4 ms·
In case of sensitive HF inputs (eg. oscilloscope inputs) there is not much you can do about protecting them from overvoltage without significantly harming sensi
by dfox 17y ago
In case of sensitive HF inputs (eg. oscilloscope inputs) there is not much you can do about protecting them from overvoltage without significantly harming sensitivity or bandwith. In most cases such things are designed such that something relatively cheap blows up and can be easily replaced. But that something is usually input amplifier itself (overvoltage protection diodes that are fast enought tend to be more expensive and will also burn out so they are not used). It is worth to note that input amplifier transistors are cheap compared to whole scope, not compared to anything you would call cheap.
But miniaturization (and also precision requirements) tend to make replacing such things extremely labor intensive, so it might be more cost effective to simply throw the whole thing away.
- Retric 17y agoThis seems like the type of thing you would have some sort of replacable card for. Assuming it's a fairly common problem.
- dfox 17y agoMany components of oscilloscope have to be physically close (because of delays, signal loss and interference) to input (ie. on same card) and in case of small 2-channel scope it can easily be third of whole scope (and more than third of price). Larger scopes tend to have replaceable cards for inputs, but such scopes are too large (and of course expensive) for most applications.
- CamperBob 17y agoThere are actually several ways in which LeCroy could have protected the input against moderate overvoltage and ESD, such that repairs could be made without replacing the input hybrid. If nothing else, the guy could buy another half-dead scope on eBay for a couple hundred bucks, fix his bad channel, and have a near-complete parts donor left over for future repairs. If he's the sort who's afraid of replacing the battery in his iPhone, he has no business monkeying with oscilloscopes and such anyway.