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SX1050 Thumps at power on

qguy

qguy

Super Member
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This thread started with a few small issue and eventually turned into a full recap, except for the Main filters, Tuner and Phono section. Before and After Photos on Page 4
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Having a few issues with my SX1050

1. Its thumping at power on, there a pop and the woofer moves
2. I can hear a very weak tick on the tweets and mids and I can feel a very slight movement on the woofer when the source is AUX and the source is not on. Its hardly noticeable, except when your very near the speakers.

more info

I tried disconnecting the pre-power connector and when disconnected the thumps is noticeably weaker

is it "safe" to use or should i bench this for the time being ?
 
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is there a delay of several seconds between powering on and the thump?

HOW LONG is the time between power on and the thump - your protect delay is probably reduced due to old capacitors. Just because a few caps were replaced on your inputs doesn't mean that other caps aren't also in trouble.

PLUS the power supply stabilization time with older caps could be taking longer.

This is some of the things I WOULD have discussed with you earlier, if I had a chance.

Basically your protect circuit and power supply SHOULD be recapped. It can be deferred for a year or so if certain things aren't happening, but they WILL finally start.

We (I) can come up with a list of capacitors to do that will get you on a solid footing, or a list that will cover everything but the tuner (alignment issues occur with cap replacements) and also where to order that list of parts from (no affiliation).

Then instead of chasing a hodepodge of symptoms almost incessantly, you can do it once, get it over with and enjoy the thing FOR YEARS...

oh yeah, and as Avionic said - check your DC offset, and watch it as the unit "warms up".
 
I thought the selector switch capacitors was the only problem (well I was hoping)

Theres about 3 seconds from powering on and thump, thump happens the same time as relay click

DC 0ffset Right is 6 -7 mV. Left is 7-8mV after 3 minutes after power up, AUX, 0 volume. Similar results after 10 minutes

Protection Circuit assembly
AWM-090 board

Power supply board
Power Supply circuit Assembly -A AWR -103
Power Supply circuit Assembly -B AWR -104

Do i replace all caps in these three boards or certain types /size of capacitors last longer ?

You mentioned "We (I) can come up with a list of capacitors to do that will get you on a solid footing" I think this is a good start as covering everything might be a bit too overwhelming for me.

thanks
 
thanks I am looking at these, let me know if i am on the right track

protection
awm-090 c1 0.22 25 cssa 0.22 50 598-DSF050J224
awm-090 c2 0.22 25 cssa 0.22 50 598-DSF050J224
awm-090 c3 470 6 cea 470 10 647-UPW1A471MPD
awm-090 c4 470 6 cea 470 10 647-UPW1A471MPD
awm-090 c5 2.2 50 cea 2.2 50 647-UPW1H2R2MDD
awm-090 c6 47 50 cea 47 50 647-UPW1H470MED

PS board A
awr-103 c1 220 80 cea 220 100 647-UHE2A221MHD
awr-103 c3 47 16 cea 47 35 647-UPW1V470MED
awr-103 c6 47 35 cea 47 35 647-UPW1V470MED
awr-103 c7 10 35 cea 10 50 647-UPW1H100MDD
awr-103 c8 1 50 cea 1 100 647-UPW2A010MDD
awr-103 c9 220 80 cea 220 100 647-UHE2A221MHD
awr-103 c12 47 16 cea 47 35 647-UPW1V470MED
awr-103 c14 47 35 cea 47 35 647-UPW1V470MED
awr-103 c15 100 35 cea 100 35 647-UPW1V101MPD
awr-103 c16 220 25 cea 220 25 647-UPW1E221MPD
awr-103 c17 47 10 cea 47 35 647-UPW1V470MED
awr-103 c20 100 25 cea 100 35 647-UPW1V101MPD
awr-103 c22 47 10 cea 47 35 647-UPW1V470MED
awr-103 c23 2.2 50 cea 2.2 50 647-UPW1H2R2MDD
awr-103 c24 220 16 cea 220 25 647-UPW1E221MPD

PS board B
awr-104 c9 470 100 ach-038 470 100 647-UPW2A471MHD
awr-104 c10 470 100 ach-038 470 100 647-UPW2A471MHD
awr-104 c11 2200 25 cea 2200 35 647-UPW1V222MHD
 
Also check the two main fiilter caps. If you remove the bottom cover, you can inspect the terminal ends of the big caps for leakage. My SX-1050's 22,000uf 80V caps had cracks and were seeping when I bought it last November.

IMG_4839.jpg


IMG_4889.jpg
 
Yes, you are on the right track. :D

You could order the other caps as well to save on shipping if you wish, considering how inexpensive the caps are. Your call. None of your troublemaker transistors are making trouble at the minute.

here's the power supply warning:
SOMETIMES
the new caps in the power supply are too much for old heat stressed and marginal transistors, and they give up the ghost. It's not a certainty, but a possibility.
also
in the protect circuit, there are two transistors (q6,q7) that are in similar straits.

You don't have to do them now, but it would be nice to have them just in case. I AM successful in talking people through transistor replacement.

don't be intimidated by the extra parts lists below:
awr-103 q1 2sd313 512-ksc2073TU
awr-103 q2 2sc869 512-KSC2383YTA
awr-103 q3 2sc869 512-KSC2383YTA
awr-103 q4 2sc1318 512-KSC2690AYS
awr-103 q5 2sb507 512-KSA940TU
awr-103 q6 2sa528 512-KSA1013YBU
awr-103 q7 2sa628 512-KSA1013YBU
awr-103 q8 2sa720 512-KSA1220AYS
awr-103 q9 2sd325 512-ksc2073TU
awr-103 q10 2sc945 512-KSC2383YTA
awr-103 q11 2sc945 512-KSC2383YTA
awr-103 q12 2sd325 512-ksc2073TU
awr-103 q13 2sc945 512-KSC2383YTA
awr-103 d1 wz-140 512-1N5244B
awr-103 d2 wz-130 512-1N5243B
awr-103 d3 wz-061 512-1N5234B
awr-103 d4 wz-061 512-1N5234B

awm-090 q6 2sc945 512-KSC2383YTA
awm-090 q7 2sc1384 512-KSC2690AYS
awm-090 d5 eqa01-33r 512-1N5257B

all this is slightly over 6 bucks... and is in stock. parts numbers from old lists that have been obsoleted have been changed to currently available transistors.
 
@Marty,

I did check the large capacitors and their looking fine, that was the first one I checked :)

@Mark,

Any tips on how to attack this, like I am thinking of going through one board and then test and then go to the next board, is there a protocol on which board to do first ?


"You don't have to do them now, but it would be nice to have them just in case. I AM successful in talking people through transistor replacement" GULP


Thanks for all your responses
 
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Let's do the protection first. Get that time delay squared away. Get a good feeling first with the caps, then the transistors. Small board, easily worked on IIRC....
 
we got lots to talk about, before you turn a screw or heat up an iron.
alternately, a lot of reading.

caps have + and - polarity with a few non-polarized exceptions.

eventually we will discuss the three leads of a transistor, and eventually their installation.

By the time you start opening it up and heating the iron, you will have a pretty clear idea of what to do.
 
Thanks..

I have assembled an electronic crossover (qguy bragging here :D), but it was a kit, a very very small kit with a walwart power supply. I was confident enough to do the assembly as it was cheap enough and cost next to nothing and did not mind the kit exploding. I am little bit scared as this DIY might turn into a DIM (Destroyed It Myself).

I will take detailed photos before doing anything :D



markthefixer said:
we got lots to talk about, before you turn a screw or heat up an iron.
alternately, a lot of reading.

caps have + and - polarity with a few non-polarized exceptions.

eventually we will discuss the three leads of a transistor, and eventually their installation.

By the time you start opening it up and heating the iron, you will have a pretty clear idea of what to do.
Click to expand...
 
identifying transistor symbols and installing transistor leads

well, you do need to get the parts, first.... :D

and when ordering the transistors, mouser has links to the transistor's data sheets, DOWNLOAD the data sheets!!! THEY are your BEST guide as to the correct lead connections for THAT particular transistor.

Do you understand the transistor symbol? enough to identify the emitter, base and collector from it? Because most boards (Pioneer) have the symbol printed on it, with holes around it, and it is orientated so there is an emitter hole, a base hole and a collector hole. And obviously, only the transistor's emitter goes into the emitter hole, the base into the base's hole and the collector into the collector's hole. IF you want it to work... :D

oh, and by the way, the symbol usually DOESN'T have the E, C and B letters ON on it... :stupid:
there are two flavors,
pnp: arrow pointing in, 2sa,2sb, ksa, ksb part number prefixes
npn: arrow pointing out, 2sc,2sd,ksc,ksd part number prefixes

attachment.php


hint: if "rotating" it in your mind is a puzzler, orient it in the hole this way(transistor hole arrangements are usually triangular):

choose the leftmost lead, use the data sheet to identify it... for example it is the emitter
put it in the emitter hole

choose the rightmost lead, use the data sheet to identify it... for example it is the base
find the base hole, rotate the transistor line of leads around the inserted leftmost lead to point at the base hole
put the rightmost (base) lead in the base hole.

the THIRD hole is now either in front of or behind the transistor, in this example the collector is "left over"
bend the center lead forward or back to go into the hole.

easy...

notice that this example had the lead order of emitter, collector, base which is a common lead arrangement

that means that:

looking at the transistor, with the leads pointing DOWN, and the flat part (or lettering in the case of some zetex transistors) FACING YOU
going from left to right has the lead order of emitter, collector, base
 

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qguy said:
Thanks

Second photo not showing :-)

What happens if i screw the orientation ?
Click to expand...

You stand a good chance of letting the magic smoke out.

Magic smoke is an essential part in any electronic device's function. Once let out, the magic smoke cannot be put back in. :tears:
 
Ok ... after reading this several times

On the board, The arrow pointing outside or inside is always Emitter
Center is Base
the last one is collector
E-B-C

On the Transistor, Emitter is on the left when flat side is facing me with the pins pointing down.

Is It safe to just follow the orientation of the existing transistor ?
 
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You have it down pretty good, until:

Is It safe to just follow the orientation of the existing transistor ?
Click to expand...
and the answer to THAT is:

NO, because they are most likely to be different than the originals.

You MUST go by the datasheet and the symbol on the board. NO exceptions. We ALL do it that way.

BTW that was an example. other layouts are also probable. different case styles MAY have uniform layouts (to-220, to-126 etc) but to-92's (the little black epoxy ones) can be all over the map.

It is a good example because a lot of the lead arrangements of transistors that I recommend just happen to be ecb.
 
Not necesssarily. Some are ebc some are ecb, and some are bce or cbe. Match the data sheet vs. the printed layout on the board.

You are in the Best of Hands with Mark. I've seen him take guys who couldn't find their a%$ with both hands in a lit room and a squad of Marines, and walk them thru rebuilds on SX-1010's, and other high end Pioneers and they worked the 1st time. Some of these units looked like they had been soaking in the Ocean mud for years.
Just follow Marks instructions to the letter. Don't get ahead of him and you'll have a working unit in no time.

Take your time and concentrate on one board at a time. Finish the board, test, make adjustments as necessary and move on to the next board. DON'T RUSH!

Good Luck.

Larry
(One of those guys above!)
 
The Pin layout is dictated by the transistor number right ? regardless of the manufacturer of the transistor, Is this correct ?

Some of those transistors are supposed to be screwed to a heat sink right ? I noticed there is a white substance between the transistor and the heat sink ? What is this called ? ... i guess i should get a "can" of this right ?

Any tell tale signs that the transistor may be ok to retain ? or the reverse, like you should definitely replace this if..... its guts is pouring out of the casing



markthefixer said:
.

You MUST go by the datasheet and the symbol on the board. NO exceptions. We ALL do it that way.
Click to expand...
 
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