Hi All
Made a mistake - put a single channel op amp into this pre amp with a dual op amp socket. Now only one channel working when I put the original op amp back in. There is also a lot of grounding type noise! What have I blown?
Ordered replacement op amp and one for the tone control as well.
Thanks
Made a mistake - put a single channel op amp into this pre amp with a dual op amp socket. Now only one channel working when I put the original op amp back in. There is also a lot of grounding type noise! What have I blown?
Ordered replacement op amp and one for the tone control as well.
Thanks
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With the black lead of the DVM connected to ground (the metal chassis) then you should have around PLUS 16 volts on pin 8 and MINUS 16 volts on pin 4 of the opamps.
So the positive rail is down.
First thing... have you checked the two 500 milliamp fuses F901 and F902 ?
First thing... have you checked the two 500 milliamp fuses F901 and F902 ?
No problem 🙂
Those voltages are fine.
All the other pins (so 1,2,3,5,6 and 7) on all the opamps should be at approximately zero volts.
Is it possible you have blobbed any solder onto the print (shorting something out) while working on this ?
It should all work given the correct supplies, there is nothing else really that could cause problems.
A good test might be to see what it is like with headphones.
I'll look in again tomorrow... good luck.
I mentioned the fuses in response to the -12, +3 result 🙂 We both posted together after that.
I would suggest to check your work carefully around the opamp you replaced.
The power supply appears fine at -/+17.5 volts and so refitting the original good opamp should bring it all back to how it was. Everything now points to something else that has happened while you have been working on it.
Check the print very carefully for good connectivity to the actual opamp pins by using your meter on a low ohms range. Measure from the opamp pin itself to the surrounding print that the pin in question goes to. Do that for all the pins on the opamp you replaced.
I would suggest to check your work carefully around the opamp you replaced.
The power supply appears fine at -/+17.5 volts and so refitting the original good opamp should bring it all back to how it was. Everything now points to something else that has happened while you have been working on it.
Check the print very carefully for good connectivity to the actual opamp pins by using your meter on a low ohms range. Measure from the opamp pin itself to the surrounding print that the pin in question goes to. Do that for all the pins on the opamp you replaced.
On the op amp I messed with on one side all pins reading around 17v and on other side just one pim -17v and the other low mv
I'm going to have to leave it for tonight but this absolutely sounds like you have damaged the print around the IC. If the print is broken then the DC conditions around the IC will be wrong because the feedback will missing.
Apart from the +17 volts on pin 8 and -17 volts on pin 4 then all the other pins should be at near to zero.
Which opamp did you replace as there are a few in this preamp ?
One for tomorrow 🙂
Apart from the +17 volts on pin 8 and -17 volts on pin 4 then all the other pins should be at near to zero.
Which opamp did you replace as there are a few in this preamp ?
One for tomorrow 🙂
Hi
Reflowed solder on the opamp and some of the surrounding solder joints and it lives. Thank you.
Reflowed solder on the opamp and some of the surrounding solder joints and it lives. Thank you.
Hi
Obviously I am an amatuer and tried to follow a tutorial and change the op amp to a Burr-Brown OPA627APand failed to realise that it was mono and I needed 2 of them. I got the amp / pre amp combo for free from a relative so thought it was worth a go as it is my new weekend hobby.
I have now ordedred a dual op amp adapter and looks like I will have to shell out for another Burr-Brown OPA627APat some point - quite pricey from RS components!I really thought I had killed it. Thanks for the help Mooly. Sometimes you just have to keep calm!
Obviously I am an amatuer and tried to follow a tutorial and change the op amp to a Burr-Brown OPA627APand failed to realise that it was mono and I needed 2 of them. I got the amp / pre amp combo for free from a relative so thought it was worth a go as it is my new weekend hobby.
I have now ordedred a dual op amp adapter and looks like I will have to shell out for another Burr-Brown OPA627APat some point - quite pricey from RS components!I really thought I had killed it. Thanks for the help Mooly. Sometimes you just have to keep calm!
Another question. Am I likely to have damaged the Burr-Brown OPA627AP by dropping it into a dual op amp socket? If so how can I test it out of circuit as it may be time to cut my losses on this project if it is damaged!
WHY did you not put in a DIP8 socket after removing the older opamp ? You should have known that pcb's don't take too kindly to desoldering/soldering several times. Sometimes even a couple of times ! With a dip in place you can try out any opamp later on without desoldering/soldering anymore.
Besides you seem to break many standard rules. ALWAYS check the data sheet of what you are putting in EVEN if you know the part or 'think' you know the part. A double check will catch mistakes before they happen.
Besides you seem to break many standard rules. ALWAYS check the data sheet of what you are putting in EVEN if you know the part or 'think' you know the part. A double check will catch mistakes before they happen.
The long answer was here:
http://www.diyaudio.com/forums/site...atabase-restore-2017-07-01-a.html#post5121249
Short version... it should be OK. There is no internal connection to pin 8 of the OPA627.
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