I forget that there's a "like" feature on this forum. I only have flux paste in the house and by the time the soldering iron melted it, it was too late for me to realize I put too much. I'll put up a YouTube video soon of my whole process 😀.

 

Well... Here's my YouTube documentation...

Part 1: Cluster Removal

Part 2: Tach Repair

I didn't record the part where I removed flux.

And I would appreciate it if you guys like, comment, subscribe and share!

 

Billy,

Well done on the video! And a very special thanks for the credit in your videos too! BTW, I like your JDM spec radio unit. How long have you had it?

Wow, that was a lot of flux!

I have a couple of recommendations during the soldering steps.

1. Use a small amount of flux per solder joint.
2. Work with one solder joint at one time.
3. Clean off flux then move on to the next solder joint.

This will take longer for an amateur behind a soldering iron. Most veteran solder technicians (I am not one) have plenty of experience working across a row of solder joints like that. The reason why I recommend those 3 tips is to prevent solder bridges. A solder bridge is a glob of solder that accidentally connects 2 solder joints. This condition could cause a malfunction of the IC chip, cause temp/permanent damage to it, etc...

In the case of IC1 on the tach board, these solder joints are positioned much closer together than a typical DIP (IC Chip). So when excessive flux, a strand of solder, a shaky hand, and tightly quartered solder joints come together, they make a recipe for a solder bridge.

I didn't see any solder bridges in your video, I just want to create awareness because that can easily happen.

I also want to point out that IC1 has no known replacements. If it gets damaged then the only way to replace it is through cannibalization of another tachometer.

Another tip about soldering IC chips (others may disagree): an IC chip is designed to be soldered twice - once during installation and a second time during its removal. The reason why it should only be soldered twice is because ultra-fine wires connect the legs of the IC chip to the dye. Repeated or excessive heating and cooling cycles may cause these ultra-fine wires to break, like a light bulb filament.

With that said, I re-flowed solder joints to IC chips in the past with good success. If I have to touch up the solder joint then I wait until that area fully cooled down and keep the applied heat from a solder iron down to less than 2sec of contact.

Most of this advise should be covered in my general soldering thread but in case it wasn't and while on topic, it's a good idea to reiterate some highlights specific to soldering IC chips.

Once again, good work on your video and I'm happy to hear that your tachometer works!

 

Thanks! Yea, I'm still a beginner when it comes to this, the only time I touched a soldering iron was a failed PFC repair and just soldering pickups for my guitar(s). I made sure no solder bridges were made and you're right about the tight space and flux (I found out later that this could happen as the flux melted...)

The radio is a NB Miata radio, with the Sylfex Aux-In Mod (hides behind the cover which used to be a cassette deck). Added a Bluetooth receiver to Aux-In and the car is now modernized.

 

Well, just wanted to update. I've had a chance to take my cluster out and re-flow the solder on the IC1 chip. I installed it and the tach is still intermittent. Through reading what you've been saying (Gen2n3) about the IC1 chip and it being so delicate, Im wondering if I was a bit too delicate and didnt get the solder to re-flow properly. I didnt want to apply too much heat like you said and melt any internal wiring etc. That being said, i'll try again.. however, rather than having to remove/install/run my car to see if the repair worked, would there be some sort of way to bench test the tach? that way I could see if it was all good before installing it in the car for the 10th time. Plus im sure the ribbon board on the back of the cluster is taking some abuse from connecting/disconnecting etc. any thoughts/ideas?