Hi. News about Sakis/Spanish KA-5700. I have connected some speakers wrong and now the relay does not turn on. I think one of the outputs has burned out. My idea is to change both with these chinese NEC, what do you think abaout this idea?
Would any further adjustment be necessary? What trimmer should be adjusted and to what values? Thank you.
Manuel
Would any further adjustment be necessary? What trimmer should be adjusted and to what values? Thank you.
Manuel
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Do you mean a Kenwood KA-5700 ?
Always use a DBT (dim bulb tester). I would advise against buying any semiconductors from ebay as there are to many fakes around... if you do then be careful.
Any trimmers should be adjusted as per the service manual, usually bias current adjustment and sometimes there is a DC offset adjustment.
Always use a DBT (dim bulb tester). I would advise against buying any semiconductors from ebay as there are to many fakes around... if you do then be careful.
Any trimmers should be adjusted as per the service manual, usually bias current adjustment and sometimes there is a DC offset adjustment.
Trio/Kenwood, thought so 🙂
It is up to you on those transistors, I can't decide for you.
For myself I would look at seeing if more conventional outline parts like TIP41C and TIP42C might be able to be fitted and mounted. $38 for a pair of transistors is only worth it if you are sure of success. There could be other collateral damage such as driver transistors and possibly low value resistors around that stage.
It is an easy repair... but it may well be considerably more involved than just replacing the output transistors. Just be aware of that.
It is up to you on those transistors, I can't decide for you.
For myself I would look at seeing if more conventional outline parts like TIP41C and TIP42C might be able to be fitted and mounted. $38 for a pair of transistors is only worth it if you are sure of success. There could be other collateral damage such as driver transistors and possibly low value resistors around that stage.
It is an easy repair... but it may well be considerably more involved than just replacing the output transistors. Just be aware of that.
My amp, serviced by Sakis in 2012:
https://www.diyaudio.com/community/threads/the-spanish-trio-5700-story.224019/
https://www.diyaudio.com/community/threads/the-spanish-trio-5700-story.224019/
Interesting 🙂 but you still have an amp to fix 😉
A lot depends on your skill level and confidence with something like this. Have you actually confirmed the transistors have failed short circuit?
A lot depends on your skill level and confidence with something like this. Have you actually confirmed the transistors have failed short circuit?
You can initially test them in circuit as a short will always show up. Just measure from collector to emitter.
Well... you have to start somewhere. Seeing as you have the transistors removed here is what I would do. (Leave them out for now):
1/ Check that the four 0.33 ohm emitter resistors are OK and not open circuit. These can be checked in circuit.
2/ Link out the series diode pack on both channels.
3/ Power up the amp and using a bulb tester check that the bulb is out or dim.
4/ Check the DC voltage on any leg of either 0.33 ohm in each channel. It should be close to zero.
Also and before doing any of the above did you check that both rail fuses are OK?
1/ Check that the four 0.33 ohm emitter resistors are OK and not open circuit. These can be checked in circuit.
2/ Link out the series diode pack on both channels.
3/ Power up the amp and using a bulb tester check that the bulb is out or dim.
4/ Check the DC voltage on any leg of either 0.33 ohm in each channel. It should be close to zero.
Also and before doing any of the above did you check that both rail fuses are OK?
Those tell us much.
So the 0.33 ohms are OK, the fuses are OK and I assume the rails are up and correct (the - and + 40 volts)
Did you link the diode pack out as per post #14?
If so then all looks OK at this point. The next thing would be to switch off and make sure the -/+40v rails are discharged. They should be but just check, I would now refit the output transistors to one channel only and leave the diode pack shorted. Switch on and check the bulb is still out and that the DC offset is still around zero volts on the 0.33 ohm.