Thread: 1988 C4 Corvette

Originally Posted by rdholtz

You might hook a speaker or a set of headphones to the Audio Out port, and listen for beep codes.

That's one of those, "why didn't I think of that" suggestions. Great idea. I tried it and had no beeps.

So I decided I needed to see what was going on inside and built a plexiglass lid. It turned out great and if I weren't concerned with RF interference from the PC I'd keep it.
Here's a picture:


I clamped the plexi between two pieces of wood along the bend lines and then clamped whole thing in my vice. I then applied pressure while I moved my plastic welder back and forth along the bend line. As soon as it got to the right temperature it bent and then I let it cool in place.

Interestingly, the computer still acted exactly the same as with the metal lid!

This tells me a couple things. The metal lid wasn't causing any short, the wires aren't getting bent out of shape, and the memory chip isn't getting displaced.

I did another test and started the computer with the lid off and then slowly put the lid on. As soon as the lid was on the computer shut down. But it gave me a clue. The computer actually started hibenating before the power shut off completely. This made me think something was going on with the on/off switch from the PSU. So I removed the wire from the PSU to the mother board on/off pins and used a separate manual switch.

Voila, the computer runs! But I have to turn it on/off manually.

So that confirms the cables are good and airflow isn't causing the problem (although it still needs better airflow)

I ran out of time last night but I plan on taking a closer look to see if there is something shorting the on/off line to ground on the PSU. There is a rivet in the vicinity. I'll drill that out and see if it is the culprit. It might even be the metal case itself. One of my coworkers noticed from the picture that the case may be bowing when the lid is on. Perhaps it's touching somewhere.

I appear to have the M4 working stably now, but I can't explain why exactly. Since my last post I tried a bunch of things. I removed the rivet, no help, I moved the psu away from the walls at least 1/2", no help. I cut out more of the case around the battery cable connections, no help. So finally I started thinking it was either a problem with the PSU or my shortened cable. The FAQ on the M4 has a lot of old posts where people upgraded their firmware and solved similar problems. I had no idea what version my firmware was so thought maybe I was shipped an old unit. I couldn't find any appropriate cables at Fry's to connect the USB so I could run the M4ATX utilities. I ended up having to make my own. It isn't pretty, but I just wanted it for testing. Here's a pic:


Now here's the surprising part. I thought I'd have to jump through some hoops to get the computer running long enough for me to run the utilities, instead it booted right up, even with the metal lid on! The utility says I have version 2.0 of the firmware which surprised me because I thought they were only up to version 1.3


I went back and forth about half a dozen times removing and connecting the USB connector from the motherboard and it never failed to start with the USB connected. It always failed with the USB disconnected.

I'm not thrilled with the prospect of losing one of my 8 USB ports but I might be able to get away with it. I'll have to take a look at what I plan on connecting and make sure 7 ports is enough.

Now I just have to make a cable that isn't so hideous looking!

This power supply problem derailed me for so long I have to regroup and remember what I was going to do next. I'll keep you posted.

Ron

I guess I'm becoming a little obsessive about cable management since there are so many wires in such a small space. The 18" SATA cable was definitely in the way. I was seaching on the internet looking for a shorter cable with a right angle connection facing the right way and I stumbled upon this youtube video
http://www.youtube.com/watch?v=H_RT-5Mgluo

It's one of those simple cheap mods that's just plain elegant.

Here's a picture of it in my case: ( I may have to edit this later, I appear to be having problems uploading pictures right now )


The next thing I did was take your advice and increase the airflow in the case. I enlarged the exhaust holes in the lid and added a lot more holes in the sides of the case. I was using the M4 ATX monitoring program to see how hot things were getting and before I added the holes it was getting up to 50c and now doesn't go above 32c. Of course it's still sitting on my desk and isn't nearly as restricted as it will be in my dash.

Then, I hooked up cables to power my llliput from the M4. I originally was going to use an M sized power plug as suggested in the FAQ and the cables I was going to use were just to big to solder to the plug. So I was looking around for some smaller wire and realized, I'll never use the cigarette lighter adapter that came with the lilliput. So I cut off the wire and connected the bare ends to a molex connector and plugged it into the power supply via one of the open hard drive plugs. That worked great and now the monitor starts up when the computer starts up.

I did something very dumb. It was getting late and I wasn't paying attention to what I was doing and I removed the lid with the power supply, but forgot to shut off the power. I bumped the 12 volt -in against the case and saw a spark and it even stuck to the case a bit.

Well it turns out I killed my power supply. I was hoping I just blew the fuse, but it's intact. I used my power supply tester and I'm getting nothing from it. I can't see any burned out components so I don't know what actually blew. Luckily the PC is ok. I can run it off my desk psu just fine, whew!.

Now I'm trying to figure out my options.
1. If I knew which components blew I could replace them.
2. Maybe Mini-box can repair it?
3. Buy a new one.

Do you have any other options?
How about which components are the likely candidates for replacement?

I went to bed fuming last night; how could I be so careless?

Ron

As I mentioned earlier in this thread I decided to build one of the 41hz Amp9-Basic amplifier kits. Here's a link to my building experience:

I finally got around to building a box for it and decided to include a couple of goodies. I pulled the circuit board from the ground loop isolator out of its case and installed it in the box with the amp. I also added a micro relay to control the mute function with the "anti thump" capability of the power supply. Here are some pictures:

As with the PC case I decided to mock this up in cardboard
You can see the ground loop isolator and relay


I wired in some RCA jacks for the input, and 3.5mm jack for the mute function.


Speaker connections


I need to keep it cool so I'll convert this CPU heat sink


It's too big so I'll cut it down


That fits much better. Time to make the case out of metal


Testing the amp in the metal case. All the connections are labeled so I won't forget what goes where.


I tested the anti-thump using a 12-volt signal from two lantern batteries


I needed some speakers so I pulled two out of the back of my car and two off my home stereo.
The amp stayed nice and cool. I was a little concerned because the car speakers are 2 ohm and the stereo speakers are 6 ohm. I'm not sure if that's bad for the amp, but I won't listen this way for very long.


Now I have to figure out what I'm going to do next. I think I'll mod to the directed radio to automatically raise the power antenna using the procedure I found on this forum. (I hope I can find it again!)

Ron

So I was going to do the mod on the Directed radio to make the output antenna hot to raise the power antenna. I only want the antenna up when I'm listening to the radio though and it turns out that the radio is turned on as soon as RideRunner starts. This means the antenna would be up all the time which I don't care for. So I began looking at controlling the antenna through software and ended up compiling a small C++ program I found on the net I can use to turn the parallel ports on/off using command line commands. I then started working on a circuit to trigger a relay. I found several designs via google and started building it, but now I'm rethinking how I want to do it. My antenna already uses a relay to turn on/off and it didn't make a lot of sense for me to use a relay to power a relay so I'm thinking of shortcutting the whole circuit design. I need to do some experiments and think this through so I'm turning my attention elsewhere for now.

Ron