Yes, but it should be 10R, not 100R
Thanks neychi I will change them to 10R.
Hi thanks for your help grimberg
I tried it with output boards removed with and without 25R resistor and speakers conected.
I get a low distorted sound from speaker of music playing.
Another thing is with no output boards 25R resistor meter conected my dc trim pot does nothing when I turn it and shows -0.7v.
Dave,
The 25R emitter resistors must remain in circuit for it to work properly.
Before connecting the output devices I tested my main boards with a small 8 ohm speaker attached and was able to hear music playing clearly. If the sound you hear is distorted, chances are that one half of the input is not reaching the output. Remove and test the drivers (1503x) to which the 25R resistors are attached.
The 25R emitter resistors must remain in circuit for it to work properly.
Before connecting the output devices I tested my main boards with a small 8 ohm speaker attached and was able to hear music playing clearly. If the sound you hear is distorted, chances are that one half of the input is not reaching the output. Remove and test the drivers (1503x) to which the 25R resistors are attached.
Thanks grimberg I fitted the other krell ksa pcb but have exactly the same problem 1.5v dc.
I removed speaker protection and set bias to 280mv transistors reach 46c at heatsink after 45 minutes in hotest part.
Speaker I am using is a old 6 ohm centre speaker which works fine didn't fancy plugging my good speakers in until I have got rid of dc.
Thanks itsme didnt understand what you mean at wrc but had already started swapping boards over.
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Hi supply rails + side I get +46.1v - side -46.6v but noticed -48v side transisters bias to 150mv when +48v side are at at 220mv bias.
Just noticed without speaker conected both sides are 46.8v and I get 190mv at resistors both sides
Hi supply rails + side I get +46.1v - side -46.6v but noticed -48v side transisters bias to 150mv when +48v side are at at 220mv bias.
Just noticed without speaker conected both sides are 46.8v and I get 190mv at resistors both sides
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Hi Dave,
Oh dear, smoked resistor, clean up and replace it, check the MJE15031 to see if its dead.
It looks like you have your output stage connected, I thought you had disconnected it?
Get the driver working and test the output devices before reconnecting them, don't forget to check the transistor/heatsink insulation.
Oh dear, smoked resistor, clean up and replace it, check the MJE15031 to see if its dead.
It looks like you have your output stage connected, I thought you had disconnected it?
Get the driver working and test the output devices before reconnecting them, don't forget to check the transistor/heatsink insulation.
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Yes I have blown my 15030 and 15031 transistors and all the output stage on the -48v side.
I was testing voltages with my meter not that I had a clue what to test and my meter probe slipped and shorted something out didnt see what.
I stripped all my output stage down checked all transistors are mounted properly amp actually works with a capacitor in line with speaker wire to get rid of dc.
Dc is coming from main pcb board just can't work out why.
I was wondering if it could be I have chosen a wrong type capacitor eva my jantzen mkp 0.1uf caps or my silver mica caps as both board's are doing the same fault.
My only other option is are those c2238B and A968B transistors can I test these somehow.