

We need to find the power supply board, and test the six diodes on it for short circuits, then the caps connected to those diodes, and probably the two larger ones on the chassis.

You could follow the red and yellow wire pairs from the transformer to find the power supply board, and unsolder the four wires, isolate them, and see if the fuse blows or the lightbulb doesn't dim (indicating the presence of the short)...

then connect the yellow wires again and repeat the power test. This is the lower power circuit.

if that doesn't do it, then reconnect the red wires and try again.

one set when removed will clear the short. Then unscrew the board, expose the components and test the diodes, and in the case of the yellow wires causing the short, ohm test the three 220uf caps on the board.

Mark,
I understand your not being able to identify what's what from those pics.
Hopefully this helps:
I traced the red pair and the yellow pair coming off of the trans. to the board that you see in the pics.
Assuming that this is the power supply board, I detatched the reds and the yellows from the board, put a new fuse in the unit (voltage selector at 117v) and powered the unit up. It didn't come on of course, but the fuse didn't blow.
I don't know if this tells us anything, but I figured that I'd do it in any case.
The pictures show the bottom of what I assume is the power supply board with the numbers printed on the board (1 - 12). Red circles indicate locations of the red pair (2 & 3); yellow circles indicate locations of the yellow pair (9 & 10). The second picture shows the corresponding numbers from the bottom of the board.
Note: Although the red pair from the transformer look as though they're still attached to the board in the pic, they aren't.

well, as per my post, you have two ways to go to take the next steps
either
test the 6 diodes for shorts, and the capacitors as well
or
reconnect one of the two sets of wires with the dim bulb rig attached and see if the bulb glows - which indicates a short. you have a 50 percent chance of finding which pair (red or yellow) feeds the shorted circuit the first time.

GREAT picture... the red "3" and "2" , you can see the markings on the top of the board indicating the foil pattern on the bottom? follow them to the four components connected... those wierd shapes are the diodes. four of them. test those with the diode test on the dmm. SOMETHING on them will differentiate the "a" and "k". The other two that look like them at "9" & "10" shoulkd be tested too.

then set the dmm to regular ohms and test the 5 can shaped things (caps) on the board. a reading that continues to climb to a high value is good, a reading that stays at a low number is bad.

report ALL readings, and somehow you will have to keep track of which is which, mark the designations on a new modified version of your posted photo with the red and yellow numbers, and post it. I prefer not to invest the time necesary to match the foil pattern to components to schematic designations.

or pm me an emial address that I can do it and send it to. my posting allowance is getting strained. you can imagine after several years of this how big it could get.

wow, ccheath has started a thread with power supply problems on this model, so now the parts list applies to TWO threads in one day!! That's an unusual and welcome development!! (plus I had just gotten some bad news today)

Could you re-post that marked up picture I emailed you? I have the original, and if somehow we can communicate the resistor color codes and transistor numbers and their locations on the board, it'll be a whole lot quicker getting at least this board marked up...

here's a duplicate of the parts list:
here is a parts list for a power supply regulator rebuild:

6x 512-1N5404 3a (just to be safe) 400v general purpose rectifiers. $0.19 ea

d301 sw-1-02 512-1N5404 3amp 400v diode $0.19 ea
d302 sw-1-02 512-1N5404 3amp 400v diode $0.19 ea
d303 sw-1-02 512-1N5404 3amp 400v diode $0.19 ea
d304 sw-1-02 512-1N5404 3amp 400v diode $0.19 ea
d305 sib-01-01 512-1N5404 3amp 400v diode $0.19 ea
d306 sib-01-01 512-1N5404 3amp 400v diode $0.19 ea

and the capacitors

c301 100uf 50v 647-UPW1J101MPD 100uf 63v $0.55
c302 10uf 50v 647-UPW1J100MDD 10uf 63v $0.26
c303 100uf 50v 647-UPW1J101MPD 100uf 63 $0.55
c304 220uf 25v 647-UPW1H221MPD 220uf 50v $0.60
c305 220uf 25v 647-UPW1H221MPD 220uf 50v $0.60
c306 220uf 16v 647-UPW1H221MPD 220uf 50v $0.60

some cap voltages are higher, the difference is pennies...
but newer caps have less "headroom" than the older ones
because the manufacturing tolerances are held tighter.

all three transistors:
Q301 2sc627 522-ZTX694B $1.46
Q302 2sc620 522-ZTX694B $1.46
Q303 2sc486 522-ZTX694B $1.46
transistors can be replaced by
522-ZTX694B NPN TO-92E ebc 120v 0.5a 1.5w 130mhz 150-500hfe $1.46 ea

they're a bit pricey, but will handle everything the receiver will throw at it.
current , voltage and dissapation..

and since it's cheap, just in case:
d301 1s338q 512-1N4743B Fairchild 13 V, 1.0W Zener $0.08

That's the current, in-stock mouser.com parts numbers list to rebuild the power regulator board with current prices

it still needs the main capacitors and etc added to the list.

eventually you will probably want to go further and replace many of the small electrolytic signal capacitors as well elsewhere in the unit.

Mark,
The linked image is your markup of the components on the power board.
For clarification, could you explain the numbering system?
I.e. your parts list mentions
"6x 512-1N5404 3a (just to be safe) 400v general purpose rectifiers. $0.19 ea"
I assume that rectifiers are diodes since you mention 6 of them....are they not? (I'm electronically ignorant, but I'm trying) I see "D" in the picture labeling what I assume are the diodes.
The list includes "Q" numbers, which you refer to as transistors. Are those on this board or elsewhere.
The "C" components are what I assume are caps.
As an update, I dim bulb tested the red pair and the yellow pair. Red pair failed (25w bulb lit brightly) with both wires attached. Either single red wire didn't light the bulb.
The yellow pair passed. Both wires didn't light the bulb.
The "D" components that I gather are diodes have ---l>l marked on them. In order to test these, doesn't one lead have to be lifted from the board?
What about the caps? I mapped the readings for the caps, done @ my DMM's kΩ setting. However all caps were attached to the board. Does one lead have to be lifted in order to test? If so, my readings are moot. If not, I've mapped the readings in the second picture (thumbnail).
I assume that there's no diff. for pos. and neg. on a cap test? The readings seemed to increase for C301 thru C303; however there was a drop in kΩ w/a retest of C306. C304 & C305 had an initial drop from 2.3m range and 1.8m range respectively.
http://members.rennlist.com/jptl/SX-1000-PS-V1.jpg

The linked image is your markup of the components on the power board.
For clarification, could you explain the numbering system? I.e. your parts list mentions "6x 512-1N5404 3a (just to be safe) 400v general purpose rectifiers. $0.19 ea"
I assume that rectifiers are diodes since you mention 6 of them....are they not? (I'm electronically ignorant, but I'm trying) I see "D" in the picture labeling what I assume are the diodes.

I clarified the listing, and diodes and rectifiers are the same thing... the parts numbers are underlined.


The list includes "Q" numbers, which you refer to as transistors. Are those on this board or elsewhere.The "C" components are what I assume are caps.

I can tell that you haven't even looked at the schematic,(with what is posted so far, it would ring some bells, and make some connections in your mind) yes, the q's are transistors, I didn't mark them on the picture because it would have taken even longer to identify them than it took with the diodes and caps, while YOU could read the numbers off the actual parts and positively identify them accurately, and this also applies to the resistors and the colored bands on them. In fact with that information I can update my copy of the picture with more parts numbers.
Here is a graphical "decoder" of those color bands that's fun to mess with:
http://www.dannyg.com/examples/res2/resistor.htm


As an update, I dim bulb tested the red pair and the yellow pair. Red pair failed (25w bulb lit brightly) with both wires attached. Either single red wire didn't light the bulb.
The yellow pair passed. Both wires didn't light the bulb.

That's good news, we're slightly closer to a fix


The "D" components that I gather are diodes have ---l>l marked on them. In order to test these, doesn't one lead have to be lifted from the board?

Sometimes yes, sometimes no, you try and see what happens, then if the readings don't make sense (to me) then we unsolder one lead and try again, sometimes faults are glaringly obvious, like when they are bad enough to blow fuses or light the dim bulb tester.


What about the caps? I mapped the readings for the caps, done @ my DMM's kΩ setting. However all caps were attached to the board. Does one lead have to be lifted in order to test? If so, my readings are moot. If not, I've mapped the readings in the second picture (thumbnail).
I assume that there's no diff. for pos. and neg. on a cap test? The readings seemed to increase for C301 thru C303; however there was a drop in kΩ w/a retest of C306. C304 & C305 had an initial drop from 2.3m range and 1.8m range respectively.

With the dim bulb lighting, the bad cap would have obvious with an ohmmeter reading.
A cap's function is to store energy, as such it should have a VERY high resistance. A cap fails in two ways, either it looses the ability to store energy, or it short circuits, an ohmmeter would read the short circuit as a very low resistance. So a climbing resistance reading is a cap charging up energy that is applied by the resistance test (the ohms reading uses a battery inside the meter and wouldn't work without it) and at the low voltages used by the meter, reversing the probes would discharge whatever charge is there and recharge at the reversed polarity. Different resistance ranges will show different charge rates. If your ohmmeter automatically switches ranges to read higher resistances, you will see a change in the charging rate (usually slower).

You need to do this ohms test on the four can capacitors mounted on the chassis around the power transformer.

Ohms tests are always done with the power disconnected, and the (wait for them to discharge, i.e. zero volts) capacitors discharged.

So, the red wire circuits have the short, you need to
1) test the diodes (with the diode test) in circuit and report the results,
2) since none of the capacitors on the printed circuit board showed a low ohms reading (less than 100 ohms) they are ok.
3) test the 4 chassis mounted capacitors if the diodes don't show shorted (UNDER 500 on the diode test in either or both directions)
4) if the diodes don't show shorted, and the chassis caps don't show shorted, then reconnect the red transformer wires to 2 & 3 and disconnect the red wires connected to 5, then see if the dim bulb tester glows, then one at a time, reconnect the red wires until one of them causes the dim bulb tester to glow.



until this line disappears the post is NOT COMPLETE!!

Tested the diodes in circuit and got a 5/100v+/- variation when switching from pos:a/neg:k to pos:k/neg:a, except for D305 & D306 which gave an .OL reading when polarity was switched to pos:k/neg:a. (see pic):


http://members.rennlist.com/jptl/Pioneer%20full%20readings.jpg


Tested the chassis mounted caps. and got an immediate drop to a very low reading for the two large caps.
The smaller caps gave a climb to 323.5 ohm & 1.952k ohm respectively. (see pic):


http://members.rennlist.com/jptl/Big%20caps.JPG


I held off on reattaching the reds and removing #5 red for now.

Disconnect the red wires at 5 and retest those 4 diodes that had the same reading both ways after lifting one leg each of the 4 diodes while you have the iron hot. If you get the same readings as the two that had OL as part of the reading they are fine, so reconnect them and go to the next step. If not, stop.

Disconnect ALL the red wires at those two capacitors (one cap at a time) marked "drop from 2.7 to 1.8 ohm", and retest them.


The reason I took the time to MARK the picture up with stuff like d306 c304 etc... is so you could post things like :

D306 .495/.OL
C304 drops from 2.3m range
instead of having to look back and forth at two pictures and posted text.



The color rendering of the last picture is much better and shows that the resistor and it's leads with the kanj japanese characters on it have been badly overheated, the color of the wire from the negative side of the cap to the soldered ground connection confirms this. It is part of the amplifier circuits as far as I can tell.....

because of:
1. the extremely poor service information available
2. the point to point scrambled nature of the wiring and construction of the unit, this is literally a can of worms.
3. The fact that the comparatively burned resistor is part of a spread out amplifier circuit
4. the entire nature of this thread, and the progress exhibited in it, mainly compounded by # 2 above... later models with more regularized construction, I feel we could tackle....

It is my judgement that this unit needs to be worked on IN PERSON by qualified personel.

You can do the tests at the start of the post, but I am reasonably sure the problem is not in the power supply, and in fact there are at least two blown output transistors in one amplifier channel. These tests will only prove me right, not fix it.

The best thing to do is to put it all back together, and find a shop willing to take it on. You may need to provide them with the schmatics, or they will buy a manual, ususally for 20 bucks or so.

If all else fails, I am willing to continue fixing it in person, should you decide to ship it to me.

Mark,
Thanks for all of the time that you've dedicated to this. I truly appreciate your effort. Even though I didn't get the 'easy fix' that I was hoping for, I feel like I haven't abandoned this unit without at least trying....certainly a valiant attempt on your part.
Although I hate to give up on something that may be fixable, there does come a point at which I throw the towel in...particularly when I'm a novice in the field of repair.
As far as having it repaired at a shop willing to take it on is concerned, I'm guessing that it will go beyond the $ that I'm willing to dedicate to this....certainly if it involved shipping to & from (this is a heavy unit).
I have no idea as to the demand for parts for these, but if you know of anyone interested, let me know....otherwise it's going into the old receiver amoire in the sky.
Thanks again for your help.

I was about to ask you if you really want to close curtain on this because it looks you are getting closer to the problem. I reread the thread and found Mark suggesting you take it to the qualified tech. I know you are pretty new in this area of electronics but you seem to pick up well even with the diode testing. I'd be interested in the receiver but I just bought one off ebay the exact model you have. :D I personally think it's a nice receiver. I had an SX-700t in my teen year and I like the way it sounded. SX-1000tw is close as it gets and sounded the way I remembered. I will be working on my power supply too even though it still works. Mark's part list for the power supply pretty much got me a head start.

If you like the receiver but not willing to shell lotta greens for the tech to fix, you can put it aside until you get yourself more familiarized with electronics. I did that with my Kenwood KR-9400. It was shorted out that it wouldn't even power up and been blowing a couple fuse I tested it with. I thought the problem might lie in the power supply problem. As I tested, I was unable to find it at the moment so I put it aside. When the day allows, I spent more time on it and aggressively trouble shoot alongside using AK forums (I didn't join at that time) for research and lead me to finding 2 of the 4 output transistors in right amplifier perfectly shorted anongside with 2 cracked power resistors but not open yet. Not visible but I was able to locate it using the meter alongside with reasoning. Now I'm using it as my living room receiver regularly. I used to be good with EZ fixes but never really good with deeper fixes. Because AK forum helped me with this issue, I decided to join. There's wealth of info with patience of researching, asking questions and so forth. So far I fixed several receivers. Thanks to AK and AKer's for their help. Not to interfere with Mark's suggestion, you can do it too if you want but you have to be patient in researching and learning. Not everything has an easy fix.