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SX-1050 Blowing Fuses

just kidding mark, i didn't see anything but your signature....now i see and as always very clear very precise
 
ok, all transistors look like i put them in properly, except i don't understand Q8-Q6-Q5-Q7, the emitting arrow is facing inward, how do you set this up, the same way as the outward arrow?
 
tsd71 said:
ok, all transistors look like i put them in properly, except i don't understand Q8-Q6-Q5-Q7, the emitting arrow is facing inward, how do you set this up, the same way as the outward arrow?
Click to expand...

Yes.

outward arrow = npn = 2scxxxx , 2sdxxxx
inward arrow = pnp = 2saxxxx, 2sbxxxx

all caps are marked with a black bar or something to indicate the MINUS terminal, and new caps have the PLUS terminal wire a little longer.

That is a serious short to smoke the 10 ohm input resistor.

and with the main draws off the power supply board disconnected, the short has to be on the board.
 
ok, mark, i have found maybe the culprits? Q6 &Q7 were installed incorrectly, could this be frying the 10 ohm?
 
Q6 & Q7 are used in the -60v regulator (pin 8)

BUT R20 (and I don't know HOW I missed this) is part of the 13v tuner power circuit, pins 5 & 6...

open up 5 & 6 and see if it stops burning.
 
markthefixer said:
Q6 & Q7 are used in the -60v regulator (pin 8)

BUT R20 (and I don't know HOW I missed this) is part of the 13v tuner power circuit, pins 5 & 6...

open up 5 & 6 and see if it stops burning.
Click to expand...

tsd71 said:
mark, do you mean, disconnect the wires from pins 5 & 6?
Click to expand...

Yes, there's probably a shorted cap in the tuner section, across the 13v line. It won't be fun to find....

Meanwhile I will look up the circuits pins 5 & 6 feed.
 
mark, after replacing the two incorrect transistors, and removing wires from pins 5 & 6 R20 is still smoking at 40-50 watts
 
tsd71 said:
mark, after replacing the two incorrect transistors, and removing wires from pins 5 & 6 R20 is still smoking at 40-50 watts
Click to expand...

Pull C24 (220uf 16v) off and try again.

If it doesn't smoke, then read the voltage on pin 5 referenced to a metal chassis ground. It should be 13v but the regulator could be damaged if C24 was shorted. If it is 13v then check pin 18 for 5.4v .

If it DOES smoke, turn it off and feel around for other hot components:
Q9, Q10, Q11, D4, C22, C23...
 
ok, pulled C24 still smoking....with C24 off the board am i still removing wires from pin 5 & 6
 
tsd71 said:
D4 getting hot, all the others Q9-Q10-Q11-C22-C23 cool
Click to expand...


Replace (test for now) the transistors, diodes and capacitors I mentioned, the regulator is shot.

There are several lists for the 1050 power supply rebuild posted by me.

q9 2sd325 to-220 bce npn 35v 3a 10w 8mhz
replacement part # 512-KSC2073TU_Q @ $0.53 ea (bce, same layout) 150v 1.5a 25w 4mhz
q10,q11 2sc945 to-92 ecb npn 50v .1A .25w 150mhz
replacement part # 512-KSC2310YBU to-92 ecb 150v .05a .8w 100mhz 40-240hfe $0.12 ea same layout

C20 100uf 25v 647-UPW1H101MPD 100/50 $0.50
C22 47uf 10v 647-UPW1H470MED 47/50 $0.34
C23 2.2uf 50v 647-UPW1H2R2MDD 2.2/50 $0.23
C24 220uf 16v 647-UPW1V221MPD 220 / 35 $0.56

D4 6.1v 0.5w 512-1N5234B Fairchild 6.2V, 0.5W Zener $0.06
 
tsd71 said:
i have all of these components except the diode D4,i only have a 14v 0.5w zener
Click to expand...

If the diode was hot, it's likely toast, BUT a failure of the 6.1v zener will show up as a DEVIATION from the OL in one direction and a (approx) 600 (millivolts forward drop) in the other on the dmm diode test.

Usually they show up either blown open (but then they won't heat up) or a dead solid short.'

so you have a ksc2073 and a pair of ksc2310's... (the ksc945 that was first in this post (a leftover from the text i lifted) would work, and the lower voltage rating won't hurt on this regulator (just in case..))

To test zeners, I take an external power supply greater than 15v, and with a 2 to 10 k series resistor I energize the diode and read the voltage across it to be SURE it will work... this is an actual in-circuit test. If you want to be picky, the diodes are specified at 7 milliamps of current, so subtract the zener voltage from the supply voltage and divide by 0.007 to get the ideal series resistance to use to get 7 ma through the zener diode. (15-6.1) / 0.007 = 1271 ohms....
 
ok mark, got the parts from mouser today, i'm going to install them tonight, just to make sure about the pin locations on the transistors, the silkscreen with the inward arrows for transistors q5-q6-q7-q8...do i line up the emitter leg with the inward arrow or do i line up the collector leg with the inner arrow...in other words do i line them up as i did with the outward arrow of the other transistors, emitter on out arrow??
 
tsd71 said:
ok mark, got the parts from mouser today, i'm going to install them tonight, just to make sure about the pin locations on the transistors, the silkscreen with the inward arrows for transistors q5-q6-q7-q8...do i line up the emitter leg with the inward arrow or do i line up the collector leg with the inner arrow...in other words do i line them up as i did with the outward arrow of the other transistors, emitter on out arrow??
Click to expand...
Normally the line with the arrow is the emiter regaurdless of arrow direction the arrow designates PNP or NPN.
The straight line is the collector and the short side ways flat line is the base.
Be sure to verify the new transistors pin layout,you can pull a data sheet on mouser.com of the part# to verify.
Also be sure to verify the new part#s and if they are PNP or NPN.I didnt see were you got your Part#s for Q5,6,7 and 8 from in this post.

Steve
 
Stevesmullen said:
Normally the line with the arrow is the emiter regaurdless of arrow direction.
The straight line is the collector and the short side ways flat line is the base.
Be sure to verify the new transistors pin layout,you can pull a data sheet on mouser.com of the part# to verify.
Also be sure to verify the new part#s and if they are PNP or NPN.I didnt see were you got your Part#s from in this post.

Steve
Click to expand...

YUP....

The arrow facing out is npn which is 2sc, 2sd, ksc, ksd

The arrow facing in in pnp which is 2sa, 2sb, ksa, ksb
 
ok mark, i'm about to give up on this one....very frustrating to say the least...i recapped, retransistored and redioded the whole board (awr-103), i am having the same problem with R20 smoking after applying 50 watts with the variac...i also noticed that R19 was also getting hot but not smoking...i checked and rechecked the legs for all the transistors and caps and they are all good...maybe there is solution before i have a new boat anchor..
thanks as always
 
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