just picked up an sx 1250....some issues..no sound, blowing fuses, etc

[markthefixer]

First <snip>
secondly you have caught me at the peak of my offline responsibilities, thus any answers I give will probably be the last until Friday, as I will be quite busy later today, and not even online Thursday.

for the next five weeks I am going to be busier than the Devil in Las Vegas.... so my time on the forums will be severely reduced. If I catch up, Then I will be on the forums a bit more often....

BUT I stole too much time from this outside issue to instead post on this forum, and now it's coming back to bite me on the a** with a vengeance. It's a deadline I have no control over, and a longstanding commitment I cannot shortchange.

"512-KSC2690AYS" vs "512-KSC2690YSTU"...is this ok? YES

Lastly...I think there may have been a mistake in the pin-out for Q6...but I wanted to make sure before I messed with anything....you listed:

Q6: 2SA628A-D to-92 ecb 25v .1a .15w 55-800hfe 100mhz q6 darlington dvr

The old transistor layout doesn't matter much because you NEVER use the old transistor to determine how the new transistor is installed. As for the 2sa628a pinout, that's how the manual (which in earlier series like the x3x through the 1010 was known to be wrong) has it. The online data sheet is in Japanese... I don't read Japanese... it may be bce.... but I'm just guessing. and like I said, it shouldn't matter.

re: power transistors

Q1, Q5, Q9...any guideance on these remaining? I am a little nervous about using the compount, plastic gaset, etc...

MICA insulator, non-conducting (NOT SILVER) thermal compound.

Q9 has just compound and has an electrically live heat sink.

Q1 and Q5 use the mica and compound, and the mounting screws are electrically insulated from the heat sink.

Install the transistors mechanically, THEN solder the leads.

Minimal squeeze out of thermal compound - it is intended to fill gaps of thousandths of an inch - so you don't need to glop it on.

When you are done, do an ohmmeter check to the heat sink to see if there are any short circuits, you HAVE to hit bare metal, the anodizing insulates, BUT we cannot COUNT on the anodizing to insulate the transistor, just to only screw up our short circuit probe point tests. It could be shorted and your probe be isolated by the anodizing.

If you need further help someone else will have to jump in. I'm toast...

 

[tsd71]

ok...so the other day and went ahead and replaced all of the transistors except the large ones connected to the heat sinks:
Q1, Q5, Q9...any guideance on these remaining? I am a little nervous about using the compount, plastic gaset, etc...

also...for Q4, your BOM which I used said the model was "512-KSC2690AYS" and the one i received and installed was "512-KSC2690YSTU"...is this ok?

Lastly...I think there may have been a mistake in the pin-out for Q6...but I wanted to make sure before I messed with anything....you listed:

Q6: 2SA628A-D to-92 ecb 25v .1a .15w 55-800hfe 100mhz q6 darlington dvr
512-KSA1013YBU to-92 ecb 160v 1a .9w 50mhz 160-320hfe $0.17

I'm pretty sure the pin-out is BCE...that's what it appears to be on my circuit board..??


wooohooo..almost done

the new transistor 512-KSA1013YBU to-92 is ECB

 

[91rtstealth]

no worries man..I understand you are busy as we all are. Get back to me whenever you can..i'm in no rush...take your time...

The old transistor layout doesn't matter much because you NEVER use the old transistor to determine how the new transistor is installed. As for the 2sa628a pinout, that's how the manual (which in earlier series like the x3x through the 1010 was known to be wrong) has it. The online data sheet is in Japanese... I don't read Japanese... it may be bce.... but I'm just guessing. and like I said, it shouldn't matter.

ok..so should I just ignore the way the old one is installed and focus on what you listed: 512-KSA1013YBU to-92 ecb
which is referring to leads down, writing facing you, ECB pin out? just want to make sure i'm following correctly...

MICA insulator, non-conducting (NOT SILVER) thermal compound.

Q9 has just compound and has an electrically live heat sink.

Q1 and Q5 use the mica and compound, and the mounting screws are electrically insulated from the heat sink.

Install the transistors mechanically, THEN solder the leads.

Minimal squeeze out of thermal compound - it is intended to fill gaps of thousandths of an inch - so you don't need to glop it on.

When you are done, do an ohmmeter check to the heat sink to see if there are any short circuits, you HAVE to hit bare metal, the anodizing insulates, BUT we cannot COUNT on the anodizing to insulate the transistor, just to only screw up our short circuit probe point tests. It could be shorted and your probe be isolated by the anodizing.

If you need further help someone else will have to jump in. I'm toast...

I guess I'll have to take a look at the board and start messing around before I respond to anything of this...not really sure what I'll be doing with a OHM meter when I get to that point..where do I put the pot and neg leads and what setting do I have the meter on?

I really don't understand if I put the compount betweenthe mica and transistor...or between the mica and heat sink..etc..no idea...i've never done anything like this before...

also..i must remove the old compound with nail polish remover, correct?

anyone?

 

[anderslober]

The 2sa628A is BCE...........be careful with that one. I translated the japanese data sheet. (well....google translate did1;-))

Just make sure you put the sa1013(ECB) in correctly.

 

[markthefixer]

clean off old compound. acetone, or wd40 and then clean off the wd40.

then this order:

transistor
compound (thin, fills gaps of thousandths of an inch)
mica
compound (thin, fills gaps of thousandths of an inch)
heat sink
socket on other side of heat sink

socket has bumps that fit into heat sink, tighten it with bumps out and you destroy the socket.

ohmmeter is looking for shorts from ANY pin to the heat sink, set for 200 ohms range. shorts will lokk like constant 1 ohm or less connections.

the black covering on the heat sink insulates (but we cant trust it), thus you MUST pierce the black to get to the metal.

and if your probe slips off that bare spot you pierced, you will MISS a short to any of the transistor's connections until the flames erupt.

SO

pierce the covering with BOTH PROBES, then KEEP ONE PROBE UNMOVING, USING THE OTHER TO TEST, OCCASIONALLY GOING BACK TO THE ORIGINAL SECOND PIERCING OF THE COVERING TO DOUBLE CHECK THAT THE UNMOVING PROBE IS STILL HITTING BARE METAL for a reliable test.

old transistors have NO effect upon the replacement transistors - you MUST get the correct data for the new transistor.

i am tired and cranky, and have typed this dozens of times before.

ok..so should I just ignore the way the old one is installed and focus on what you listed: 512-KSA1013YBU to-92 ecb
which is referring to leads down, writing facing you, ECB pin out? just want to make sure i'm following correctly...

if the data says it's ecb, yes. bold stuff is correct.