testing testing 1,2...aww crap

[dodgedifferent2]

just wondering how i can test the dash lights on the bench?

anybody have a way that will work? i heard 3 D cell batteries ..... will that be enough juice to light em up?

 

[69.5CUDA]

got an old pc power supply?..certainly you have a car battery..or a charger....3 D's willl NOT be enuf as thats only 4.5v maxx!!!....

you need 12 small batterys if you want to test that route.....as that will add up to about 12v

another option to consider and im willing to bet you have some around...look at your phone power suply..or any device that has one of those lil boxes that plugs into the wall and has a lil 2 pin end...you will often times find most are in the 9-14v range..and will say on them what they output as well as if the center is ground or power...most cordless phones are 9vish....most game system power supplys are generaly 12ish....but that should give you some ideas of where to look right?

 

[Dr.Jass]

A standard battery is 1.5V, be it AAA, AA, C, D, etc. Dash lights are 12V but will light with much less. They'll just be dim, that's all.

However, if you're going to test the gauges themselves you will want to use only 3 batteries since other than the ammeter, tach, and speedo ALL classic Mopar gauges operate on 5V. 4.5V is enough if you're testing them individually; if you're running through the original connections on the cluster you'll want 12V because of the regulator.

It isn't that hard to convert a PC power supply to provide both a 12V and 5V output--that's what they do, but to use them as a power supply modifications are required. Simply hooking one to your cluster won't do a damned thing... there's not enough draw to keep it switched. Audio amplifier "dummy loads", used for testing, are great for keeping them on but you lose a bunch of wattage in the process. My best luck has been with specialized resistors.

 

[69.5CUDA]

you jump the purple wire to ground as i recall to force switched...and they actualy do 3.3, 5, 9 and 12 for outputs...i have one setup for all 4 so i can do led testing as well as anything else i need...oh and rechargeable batterys are generaly 1.2v

 

[Dr.Jass]

You need to have a constant load on the 12V output of a PC power supply to keep it engaged. I've never seen a 9V output on a PC power supply, but I only have about 12 of them here, one or two going back to pre-AT days and others set up for SATA drives.

Max forward voltage of 95% of LEDs is only 1.6-1.8V. Push 3.3V through them and they go off like a leetle tiny firecracker. Some of the high-brightness ones allow for more voltage, but those still aren't common.

Every rechargeable battery I have (about 16 in all), both NiCad and NiMH and be they AAA or AA, are 1.5V. Some of those batteries date back to the early '90s.

 

[69.5CUDA]

no you dont have to have a load on it..trust me on this ive converted and burned out more than i can remember..from testing units to car sterio amp drivers...the old load required on the non integrated on/off switch wired units(im not talking the main power on the back but the old days wired switch units) can be done by a single jumper of what i remember being the purple wire on the main connector..that is the same as the load.....