Greetings from Norfolk
Can anybody help please, I have this Sansui Amplifier which I use for a dance class, BUT it has a speaker protection circuit which seems to be either
(a) not working properly or
(b) the amplifier output is out of limits for some time.
The effect is that when switched on the output protection circuit operates to protect the speaker and remains in the 'protect' state for a long period (many minutes) Once it has operated (i.e. to output signal to speaker) then if switched off and then on after a short period the delay is much shorter.
I suspect either a leaky capacitor, or an out of adjustment on the dc level of the output. Can anybody advise with data to enable me to rectify.
I have traced out most of the protection circuitry, but parts are not sensibly accessible, even to determine values.
Richard
Can anybody help please, I have this Sansui Amplifier which I use for a dance class, BUT it has a speaker protection circuit which seems to be either
(a) not working properly or
(b) the amplifier output is out of limits for some time.
The effect is that when switched on the output protection circuit operates to protect the speaker and remains in the 'protect' state for a long period (many minutes) Once it has operated (i.e. to output signal to speaker) then if switched off and then on after a short period the delay is much shorter.
I suspect either a leaky capacitor, or an out of adjustment on the dc level of the output. Can anybody advise with data to enable me to rectify.
I have traced out most of the protection circuitry, but parts are not sensibly accessible, even to determine values.
Richard
Monitor the DC status before the relay. If that is fine, suspect the protection circuit. Look for capacitors, sometimes bipolars are used in that area.
If sufficient DC is present, change some caps in the signal path.
Measure and suspect the diff pair. A schematic would be handy in this particular case.
/Hugo
If sufficient DC is present, change some caps in the signal path.
Measure and suspect the diff pair. A schematic would be handy in this particular case.
/Hugo
Greetings from Norfolk
Having looked into the circuit to the extent that I have identified the area of the circuit, it is either the protection circuit timing (a 47 uF charged via 180 K from 3 V, 'clearing' the protection circuit when charged to 1.36 V. The rate of charging also appears to be controlled by some other factor than the resistor (180 K). dc monitoring of the amp output signals is also probably a factor - there is an 'integrated / thick film circuit' which takes these signals in, as well as others and appears to be involved in the protection.
Richard
Having looked into the circuit to the extent that I have identified the area of the circuit, it is either the protection circuit timing (a 47 uF charged via 180 K from 3 V, 'clearing' the protection circuit when charged to 1.36 V. The rate of charging also appears to be controlled by some other factor than the resistor (180 K). dc monitoring of the amp output signals is also probably a factor - there is an 'integrated / thick film circuit' which takes these signals in, as well as others and appears to be involved in the protection.
Richard
Hi Richard,
The IC is probably a SIP, TA7317P. It has AC detect too, if they are using it. This IC is seldom defective.
Look for a single diode charging a 1uF (normally) cap. If you look at the waveform with a 'scope, it should be DC with a 60Hz sawtooth on it. They go open so the DC component is reduced as the capacitance goes down.
Other problems have been detailed by Hugh.
-Chris
The IC is probably a SIP, TA7317P. It has AC detect too, if they are using it. This IC is seldom defective.
Look for a single diode charging a 1uF (normally) cap. If you look at the waveform with a 'scope, it should be DC with a 60Hz sawtooth on it. They go open so the DC component is reduced as the capacitance goes down.
Other problems have been detailed by Hugh.
-Chris
Sansui Au-G11X - problem with the case
Hi,
My new – old AU-G11X needs to be repaired. I have a problem with the top plate. How to remove it? There are only two screws at rear panel (cover). The both sides aren't connected with the case. The top plate seems to be connected with plastic front panel in the central part. Can You help me?
Regards,
fonon
Hi,
My new – old AU-G11X needs to be repaired. I have a problem with the top plate. How to remove it? There are only two screws at rear panel (cover). The both sides aren't connected with the case. The top plate seems to be connected with plastic front panel in the central part. Can You help me?
Regards,
fonon
In 'cases' like this, I take out every screw I can find, till the whole lot falls appart. No kidding.
/Hugo 🙂
/Hugo 🙂
Hi Fonon,
If it has wooden side panels, the other screws are under there. Some have a top panel that will slide back if you undo those two screws.
Hey Hugo,
-Chris
If it has wooden side panels, the other screws are under there. Some have a top panel that will slide back if you undo those two screws.
Hey Hugo,
Ever do that and hear a heavy thump inside? Followed by the sound of little pieces rolling around?
-Chris
I noticed you got some nice replies at Audiokarma.
Did you try what was suggested there and also in this forum?
/Hugo
Did you try what was suggested there and also in this forum?
/Hugo
How many screws are still in place? It is perfectly possible that you need to remove the front.
Look everywhere, top, bottom, sides. I'm sure you must have missed a screw or two. 🙂
/Hugo
Look everywhere, top, bottom, sides. I'm sure you must have missed a screw or two. 🙂
/Hugo
Hi,
I have experience with audio units, but this case is simply strange. AU-G11X is a very rare amplifier. There is no information about the case in the service manual. Some parts are made of fragile plastic. I'm afraid to cause damage to something. I'm looking for a person (like Gandalph) who has this amplifier or other similar unit.
fonon
I have experience with audio units, but this case is simply strange. AU-G11X is a very rare amplifier. There is no information about the case in the service manual. Some parts are made of fragile plastic. I'm afraid to cause damage to something. I'm looking for a person (like Gandalph) who has this amplifier or other similar unit.
fonon
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