Plz help me repair my sansui G 6000 amp, I was biasing the amp, when the fuse got blown fuse ratings 125v 4 amperes replace the fuse with 250v 2 ampere it got blown too instantly. Then got one from my old sansui it was rated 125v 5A I turned the amp on, smoke came out of left channel probably from a resistance next to petentiometer.
Then I Immediately switched it off, kept the bias settings to low by anticlockwise turned it on. now smoke from right side resistance most probably.
I have no idea what damage did I do the driver board F-2856.
The board looks okay there is no black joint or contact.
plz help me fix this.
here is the video of the last time I checked it
https://drive.google.com/file/d/1BNkQ8OO2RzytRr6PtP-nQAlt-XW_jv_3/view?usp=drivesdk
Then I Immediately switched it off, kept the bias settings to low by anticlockwise turned it on. now smoke from right side resistance most probably.
I have no idea what damage did I do the driver board F-2856.
The board looks okay there is no black joint or contact.
plz help me fix this.
here is the video of the last time I checked it
https://drive.google.com/file/d/1BNkQ8OO2RzytRr6PtP-nQAlt-XW_jv_3/view?usp=drivesdk
VR05 & VR06 get tarnished and, just like a volume control, go scratchy. If it goes to a scratchy part, it effectively becomes open circuit, the result is excessive bias current and if you fit the wrong fuse ... magic smoke.
Replace the output transistors if short circuit, replace the emitter resistors and check all of the drivers for damage.
Replace the pre set pots before you even think of powering it back up.
Proceed as per the service manual.
Replace the output transistors if short circuit, replace the emitter resistors and check all of the drivers for damage.
Replace the pre set pots before you even think of powering it back up.
Proceed as per the service manual.
Thank you
I agree this is exactly what happened as I remember the flow of things.
I am new to this stuff, and probably have to learn a lot of things before I could do it comfortably and without damaging the amp any further. here in my town no one is competent enough to do the job well.
just give me an idea that how much damage did the amp sustain? give me likely, most likely and worst case scenario estimates.
can this amp recover from such damage?
Can I find the required parts?
is there any IC on the board which could have been damaged?
what do you mean by drivers? if you mean the rest of the circuit boards. while biasing I put the volume at min and all the buttons switched off except power one.
I know this is basic knowledge but this is the only way I could fix it by learning from you guys.
Thank you dear,
I agree this is exactly what happened as I remember the flow of things.
I am new to this stuff, and probably have to learn a lot of things before I could do it comfortably and without damaging the amp any further. here in my town no one is competent enough to do the job well.
just give me an idea that how much damage did the amp sustain? give me likely, most likely and worst case scenario estimates.
can this amp recover from such damage?
Can I find the required parts?
is there any IC on the board which could have been damaged?
what do you mean by drivers? if you mean the rest of the circuit boards. while biasing I put the volume at min and all the buttons switched off except power one.
I know this is basic knowledge but this is the only way I could fix it by learning from you guys.
Most likely scenario would be failed output transistors and the transistors in front of those (drivers).
The first thing to do is just see if the output transistors read short circuit from collector to emitter.
Also check any low value resistors connected to these transistors. You saw smoke so at least one must have burned.
I suspect this is going to be to ambitious to learn on tbh, not just finding obviously failed parts but also finding replacements. These are old amplifiers and genuine parts could be hard to come by. Although you can substitute transistors with modern types it is not always easy and might require more advanced analysis and possible slight tweaking of the circuit.
Thank you Moly,
Now I know that the output transistors are the big ones attached with the back heat sink, and the drivers are the ones which regulate the function of those output trannies. According to different resources.
G6000 Output Transistors are 2 pairs of Sanken 2SC2261 and 2 Sanken 2SA981 which are complementary Transistors
G6000 Driver Transistors are 2
Output transistors are Sandek
Now I know that the output transistors are the big ones attached with the back heat sink, and the drivers are the ones which regulate the function of those output trannies. According to different resources.
G6000 Output Transistors are 2 pairs of Sanken 2SC2261 and 2 Sanken 2SA981 which are complementary Transistors
G6000 Driver Transistors are 2
Output transistors are Sandek
Thank you Moly,
Now I know that the output transistors are the big ones attached with the back heat sink, and the drivers are the ones which regulate the function of those output trannies.
According to different resources.
G6000 Output Transistors are 2 pairs of Sanken 2SC2261 and 2 Sanken 2SA981 which are complementary Transistors
The replacement for those could be MJ15022 (NPN)/MJ15023 (PNP)/MJ15025 (PNP)
G6000 Driver Transistors are 2 NEC 2SD381 and NEC 2SB536
According to Schematics these are TR 11,12 TR 13,14 on the Driver Board, tell me if I am wrong.
These transistors are available on the internet especially eBay but the repairing community says that these may be counterfeit and may not work or further compromise the system. kindly advice me on this .
PS: I know I am a beginner with regard to having the required Hands on Experience but I am the Student of MS Computer Science and have some Basic Knowledge of Electronics and Automata Machine Signaling which might help me catch up with things on a fast pace.
On the Board 's Schematics
R represents resistance
VR is variable resistance
TR represents Transistors
D represents Diodes
ZD represents Zener Diode
C are the Capacitors
Now I know that the output transistors are the big ones attached with the back heat sink, and the drivers are the ones which regulate the function of those output trannies.
According to different resources.
G6000 Output Transistors are 2 pairs of Sanken 2SC2261 and 2 Sanken 2SA981 which are complementary Transistors
The replacement for those could be MJ15022 (NPN)/MJ15023 (PNP)/MJ15025 (PNP)
G6000 Driver Transistors are 2 NEC 2SD381 and NEC 2SB536
According to Schematics these are TR 11,12 TR 13,14 on the Driver Board, tell me if I am wrong.
These transistors are available on the internet especially eBay but the repairing community says that these may be counterfeit and may not work or further compromise the system. kindly advice me on this .
PS: I know I am a beginner with regard to having the required Hands on Experience but I am the Student of MS Computer Science and have some Basic Knowledge of Electronics and Automata Machine Signaling which might help me catch up with things on a fast pace.
On the Board 's Schematics
R represents resistance
VR is variable resistance
TR represents Transistors
D represents Diodes
ZD represents Zener Diode
C are the Capacitors
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No, I haven't done anything hands on just researching on the board and transistors and their availability. tell me if I am going in the right direction .
It may take longer please bear with me for a while.
You have to measure them as a first step. It takes seconds to do and would at least give an idea of what might have happened. We are only looking for a short/not short result at this point.
Counterfeit transistors are the big problem and while using other modern parts is possible (and probably preferable) they may not be able to work without other minor changes to the circuit... minor in terms of what has to be done but much involved in determining the required component change/s needed.
Emitter resistors refer to the low value resistor connected to the output transistor emitters, typically these are 0.47 ohm or lower. I haven't got a circuit in front of me to give you numbers.
It is time to check your output transistors then check your driver board transistors on the left channel then check your resistors associated with the Transistors that are blown . I am currently helping a friend of mine put back together a Sansui 9090 Most of the driver board transistors were shorted on the right channel It has been just about resurrected back to life
hello Molly,
I have been researching on the amp and pretty much figure out 30% of the theoretical know how, but I am a beginner in terms of hands on experience.Therefore in order to save time and my amp I decided to call it a day.
you guys are right. Got the fried outputs on right channel according to my beginner level transistor testing.
But the good news is I found a technician in my town who can fix my amp. But he said if he could not find the suitable original TO3 outputs then he had to replace them with the transistors which are prevalent these days.
I hope he will fix my amp, I told him to document everything he changes about the amp and should not alter it in any way unnecessarily. Moreover, I told him to tell me what went wrong with the amp.
I will update you guys about the developing situation.
I hope I did the right thing.
I'm sure you have done the right thing 🙂 and a good tech will be able to fit suitable replacements. It will b interesting to hear how it all works out.
Looking at the schematic, I see the bias pot is wired as a rheostat in series with some diodes., no vbe multiplier. This is a disaster waiting to happen the first time someone touches the bias pots. At a minimum, I would add a safety shunt diode across the pot, if not replace the bias circuit with a vbe multiplier where an open corroded pot causes less bias and not more. When I was in the business, I sometimes selected a fixed resistor to replace the pot so that the corrosion hazard was gone. If it isn't clear from other comments, we think it's time you took your receiver to a professional.
Hello guys and dear Mooly,
At last the Sansui G-6000 is back with the new output transistor and few changed resistors.
Problem: According to my newly found tech, It appears that the amp has very sensitive bias setting setup, a slight turn or a light push on the bias pots changes the bias voltage go haywire and that was what actually happened, too much current fried the output transistors along with few resistors. Driver transistors come out alive and okay from this.
The new transistors are pull outs from another stereo amplifier which makes these genuine transistor with same hfe.
The equivalent replacements available here and those were also a match according to alltransistor.com are (please verify before using these )
2SA2151 for Sanken 2SA981
2SC6011 for Sanken 2SC2261
He also changed some resistors according to new transistors requirements . one resistor was also fried and he changed two more to different ohms value.
Thank you guys for you help and support.
This is how the new setup looks like, hope it holds for years to come.
At last the Sansui G-6000 is back with the new output transistor and few changed resistors.
Problem: According to my newly found tech, It appears that the amp has very sensitive bias setting setup, a slight turn or a light push on the bias pots changes the bias voltage go haywire and that was what actually happened, too much current fried the output transistors along with few resistors. Driver transistors come out alive and okay from this.
The new transistors are pull outs from another stereo amplifier which makes these genuine transistor with same hfe.
The equivalent replacements available here and those were also a match according to alltransistor.com are (please verify before using these )
2SA2151 for Sanken 2SA981
2SC6011 for Sanken 2SC2261
He also changed some resistors according to new transistors requirements . one resistor was also fried and he changed two more to different ohms value.
Thank you guys for you help and support.
This is how the new setup looks like, hope it holds for years to come.
that's excellent news and it's good your tech had some similar transistors on hand.Thank you, here the good techs prefer pull outs parts from old unfortunate units.
If I recall, I heard him saying he arranged them from another shop who also deals with old IC chips, transistors you name it.
BTW every thing looks hunky dory.
I am one happy man.
Thank you guys.
If I recall, I heard him saying he arranged them from another shop who also deals with old IC chips, transistors you name it.
BTW every thing looks hunky dory.
I am one happy man.
Thank you guys.