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SX-1050 Blowing Fuses

tsd71 said:
parts are in for the 1050, i will start getting to it later today, i will keep you posted...by the way my neighbor had a sx-1250 in the garage, got it for 25.00,musty dusty but very nice and very heavy....this is my next project...plugged it in, nothing, checked the fuses, no fuses, replaced all the fuses, clicked the on switch and the (R1)wire wound 20w 3.3ohm resistor(ACN-003) on the power board is smoking, it's attached to the microtemp(AEX-005) with a twist tie...now what???
Click to expand...
Great Score:banana:
 
mark,i've finished with the 104 board, i'm working on the 103 board...all the caps are installed, and i have a question...are any of the transistor pin layouts different from the originals? they aren't silkscreened on the board or in the manual...

thanks
tim
 
mark....are the transistor pin layouts any different from the originals on AWR-103, i'm not understanding the other thread on this,thanks
 
Well, I should have added that, if you couldn't find the data sheets, post the devices you're looking for and I'd help.

...but, looks like you did fine on your own.
 
I don't know how I missed this...

Page 46 of the pdf manual shows the lead layouts of each transistor

The lead layouts of the replacements were in the post where the parts numbers were

Page 80 of the pdf has the 103 board layout shown from the foil side

and unless I am horribly mistaken, or the board you have was not silkscreened, Pioneer silkscreens the transistor symbol (at least) to identify the leads..
 
ok, i'm not a pro here, i am very green when it comes to reworking pc boards, my specialty is computers, i am a computer tech, which does help, but usually if a board is bad we just get a new one...this is a little different...but i think i'm doing pretty good, i just didn't understand the pin layouts from old to new, i think i have it figured out, i checked each data sheet for each resistor and went from there...also mark's earlier post(http://www.audiokarma.org/forums/showthread.php?t=124156&page=2) basically spelled it out for me, i had to bend some leads in different ways to get the right layout, hopefully i got them right, i will know tonight when i try to fire it up on the variac....any suggestions before i do so, and what am i looking for smoke, sparks, fire???? or clear sounding audio??

thanks
 
Well, you should be ok, as long as you remembered that the only differences were a 180 degree reversal...

Still, when it's up, check the voltages one last time...

You could post clear closeups of the board from several angles, and I could look at the transistor alignments...

You DID see the symbols silkscreened on the board?
 
ok,.... not ok, slowly brought up wattage with variac, got to 50 watts and saw smoke, looked at the board, it seems R20 10ohm 1/2 watt resistor is burning, it's covered by an insulated cover, i peeled it off and yes it's fried, i examined everything else under a magnifier and everything looks ok...now what...i'm thinking new boat anchor!
 
tsd71 said:
ok,.... not ok, slowly brought up wattage with variac, got to 50 watts and saw smoke, looked at the board, it seems R20 10ohm 1/2 watt resistor is burning, it's covered by an insulated cover, i peeled it off and yes it's fried, i examined everything else under a magnifier and everything looks ok...now what...i'm thinking new boat anchor!
Click to expand...

Disconnect the + / - 60v wires, pins 8, 16 & 17. That will take the load off.

Is the 10 ohm resistor still 10 ohms?

If so try again. Probably a short on the amp board. Read the voltages if the 10 ohm doesn't get too hot...

You talked about pulling some lines from the amp board, what's up with that?

Check Q13, Q14, Q15 & Q16 on the amp board... they could look cooked...

Boatanchor... no way... but if you want somebody else to do the work, that's fine.... take off the feet and the tuning dial for shipping. My backlog has been shortened considerably.
 
i didn't pull any lines from the amp board, that was suggested to me by someone else but i didn't go through with it...ok so pull the 3 lines off the board pins 8, 16 & 17, should i then still use the variac for starting the unit,
the resistor is reading 10ohms
 
tsd71 said:
i didn't pull any lines from the amp board, that was suggested to me by someone else but i didn't go through with it...ok so pull the 3 lines off the board pins 8, 16 & 17, should i then still use the variac for starting the unit,
the resistor is reading 10ohms
Click to expand...

Yeah, I hate to pull the regulated power lines, but....

Yes use the variac... eventually the 10 ohm gets replaced.... no hurry at 10 ohms.

Watch it close, the (+/-) 30v and the (+/-) 60v, although the 30 cant pull enough to smoke the 10 ohm....
 
tsd71 said:
mark, even with the 8,16,&17 taken off the resistor is smoking at 50 watts
Click to expand...

Look for the other parts getting hot... There are no other obvious HEAVY current paths if all the components are undamaged, assuming you didn't make any inadvertent connections. The most obvious path is through Q1, Q2, Q3 & D1, and that would mean all are shorted.

Dial up the variac until R10 is getting warm but not hot just for a minute, and see if anything else is warming up. Otherwise there's a heck of a lot to test.

First what did you change in the +60v circut, and what is original?

Take and post those pictures to see if there are transistor reversals.

THEN Pull the transistors (Q1-Q4) and test them, when they are out, turn up the variac to eliminate possibilities of shorts...

I am ASSUMING that you understand this procedure:
http://www.audiokarma.org/forums/showthread.php?t=43186

Careful of C1 then (220uf 80v), after turning off, clip a ground to the junction of R1 and R2 to slowly discharge the cap.

Diode test d1, and ohmmeter test all the resistors.

Q4 will NOT go back in until the +60v is working...

Look at the schematic, to see what is and isnt connected without the transistors installed, for your benefit.

The shotgun 1 fell swoop procedure didn't work, time for the gritty nitpicking....
 
ok, mark, i'm back on this one, got the 850 and the 980 working great now it's back to this monster...as i last left you on this i was rebuilding the awr-103 power board, after finishing recapping and replacing all the transistors, it keeps blowing R20 (10 ohm 1/2 watt) i am convinced i have the pin layouts wrong on some if not all the transistors, i have replacements but i do not know how to read the silkscreen for the legs E-C-B, marantz units silkscreen the letters into the board, pioneer is different they have an arrow, can you please school me on how to insert the legs in the right holes i have the manual and i have pages 46-80 printed out...if this makes no sense let me know

thanks again
 
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