Printed circuit board

[Her69fastback 3]

I need to replace the printed circuit board on the mustang. I burnt mine up. Who makes a good one to get? I’ve searched there’s a lot of them out there. Thanks for the help

[Brian Conway 264]

I got one from Mustangs Unlimited in 2009.  Brian

[bigmal 225]

I replaced mine with an aftermarket one and still had problems. Ended up with a replacement from Midlife. It really is a big improvement and with the length of the harness it's easy to troubleshoot instrument panel issues as you can pull the panel out a considerable way while it is still connected.

http://midlife66.com/harnesses/products.html

[Midlife 814]

It turns out that a majority of the problems revolve around the gauges not working.  Rays69mach1 reminded me that when you remove the circuit board, you have to remove the nuts holding the gauges in place.  The gauges can move around and the posts can inadvertently contact the metal case when you install the new circuit board and tighten down the nuts.  When any of the gauges get grounded, they all get grounded to a certain extent, so it is best to check continuity between each gauge post and the metal backing.  You should not see resistance below 100 kilo-ohms.

[bigmal 225]

11 minutes ago, Midlife said:

It turns out that a majority of the problems revolve around the gauges not working.  Rays69mach1 reminded me that when you remove the circuit board, you have to remove the nuts holding the gauges in place.  The gauges can move around and the posts can inadvertently contact the metal case when you install the new circuit board and tighten down the nuts.  When any of the gauges get grounded, they all get grounded to a certain extent, so it is best to check continuity between each gauge post and the metal backing.  You should not see resistance below 100 kilo-ohms.

Yep, exactly the issue you helped me with.

[1969_Mach1 333]

In my experiences with repro parts (other than sheet metal), there are generally one, maybe two mfgs. for any given part.  So it generally doesn't matter where you purchase it.  Most all suppliers will sell the same thing.  I got mine through NPD.  Works fine, no strange issues.  

[69ShelbyGT350H 61]

54 minutes ago, 1969_Mach1 said:

In my experiences with repro parts (other than sheet metal), there are generally one, maybe two mfgs. for any given part.  So it generally doesn't matter where you purchase it.  Most all suppliers will sell the same thing.  I got mine through NPD.  Works fine, no strange issues.  

Good to hear about the NPD ckt board. I have mine, just have not finished cleaning up the gauge cluster enough to re-assemble it. 

[Guillaume69 150]

New printed circuits work fine but as mentioned above, it takes patience and finesse to set them properly. Everything ties down to centering everything carefully when tightening the gauges nuts so that the threaded studs don’t ground on the metal frame, as Midlife explained.

G

[Midlife 814]

I just got a new circuit board from NPD for a customer who was having problems with his dash cluster.  The CB has a different design: the traces are now solidly within the lamination, and only exposed where the lamps and gauges are applied.  A much better design.  I have not seen this type before... Anyway, I installed the new CB and after futzing with the gauge nuts, I finally got everything to work as expected. 

[ralt962 11]

On 5/8/2018 at 5:59 PM, bigmal said:

Yep, exactly the issue you helped me with.

Ive install a new CB but didnt realize there was a level of finesse needed to reinstall the gages.  My turn signals and brake warning light I know work, but it seems my cluster lights are not working.  Would they not work if the gages are grounded as described?

[Midlife 814]

7 hours ago, ralt962 said:

Ive install a new CB but didnt realize there was a level of finesse needed to reinstall the gages.  My turn signals and brake warning light I know work, but it seems my cluster lights are not working.  Would they not work if the gages are grounded as described?

No.  Dash lamps on completely different circuit than gauges other than sharing a ground.

[smh00n 87]

I just replaced my circuit board with a Scott Drake one.

My dash lights and the indicator lights now do not work (but the brake fail is lighting up when cranking - go figure) and none of the engine gauges are working; oil, temp and gas. I'm not sure if the dash lights worked before but the oil, temp and gas did.

How can a dummy work out if the nuts/posts are in the right spot?

Interior lights work on the light switch btw

[Midlife 814]

Measure resistance from the post to the chassis ground: should be about 14 ohms if they are not touching the metal. 

[smh00n 87]

On 5/28/2018 at 9:13 PM, Midlife said:

Measure resistance from the post to the chassis ground: should be about 14 ohms if they are not touching the metal. 

I've got 16. Is that in tolerance?

[Midlife 814]

Perfect.

[smh00n 87]

And now I have working gauges.

 

But, the oil pressure gauge is pretty slow to react; it slowly comes up to pressure and not really moves when revved from idle.

I have 4.8V at the gauges so the regulator is working.

Is the slowness of the gauge normal? I will be putting a pretty good engine in this and don't want to know after is blows itself to pieces the oil pressure was low or off.

Am toying with a set of New Vintage Instruments for it, or are the Dakota ones better? A 6 dial dash would be neat but I don't know I want 5" speedo and tach

[Midlife 814]

Gauge response is fairly slow, but you can best judge their response with your gas gauge.  All gauges are the same with different face plates.  I found with my 66 that gas would not read fully correctly until about 45-60 seconds after starting, but almost correct within 10 seconds or so.

[ralt962 11]

Between chassis ground and the gauge post I'm seeing between 2 and 8 ohms.  Looks like they are grounding out.  

the 100K ohms mentioned by Midlife is for the stud to gauge case?

[Midlife 814]

2 to 8 ohms is a bit too low; most gauges have resistance on the order of 12-16 ohms.  Check both posts: if one is 2 to 8 ohms, the other might be 0-1 ohm and that indicates that that particular post is grounded.  You should see at least 10k ohms if everything is not grounded/touching.  The ammeter posts should not read anywhere close to 10 ohms to ground; they should be much higher than that. 

[ralt962 11]

Interesting, just working on this.  I can tighten one stud and keep the resistance in the 100K+ range, but tightening the other brings it down to the 2 ohm range.

Is there supposed to be a rubber or plastic washer under the nut?  Mine has a copper wavey washer.  Seems that grounds it out.

[Midlife 814]

There shoulld be a cardboard-like plate, about 1" x 3" with holes for the studs that acts as an insulation barrier.  Yup, you need to get rid of that metal wavey washer and get something else.  Some stiff rubber might work; for my bench work I use thin cardboard, but I don't have to worry about water leakage destroying the cardboard. 

[bigmal 225]

9 hours ago, Midlife said:

There shoulld be a cardboard-like plate, about 1" x 3" with holes for the studs that acts as an insulation barrier.  Yup, you need to get rid of that metal wavey washer and get something else.  Some stiff rubber might work; for my bench work I use thin cardboard, but I don't have to worry about water leakage destroying the cardboard. 

Will this picture help?

[Midlife 814]

Perfect picture of the insulating pads.  They are not reproduced...

[RPM 1,190]

So bigmal posts 2, not 1 but 2 pics of his huge Makita block grinder, and not one word from you people. Sheesh! Bigmal, I have some major envy happening.

[ralt962 11]

2 hours ago, bigmal said:

Will this picture help?

Thanks Bigmal.  Perfect picture.  Exactly what I needed.  I thought something wasn't right  I can get something to work there.

 

Nice bench grinders! and what looks like the parachute guy in the background!

 

thanks for all the help!