Can the Instrument Cluster be Hard-Wired?

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midlife

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Jeff73Mach1 kindly sent me a 71 standard dash cluster for an experiment: can the crappy circuit card be eliminated and the dash cluster hard-wired for greater reliability?

I don't believe anyone has attempted this, so I'm going to attempt it. The dash cluster has 14 bulb sockets, two posts for the fuel gauge, and contacts for the constant voltage regulator (snap-on clips). I'm kind of surprised that the cluster is basically all lamps, and I was planning on using the snap-in 2 wire sockets used in 64.5-68, which I have a ton of. So...I tried fitting them in, and nope...the holes in the dash cluster are too small. I know the cluster uses 194 bulbs, but every catalog says that the 1895 bulbs are used for the instrument cluster for 71-73. WRONG! There's no bulb chart in the 71 FSM that I could find for the instrument cluster, so I went to my Wiring and Vacuum Diagrams that the service technicians used: yup...194 bulbs.

OK...there's many sockets for 194 bulbs, but the instrument cluster sockets are fairly unique, as there are no wire pigtails, just contacts to the circuit board. OK...they lock into place...1/2" in size. Does anyone make a replacement with pigtails? After spending 1.5 hours Googling, I think I found a replacement locking socket, and they should be here by the end of the week.

For the CVR, I plan on replacing the 71-73 version with the 66 version which has spade lugs.

I'll take pictures as I start working on this, and with luck, I should have a working dash cluster by the end of the weekend. I have a 12V power supply so I can actually test everything on the bench.

If successful, I'll then figure out if it is economical to do this, and if so, what the costs might be.

This should be interesting! And thanks, Jeff!

 
From our short experience here I would say if anyone can make this happen it would be you. Anxious to see your progress

 
I can see hard wiring the back of an instrument cluster if you can find

the bits like you say with the bulbs.

I'm curious about finding a multi pin plug to use with it to

make unplug-able for removal ?

Do you have a source for multi pin generic plugs as this info would be valuable to me?

Appreciate your efforts and information!

Paul

 
I have "kinda sorta" hard wired the cluster on a 68 Torino by jumping directly from the harness to the bulbs that were not getting current from a very rusty and separated printed circuit board.

20 years later they all still work and it still looks like spaghetti behind the dash.

Bet yours will look much better.

- Paul of MO

 
I can see hard wiring the back of an instrument cluster if you can find

the bits like you say with the bulbs.

I'm curious about finding a multi pin plug to use with it to

make unplug-able for removal ?

Do you have a source for multi pin generic plugs as this info would be valuable to me?

Appreciate your efforts and information!

Paul
Yeah, that's not a problem. Molex still makes multi-pin connectors that were used up to 1968 (and also the connector for the 71-73 center 3 gauge harness). I have a male/female 12 pin plug set, just right for the standard cluster. The tach cluster uses less pins.

 
Do you have a source for multi pin generic plugs as this info would be valuable to me?
As Midlife mentioned, Molex still manufactures a variety of connectors. They have been around for a long time and are an industry standard. I used to just drive down to Radio Shack and pick up what I needed, but looks like I'll be using Amazon more, now:

http://www.amazon.com/s/ref=sr_in_-2_p_89_29?fst=as%3Aoff&rh=n%3A172282%2Cn%3A281407%2Cn%3A172532%2Cn%3A172544%2Ck%3Awire+connectors%2Cp_89%3AMolex&bbn=172544&keywords=wire+connectors&ie=UTF8&qid=1423577566&rnid=2528832011

You can get a variety of connectors, including weather proof, at auto parts stores:

http://www.oreillyauto.com/site/c/search/Wire+Terminals/N2160/C0335.oap

http://www.summitracing.com/search/department/ignitions-electrical/part-type/wiring-connectors-and-pigtails/universal/yes?N=4294951516%2B4294947819%2B4294951518

 
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yes it can be done, it is a lot of wires and connectors.

you might want to make a wiring manifold and attach it to the backside of the cluster then wire everything off that. basically you end up breadboarding the PCB board. the manifold is going to have to be placed carefully so that it does not interfere with the the dashboard frame or other items behind the cluster.

another option is coping the pcb mylar onto a proper copper etched board part of the issue is the mylar pcb board is deformed easy and the copper contacts pop off the plastic, if you used thin copper etched board then you could even reuse the original light sockets. otherwise using a hard board as opposed to a soft board will increase reliability because you will have a proper place to hard solder wires onto and use that as the wiring manifold.

now there are also special liquids you can brush onto the Mylar PCB to increase conductivity and stop oxidization at contact points.

you can use model train rail treatments like: Aerocar Rail cleaner and conditionar.

http://achlubes.com/

or rail zip.

http://www.amazon.com/Pacer-PT23-Rail-Zip-1oz/dp/B0006O8EKS

you brush these on contact points let then dry back a little then install the connections. they protect long term against oxidization much in the same way dielectric grease does. aerocar actually increases electrical conductivity, where the others install a air/copper barrier.

if the contacts are clean at connection points then you will not have a reliability issue even over time.

 
Rather than using a wiring manifold or creating another PCB board, I plan on using wired lamp sockets, spade leads, and 90* slip-on connectors that were used in earlier years. Yes, there will be a lot of wires going to a connector and a mate will have to be created on the underdash harness side to mate with it. This was a very reliable design for Ford, but they wanted to go high tech in 1969 with PCB's. Little did they know that flexible PCBs were unreliable over the long run.

Examining the PCB board on the dash cluster Jeff sent in, it appears that there are traces that are not used in every application. I think that for 1971 (the cluster I received), the circuit board was designed for both the standard dash alone and the standard dash/3 center gauge cluster connector.

I realized I didn't order enough lamp sockets this AM. Probably a good thing as I'm not sure they will work. Rather than going all-out on my first attempt, I think it would be wiser to do a feasibility run. I can test everything but not all at once. If it looks promising, I'll re-do it with more attention to detail and wire lay-outs to make everything cleaner.

One thing I don't have a good feel for is how much room is available back behind the dash cluster for the wire pigtails and connectors. Also, after undoing the speedo cable, how far can you pull out the dash cluster to disconnect the connectors? The style I'm looking at may require two hands. I'm hoping that one can rotate the entire dash cluster face down onto the steering column and connect/disconnect things a bit easier.

 
Things were frustrating this past week as I focused upon finding the right bulb sockets with wires. The original company held up my shipment because they did not have all 10 in stock and failed to contact me. After a few days, I e-mailed them and got them to send what they have, but they won't arrive until Monday. I found another possible source on Thursday, posted next day FedEx, but that is also Monday. Found a third source this morning, and the bulbs will arrive sometime next week. All three sources have different bulb sockets, so I'm hoping at least one will work.

Spent this morning confirming the wiring traces on the circuit card, finding one trace broken. This allowed me to identify all socket functions, which are fairly obvious by looking at the front. I then converted the physical layout to an electrical schematic. Found three traces not used, they are circled in red in the following two pictures.

The first picture shows two contacts, one for fused power and the other is ground, which I think is for a center clock, only used in 1971 with a standard dash and 3 gauge center cluster.

clockQ.jpg


The second image compares the actual dash cluster connector to the circuit card side. The trace circled in red is not found on the standard dash cluster, but its function is to transfer the CVR output to the 3 gauge cluster.

connector.jpg


I then removed the circuit card and cleaned things up a bit.

cleanback.jpg


I then ordered 16 pin molex connectors for connecting the dash cluster harness to the underdash. I then fitted a 65/66 CVR to the back of the dash, but realized that that unit doesn't use the resistor wire to reduce the voltage. It is also expensive: $20. To save money, I'm figuring it is better to re-use the existing CVR, but that uses battery snaps.

Next frustration: the battery snaps usually come in a pair to mate to a 9V transistor battery, but the CVR's contacts are much wider apart. I finally found individual male and female wired battery snaps, but everyone wants a minimum order of 100. Screw that...I bought 9V battery snaps that I can cut apart into single wires. So far, I'm estimating the parts costs to be about $4 but that's without the 14 bulb sockets, which range from $1.40 to $5.00.

So...I do have some questions before continuing, and that'll be in another post.

 
Good news! I received one of my three shipments of bulb sockets, and this set works! Although each bulb socket is $2, that drives the material costs of the conversion to near $30.

The excellent news means that this conversion is entirely feasible; now the question is how much effort it will take and thus how much it will cost. I'm excited! Say good riddance to those nasty crappy flexible circuit cards.

 
Congrats as well!

Thought...

I'm just concerned about average Joe cutting off original

cluster connector and attaching new multi-pin connector

correctly, that phase is out of your hands.

As always we all appreciate your efforts!

Paul

 
Congrats as well!

Thought...

I'm just concerned about average Joe cutting off original

cluster connector and attaching new multi-pin connector

correctly, that phase is out of your hands.

As always we all appreciate your efforts!

Paul
I would be supplying the connector already wired; the owner would just have to match wire colors and splice his existing wires.

The conversion would be much better when tied to an order to refurbish the underdash.

 
MidLife-

I was thinking about your project, and was wondering if you checked how the Dakota Digital units are wired? Wold be interesting to see what tech they use....

Good luck wit the next steps!

Butch

 
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