Hello everybody
A friend of mine given me a old SU-V2X. I've noticed that this amp runs very hot, even on low volume.
It was working fine until the moment it made a clic and enter into safety mode.
I had a look on the net on what could be the root cause and, to stay on the safe side, changed Q501-504.
But no, luck, the problem is somewhere else.
So i did check volatges ou the STK2038 and got strange results
Pin 12 gives 31,4V (supposed to be 1.8), pin 14 : 34.3 (suppesod to be 0) and pin 16, 35.2V (suppsed to be 1.8). All other are according to service manual.
I suppose that the safety feature is detcting this values.
Now, what could be the root cause ? Can you help ?
Any advices are welcome.
JM
A friend of mine given me a old SU-V2X. I've noticed that this amp runs very hot, even on low volume.
It was working fine until the moment it made a clic and enter into safety mode.
I had a look on the net on what could be the root cause and, to stay on the safe side, changed Q501-504.
But no, luck, the problem is somewhere else.
So i did check volatges ou the STK2038 and got strange results
Pin 12 gives 31,4V (supposed to be 1.8), pin 14 : 34.3 (suppesod to be 0) and pin 16, 35.2V (suppsed to be 1.8). All other are according to service manual.
I suppose that the safety feature is detcting this values.
Now, what could be the root cause ? Can you help ?
Any advices are welcome.
JM
Let’s look at core voltages
Pin 1 (1.8)
Pin 3 (0V)
Pin 5 (-1.8)
Pin 12 (-1.8)
Pin 14 (0V)
Pin 16 (1.8)
Pin 1 (1.8)
Pin 3 (0V)
Pin 5 (-1.8)
Pin 12 (-1.8)
Pin 14 (0V)
Pin 16 (1.8)
Sounds like Q502 is short
can try and unsolder Q502 and Q504.... then connect COLLECTOR of Q504 to ground via 6.8K resistor
Check for safety operation.
can try and unsolder Q502 and Q504.... then connect COLLECTOR of Q504 to ground via 6.8K resistor
Check for safety operation.
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Hello SVI2004A
Thanks for the reply.
Q502 and 504 where brand new ones (checked before install).(replaced following your recommendations from another post)
How do I connect Q 504 to ground if its unsoldered form the board ?
(sorry, i'm not a deep expert in electronics, but willing to learn)
I'll do it end of this week, if we are allowed to move (the amp is not where i'm during the week).
many thaks for your help, I'll keep you posted of the outcome as soon as possible.
BR
JM
Thanks for the reply.
Q502 and 504 where brand new ones (checked before install).(replaced following your recommendations from another post)
How do I connect Q 504 to ground if its unsoldered form the board ?
(sorry, i'm not a deep expert in electronics, but willing to learn)
I'll do it end of this week, if we are allowed to move (the amp is not where i'm during the week).
many thaks for your help, I'll keep you posted of the outcome as soon as possible.
BR
JM
Ahh yes
Solder resistor to collector point (where Q504 would go) this straps -Rchin power IC to ground (stops output stage drifting)
Power ic sounds like it’s driven to full output
So with Q502 and 504 removed, and 504 collector terminal connected to ground via 6.8K resistor
Pin 14 should be 0V
Solder resistor to collector point (where Q504 would go) this straps -Rchin power IC to ground (stops output stage drifting)
Power ic sounds like it’s driven to full output
So with Q502 and 504 removed, and 504 collector terminal connected to ground via 6.8K resistor
Pin 14 should be 0V