As Andrew said, sort out the LM317 first. I would consider replacing the other LM317 also. Since you are only getting -9.8V, it may have been damaged in the same event as the positive LM317. You might also consider D015/D205. The are cheap and easy to change and diodes can be a weak link.
The good news is that your main power supply seems to be working well now.
The reason that LED1 comes on and then goes off is likely because you are developing DC at the output. Not to surprising when one half of your LM318 power supply isn't working. Once you get things going again, it would be good to check for DC at the speaker outputs.
I also hope you don't have to change LM318, but it isn't too bad if you use a SMD removal solder like Chip Quik. Fingers crossed you don't need to.
Jac
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Question: did You check T101 /T201 for a possible position swap? orientation? I'm asking because it already happened here.
Also, check the famous R11 (1ohm) ground separator resistor. It should read exact 1ohm, if it is intact.
(and I still would do the straightest thing and swap out all active parts possibly involved..)
Ciao, George
Also, check the famous R11 (1ohm) ground separator resistor. It should read exact 1ohm, if it is intact.
(and I still would do the straightest thing and swap out all active parts possibly involved..)
Ciao, George
Joseph, good point.
I didn't notice that T101 (BD139) is rotated by 180 degrees!
I resoldered both LM317 and T101 and T204 yesterday but still no success.
I measured -10V (instead of -14V) and 2V (14V).
I will try with new 14v zener diodes if I find some in my drawer but I just wonder why the other channel works ok?? I did exactly the same mistake.
Thanks again for all your help.
I didn't notice that T101 (BD139) is rotated by 180 degrees!
I resoldered both LM317 and T101 and T204 yesterday but still no success.
I measured -10V (instead of -14V) and 2V (14V).
I will try with new 14v zener diodes if I find some in my drawer but I just wonder why the other channel works ok?? I did exactly the same mistake.
Thanks again for all your help.
Ok.. Now there is a hint that You might have too much current drawn at the load side.
If it tries to exceed that of the CCS (LM317) then simply the output voltage sinks.
To understand if this is the case, measure the !floating voltage drop over R101; R201.
It should be 1.2V if it's working. Maybe now it's less.
Floating means you must use a portable DMM.
I hope You controlled the value of these resistors with the circuit open?
(50ohm)
If my suspicion get's confirmed, than the LM318 is to be changed, sorry..
That is, to confirm that one should first remove the chip.
And repeat the test of the supply voltages.
Ciao, George
If it tries to exceed that of the CCS (LM317) then simply the output voltage sinks.
To understand if this is the case, measure the !floating voltage drop over R101; R201.
It should be 1.2V if it's working. Maybe now it's less.
Floating means you must use a portable DMM.
I hope You controlled the value of these resistors with the circuit open?
(50ohm)
If my suspicion get's confirmed, than the LM318 is to be changed, sorry..
That is, to confirm that one should first remove the chip.
And repeat the test of the supply voltages.
Ciao, George
Joseph, If I remember correctly I measured the voltage drop of 0.9V and it was even lower (0.6V) before the LM317 change.
Do you mean to control the resistance value of R101 and R201 when LM317 was removed?
So I understand the next step would be to remove lm318 and check -14V/14V rails.
If the voltage is correct (no load) then LM318 needs replacing?
Do you mean to control the resistance value of R101 and R201 when LM317 was removed?
So I understand the next step would be to remove lm318 and check -14V/14V rails.
If the voltage is correct (no load) then LM318 needs replacing?
The important thing is to control that drop now, with the new transistors and LM317 in place. It could tell if the replacement works.
Also, you could also just measure the value of the 50ohm resistors in-circuit, with power supply off, naturally.
And yes, if removing the load of the chip (lm318) things get back to normal, that is telling tales..
(we are just passing through all the steps that could have been avoided with a radical clean new start.. excuse me if I insist. You had a 'major' incident, with a lot of possible consequences -- cleaning up each by each is possible-- but I don't see the enjoyment part..)
Ciao! George
Also, you could also just measure the value of the 50ohm resistors in-circuit, with power supply off, naturally.
And yes, if removing the load of the chip (lm318) things get back to normal, that is telling tales..
(we are just passing through all the steps that could have been avoided with a radical clean new start.. excuse me if I insist. You had a 'major' incident, with a lot of possible consequences -- cleaning up each by each is possible-- but I don't see the enjoyment part..)
Ciao! George
since you are there, you could take the chance to replace the LM318 with ADA4627 or OPA827, following George's instructions...
since you are there, you could take the chance to replace the LM318 with ADA4627 or OPA827, following George's instructions...
I wouldn't in this case... the other channel has the LM318 and he's troubleshooting the board.
He can eventually do the upgrade when all problems will be sorted out, IMHO.
It wasn't that bad. Much easier then desoldering the regulators and transistors
I used the copper braid and losts of flux (soldering station set to 300 celsius degrees). Once I was sure I removed all the solder I started to push a small screwdriver underneath the chip while heating all chip legs on one side.
I will make sure everything is working properly before doing any upgrades.
Anyway is the swap easy, I mean the compatibility of ADA4627/OPA827? Or adaptation need to be made?
Thanks again
I used the copper braid and losts of flux (soldering station set to 300 celsius degrees). Once I was sure I removed all the solder I started to push a small screwdriver underneath the chip while heating all chip legs on one side.
I will make sure everything is working properly before doing any upgrades.
Anyway is the swap easy, I mean the compatibility of ADA4627/OPA827? Or adaptation need to be made?
Thanks again
Very good news.
I would leave it 'sink in' for a good while. It's a good amp already as it is.
Then maybe You can try at a later moment the mods discussed here.
http://www.diyaudio.com/forums/chip...on-build-thread-tutorial-309.html#post5075027
Ciao, and enjoy! George
I would leave it 'sink in' for a good while. It's a good amp already as it is.
Then maybe You can try at a later moment the mods discussed here.
http://www.diyaudio.com/forums/chip...on-build-thread-tutorial-309.html#post5075027
Ciao, and enjoy! George