Reverend Drivetrain II IC Socket Installation Problem: Fixed

[rickortega]

I soldered a socket for the IC chip for the Reverend Drivetrain II and bad things have happened. I can't get a good signal out of the pedal...some chip are poor, others are just really bad or non existent. When I reinstall the original chip in the socket, there is no signal. I tried changing the orientation of the chips but nothing fixes my screw up.

Any ideas? It sounded prety good before I "de-modded" the DT-II. I'd like to get it back to semi-original. Help...Help

Thanks,

Rick

[rickortega]

Help...

[petemoore]

Check for solder traces across wrong connection points visually, and using the DMM beep mode...touch pins 1&2, 2&3, 3&4, 5&6, 6&7, 7&8...any continuity between the IC pins like this need to be eliminated.
 Stick yer OA in the socket, supply power, and take IC pin readings...DMM black lead to ground, red lead...touch each pin 1-8 on the opamp, note and post these readings, include battery or supply voltage.
 Audio Probe...

[rickortega]

I'll do it...Thanks!!

Rick

[Phorhas]

Can you please post some photos of the components and traces sides (as well as wiring) - if it's not too much trouble?

I'm wondering whats going on inside the drivetrain

[rickortega]

Check for solder traces across wrong connection points visually, and using the DMM beep mode...touch pins 1&2, 2&3, 3&4, 5&6, 6&7, 7&8...any continuity between the IC pins like this need to be eliminated.
 Stick yer OA in the socket, supply power, and take IC pin readings...DMM black lead to ground, red lead...touch each pin 1-8 on the opamp, note and post these readings, include battery or supply voltage.
 Audio Probe...

I have a Burr Brown OPA2134PA chip installed. I did not get any beeps when I checked the adjacent pins.

The pin voltages are: 1- 8.42v, 2- 8.41v, 3- 8.02v, 4- 8.41v, 5- 8.40v, 6- 8.04v, 7- 8.04v, 8- 0v. The supply voltage (battery) was 8.43v.

Thanks...I'll get some board pics later today.

Rick

[R.G.]

The pin voltages are: 1- 8.42v, 2- 8.41v, 3- 8.02v, 4- 8.41v, 5- 8.40v, 6- 8.04v, 7- 8.04v, 8- 0v. The supply voltage (battery) was 8.43v.

Either you have it in the socket backwards or you are reading the pins incorrectly from the chip or you have solder bridges in your solder work, or some combination of the above.

The power supply voltages are present on the wrong pins from your description. Pin 8 must be the same as the battery voltage, and pin 4 must be at 0V. You show pin 1 at battery and pin 8 at 0V. Pin 1 and pin 8 are directly across from one another across the chip.

The most likely thing that has happened is that you have some bad solder joints and the chip is turned around.

1. look at the chip. Pin 1 and pin 8 are on the end of the chip with an indentation on the plastic. With that end toward you, pin 1 is on the right, pin 8 on the left, and the pins count from 1 away from you to 4, then across the chip to 5 and back up toward you to 8.
2. remove the chip from the socket. Using a multimeter set to the ohms range, measure resistance to ground. One pin will be 0 ohms (about) to ground. That is pin 4. No other pins should measure 0 ohms to pin 4. If they do, correct the wiring/soldering until this is true. You may need a magnifying glass to see solder threads.
3. Using the multimeter on ohms again, measure for 0 ohms to the wire where the +9V/battery comes onto the board. One and only one should  connect to there, and that is pin 8. If this is not true, correct the soldering until it is.
4. Insert a chip the correct way. Measure voltages, and report back here.

[rickortega]

I did not have the pin designations correct. I re-checked and pin 4 measures 0 ohms and none of the others measure 0 ohms. Also, pin 8 measures 0 ohms where the battery comes to the board.

Now, as careful as possible with a chip inserted and the battery in (10v), I get 0v at all IC pins. Visual of the solders doesn't show a bridge. However, the "eye" at pin one is gone leaving only the exposed board...obviously a defect from my original chip removal. Could this be the missing electrical link?

Thanks

[niftydog]

However, the "eye" at pin one is gone leaving only the exposed board

um... the pad is missing!?!? Ok, there's one of your major problems. No pad, no electrical connection.

A word of advice, when you quote voltages and resistances, you need to give a reference point. Like, when you say

I re-checked and pin 4 measures 0 ohms

we don't know what point you referenced pin 4 to. So are you saying pin 4 reads 0 ohms to ground? If this is correct, and pin 8 ALSO reads 0 ohms to ground, then you've got big troubles! Pin 8 is your V+ supply!

1- 8.42v, 2- 8.41v, 3- 8.02v, 4- 8.41v, 5- 8.40v, 6- 8.04v, 7- 8.04v, 8- 0v.

everything is wrong. You've virtually got the supply voltage on every pin, excpet for the V+ supply pin!!! Are you sure you put the IC back in around the correct way???

This may have fried the chip as well, so no amount of changing its orientation will help!

[rickortega]

I did measure pin 4 as 0 ohms to ground. I also measured pin 8 as 0 ohms where the +9v battery comes to the board.

I did not have the pin designations correct in my 10/22 post.

Can I repair the board and make a connection if a "pad" is gone? Can I jumper that connection to another and get a connection? Or, is the board useless at that point?

Any more help is REALLY appreciated. My DT II is dead at this point.

Thanks,

Rick

[petemoore]

I did measure pin 4 as 0 ohms to ground. I also measured pin 8 as 0 ohms where the +9v battery comes to the board.

I did not have the pin designations correct in my 10/22 post.

Can I repair the board and make a connection if a "pad" is gone? Can I jumper that connection to another and get a connection? Or, is the board useless at that point?

Any more help is REALLY appreciated. My DT II is dead at this point.
 >>The dot on the IC is next to pin 1, rotate the IC till the dot is on the left top corner....down the left side is pin 1 2 3 4...four is ground.
 >>IIUC the socket lost a lug? The little metal piece that accepts an IC pin is missing?...really this pin should be firmly soldered in place...making me think you may want to go check all connections...if a piece is falling out, there's a decent chance one of the others isn't conducting...anyway...I've stuck a lead in the socket where a lug was missing.
 since there probably solder blocking the hole, you'll have to feed a solid core wire [like 1/8w resistor lead] through the socket where the lug is missing, then past the edge of the top of the board [you may have to wiggle the wire through while the solder is hot] while heating only the solder at that pad...trim the wire just above the IC socket, and carefully insert the IC into the socket being careful not to bend the pin of the repaired socket lug, you should be able to repair it to full conductive contact this way...the other pins will hold it in place...make sure the repair wire touches the IC pin....Oh I flattened the wire too, so there would be room in the socket lughole for the wire and the pin.
  >>>Also if there's a big glob of solder, I'll touch the tip to it, get some on the tip, then 'knock it off the tip, and repeat until only some solder is left...you could use wire braid solder remover...

Thanks,

Rick

[rickortega]

Thanks, guys. All of your info helped. However, it was the continuity test that solved the problem. I had installed the socket correctly but had apparently fried severed two adjacent connections. When I didn't get a beep for two leads that had to beep, I put in a jumper and viola.

I learned a lot and hope that I didn't frustrate you guys too much as you chimed in.

Thanks again,

Rick

[cd]

Are we going to get to see pics of the top and bottom of the board?

[rickortega]

I'll try to get some pics tomorrow. I should have done it while it was apart...forgot.

[niftydog]

Can I repair the board and make a connection if a "pad" is gone? Can I jumper that connection to another and get a connection? Or, is the board useless at that point?

it depends. If there's only one connection to that pin, then yes, it's viable. But more than that and it starts to become a bit messy.

I have done that on many occasions; simply solder a length of insulated wire from the IC pin to it's destination pin. You can also solder directly to the copper track, but that's a bit more fiddly and can damage the board even more.