Need a reasonably priced DVA - Suggestions?

[Steve2ManyBoats]

A recent wrestling match with my Merc 2.5 200 ignition system showed me that a DVA could have made the diagnostic process much easier and quicker. I'm in the market for a reasonably priced DVA. Don't want any junk but don't necessarily need industrial quality since it won't be used daily.

Found this Sierra unit on Amazon - http://www.amazon.com/Sierra-International-18-9801-Marine-Tester/dp/B002IVEERO

Any opinions on this DVA or suggestions for a better choice.

Thanks...Steve2ManyBoats

[h2oskiier30]

If you already have a good multimeter, you can buy a DVA adapter for about 1/3 of that price.

[Go Time]

I have the CDI multimeter and DVA adapter kit, it works great and was reasonable for the quality. H2o is right, if you already have a good VOM, all you need is the adapter. Someone on the board a while back posted insrtuctions on how to build your own...... if you really feel froggy :eek:

[pyro]

Good lord... Looks like I'm going to have to build some DVA adapters soon. Something that plugs into the top of an ordinary Fluke-style VOM tester between the test leads and the unit. Everybody already has a good voltmeter, it's just the DVA part that reads the peak voltage that makes it a necessary tool for troubleshooting ignition systems.

[j_martin]

All it is is a diode and a capzapiter.

[wired247]

http://www.tooldiscounter.com/ItemDisplay.cfm?lookup=ESP640&source=froogle&kw=ESP640

Its cheap, it works and it wont get broken in the bottom of your tool box.

[pyro]

Like jmartin said, there's not much to it. A rectifier diode, a high-voltage capacitor to hold the peak value, and ideally a small resistor to discharge the cap after you unhook it so you don't get jolted.

The value of the capacitor depends on how much your voltmeter "loads" the circuit.

[Euroski]

Why not just buy a good FLUKE meter and be done? Most have min/max function.

[flabum1017]

Here's the schematic... get the parts at radio shack.........

304671

[wired247]

Why not just buy a good FLUKE meter and be done? Most have min/max function.
I have 5 flukes. None of them are fast enough to pick up peak on a stator except my oscilloscope.

[pyro]

Here's the schematic... get the parts at radio shack.........

304671

Radio Shack does not carry capacitors rated above 50-100 volts.

It would be foolish to not put a 1 Meg ohm resistor across the output side, to slowly discharge the capacitor when you're done using it. It's not wise to leave lethal voltages charged up sitting on your bench. A high-current 300 volt DC shock can stop your heart.

The diode should be 1N4007, just to play it safe..

The min/max function is not ideal for every purpose, especially if you're troubleshooting an intermittent issue. You need to be able to watch the peak value rise and fall. This is why it's best to use a 1 uF to 2.2 uF capacitor. Some online diagrams specify a 22 uF, but this value is too high. It puts a strong surge load on the diode when it first gets charged, and it takes forever to come back down from a stored peak value, it will literally take several minutes to register a 100 volt drop in peak voltage value.

...Or just spend $25 and get the adapter linked above.

[Steve2ManyBoats]

I have a good digital VOM. Just to be clear, will the adapter work with a digital VOM or do I need an analog meter to check the sweep?

Thanks...Steve2ManyBoats

[Go Time]

Mine is digital, works fine....

[CharlieN]

I have a good digital VOM. Just to be clear, will the adapter work with a digital VOM or do I need an analog meter to check the sweep?

Thanks...Steve2ManyBoats
Digital, the adapter does the conditioning so the meter can capture the peak.

The analog has value when watching a sweep from say a throttle sensor.

[powerabout]

there are times when a dial ( moving coil) meter works better than a digital and this is one of them
( I guess i am still waiting for the min max button though?)

[Steve2ManyBoats]

Thanks so much for the great advise folks. Just ordered up a DVA adaptor from Tool Discounter.

Steve2ManyBoats

[mackeral5]

Don't forget a good pair of piercing probes, makes life a lot easier, especially when working on johnnyrudes....