Overhead Console Computer

I also found out the grid voltage comes from a pair of resistors connected to a L4812 regulator. The filaments also source their power from elsewhere on the board. I thought the display driver was responsible for that, but I guess not. So that means I have no idea if the display driver is functioning at all! I mapped the pinout of the display driver. I upload the picture tomorrow. There's 3 pins that connect to the microprocessor, and they each have about 3 volts on them.
 
I'm gonna go ahead and guess that's a SPI or I2C bus, but I could be entirely wrong. If you hang an oscilloscope on em, what do you see at around 50uS to 1uS and 1V/div settings?

I didn't even think about exposure time on the picture, I'm not much of a photography person :dunce: PBS cameras (Push Button, Stupid!) are about as advanced as I get with my picture taking.
 
Alright. I've been pretty busy between the holidays and having a cold. I just got around to messing with this PCBs again. I don't have access to an o-scope right now, so I couldn't run the test that you suggested.

I had one board that looked perfect, with the exception of a burnt ceramic capacitor.. specifically the one that connects to the quartz crystal. The crystal itself had signs of electrolysis on the metal casing, so I assumed it had failed and took it's companion capacitor with it.

On that board, I replaced all 4 ceramic capacitors, all the 100uf35v caps, the 220uf16v cap, and the 4MHz quartz crystal. Powered it up... nothing. Thinking the display driver chip might be bad, I lifted it off with my hot air pen and transplanted one from a working ZJ computer (same chip). Still nothing. I tried one last thing, which was replacing the voltage regulator with a newer part that had the same specs. I powered the board up, and the F/C segments on the VFD lit up for about 1 second, and I couldn't get it to happen again. Got frustrated with this board and pushed it aside.

Here's where things get interesting. I have a Rev. E board which had been dead, but I haven't tried to repair yet. The Rev. E is almost exactly the same as the more common D, but it has a 3-pin ceramic quartz crystal, and no 4th ceramic cap. I plugged this board into my power supply and it came on! Compass worked and temperature display was dead on at 66 F. However after a minute or two it started to act funny. The temperature changed to -61 F, but when you switched to Celsius it said -50 C, which doesn't even convert right.. WTF? Then it got even further into the negatives. Thinking the temp sensor was bad, I switched it out for another. When I unplugged it, the display said OL as it should, but the new sensor still read -115 F. After a couple minutes went by, a couple other segments in the VFD lit up that weren't supposed to be active. When I pressed the comp/temp button to turn the display off, those segments got dim, but were still on.

It seemed like something was overheating, but nothing was really hot except for that damn voltage reg which I could barely touch. I took my hot air pen and gently heated different parts of the board looking for a change in behavior. I passed over the ceramic crystal and the display flashed 2x as bright. I went back and warmed it up a little more and the display got bright again, and then it flickered, and then shut off. Letting it cool for a few seconds and power cycling the board would get it working again, although the temperature was still wrong (+95F this time).

If I let the board sit and cool down to room temperature, it starts up and works fine again, and then it goes bezerk.

I'm assuming that this poor voltage regulator placement and inadequate cooling is what kills these boards. I think the ceramic crystal on this one board is on it's way out, and I don't have any on hand ATM to replace it. I don't think it should be that sensitive to heat. If I had an o-scope in front of me, I could really see what's going on with it. I think the frequency is unstable and the microprocessor is having a conniption because of it. Maybe the metal crystals on my D boards failed and caused irreparable damage to the processor? If that's the case, I'm SOL because I can't even find evidence of these Motorola ICs even existing.

I'm going to order some of these 4MHz ceramic caps and update my progress here. If you have any ideas in the meantime, feel free to share.
 
Crystals can be fairly sensitive to heat but I'm not sure how sensitive. The crystal (depending on whether it's parallel or series resonant) requires "loading capacitors" commonly in the range of 1-25 picofarads from each pin to ground, which I think are the ones you're talking about. A 3 pin crystal typically is actually just a 2 pin with a ground pin for the can included. There are also ceramic resonators, which typically have a ground pin as well as the 2 active pins, and have somewhat different temperature coefficients and available frequency ranges.

I'd try replacing the caps that connect to the crystal wiring if they are looking crispy or chemically destroyed.

And yeah I agree on the heat. Usually what kills electronics is heat, overvoltage, reverse voltage, or dried up electrolytic capacitors.

I believe that's just a linear voltage regulator, which is why it gets so damn hot. Converting 13.8 volts to 5 volts by just dumping the extra power as heat (your heat dissipation will be (13.8V - 5V) * current output, plus a little bit) is very very inefficient. A modern design would use a switch mode power supply rather than a linear, but back in '87 implementing those for every embedded system in a vehicle was a fairly pricey proposal and switchmode converters were nowhere near as efficient or cheap as they are today. It shouldn't be too difficult to retrofit with a switch mode converter if you wanted to - might have to put a daughterboard in to make it fit well, though. I'd start with an LM2575 Simple Switcher(r) and the 3-4 support components it requires if you want to take that route. There are probably others available that are more efficient (the LM2575 is usually around 77% efficient, a significant improvement over a 5 volt linear in this case, which is around 36% efficient!) but that's the first one that comes to mind.
 
I know that this is an old thread but I have now fixed a bunch of these things and thought I should update with more detail.

Electrolytic Capacitor failures. This is the big one and has been covered extensively in this post but I want to add that I have been using the high temperature capacitors at this link with better long term success:


http://www.mouser.com/Search/ProductDetail.aspx?qs=9rQVDmoPMIQrjoUI1ogLLg==

The isolating capacitors are available at this link:
[FONT=&quot]

[/FONT]
[FONT=&quot] http://www.mouser.com/ProductDetail...=sGAEpiMZZMuMW9TJLBQkXsjX9hJVC7r9GotYpTs8phg=

2) Clock issues. I am finding that the later rev's of the board use a different clock as shown in the pics below. The newer ones (blue in the pic) fail VERY easily so I recommend replacing them with a standard 4MHz crystal as I have done in the second pic below.



[FONT=&quot]Note: the old crystal has three pi[FONT=&quot]ns w[FONT=&quot]hile the new one only has two but don't worry about it, just connect the new one to the two outer holes and leave t[FONT=&quot]he center one ([FONT=&quot]ground as Karsten noted[FONT=&quot] earl[FONT=&quot]ier) disconnected.[/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT]

The new Crystal is available at the link below:

[/FONT]
[FONT=&quot] http://www.mouser.com/ProductDetail...=sGAEpiMZZMsBj6bBr9Q9aew7Ki0pGAG0ES4bPHSHRXY=


When you go to replace the capacitors, I find it easier to connect the isolating capacitors from the bottom as shown in this pic (I use some shrink tubing on [FONT=&quot]leads that could contact other solder join[FONT=&quot]ts)[/FONT][/FONT]:


Also check:

1) the trace that connects the CPU to the display chip runs through the "hot zone" and often breaks. You can easily check it from the backside with a meter by testing the the points where I have connected the blue wire. If you measure an[FONT=&quot] open circuit,[/FONT] this needs to be repaired and I recommend using the jumper wire at the link below (insulation can handle high temps)


2) the trace that connects the 220uF capacitor to the display chip is also in this area and can break. Test by connecting your multi-meter between the second set of points below and repair as necessary.



The wire I recommend is available at this link:
[/FONT]
[FONT=&quot] http://www.mouser.com/ProductDetail...P7B8cvTVWw==&gclid=CNyhk7iM-84CFQEOaQodfwcMxw

With these changes, I have been able to fix every board I have seen. Grand total cost from the sour[FONT=&quot]ce abo[FONT=&quot]ve comes[FONT=&quot] to $14.4[FONT=&quot]9 and all repairs can be accomplished with a basic soldering [FONT=&quot]iron.[/FONT][/FONT][/FONT][/FONT][/FONT]

HTH
Todd

[/FONT]
 
tjmotter said:
The Problem

First, the area that typically gets fried sits around a 5volt regulator which is highlighted with a white arrow in the picture below. From what I am seeing, the cause of failure always seems to be one (or all) of the electrolytic capacitors highlighted in the blue boxes. This makes sense because electrolytic capacitors tend to last a LONG time but what can kill them is heat and sitting next to the roof of an XJ for 20 years is a pretty sure way to accelerate their demise. The problem is that when they blow, they take other components (and traces) with them. The 3 small ceramic capacitor to the right of the voltage regulator (numbered 1-3 in orange)are prime targets for this. These 3 capacitors can actually be removed since they aren't really needed in this circuit but I will include a section below on how to change them out if you prefer.

Power Circuit
The real issue is that when the electrolytic capacitor blows, these little caps get really hot and often cause some of the traces to break. The one highlighted in red is often bad and this one is very important since it is what provides the ground signal to two of the electrolytic capacitors. To test this, turn the board over and connect a mult-imeter (set to ohms) between pin 3 of the regulator and the negative pole of each capacitor (marked with the white bar and a "-" sign on the sides of the capacitors). When you connect your meter to these points, each should read close to 0 ohms.

CPU Reset Circuit
The other trace that tends to get burned up is the one that connects pin 2 of the regulator to the CPU. This pin provides a 4.6-4.7v reset signal to the CPU and if it is broken, the CPU won't turn on. The best way to check this trace is to use your multi-meter again (still on the ohms setting) between pin 2 of the regulator and pin 5 of the CPU (both ends highlighted with the yellow arrow). When you connect to these you should also get a reading of close to 0 ohms.

The Fix

If both of your multi-meter tests are good, you should be able to simply replace these three capacitors. All 3 are 100uF 35V capacitors and are available online or from places like Fry's Electronics. Typical cost is ~$1.50 each (3 needed).

Power Circuit fix
If you found a broken trace between pin 3 and the negative poles of the electrolytic capacitors, the easiest fix is to turn the board over and solder a wire between pin 3 (ground) of the regulator and the negative pole on one of the new electrolytic capacitors. This essentially re-attaches the connection I highlighted with the red line in the pic. Here is an easy trick: rather than looking for small wire, simply use some of the excess wire you will cut off the bottom of the capacitors and slide some heat shrink tubing over it. This will insulate the wire to keep it from touching any other part of the circuit.

CPU Reset Circuit fix
If you found a broken trace when you checked the connection between pin 2 of the regulator and pin 5 of the CPU, the fix is a little harder. The break is usually on a small trace that runs right between the orange 2 and 3 in the pic. If you look closely at the pic, there is a small solder spot directly under the orange number 3. What this hole does is connect the trace on the top of the board to another trace on the bottom of the board. If you connect your multi-meter between this solder blob and pin 5 of the CPU, it should read 0 ohms and if so, I typically turn the board over, heat up this blob and feed a small wire through it. I then attach the other end of the wire to pin 2 of the regulator (using heat shrink insulator again).

Burned up ceramic capacitor fix
This fix isn't really necessary since the board will work perfectly without these capacitors but if anyone wants to change them out, they are all 100nF and can be replaced on the backside of the board with traditional ceramic capacitors. These cap's are simply used to try to protect the voltage regulator when something goes wrong. I have numbered them in the pic and the connect as follows:

#1 - connects between pin 2 of the regulator and the positive side (opposite of the side marked with the white bar and "-" sign) of the middle electrolytic capacitor.
#2 - connects between pin 2 and pin 3 of the regulator
#3 - connects between pin 3 of the regulator and the positive side (opposite of the side marked with the white bar and "-" sign) of the right-most electrolytic capacitor.






tjmotter said:
I know that this is an old thread but I have now fixed a bunch of these things and thought I should update with more detail.

Electrolytic Capacitor failures. This is the big one and has been covered extensively in this post but I want to add that I have been using the high temperature capacitors at this link with better long term success:


http://www.mouser.com/Search/ProductDetail.aspx?qs=9rQVDmoPMIQrjoUI1ogLLg%3d%3d

The isolating capacitors are available at this link:
[FONT=&quot]

[/FONT]
[FONT=&quot] http://www.mouser.com/ProductDetail...=sGAEpiMZZMuMW9TJLBQkXsjX9hJVC7r9GotYpTs8phg=

2) Clock issues. I am finding that the later rev's of the board use a different clock as shown in the pics below. The newer ones (blue in the pic) fail VERY easily so I recommend replacing them with a standard 4MHz crystal as I have done in the second pic below.



[FONT=&quot]Note: the old crystal has three pi[FONT=&quot]ns w[FONT=&quot]hile the new one only has two but don't worry about it, just connect the new one to the two outer holes and leave t[FONT=&quot]he center one ([FONT=&quot]ground as Karsten noted[FONT=&quot] earl[FONT=&quot]ier) disconnected.[/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT]

The new Crystal is available at the link below:

[/FONT]
[FONT=&quot] http://www.mouser.com/ProductDetail...=sGAEpiMZZMsBj6bBr9Q9aew7Ki0pGAG0ES4bPHSHRXY=


When you go to replace the capacitors, I find it easier to connect the isolating capacitors from the bottom as shown in this pic (I use some shrink tubing on [FONT=&quot]leads that could contact other solder join[FONT=&quot]ts)[/FONT][/FONT]:


Also check:

1) the trace that connects the CPU to the display chip runs through the "hot zone" and often breaks. You can easily check it from the backside with a meter by testing the the points where I have connected the blue wire. If you measure an[FONT=&quot] open circuit,[/FONT] this needs to be repaired and I recommend using the jumper wire at the link below (insulation can handle high temps)


2) the trace that connects the 220uF capacitor to the display chip is also in this area and can break. Test by connecting your multi-meter between the second set of points below and repair as necessary.



The wire I recommend is available at this link:
[/FONT]
[FONT=&quot] http://www.mouser.com/ProductDetail...P7B8cvTVWw==&gclid=CNyhk7iM-84CFQEOaQodfwcMxw

With these changes, I have been able to fix every board I have seen. Grand total cost from the sour[FONT=&quot]ce abo[FONT=&quot]ve comes[FONT=&quot] to $14.4[FONT=&quot]9 and all repairs can be accomplished with a basic soldering [FONT=&quot]iron.[/FONT][/FONT][/FONT][/FONT][/FONT]

HTH
Todd

[/FONT]
Click to expand...
First, thank you VERY much for updating this thread. It's perfect time because I was at the point where I wanted to try and fix my own console.

Before I go tearing into mine, I thought I'd ask a few questions.

Referring to both your previous posts:

Power Circuit
Is it best to go ahead and replace the 3 electrolytic capacitors while I've got it apart, even if the test between pin 3 of the regulator and the negative pole of each capacitor results in 0 ohms?

I've already purchased both the high temperature capacitors from Mouser. I'm assuming it would be best to use the 150c models over the 105c, if I feel like attempting them?

CPU Reset Circuit
When I test between pin 2 of the regulator and pin 5 of the CPU I get 68.2k ohms.
When I test connect between this solder blob and pin 5 of the CPU I get the same reading.
Should this reading be 0 if the trace is broken, or 0 if the trace is intact?

Are the blue isolating capacitors meant to replace the orange #'s 1,2, and 3 in the first picture? If so, do I need to remove the originals or does it not matter since they're being bypassed?

Does it matter which way the [FONT=&quot]4MHz crystal is installed?[FONT=&quot] I don't see any markings on it, so I'm as[FONT=&quot]suming not. [/FONT][/FONT]
[/FONT]
Click to expand...
 
Last edited:
hidperf said:
tjmotter said:
First, thank you VERY much for updating this thread. It's perfect time because I was at the point where I wanted to try and fix my own console.

Before I go tearing into mine, I thought I'd ask a few questions.

Referring to both your previous posts:

Power Circuit
Is it best to go ahead and replace the 3 electrolytic capacitors while I've got it apart, even if the test between pin 3 of the regulator and the negative pole of each capacitor results in 0 ohms?

I've already purchased both the high temperature capacitors from Mouser. I'm assuming it would be best to use the 150c models over the 105c, if I feel like attempting them?

CPU Reset Circuit
When I test between pin 2 of the regulator and pin 5 of the CPU I get 68.2k ohms.
When I test connect between this solder blob and pin 5 of the CPU I get the same reading.
Should this reading be 0 if the trace is broken, or 0 if the trace is intact?

Are the blue isolating capacitors meant to replace the orange #'s 1,2, and 3 in the first picture? If so, do I need to remove the originals or does it not matter since they're being bypassed?

Does it matter which way the [FONT=&quot]4MHz crystal is installed?[FONT=&quot] I don't see any markings on it, so I'm as[FONT=&quot]suming not. [/FONT][/FONT]
[/FONT]
Click to expand...

Happy to help. Answers in order:

Is it best to go ahead and replace the 3 electrolytic capacitors - ABSOLUTELY. One of the primary causes of failure in capacitors is heat. That area gets hot so even if they seem to test ok, they are likely near the end of their life.

high temperature capacitors- since this area gets hot, high temp caps will last longer. Note that they tend to be quite a bit bigger so you may have to get creative (lay them on their side for example) to get them to fit. The 105 degree ones will work and you will probably get another 15 years out of them.

When I test between pin 2 of the regulator and pin 5 of the CPU I get 68.2k ohms. - You should be getting a reading close to 0 which would confirm that the trace is perfect. You may want to add a wire on the bottom to ensure a good connection here.


Are the blue isolating capacitors meant to replace the orange #'s 1,2, and 3 in the first picture? - yes. I would remove them but it shouldn't hurt anything if you leave the old ones in.


Does it matter which way the [FONT=&quot]4MHz crystal is installed? - shouldn't matter but if you look closely [FONT=&quot]the crystal [FONT=&quot]should have some light pri[FONT=&quot]nting on it. I usually place the printing side faci[FONT=&quot]ng away from the LED display simply so that I can see it. I should add that[FONT=&quot] on one of the boards where I added a new crystal, I had some issues. The reason was that a new crystal puts out a really strong si[FONT=&quot]gn[FONT=&quot]al so it was necessary to add a small capacitor (47pF) to get the cir[FONT=&quot]cuit to work properly (only with [FONT=&quot]the [FONT=&quot]new crystal). [/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT]I[FONT=&quot]f you look [FONT=&quot]closely you will see that the old crystal had 3 pins while the new one has 2. The center pin ties to ground so [/FONT][/FONT]I simply soldered[FONT=&quot] thi[FONT=&quot]s capacitor between [FONT=&quot]that point and the pin closest to the center of the board. It now works perfectly.

[FONT=&quot]I have do[FONT=&quot]zens of these 47pF capacitors so feel free to send me a note and I will mail [FONT=&quot]a couple to you. I can also post a pic of the working board if you would like.

[FONT=&quot]My last offer would be that I have 3 good boards at the moment so if you run into tr[FONT=&quot]oubles [FONT=&quot]ping me and I will swap with you.

[FONT=&quot]HTH
[FONT=&quot]Todd[/FONT]
[/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT]
Click to expand...
 
i never got the 2 compasses i had working. i ended up swapping a Grand Cherokee console into my renix jeep.and that worked for a bit then it was stuck on calibrate. turns out it needs a speed input on the ccd bus. so a little creative ingenuity and i have an ecu from a 95 Cherokee under my back seat with it tapped off of the speed signal from the tpu. the speed signal that the transmission puts out is not the correct type so vehicle speed is about 1/3 slower than actual speed but at least the compass works for now.

at some point i'll build some kind of arduino based compass and temperature display
 
They can be a bit of a bear, particularly if the traces fry. As you can see from that one pic, I even went so far as to remove the chips so that I could figure out where the traces were supposed to go. Fortunately I have the equipment to resolder surface mount devices so it wasn't too hard to do. The most common fault is broken ground traces but as you can see from the pics, I have found broken data traces as well.
 
tjmotter said:
hidperf said:
Happy to help. Answers in order:

Is it best to go ahead and replace the 3 electrolytic capacitors - ABSOLUTELY. One of the primary causes of failure in capacitors is heat. That area gets hot so even if they seem to test ok, they are likely near the end of their life.

high temperature capacitors- since this area gets hot, high temp caps will last longer. Note that they tend to be quite a bit bigger so you may have to get creative (lay them on their side for example) to get them to fit. The 105 degree ones will work and you will probably get another 15 years out of them.

When I test between pin 2 of the regulator and pin 5 of the CPU I get 68.2k ohms. - You should be getting a reading close to 0 which would confirm that the trace is perfect. You may want to add a wire on the bottom to ensure a good connection here.


Are the blue isolating capacitors meant to replace the orange #'s 1,2, and 3 in the first picture? - yes. I would remove them but it shouldn't hurt anything if you leave the old ones in.


Does it matter which way the [FONT=&quot]4MHz crystal is installed? - shouldn't matter but if you look closely [FONT=&quot]the crystal [FONT=&quot]should have some light pri[FONT=&quot]nting on it. I usually place the printing side faci[FONT=&quot]ng away from the LED display simply so that I can see it. I should add that[FONT=&quot] on one of the boards where I added a new crystal, I had some issues. The reason was that a new crystal puts out a really strong si[FONT=&quot]gn[FONT=&quot]al so it was necessary to add a small capacitor (47pF) to get the cir[FONT=&quot]cuit to work properly (only with [FONT=&quot]the [FONT=&quot]new crystal). [/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT]I[FONT=&quot]f you look [FONT=&quot]closely you will see that the old crystal had 3 pins while the new one has 2. The center pin ties to ground so [/FONT][/FONT]I simply soldered[FONT=&quot] thi[FONT=&quot]s capacitor between [FONT=&quot]that point and the pin closest to the center of the board. It now works perfectly.

[FONT=&quot]I have do[FONT=&quot]zens of these 47pF capacitors so feel free to send me a note and I will mail [FONT=&quot]a couple to you. I can also post a pic of the working board if you would like.

[FONT=&quot]My last offer would be that I have 3 good boards at the moment so if you run into tr[FONT=&quot]oubles [FONT=&quot]ping me and I will swap with you.

[FONT=&quot]HTH
[FONT=&quot]Todd[/FONT]
[/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT][/FONT]
Click to expand...


Awesome! Thanks for the info. I'm hoping to attempt this before the weekend if my other project gets finished.

I'll let you know how it goes.
Click to expand...
 
tjmotter said:
They can be a bit of a bear, particularly if the traces fry. As you can see from that one pic, I even went so far as to remove the chips so that I could figure out where the traces were supposed to go. Fortunately I have the equipment to resolder surface mount devices so it wasn't too hard to do. The most common fault is broken ground traces but as you can see from the pics, I have found broken data traces as well.
Click to expand...

the one of the ones i had would intermittently work. then i did the ground cable upgrade and it didn't like that. lasted 2 days after.
 
90xj06 said:
the one of the ones i had would intermittently work. then i did the ground cable upgrade and it didn't like that. lasted 2 days after.
Click to expand...

I had 1 with the same issue (intermittent). Turns out the clock was bad. A new crystal (with the 47pF cap I mention below) fixed it.

HTH
 
Yes it can. If the CPU doesn't get a clock it has nothing to display so the screen stays blank.

HTH
 
Does anyone have a definitive interchange list of what these units were in?

I gave mine a shot at repairing but no luck. I'd like to check my local yards this weekend.
 
hidperf said:
Does anyone have a definitive interchange list of what these units were in?

I gave mine a shot at repairing but no luck. I'd like to check my local yards this weekend.
Click to expand...

Not a definitive list but I have found them in early '90's XJ's as well as in the same era Chrysler and Dodge Minivan's.

As I mentioned in an earlier post, I would be happy to exchange one of my working boards for your old one. Net cost would be shipping to/from Houston.

Send me a PM if you are interested.
 
Thanks for this, Todd. I got smoke from my second board the other day and wonder about repairing it. Since I need a few things from Mouser/Digikey, I can add a few things to the order and maybe get the board fixed. Don't recall what I did with the other board I swapped out, maybe it is around somewhere.

I'm looking forward to knowing it is -50°C or F outside until the module settles in on the temp and I just add 180° to the compass setting to know which way the Jeep is headed.

Maybe I need to find that ground cable upgrade info, get in there and fix some stuff. The radio only works when hot. Seems it does everything except power the speakers. Might be a connection coming loose, like the pass power window. About time for these to have electrical issues.
 
For those of you who might want to take a shot at changing the crystal, as I noted below, if you use a new crystal you will find that the board may not turn on and if it does (it may turn on after a minute or so), it will be flaky. The technical reason behind this is that a new crystal will generate a sine wave with an amplitude of 0.5mv which is too high for the control chip to sync off of. The trick is to add a 47pF capacity (as I noted below) to the circuit to bring that amplitude down to 0.3mV-0.4mV. At this level the board will work perfectly. Below is a pic of where to put this capacitor. They are pretty cheap (32 cents) and the one at the link below should work. As I said earlier, I have 50+ of these so if you would like, just send me a PM and I will mail a couple to you.

http://www.mouser.com/ProductDetail...EpiMZZMsh%2b1woXyUXj%2by1qj0MYuBIwPLqFvQbIiE=

 
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