Hello this is my first post here, i thought id ask for help since am at a complete loss as to whats wrong with it
so my father has this Sony TA-1010 that unfortunatedly a couple of years back someone that didnt know how to operate it shorted the left channel speaker terminals, after some troubleshooting i found the 2 fuses burned out and like 3-5 burned resistors, we got all those things replaced and we turned on the amp hooked up to a 200W bulb tester, since the left channel was the one with the issue we desoldered the 2 output transistors since if i recall correctly the bulb turned on with those connected, anyway the amp turned on fine, right channel worked fine no distortion at all good volume (as much as can be expected of a 15W unit) all was good and was left alone until the next weekend
so since my father has a friend that fixes these things for a living (atleast the big PA ones with 1500Watts 3000 watts per channel and such) he gave him a couple of transistors to install, one of them is a C2073 and we soldered it on, amp turned on but shortly after it smoked some stuff, 2 or 3 resistors were burned, so we left it alone for quite a few months
unitl a couple of weeks ago i decided to pick it up again on my own and find once and for all whats wrong with it, so so far ive found 3 bad transistors, sadly the 2 Sony 2SC895 outputs from the left channel have continuity between emitter and collector (made double sure since continuity isnt present on the same legs on the right channel ones), and one Sony C1124 transistor meassured 0.0v on a multimeter on diode mode beteen base-emitter and base-collector, the other C1124 is safe
now the problem lies is that while the amp turns on fine, and plays music on the right channel perfectly theres a certain resistor on the left channel that gets hot very very hot, if left on long enough it will start smoking, even bigger problem is that this particular unit is completely different from any TA-1010 ive seen online, it isnt even an exact match of the service manual either.
things that are different is that the solder mask is green which i havent seen anywhere online.
second on the amp pcb according to the service manual has 3 big capacitors on that pcb but this one only has one
third the service manual says it has only 2 different references of transistors on the pcb but mine has 3 and one of them is in a different packaging than what the service manual says
the rail its supposed to be 53 volts as per service manual, and its shared by both channels and only that resistor that is not present on the service manual nor the right channel hats up, the rest of the resistors are stone cold
ive since identified the legs order on the good C1124 and have extended those and twisted them to order on the C2073 but that resistor still heats up, and am against swapping it for a bigger wattage one since well... it has to work correctly with a 0.25 watt one it how it was designed to work
i feel like if i can find that issue and what causes it it should be a matter of finding the equivalent modern replacements swap those and maybe re-adjust the dc bias and the amp should be good to go again
on the front top photo f the pcb the resistor circled on blue is the one that heats up, and both it and the one circled on red arent present on the service manual (the yellow ones are the ones that got burned during transistor legs mix-up)
and heres the only available service manual i found for comparison
on the back photo the one encircled on blue is the same resistor that heats up
the resistor is a 6.8k ohms 5% one, this one is a replacement of the original one that was burned out, i removed it and it measures within spec, it only started hating up a lot only after the error was made of soldering a transistor with wrong order legs
sorry for the wall of text but i thought it was best to have as much information necessary for someone that might have a clue of what to do
thank you all for your attention any sort of help is appreciated
so my father has this Sony TA-1010 that unfortunatedly a couple of years back someone that didnt know how to operate it shorted the left channel speaker terminals, after some troubleshooting i found the 2 fuses burned out and like 3-5 burned resistors, we got all those things replaced and we turned on the amp hooked up to a 200W bulb tester, since the left channel was the one with the issue we desoldered the 2 output transistors since if i recall correctly the bulb turned on with those connected, anyway the amp turned on fine, right channel worked fine no distortion at all good volume (as much as can be expected of a 15W unit) all was good and was left alone until the next weekend
so since my father has a friend that fixes these things for a living (atleast the big PA ones with 1500Watts 3000 watts per channel and such) he gave him a couple of transistors to install, one of them is a C2073 and we soldered it on, amp turned on but shortly after it smoked some stuff, 2 or 3 resistors were burned, so we left it alone for quite a few months
unitl a couple of weeks ago i decided to pick it up again on my own and find once and for all whats wrong with it, so so far ive found 3 bad transistors, sadly the 2 Sony 2SC895 outputs from the left channel have continuity between emitter and collector (made double sure since continuity isnt present on the same legs on the right channel ones), and one Sony C1124 transistor meassured 0.0v on a multimeter on diode mode beteen base-emitter and base-collector, the other C1124 is safe
now the problem lies is that while the amp turns on fine, and plays music on the right channel perfectly theres a certain resistor on the left channel that gets hot very very hot, if left on long enough it will start smoking, even bigger problem is that this particular unit is completely different from any TA-1010 ive seen online, it isnt even an exact match of the service manual either.
things that are different is that the solder mask is green which i havent seen anywhere online.
second on the amp pcb according to the service manual has 3 big capacitors on that pcb but this one only has one
third the service manual says it has only 2 different references of transistors on the pcb but mine has 3 and one of them is in a different packaging than what the service manual says
the rail its supposed to be 53 volts as per service manual, and its shared by both channels and only that resistor that is not present on the service manual nor the right channel hats up, the rest of the resistors are stone cold
ive since identified the legs order on the good C1124 and have extended those and twisted them to order on the C2073 but that resistor still heats up, and am against swapping it for a bigger wattage one since well... it has to work correctly with a 0.25 watt one it how it was designed to work
i feel like if i can find that issue and what causes it it should be a matter of finding the equivalent modern replacements swap those and maybe re-adjust the dc bias and the amp should be good to go again
on the front top photo f the pcb the resistor circled on blue is the one that heats up, and both it and the one circled on red arent present on the service manual (the yellow ones are the ones that got burned during transistor legs mix-up)
and heres the only available service manual i found for comparison
on the back photo the one encircled on blue is the same resistor that heats up
the resistor is a 6.8k ohms 5% one, this one is a replacement of the original one that was burned out, i removed it and it measures within spec, it only started hating up a lot only after the error was made of soldering a transistor with wrong order legs
sorry for the wall of text but i thought it was best to have as much information necessary for someone that might have a clue of what to do
thank you all for your attention any sort of help is appreciated