SX-1010 won't Power On...

LWB · Jan 3, 2009

Salty transistors

I think we're talking about all the transistors, everywhere they are, on every board. The conductive salt that can accumulate on the undersides of each and every transistor case, where the three base, emitter and conductor leads protrude from the transistor, will screw up your voltages unless you clean off the salt. I would try a small brush with fluffy bristles that you can wet with isopropyl alcohol to wash/brush the salt crystal accumulations away, to clean the transistor cases.

I haven't been able to find the original posts on this salty transistor issue.

D.E.K · Jan 3, 2009

Ah, wouldn't replacing them be a more healthy and permanent solution?

LWB · Jan 3, 2009

I'm coming round to that conclusion, but not on account of salt (not much salt air here in Alberta). My 1010 works and sounds good, but it has a bug somewhere that causes the driver amp bias current to oscillate, sorta +/- 10% on the left channel, so I think there is a sick transistor somewhere. I'm thinking I shall replace them all.

D.E.K · Jan 3, 2009

LWB said:
I'm coming round to that conclusion, but not on account of salt (not much salt air here in Alberta). My 1010 works and sounds good, but it has a bug somewhere that causes the driver amp bias current to oscillate, sorta +/- 10% on the left channel, so I think there is a sick transistor somewhere. I'm thinking I shall replace them all.

I wish my problem with it was only a MEASLY sick transistor. I once heard an old Turkish proverb "Burning the whole blanket because of one single flea in it" Why don't you just take readings and actually pinpoint your sick trasistor?

LWB · Jan 3, 2009

From other posts I gather that there are two types, in particular, in the 1010 that are problematic in their old age. Even if only one of these is bad, if one is taking the board(s) out to replace one or two, might as well do all and make the unit reliable. Markthefixer has posted these many times.

I will take some readings to see if I can figure out which is the culprit. I have an old Sansui that exhibits similar wandering bias current, so I need to know more about this issue. At the moment I have too many projects.

D.E.K · Jan 4, 2009

Crap. Deleted all the pictures by accident in photobucket. Now there are all kinds of holes in the thread. I have them in the HDD, I will retrieve all soonish.

D.E.K · Jan 14, 2009

Marksman, here they are. All those tiny components... Looks scary man.

markthefixer · Jan 14, 2009

Organize....

One step / component at a time....

Everybody's gone through it. You have a GREAT picture of the protection board from zerojunk, you can even make out the transistor lead arrangements....

Four capacitors and two transistors.

After searching several pages of posts, I still can't figure out what you ordered.... please reprint the list in a post.else

D.E.K · Jan 14, 2009

D.E.K · Jan 14, 2009

Will that do? If not, refer to post #279 on Page 19 but the list I posted just above is the most accurate in terms of quantities I ordered.

markthefixer · Jan 14, 2009

16 links to decode the list.... How about just listing (cutting and pasting or multi-quoting) the original text I posted? Or just the single line descriptions?
Please???????? I've already spent over three hours online today.

D.E.K · Jan 14, 2009

Not a problem mate. Just give me a few minutes for it will be ME going through the 16 links.

markthefixer · Jan 14, 2009

Thanks BBL.

D.E.K · Jan 14, 2009

This is EXACTLY what I have at hand:

522-ZTX1056A
(Quantity 3)

647-UPW1V101MPD
(Quantity 1)

647-UPW2A4R7MDD
(Quantity 1)

598-DSF050J224
(Quantity 2)

647-UPW1E331MPD
(Quantity 2)

512-1N4004
(Quantity 3)

512-KSA992FBU
(Quantity 12)

512-KSC1845EBU
(Quantity 6)

512-KSA910YSHTA
(Quntity 6)

512-KSC2310YBU
(Quantity 14)

512-KSA1220AYS
(Quantity 6)

512-KSC2690AYS
(Quantity 4)

512-KSA940TU_Q
(Quantity 4)

512-KSC2073TU
(Quantity 4)

647-UPW1V100MDD
(Quantity 2)

5989-100V.68-F
(Quantity 2)

D.E.K · Jan 14, 2009

As for your question, yes I have the picture of the board ZeroJunk posted. Before all that I have a few questions of my own. First thing, the 4 plastic legs that hold the board might be brittle. Is there a trick to free the board of them without breaking the plastic legs? See the picture below:

Second, I am going to have to work on the board while it's loose. I am kind of concerned about the wrap-on pins and other possible wires that might break because of flipping and re-flipping over and over again. Any tricks to that?

Third I have a pretty clear idea which components to remove (the picture is attached below) but I am not sure which ones to solder back on. I might use some help with that (as you know I also ordered crapload of components for the PA boards). Also, the polarities are might be a pain in the arse. As far as I know the positives have longer pins or marked on the units with dots etc. Are there any components that I should ignore the polarity of?

As you can see, it is something that I really have to be sure of. Once everything is clear at my judgement and I feel prepared to do so, I will begin.

markthefixer · Jan 14, 2009

The supports are pinched gently in above the board until the board will slide up top the pinch point and the board wiggled up a bit to the pinch point, repeating at each of the corners in a circular fashion, working around the corners gradually.

Get the board into a comfortable position for front and back access and then try not to flex the wires. I work on the receivers with them on their sides, transformer down, on a lazy susan turntable. Your best acccess should be directed at the solder side of the board. Be careful not to drip solder elsewhere into the unit.

Match up the values (uF) of the can shaped capacitors old to new (it's printed right on them and what I was looking for with the list - like 330uF 25v not 647-UPW1E331MPD) and notice that there is a stripe on each of the cans which denotes the negative terminal. As you remove the old, look for a plus(+) silk screened / printed on the board by the other capacitor wire, and put the stripe of the new cap in the same place.

Sometimes the locations where the circled orange cap are, use electrolytic caps instead of those, which can stay.. Those are solid caps that don't deteriorate and can stay. Until eyes are on the caps, you never know what they used. The replacement film caps and the orange caps don't have a polarity - almost everything else does.

The transistors are read C - B - E with the lettering facing you,the flat facing away, and the leads facing down. The E for the transistor symbol has the arrow, and the B is the line that the arrow is pointing away from (for an npn transistor, on a pnp the arrow points AT the line) and the C is the other line connecting to the B.

Every component that is removed on the board (4 caps and 2 transistors) has a replacement.

Like I said we get the protection working, then we start on the amp.

D.E.K · Jan 14, 2009

Sorry about the list. I will try to give you a more proper list with all the specs of the parts. I, at least, would like to separate all the Protection Circuit parts from the PA Board parts and keep them in one spot. That will give me a chance to funnel it down to a much fewer parts thus minimizing the risk to use wrong parts for the right job. As for now, I would like to look around and observe/examine the parts and get familiar with them.

LWB · Jan 14, 2009

Pulling the board away from the standoffs

Hi, DEK,

LWB here. I hope Mark won't mind me jumping in with an answer to your question about the plastic pins that hold the board in place. The standoffs are nylon and quite strong, though you are right to be cautious that they could be brittle with age. Mine were not. I used a pair of small pliers to gently squeeze each standoff pin, while pulling the board up gently with a small right-angled pick that could be inserted beneath the board near the pin. The dry old board, with a little accumulated dust, has considerable friction on the standoff pins. I found that I could pull each corner up the pin a bit and move on to the next, do the same and so on round the four corners until the board was ready to lift off. Be careful and take your time. You'll get the feel of it.

This might help: to help the board slip off the pins, I squirted a small amount of spray silicon into a cup, dipped a Q-tip in the silicon and swabbed a little on each pin.

Once the board is off the pins you can pull it aside to get access to the backside, and you'll be able to move it back and forth enough to change the components.

If you should break a standoff, they can be replaced. I noticed B&E (where I bought my deoxit) has them here in Calgary.

D.E.K · Jan 14, 2009

Hey LWB, thanks for the "Jump In" I will get the feel of it I am sure. Also, the lubricant was a good idea which I actually thought about last night but couldn't come up with a choice of lubricant. It is a relief to know that they can be replaced though I'd rather avoid that for it will cost me more time. All the same, good to know there is a back up. Cheers.

D.E.K · Jan 15, 2009

Here is the more proper and EXAGGERATED list with the pictures, part number, full specs etc. This list is of the Protection Board parts ONLY. Hope that is sufficient.

512-1N4004 (Vr/400V Io/1A T/R)

522-ZTX1056A (275 @ 10mA @ 10V)

598-DSF050J224 (.22uF 50V 5%)

647-UPW1V101MPD (105 Degree 100UF 35V)

647-UPW1E331MPD (105Degree 330uF 25V 105c 10x12.5 '20% 5LS )

647-UPW2A4R7MDD (105Degree 4.7uF 100V 105c 20% 5X11 Tol 2LS)

SX-1010 won't Power On...

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