Gooday all,
I need some help with a Technics su-v5. The amp plays fine when the volume is low but when you turn up the volume the speaker relay trips. It has got an impedance detection circuit, It might be out of adjustment. This is the adjustment procedure, I just want to make sure I understand it correctly under adjustment header. Connect a jumper between TP402 and TP404 ? I have read on AK a guy did connect the two test points and he burned stuff, not sure if he did something else. DC offset is 2mV on both channels and the bias is fine on 16mV, that's why I suspect the impedance setting is faulty and want to calibrate it. Much appreciated.
Regards
Jan
I need some help with a Technics su-v5. The amp plays fine when the volume is low but when you turn up the volume the speaker relay trips. It has got an impedance detection circuit, It might be out of adjustment. This is the adjustment procedure, I just want to make sure I understand it correctly under adjustment header. Connect a jumper between TP402 and TP404 ? I have read on AK a guy did connect the two test points and he burned stuff, not sure if he did something else. DC offset is 2mV on both channels and the bias is fine on 16mV, that's why I suspect the impedance setting is faulty and want to calibrate it. Much appreciated.
Regards
Jan
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Has this amplifier worked ok recently? Or did you get it in that condition?
Before starting adjustments I would replace C507 and C508 - if these dry and lose capacitance then the relay drive chip IC501 may start getting false alarms from the emitter resistors once you increase the volume i.e. voltage drop on them. With the same pass I would replace all "technical" lytics around the relay chip - to eliminate them from the suspects.
Before starting adjustments I would replace C507 and C508 - if these dry and lose capacitance then the relay drive chip IC501 may start getting false alarms from the emitter resistors once you increase the volume i.e. voltage drop on them. With the same pass I would replace all "technical" lytics around the relay chip - to eliminate them from the suspects.
Thanks madis64,
Right channel works fine, only the left channel that has a problem. The amp has never been worked on before.
Right channel works fine, only the left channel that has a problem. The amp has never been worked on before.
I asked if you have ever had that amp in working condition. I.e. has the defect developed slowly or fast or the amp is new for you and you have no knowledge of its history.
Now you are creating confusion - in the opening post you state that the relay trips.
How do you determine that one channel is working ok and the other one is not?
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OK, when I connect a signal on the RCA of the right channel then it works as it should. When I connect a signal in the left channel, then the relay drops out when I increase the volume. Apparently the amp was in storage according to the customer. Even when I disconnect the speaker. That's why I think the Impedance detection could be out of calibration.
So you are are a pro-tech seeking for free advice in a diy forum?
The thing is - if the community solves your financial-professional problem then how do you share your profits?
I bought the amp from the customer, I'm on pension now, this is a hobby for me, I have to keep myself busy.
Why did you start to suspect the diode? Or did you just test all components in the relay drive circuit?
I downloaded a better schematic from HIFI Engine, not single pages. The TA7317 protection chip is triggered on pin 2. Just followed the circuit to the output stages of both channels . I checked those caps that you mentioned, they were fine and I did not have bipolar caps to change the caps connected to the chip.
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