How to remove LCD connector from IP circuit board

[ghlkal]

**updated** see post 6 for the answer (thanks everyone)

I'm trying to remove the Instrument Panel circuit board so I can repair the tach (high resistor value).

I carefully pulled up and removed the gauge connectors, but I'm stuck at trying to remove the connector from the LCD (it's the only thing holding the circuit board to the cluster). There are wires (not pins) under the connector, so I assume I should pull the white connector loose from the circuit board (arrow)


But, I can't get it to come loose and I don't want to apply too much pressure.

So, how do I get this connector off?

TIA,

Gary

[Paul Workman]

Do NOT try to disconnect the wires from the white connector soldered to the IP board (arrow pointing to it in your picture). The connection to the LCD is on the other end of those wires - the redish brown is the connector that unplugs from the LCD. See pic below!



P.

[ghlkal]

**update** OK, I got it ... my problem was I was trying to remove the circuit board without removing the white "intermediate" piece between the gauge faces and the circuit board. Once that was off, it was "easy" to pop the LCD connectors (I'll add more later)

Doh ... thanks Paul! (Yes, after looking at the white connector, it's soldered to the cluster, isn't it)

Now, I'm trying to carefully pry that reddish-brown plug from the LCD itself, but ... it's not obvious to me how do that. I'm using a plastic prybar (for dash pieces) and I can't seem to wedge it anywhere. If that's where it comes off, then I'll just try a little more force ...

[Paul Workman]

Originally Posted by ghlkal

**update** OK, I got it ... my problem was I was trying to remove the circuit board without removing the white "intermediate" piece between the gauge faces and the circuit board. Once that was off, it was "easy" to pop the LCD connectors (I'll add more later)

Doh ... thanks Paul! (Yes, after looking at the white connector, it's soldered to the cluster, isn't it)

Now, I'm trying to carefully pry that reddish-brown plug from the LCD itself, but ... it's not obvious to me how do that. I'm using a plastic prybar (for dash pieces) and I can't seem to wedge it anywhere. If that's where it comes off, then I'll just try a little more force ...

I have a few hemostats in my "kit" which come in handy for things like extracting and inserting stuff in tight quarters; that connector for one.

Lucky I just happen to have an IP cluster board sitting on a table next to me when I read your post (doesn't everyone??).

P.

[DaveK]

Originally Posted by Paul Workman

Lucky I just happen to have an IP cluster board sitting on a table next to me when I read your post (doesn't everyone??).

P.

Doesn't everyone? I usually have several...

[ghlkal]

I needed to remove the Instrument Panel in order to check two things: lamps (I thought one might be out behind the speedo, since it’s hard to see in the daytime – both worked, so I guess I have an issue with the light sensor or dimmer…), and the tach fix.

I made this harder because I didn’t take the “white” housing off behind the gauges.


Originally, I just removed the circuit board from the backside. Because of that I couldn’t really tell how the speedo LCD was attached. Once I removed the housing, I could get at that reddish-brown connector on the LCD panel itself (yes, you can see it from the top too). So, don’t try to remove the white connector on the circuit board.

You can see the connector here (and also in Paul’s image above)


How come I see other circuit boards with nice component markings on them? Mine has nothing.

For others doing this, removing the circuit board from the back means you have to remove the pins from the analog gauges which push into the circuit board by pulling/prying the circuit board off. The pins will pull out of their sockets, but they take a little prying and do it evenly as Paul’s directions indicate
http://www.zr1.net/forum/showpost.php?p=143685&postcount=4

I need to get a potentiometer tomorrow and hook it up. Now, I sure hope I didn’t mess something up on the LCD or the circuit board when I was prying on it


I would love to see the schematic of the board. When I cut off the resistor (pins 4 and 10), why not put the pot for testing (and the ultimate resistor load) there, as opposed to across C4? No, nevermind, don’t tell me – I have enough to do and if this works, that’s great

[Paul Workman]

Originally Posted by ghlkal

I would love to see the schematic of the board. When I cut off the resistor (pins 4 and 10), why not put the pot for testing (and the ultimate resistor load) there, as opposed to across C4? No, nevermind, don’t tell me – I have enough to do and if this works, that’s great

Well, the "green" side of the board IS a schematic, acutally!

The points across C4 are just a whole lot easier to access than trying to solder a resistor across the pin locations. And, there's this:

Robert touched on the need for accurate resistor values; much more accurate than the typical 5%+ found in hobby stores, e.g., Radio Shack. However, when dealing with values in the 140,000 - 240,000 range, even 1% amounts to 1400 to 2400 Ω variance. Not a problem.

By using one or more small value resistors in series, it is possible to trim the ending accuracy well under 1% of the desired value while using readily available 5% resistors IF space is available and especially in DC circuits (as both are the case in this application).

You may already know this, but for other readers that might not, zeroing in on the precise resistance value can be helped with this very simple series/parallel formula and the help of an Excel spreadsheet:

=1/((1/A2)+(1/A3))+A4

Where:
A1 = the cell into which this formula is typed
A2 = one of two resistances connected in parallel
A3 = the other of two resistances connected in parallel
A4 = the total resistance of one or more resistors connected in series with the parallel resistors.

With this formula and a VOM and an assortment package of resistors (Radio Shack sells a packet of common values), one can measure the actual values and plug the measured values into the formula and determine what the actual resistance is going to be (in this application) before actually soldering them together. Once the resistors have been selected to produce the desired resistance, they then can be arranged and soldered together in a neat (flat) little pack and then attached across C4.

All this said, the ZR-1 tach is an analog (electrical and mechanical) device, and accuracy suffers especially when rpm is changing rapidly (e.g., WOT in low gears). For that reason, a (digital) shift light is far superior for indicating when a particular rpm threshold has been reached.

Hope this helps someone...

P.

[ghlkal]

Originally Posted by ghlkal

I need to get a potentiometer tomorrow and hook it up. Now, I sure hope I didn’t mess something up on the LCD or the circuit board when I was prying on it

OK, here's an interesting story. I got the pot installed and put the instrument panel back in.

I turned the ignition on and the dash works just fine. Great. I try to start the car in order to adjust the tach ... the engine turns over but doesn't start. Oh man, what did I screw up?

I look on the dash and see SYS is flashing. Well, at least I know how to check that. It gives me a code C41 - "Loss of ECM serial data communications" That does not sound good at all! OK, don't panic. I tried reseating the Instrument Panel. Nope. What else might be different? Before I began, I pulled the airbag fuse since I was working around the steering column. I reinstalled the airbag fuse and all is well.

I adjusted my tach and shut the Z down. I think I'm going to do something else for a while. Wow, is that weird. But, I'm thankful the problem is solved.

[Paul Workman]

Originally Posted by ghlkal

OK, here's an interesting story. I got the pot installed and put the instrument panel back in.

I turned the ignition on and the dash works just fine. Great. I try to start the car in order to adjust the tach ... the engine turns over but doesn't start. Oh man, what did I screw up?

I look on the dash and see SYS is flashing. Well, at least I know how to check that. It gives me a code C41 - "Loss of ECM serial data communications" That does not sound good at all! OK, don't panic. I tried reseating the Instrument Panel. Nope. What else might be different? Before I began, I pulled the airbag fuse since I was working around the steering column. I reinstalled the airbag fuse and all is well.

I adjusted my tach and shut the Z down. I think I'm going to do something else for a while. Wow, is that weird. But, I'm thankful the problem is solved.

So, you were able to dial the tach calibration in, yes? Congratz! The resistor on the ceramic substrate must have completely opened, or something, to have given you such an unusually high error %. (Sorry 'bout the "oh sheeeiiiiitttt!!!" moment! Think I would have had to go away to collect my thoughts after a moment like that as well!)

Good job!

P.

[ghlkal]

Originally Posted by Paul Workman

Good job!

Thanks! Yes, the calibration worked well. It looks like about 220K ohms will do the trick for me. I don't care if the tach is dead-on, but 70% error was weird. I need to learn how to drive again with the tach - before I was hitting 7K easily on the tach (which was really something less than 4K on the motor).

BTW, I measured resistance across pins 4 and 10 and got about 390K ohms. Since you have several IP's laying around - if any are good - what value do you get there?

Now, I need to get up the courage to pull the IP out again ... I wonder what code it will throw this time