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SX-1010 won't Power On...

I finally gathered my guts (have to start at some point) and took out the heat sinks. Then I took out the output resistors, 8 of them. Then I took the readings with the multimeter. Here are the readings, excuse my way of putting down measurements:

RIGHT SECTION (From Right to Left)
1-) 0 - 0.638
2-) 0 - 0.657
3-) 0 - 0.633
4-) 0 - 0.623

LEFT SECTION (From Left to Right)
1-) 0.007 - 0.007
2-) 0.273 - 0.274
3-) 0.001 - 0.001
4-) 0 - 0.611

I have no clue but as far as my common sense tells me, something is off. The readings on the right portion of the heat sink seems to be in order and consistent. As for the Left portion of the heat sink, the only one close to the readings on the right section is Transistor #4. The other 3 seem to be way off, unless they are different kinds of transistors which I doubt very much. Once again, excuse my description as I have never done this before. Cheers...
 
EchoWars said:
A lot of receivers of this era have two fuses...one, easily replaceable in the external holder, is a fast-blo fuse. The second, a pigtail fuse soldered in place inside, is the same amp value but is a slo-blo fuse, and is there to prevent catastrophic failure in case the fast-blo fuse is replaced with some ignorant value, like 30A 32V or something.
Click to expand...

I'm ahead of you on post #11 :tongue::D Granted I learned from your old old posting about this. ;)
 
Also, here ore some shots of the mentioned area of the receiver. I just don't know what the white, hand cream type of substance smeared on all over the back of the transistors. Looks and feels like a lubricant of some sort. Is it to be left alone or wiped off?
 
D.E.K said:
I finally gathered my guts (have to start at some point) and took out the heat sinks. Then I took out the output resistors, 8 of them. Then I took the readings with the multimeter. Here are the readings, excuse my way of putting down measurements:

RIGHT SECTION (From Right to Left)
1-) 0 - 0.638
2-) 0 - 0.657
3-) 0 - 0.633
4-) 0 - 0.623

LEFT SECTION (From Left to Right)
1-) 0.007 - 0.007
2-) 0.273 - 0.274
3-) 0.001 - 0.001
4-) 0 - 0.611

I have no clue but as far as my common sense tells me, something is off. The readings on the right portion of the heat sink seems to be in order and consistent. As for the Left portion of the heat sink, the only one close to the readings on the right section is Transistor #4. The other 3 seem to be way off, unless they are different kinds of transistors which I doubt very much. Once again, excuse my description as I have never done this before. Cheers...
Click to expand...

I hope you are very careful of removing the diode from the heatsink. It's fragile and a little hard to find.

I was putting together the pics (see pic). 1st pic outlines the transistor. 2nd pic shows detail on how to test a PNP transistor. Notice the polarity of leads connected. On NPN will be reversed in everything. 3rd pic shows the measurment of a bad transistor I pulled from my Kenwood. No matter what leads connected to what, it shows shorted. However, from your measurement so far looks like two transistors are shorted on the left section (1 NPN and 1 PNP)
 

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EchoWars said:
A lot of receivers of this era have two fuses...one, easily replaceable in the external holder, is a fast-blo fuse. The second, a pigtail fuse soldered in place inside, is the same amp value but is a slo-blo fuse, and is there to prevent catastrophic failure in case the fast-blo fuse is replaced with some ignorant value, like 30A 32V or something.
Click to expand...

Very correct. I replaced the slo-blo 6A with a slo-blo 6.3A but I had to use a 7A fast-blo instead of a 6A fast-blo. I know what you're thinking but no worries, I wouldn't go over 7A. I, however, built a bridge from the original point A to Point B (talking about the hidden fuse) using a 5 inch wire with the 6.3A slo-blo soldered in the middle since the area was extremely tight to work at, especially for replacing the fuse 3-4 times. Once everything is restored, IF everything is restored, I will solder a 6A slo-blo in the original spot.
 
At this point I think it would be useful for me to distinguish the PNP from the NPN :D

One more thing, I haven't actually used the base of the transistors for any of my readings. I should re-take readings.
 
D.E.K said:
Also, here ore some shots of the mentioned area of the receiver. I just don't know what the white, hand cream type of substance smeared on all over the back of the transistors. Looks and feels like a lubricant of some sort. Is it to be left alone or wiped off?
Click to expand...

You can wipe them off. But you'll need to get new compound grease before you reinstall them. You have 2 choices. Replace all 4 (2 NPN and 2 PNP) on the left channel OR replace ALL 8 (4 NPN and 4 PNP) for both channels. I used four MJ21193G for PNP and four MJ21194G for NPN for both channels in mine from www.mouser.com
 

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Heck why replace 4 while you can replace all 8 eh? While I'm in it, I might as well go down all the way up to my neck.
 
D.E.K said:
Very correct. I replaced the slo-blo 6A with a slo-blo 6.3A but I had to use a 7A fast-blo instead of a 6A fast-blo. I know what you're thinking but no worries, I wouldn't go over 7A. I, however, built a bridge from the original point A to Point B (talking about the hidden fuse) using a 5 inch wire with the 6.3A slo-blo soldered in the middle since the area was extremely tight to work at, especially for replacing the fuse 3-4 times. Once everything is restored, IF everything is restored, I will solder a 6A slo-blo in the original spot.
Click to expand...

You can actually remove that "hidden" fuse and use a wire. BUT you better hope noone messes with your main fuse. :D Make sure you go back to 6 amp in the main.
 
d.e.k said:
heck Why Replace 4 While You Can Replace All 8 Eh? While I'm In It, I Might As Well Go Down All The Way Up To My Neck.
Click to expand...

Well I Would!! :D But I would save the old ones. They may come in handy someday. I saved my old ones and I'm glad I did. I can use them to replace those NTE transistors I installed in my Kenwood last year. :D
 
ccheath said:
You can actually remove that "hidden" fuse and use a wire. BUT you better hope noone messes with your main fuse. :D
Click to expand...

I'd be lying if I say "I haven't thought about that" but I'd rather keep it there just to be on the safe side. Not that I will use a 30A like EW mentioned but hey, who knows :yikes:
 
Also when you order the transistors, I highly recommend replacing those old mica transistors insulators for best heatsinking results. And heatsink compound grease. Don't use any fancy heatsink compound (silver) used for computer CPU, they'll short out.
 
Don't order yet. There's still more to check on your amp board. I'll post the pic what to test next.
 
No worries, I wan't going to order just yet. I wouldn't buy 4 new tires for a car with the motor gone. :D
 
I was thinking, if I can make this work, I might consider doing it for my SA-9500 II and even the SX-950.
 
D.E.K said:
Looks like they will cost me $40+tax and that's just the beginning....
Click to expand...

Actually, other than replacing the main caps, that's about the biggest hit by far for components.

www.mouser.com
534-4662 to-3 mica insulator $0.16 each (get 8)

532-249 1 oz thermal compound $4.71
or
532-250 2 oz thermal compound $6.45

863-MJ21193G pnp to-3 250v 16A 250W 4mhz 8-75hfe $3.83 for 2sAxxxx or 2sBxxxx transistors
863-MJ21194G npn to-3 250v 16A 250W 4mhz 8-75hfe $3.83 for 2sCxxxx or 2sDxxxx transistors
(the 1010 lists several different parts numbers for them)

ccheath: gonna have him set up a dim bulb tester to save his 1010 if there are further problems when powering up?

You guys took right off without me....

Here's the transistor testing thread:
http://www.audiokarma.org/forums/showthread.php?t=43186
post #11 has an explicit test protocol and typical results for both polarities of transistor.

Be REAL careful with that little horseshoe shaped diode on the heatsinks, the wire LOVES to break, and it is the hardest to find part in the unit. Replacing just about everything else is easier.
 
It is a good idea to check the driver transistors, same way you did with the outputs but the layout will be different.

Also check those 2 diodes shown in pic. You'll notice those diodes I have in are two UF4004 replacements in series in place of STV-3 for preventative measures even though my original are fine. Using the meter checking the diode, it should check some continuity one way and one way ONLY. The problem being able to check it is difficult by default because it contains 3 diodes in series causing voltage drop. Drop high enough that some meter even with diode test cannot push through. I don't know if yours will read but mine didn't. I just used a 9v battery alongside with the voltmeter to test it. You'll have to test it out of circuit. If you want to reuse that diode, then you can test it using the voltmeter set at least 10 volts and put the black lead on the anode side of the diode (otherside from the green dot) and connect the red lead on the + side of 9v battery and touch the cathode onto the - side of the 9v battery. You should then read the voltage drop to around 7.2v. If it reads then swap the diode so that the black is on the cathode (green dot) and touch the anode to the - side. There should be no reading. If there is, there's a short on the diode as well.

Those 4 emitter resistor on the amp board, I'd just replace ALL 4 on the affected channel since they may be damaged from the shorted outputs. The other channel (good side), you can test the resistor without removing them if you still got the output transistors removed. They should be measured at .5 ohm. If they are all equal, you can leave them in.
 

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