Replacing a Power Adapter for a Microtek Scanmaker 4800



This is just a glimpse of the kinds of things I get to do day to day… A week or so ago I had a client that had received a used scanner from a friend. The scanner was a Microtek Scanmaker 4800. I was a bit concerned as her pc still has Windows 98 and I recall very many long hours of hair pulling making USB scanners and Windows 98 work years ago. Fortunately though, the driver cd was included in the bag their friend had passed along. The install process went smoothly, but there was one little detail missing.


If you read the title of this post, you know what, the power adapter. That little black “wall-wart” that takes power from the outlet and actually causes the scanner to run. I have lost track of how many devices I have now that have these ac-dc adapters. In the last few years I’ve collected a box for the leftover ones. For when a network switch fails, or a device that uses batteries comes with the ac/dc adapter. All of those situations I wind up stowing it in “the box”. According to the bottom of the scanner it accepted 12V 1.25 amp input only.

So, I told her I would have to look and see if I could find a replacement and revisit. The first stop I made at home was “the box” to see if there was a suitable match, but of course, no. It seems every device uses a different voltage. (One note on voltages…. always always try to replace adapters like this with a voltage that is as close as possible to the rated voltage. 12V in this case is necessary, 13 technically might work. I have a tendancy not to trust these adapters and test them with my meter first. (Many adapters rated at 5 volts may actually put out 7 volts… Generally less voltage could cause the equipment to not work properly, too much could actually burn out components. (A small percentage more should be okay, but as always you should try to match the rated voltage.)

The amperage is a situation where you need at least the rated amperage. More amperage is ok because the device will only draw what it needs. In this case I gave a call to the local Radio Shack to see if they had a 12V adapter that put out that many amps. They did in fact have a 12V, 1.5 Amp adapter which sounds like it would work.

Now, as you know, every electronic device ever made uses a different size barrel connector. One of the correlaries to murphy’s law must be that if you have a power adapter it will not match the jack. Radio Shack has the “adapt a plug” system which means they have the barrel plugs separate from the power supplies (which is excellent.) Fortunately, there are a few more common sizes, B and M are the most common (I had 2 M’s and a B already for some of my equipment.) In this case I didn’t have the device with me when I went to radio shack. (Always a good thing if you’re able to take the device with you.)

So, I opted for the next most popular plugs that were a close match to the size of the power jack on the scanner. K and N were the next most common plugs that looked as though they would match. So, I got one of each.

The bottom line is the adaptaplug tip K with a 12 V adapter is what I used. The fit seemed fairly snug and it seemed as though the scanner performed as it should. When I connected the 12V adapter, adapt a plug K and Microtek Scanmaker 4800 up, it power up and the computer recognized it as a new device. After that a test scan seemed ok I labeled the bottom of the scanner with the adapt a plug size (just in case we needed to replace it again.) By the way, the tip is positive on the adapter.

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