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Is the first one a capacitor and the second one a resistor? This is off of a mixing board. Where would I get these and how would I know what size they are? Please don't flame me on this, I'm trying to learn this. Thanks 
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No flames, we're glad you have joined us.
When you need help, it is good to provide plenty of information. All I know is you have R2 of R20 or R200 or something and C2 or C20 or C200 or whatever in some piece of gear.
What make and model is the unit? We can look on the schematic.
WHy do they need replacing, and are you up to doing solder work on these surface mount parts?
The resistor seems to say 104 on it. If so, that means 100k resistance.
If there is any text on the cap, I can't see it, so I have no idea what value it is.
Well, I take that back, it APPEARS that the resistor and cap are in parallel, and are between pins 6 and 7 of the IC just off to the left. Assuming it is a dual op amp, that would make it the feedback resistor and the cap would be ther for stability, so I suspect the cap is a relatively low value. SO that is my idea, but not a very specific one.Education is what you're left with after you have forgotten what you have learned. -
This is a Fostex VF160 Multitrack Digital Recorder. I had blown out the OpAmp in channel 3&4 and replaced the OpAmp. Channel 3 & 4 work now, but now channel 7&8 doesn't work. Neither the imput jack nor the xlr imput work. Peak light does not come on at all for channel 7&8. All worked fine before I replaced the OpAmp for Ch.3&4.
This Schematic is for a Fostex VF16.....but I think it is the same as the VF160
In one of the photo's it looks like the solder joints are burned but they're not, it's just shadows from the camera.
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OK, so look in that schematic, see each input stage has a feedback resistor that is 100k, and a small cap in parallel? Looks like I guessed correctly.
Why do you think they are bad. If ch7/8 is bad, my first suspect would be the op amp they share.Education is what you're left with after you have forgotten what you have learned.Comment
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I replaced the OpAmp, I was wondering if I may have damaged some of the Caps or Res. That's a tight place to work! I had to use a very powerful magnifying glass. I'm also wondering if I may have damaged the OpAm when I installed it. The OpAmps are cheap enough, I ordered 10 of them, maybe I should try reinstalling another one.Comment
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Measure resistance between the pins of the op amp. DO you get the 100k? Make the same measurement on one of the working channels to see how much the circuit paralle resistances alter the reading. If the cap is damaged, it will either be open or cracked free of the circuit, or it will be shorted. Boubtfull anything else happened. And those are really pretty doubtful. If the resistance measures OK, they are likely fine. If the cap is missing, you'd probably never know. It wouldn;t silence the channel.
Depending upon your skill level, you may have damaged the new IC, or damaged the traces removing the old one, or not made a good solder connection on the new one, or it is installed backwards, or, or, ...
Since the op amp is shared and you have both channels dead, it is not likely the resistor or cap for ONE of the two channels is killing both. SOmething they have in common is more likely. That points to either a bad IC or a missing power connection at one of the corners. Carefully measure power rails at the corners of the 7/8 IC. Both there? Measure voltage at pins 1 and 7. Zero DC like it should or sitting at 15v?
And make sure you are chasing the right goose. Plug a signal into the ch7 input. Now see if that signal shows up at the insert jack. If it does, then that IC is working. If not then it ain;t. Furthermore, plug a signal into the insert jack and see if the rest of the signal path through the unit is working.Education is what you're left with after you have forgotten what you have learned.Comment
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Ok, soldered a new OpAmp in and everything is working!!! I did learn something though.....the OpAmp is extremely static and heat sensitive. The other one that I soldered on that didn't work.....I must have applied too much heat or maybe static killed it. Anyway this time I was very careful about the heat 25watts and very careful about static. Enzo I can't thank you enough!Comment
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Can you send me the schematic for Fostex VF 16 ,i would appreciate it ,i have on that input 1 and 5 has been peaked / fried.. question ,,,the op amps doesn't share with each other do they ,maybe in virtual only like 1/9 2/10 3/11..???Comment
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Use a properly grounded wrist trap and get an ESD safe soldering iron if you are going to work on SMT boards.Comment
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I was wrong ,the op amps are shared,my input 1 and 5 has been peaked out and burnt something up.Comment
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Can you hook me up on op amp ,i'm having a hard time finding them..2068d. 3012b,,I ordered some but they are not face mounted.Comment
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I really need someone other that me to fix my burnt out op amps.I have diabetes and can't see to good .I bought the op amps,but there's no way I can solder them in..I would love just to buy the board .does anybody know were I can buy one? thanksComment
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