Numistrek09
Super Member
To begin, you need to pull the following components:
Part #s Q211 & 212, C233, 234, 237 & 238, and R253 & 254. You also need to remove C239 and 241. Replace those two bypass caps with some .22uf Panasonic ECQ films. (Digikey part # P4667-ND) Since the voltage being supplied to the chip was only around 16.8 volts in my unit, i didn't replace the voltage dropping resistors (R267 & 268). But if in your 3800 you are getting much more than 17 V supplied, you should probably increase the value of these resistors. (The existing value is 10 ohms, so going up to as little as 47 ohms might be all it'd take.) I have been told it is not advisable to let an op-amp run very close to it's max operating voltage, if possible. Next, pull the fourteen pin chip socket and replace it with the eight pin socket.
Now the jumpers. Again, i made mine from leftover leads trimmed from the new capacitors.
Pins to jump are as follows:
Pin 5 to pin 3 via the empty pad for R253. This jumper must have heat shrink on it since it is so close to the new socket base. I put heat shrink on most of the other jumpers as well, but only this one must have it i feel.
Pin 6 to pin 2 via the empty pad of C237
Pin 7 to pin 4 via the empty pad of C233
Pin 8 to pin 12 via the empty pad for C238
Pin 9 to pin 11 via the empty pad for R254.
The jumpers are flush with the board and are bent/angled a bit to not interfere with each other and the new chip socket. None cross over. Picture one shows the emptied PCB, picture two shows the jumpers installed and picture three shows the new IC socket installed. Once everything is in place and cleaned up, power up and test to see of the right voltage is on the correct pin locations. If you put everything together right, it should be. If all is well, power down, instal the new op-amp and power back up. Pictures four & five show the 2134 in place and how everything looks. Now you are ready to calibrate.
Part #s Q211 & 212, C233, 234, 237 & 238, and R253 & 254. You also need to remove C239 and 241. Replace those two bypass caps with some .22uf Panasonic ECQ films. (Digikey part # P4667-ND) Since the voltage being supplied to the chip was only around 16.8 volts in my unit, i didn't replace the voltage dropping resistors (R267 & 268). But if in your 3800 you are getting much more than 17 V supplied, you should probably increase the value of these resistors. (The existing value is 10 ohms, so going up to as little as 47 ohms might be all it'd take.) I have been told it is not advisable to let an op-amp run very close to it's max operating voltage, if possible. Next, pull the fourteen pin chip socket and replace it with the eight pin socket.
Now the jumpers. Again, i made mine from leftover leads trimmed from the new capacitors.
Pins to jump are as follows:
Pin 5 to pin 3 via the empty pad for R253. This jumper must have heat shrink on it since it is so close to the new socket base. I put heat shrink on most of the other jumpers as well, but only this one must have it i feel.
Pin 6 to pin 2 via the empty pad of C237
Pin 7 to pin 4 via the empty pad of C233
Pin 8 to pin 12 via the empty pad for C238
Pin 9 to pin 11 via the empty pad for R254.
The jumpers are flush with the board and are bent/angled a bit to not interfere with each other and the new chip socket. None cross over. Picture one shows the emptied PCB, picture two shows the jumpers installed and picture three shows the new IC socket installed. Once everything is in place and cleaned up, power up and test to see of the right voltage is on the correct pin locations. If you put everything together right, it should be. If all is well, power down, instal the new op-amp and power back up. Pictures four & five show the 2134 in place and how everything looks. Now you are ready to calibrate.