No, the lower diagram shows the bottom of the transistor, thus the emitter lead is the one farthest to the LEFT in the picture - as indicated on the diagram.
I don't know what you are doing, but the diagram is correct.
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Sansui AU-6900 Woes .......
- Thread starter camgilbert
- Start date
If you measured this +48V at R32, (or R31) this means that TR605 isn't regulating, that is a power supply voltage and it's wrong! - you'll never get the rest of the circuit to behave when it is being fed incorrect PSU voltages.
You must have +/- 40V as a supply to the earlier stages of the driver circuitry.
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The Fuxtor
Addicted Member
OK, I see now! Sorry for confusion..... Hyperion is right, the pic is from the bottom point of view... Nice having one of those eBay component testers for this stuff, it will show what leg is what . Sorry op for some reason I was looking at the diagram from on top of the transistor..... I certainly hope nothing else got messed up from my " help ".....
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camgilbert
Member
DBT has been used but dims properly.
Trying not to be too nit picky, but tr604 and 605 are not true regulators, but are"capacitance multipliers" (also called a ripple filter, or in more than one SM, a lipple filter) which means their emitters will be a few volts above (or below) their collector voltages. (and the circuit works best if they are slightly higher than the voltages on the output collectors, which come from a different winding and filter caps)If you measured this +48V at R32, (or R31) this means that TR605 isn't regulating, that is a power supply voltage and it's wrong! - you'll never get the rest of the circuit to behave when it is being fed incorrect PSU voltages.
Next - warning about schematic errors - (like r42 labeled as r41 in the manual I'm working from) and that unregulated voltages are approximate and can very with line frequency, and aren't that exact to begin with.
Also, as I have said before, your meter is your friend. You can always determine the base lead of a transistor with diode test with your meter, and will help you avoid manual and spec sheet errors (and keep your sanity in check)
WE still haven't found the root cause of all the problems. My opinion is tr04 overheating is a symptom, not a cause. Because of the +9 volts on the output, would expect tr04 to be trying to pull the output down, which would make it run hot, and stress 528 and 42. My other worry is that both channels are still high positive output voltages.
camgilbert
Member
Thanks Steve,
Very good feedback.
To avoid further errors, I purchased a components tester off Amazon, which is an amzing little device and has insured I have all tr's correct.
As of right now, all reading are high, im getting 47V @ D603 when I should be getting 37V
Is there more likely to be a schematic error, then a silkscreen error?
I guess if I could say one thing that confuses me is, if I want to work through the circuit one component at a time, am I working from the AC 100V on the left below then working to the right of the schematic or is that all wrong?
Very good feedback.
To avoid further errors, I purchased a components tester off Amazon, which is an amzing little device and has insured I have all tr's correct.
As of right now, all reading are high, im getting 47V @ D603 when I should be getting 37V
Is there more likely to be a schematic error, then a silkscreen error?
I guess if I could say one thing that confuses me is, if I want to work through the circuit one component at a time, am I working from the AC 100V on the left below then working to the right of the schematic or is that all wrong?
petehall347
the brandy coffee man
what AC voltages at the fuses ?
camgilbert
Member
Hi,
If you look at the schematic above, I was really asking for a framework for testing, so my starting point would be the wall plug AC100, then the transformer, than the fuses, then the large caps, then the diodes and so on....
Or is that not the way to troubleshoot a schematic component by component?
If you look at the schematic above, I was really asking for a framework for testing, so my starting point would be the wall plug AC100, then the transformer, than the fuses, then the large caps, then the diodes and so on....
Or is that not the way to troubleshoot a schematic component by component?
camgilbert
Member
Steve,
Re your comments above, what are 528 and 42 referring to?
Re your comments above, what are 528 and 42 referring to?
petehall347
the brandy coffee man
the rectified voltages are dependant on the AC in voltages . as i am sure you are aware .
so that is why i said at the fuses .
AC from the plug hole is also important here . i just like going the long way round . might find things on the way .
so that is why i said at the fuses .
AC from the plug hole is also important here . i just like going the long way round . might find things on the way .
Are you running a 100 volt model off of line voltage. Line voltage is normally 115 to 120 volts, and if the model is designed for 100 volt operation, all your unregulated voltages will be 15 to 20 percent higher. 100 Volts is standard Japanese line. North American is 110 to 120 V.(117?)
The components used are robust enough that they shouldn't fail, but it is an increase of stress on components over what they were designed to dissipate.
Also, unrelated but check voltage on a fresh battery. Should be 1.6 volts. Sometimes meters, when their batteries are low, will read higher voltages than they should be. (We went nuts, readjusting stuff at work once, when one of the meters had low battery) (probably not a problem but good to check)
The components used are robust enough that they shouldn't fail, but it is an increase of stress on components over what they were designed to dissipate.
Also, unrelated but check voltage on a fresh battery. Should be 1.6 volts. Sometimes meters, when their batteries are low, will read higher voltages than they should be. (We went nuts, readjusting stuff at work once, when one of the meters had low battery) (probably not a problem but good to check)
camgilbert
Member
Hi guys,
" to continue the longest thread in the history of these forums ..................."
I have taken a bunch of readings to hope trigger some ideas:
---------------------------
r608 3.3v
tr 605
b e c
50 49 51
tr604
b e c
-46 -45 -50
tr04
b e c
-28 -28 23
tr14
b e c
22 -48 23
tr06
b e c
26 23 27
tr05
b e c
-35 -35 -31
tr16, 18, 15, 17
b e c
25 25 47
23 23 - 47
-33 -33 47
-34 -34 -48
-----------------------------
" to continue the longest thread in the history of these forums ..................."
I have taken a bunch of readings to hope trigger some ideas:
---------------------------
r608 3.3v
tr 605
b e c
50 49 51
tr604
b e c
-46 -45 -50
tr04
b e c
-28 -28 23
tr14
b e c
22 -48 23
tr06
b e c
26 23 27
tr05
b e c
-35 -35 -31
tr16, 18, 15, 17
b e c
25 25 47
23 23 - 47
-33 -33 47
-34 -34 -48
-----------------------------
camgilbert
Member
Hello all,
So hopefully some progress:
1. I ordered and replaced transistors for TR01-TR04 on F2596 (2sa917 -->ksa916, 2sc1951 --> ksc2316)
2. I then swapped the two 2SA798 (IC01,IC02) (Note: I do not have replacements for these)
Any thoughts, am I going in the right direction here?
Thanks
Cam
So hopefully some progress:
1. I ordered and replaced transistors for TR01-TR04 on F2596 (2sa917 -->ksa916, 2sc1951 --> ksc2316)
- After which R70,R67,R59,R61 had measure voltages in 100-150mv range (im hoping that's better)
- However the other four emitter resistors were still high (in the 20-25V range
- I also went to check the bias voltages and found that one of the pots was intermittent so replaced both of those.
2. I then swapped the two 2SA798 (IC01,IC02) (Note: I do not have replacements for these)
- After which R42 burned up.
Any thoughts, am I going in the right direction here?
Thanks
Cam
petehall347
the brandy coffee man
you may have caused a short on the board when soldering .
camgilbert
Member
Thanks, I will check those.
petehall347
the brandy coffee man
just looking at your list of voltages and wondering why you are diagnosing both amp channels at same time ?
i find it best to get one side working then the other .
power supply voltages first .
i find it best to get one side working then the other .
power supply voltages first .
petehall347
the brandy coffee man
are all capacitors known to be good and installed correct way round ?
say if c24 was wrong way round it would cause the rail voltage to drop and burn up r42 .
say if c24 was wrong way round it would cause the rail voltage to drop and burn up r42 .
camgilbert
Member
Hello all,
I have a few basic troubleshooting questions:
Cam
I have a few basic troubleshooting questions:
- I have a resistor shown (R41) below which continues to burn out when unit is off of DBT. If I test voltages on DBT, I'm I getting accurate information?
- If I want to test power supply voltages on the F-2598, where on the schematic would you suggest i measure?
- On the AU-6900 schematic parts list, the parts TR06 and TR05 are listed as 2SC711's, however the original TR's were in fact, C1475K3's. I have now used KSC945's, will those work as suitable replacements?
Cam
Make sure basing is correct. KSC945 have base in center. KSC945C has collector in center. Original part has collector in center. 2SC945 has collector in center.You meter (or tester) should verify this quickly) I'd use something with higher max voltage (c945 is , I believe, 50 volts max) Also, maybe higher Power - like ksc2383
