Well, the Aliexpress site says I should get a refund for the first one as the seller did not respond to the case.
Now fitted the second one and again no luck 🙁
Protection relay does not operate as on one channel it gives out -2.625v and the other -0.756 with no input signal.
Feeding 1khz in still no change in output with signal reaching R507 and R508 okay but on the SVI the wave gains some distortion.
Amp model SU-X501
Time to give up on SVI modules and for a challenge I may try and replace the final stage with modern components.
Got another Technics amp to play with a failed STK2048IV. I wonder what that one will do 🙂
Now fitted the second one and again no luck 🙁
Protection relay does not operate as on one channel it gives out -2.625v and the other -0.756 with no input signal.
Feeding 1khz in still no change in output with signal reaching R507 and R508 okay but on the SVI the wave gains some distortion.
Amp model SU-X501
Time to give up on SVI modules and for a challenge I may try and replace the final stage with modern components.
Got another Technics amp to play with a failed STK2048IV. I wonder what that one will do 🙂
I know the 2048IV well.... much better setup 2ch DPP (Often faults are with pre drive transistors (2SA1123/2SC2631) or dry joints on them (often on a daughter board w/ AN7062)
Looks like the 3206D you got was used (probably cooked before pulled out of previous unit)
Looks like the 3206D you got was used (probably cooked before pulled out of previous unit)
Oooooo a V2X
The larger bolt pattern on heatsink is for SVI2003 / SVI2004
Enjoy the sound of that.... those amps have a great sound
The larger bolt pattern on heatsink is for SVI2003 / SVI2004
Enjoy the sound of that.... those amps have a great sound
Back to my sick amp...
I got my refund and just got a used SVI3205 (removed from another Technics amp).
I also made myself one of those dim bulb gadgets with a 60W lamp.
Anyway, it powers up, display works, protection relay operates but also now the fan runs.
On the output inductors I am getting a perfect 100Hz sine wave.
On R525 440mV PtoP and on the other channel R526 222mV PtoP.
SU-X501
No input signal and checking the main supply rails with a voltmeter on AC no apparent voltage.
Is this because the dim bulb is messing up the other power supply rails or something else?
Any thoughts please.
I am in the UK home of 50Hz and 240Volts 🙂
I got my refund and just got a used SVI3205 (removed from another Technics amp).
I also made myself one of those dim bulb gadgets with a 60W lamp.
Anyway, it powers up, display works, protection relay operates but also now the fan runs.
On the output inductors I am getting a perfect 100Hz sine wave.
On R525 440mV PtoP and on the other channel R526 222mV PtoP.
SU-X501
No input signal and checking the main supply rails with a voltmeter on AC no apparent voltage.
Is this because the dim bulb is messing up the other power supply rails or something else?
Any thoughts please.
I am in the UK home of 50Hz and 240Volts 🙂
A small update with my amp.
Tried it without the dim lamp and no better. As soon as the protection relay operates the fan starts and still 100hz sine wave on output.
+14.8 volt rail shows no AC but -15v has 50mV of AC voltage.
It seems to only use two very tiny 10uf 16v caps to smooth them so may try replacing them and the main two 4700uf 63v filter caps.
Tried it without the dim lamp and no better. As soon as the protection relay operates the fan starts and still 100hz sine wave on output.
+14.8 volt rail shows no AC but -15v has 50mV of AC voltage.
It seems to only use two very tiny 10uf 16v caps to smooth them so may try replacing them and the main two 4700uf 63v filter caps.
Replaced the filter caps and those other caps on the regulated supply and it made no difference 🙁
One thing I have noted is the bridge rectifier diodes are schottky ones.
I have some normal ones on order just in case.
Anyone got any ideas?
One thing I have noted is the bridge rectifier diodes are schottky ones.
I have some normal ones on order just in case.
Anyone got any ideas?
Please leave the diodes alone if they're not defective.
And Technics used premium caps in those units, there's no need to go swapping out caps unless they test poorly.
I can only assume I have yet another duff module and thus plan 2, try and replace the module with a modern alternative.
And yes, it works 🙂 The heat sink In the amplifier will need some work and the fan should still work as it seems to be controlled by speaker voltage on this model.
The module uses 2 x TD7293 amplifier chips and includes speaker protection.
And yes, it works 🙂 The heat sink In the amplifier will need some work and the fan should still work as it seems to be controlled by speaker voltage on this model.
The module uses 2 x TD7293 amplifier chips and includes speaker protection.
Attachments
Hi,
As you can imagine, there must be a lot of people in your shoes 🙂
Can you share any kind of schematics or better, a project detail on your work? That would be of extreme value!
Best regards, stay safe!