2270 no power

the smoke was likely r786 and or r787 ..both 100 ohms
h758 h759 may also be damaged .
possibly more but check those first
 
Ok thanks Pete will try to check these tonight after work. Should they be removed to be checked? And I assume it would be on the same channel as the one with the missing output?
 
yes same channel ..best removed but could be tested in circuit initially .. resistor might be obviously burned
 
Pete's a smart fella so it's great he's your advisor! I'd bet he's right that the drivers may be toast. They are the transistors right before the output stage if that wasn't explained already and are usually medium power devices. You could have safely used headphones to test for audio, still not cranking it up any more than to verify audio.

Here are the much loved and used output transistors:

863-MJ21193G (PNP)
863-MJ21194G (NPN)
532-56-03-8G (Mica insulators if needed)

Make sure to use the white thermal paste, not the silver computer stuff, it's conductive.
 
Let me just say here gentleman that I am honoured to have your guidance of which I would not even attempt the repair without it. Each and every time I get a reply to my rookie questions I feel enlightened and educated. I wish I had the same eagerness to learn so long ago as a student, but then again my grandfather always said that " Wise heads do not grow on young shoulders" which of course is so true. I tell my own grown up kids the same. I should be near done a Pioneer SX 950 very soon and want to move onto this 2270 but I want to be ahead of the game in the parts Dept so it's one order for all parts needed ( although that rarely happens). I have some thermal paste at home that a tech gave me a while back to use on my very first recap so thinking about it now I will have to check it's the proper kind. Pict below.

I would assume the the 1193/1194 outputs would be one of each on each side but which one would go on top?

Will keep it in mind about the headphones for the next time I'm about to make a stupid rookie mistake.
 

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Top transistor (PNP), which was the SJ2517, is replaced by the MJ21193. The (NPN) MJ21194 goes on the bottom. Yes, getting two each is wise! Don't replace the ones on the good channel until the bad channel is fixed. It would be prudent to check all of the transistors and diodes on the bad channel before ordering.
 
I will try to explain this without confusing it too much I hope. Haven't removed anything from the boards as of yet. Used the DMM to check H759 ...Black lead on the case of transistor and Red lead to one pin and I get .524 Red to other pin and get .524. Red and black to both pins and I get a constant beep alert.

H758.....if I do the same as the other side with Black lead on the case and Red on either pin I get a reading of 1.400 V and it climbs however if I put Red lead on the case and Black lead on one pin I get .586 and with Black on other pin I get .883.

R787 reads 97 ohms in both directions and R786 reads 97.1 ohms in both direction. Again these readings are at the solder joints. I can desolder and recheck when I get time and also pull the Transistors when I get time. Just thought I had a few minutes tonight after 12 hours at work and thought I would do a quick check to see what you guys think.
 
Sounds like H759 might be shorted base to emitter which are the two pins. Check that in resistance mode. Also to suspect then is H757. My approach to a bad amp is to check every single transistor in the bad channel before any repowering, even with a DBT. But I just said that 3 posts ago! (What memory problem?) :eek::rflmao:
 
I guess it's best to remove all transistors and diodes to test for accuracy purposes or is it good enough to leave them in place considering its only to determine if they are indeed fried or not? These 12 hour long shifts don't leave much time for the fun stuff.
 
If they appear to be bad, then remove them to check again. Man, I hope the work situation lightens up soon!
 
I work in the Automotive industry and it seems to never slow down.....6 -7 days a week with most days 12 hours... With the exception of 2008/9 its been like this for the 25 years I've been at my work place. Crazy busy all the time.I had like 5 minutes this morning before work to check the resistance Pin to Pin on H759 and got 9.5 Ohms. Will get to the others soon I hope.
 
Ok I'm really confused. Please forgive me but I'm trying to learn and understand, and I'm having a bit of a hard time doing so and would really appreciate your paitence with a slow student like myself.


I removed both H758 and H759 to test to be more accurate. ( I believe I had stated wrong previously and had H758 and H759 mixed up because I was looking at the bottom of the board and not oriented correctly with the schematic)

H758 according to the SM is a 2SC680 which is a NPN and when I put the Red lead on the Base and black lead on Emitter I get a beeeeeep indicating a short from Base to Emitter so no voltage drop. From Base to Collector I get a reading of .536.

H759 according to the SM is a 2SA566 which is a PNP and when I put the Black lead on base and Red lead on Emmitter I get a "OL" and with Red on Collector I get same reading "OL ". Shouldn't I get a reading on both of these? Reversed with Red on Base and Black on Emitter I get a reading of .649 and with Black on Collector I get a reading of "OL".

This is as far as I got time to do tonight. So would I be correct in saying both these transistors need replacing? Arrrrrg this is so fustrating not understanding. I have lots of hair to pull out even at my age. Am I making any sense at all or just confusing it more than it needs to be.
 
both appear broken according to your readings ..
to learn some more when the new ones arrive repeat the tests with the new ones ..
 
Good idea. Just have to find equivalents to order. Maybe these.

2sa566 with 2n3741
2sc680 with 2n5050
 
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Take heart, you're doing fine!

I agree both are bad. You had the right methods and a good PNP would have read as expected. An OL indicates an open leg so it was trying to pass a lot of current through that branch. I don't know, good or bad on those replacements. These are the TO-66 package, like a small sized TO-3 package like the final outputs. There is a complementary pair that is in the TO-220 package so will need to be mounted a bit different. I'll try to locate a picture of when I did that. These are great parts and are MJE15030G and MJE15031G. I think the voltage rating is plenty good but if not use MJE15032 and 15033. You'll have to also get the right sized mica insulators such as these from Mouser: 532-56-77-11

Aha, found them! It was a repair of a Marantz 1030 integrated amp. I had yet to clip off the center collector lead in the lower picture. The connection was made through the screw.
Novy1030 001.JPG Novy1030 007.JPG
 
Forgive me and maybe I'm missing something Randy but aren't these in your picture for the heat sink and not the Amp board or are they interchangeable. The ones I was referring to was was on the 750 Amp board and are mounted on a small metal heat sink that is held on the board with two through screws as shown in the Picts below.
 

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Sorry I re- read your post and I believe I understand what you are trying to say now. I guess my frustration led me to think it was one more thing I didn't understand. So in this case the screw holding the body all become the " collector. " so the Center leg can be cut off?
 
Yes, again you are entirely correct. I just chose to test mine first before cutting off the center leg even though it leaves something that can be shorted to. I live dangerously! You will want to verify that the base and emitter, outer legs on a TO-220, are the right orientation before installing them.
 
Take heart, you're doing fine!

I agree both are bad. You had the right methods and a good PNP would have read as expected. An OL indicates an open leg so it was trying to pass a lot of current through that branch. I don't know, good or bad on those replacements. These are the TO-66 package, like a small sized TO-3 package like the final outputs. There is a complementary pair that is in the TO-220 package so will need to be mounted a bit different. I'll try to locate a picture of when I did that. These are great parts and are MJE15030G and MJE15031G. I think the voltage rating is plenty good but if not use MJE15032 and 15033. You'll have to also get the right sized mica insulators such as these from Mouser: 532-56-77-11

Aha, found them! It was a repair of a Marantz 1030 integrated amp. I had yet to clip off the center collector lead in the lower picture. The connection was made through the screw.
View attachment 832795 View attachment 832796

Those TO-220's look so cool mounted like that :D
 
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