This is my second LeCroy scope, bought in Austria for EUR 3000 on 7th June 2020. I became sort of addicted after buying and using an LT344. I try to write here some details of the story of refurbishment and repairs. I assume it worked really much in it's previous life which I guess based on a single fact that according to the S.M.A.R.T. data of the HDD it had nine years worth working hours. Let's see my issues in more details.

Calibration failed during startup

I had noticed this only after buying and switching it on at home the next day. It did not happen at every switch-on, and sometimes last longer, tried many times, and sometimes it ended with strange traces without input signal.
After a few weeks of investigation I figured out, that the phenomenon was caused by the power supply. The ECL circuits involved in calibration signal generation did not receive proper -5V. Of course one of my first ideas was to check the power supply voltages, but I did it after some time of warming up, when this negative supply reached a more or less correct value. I created a holder fixture for the front panel assembly, so it could be flipped up for easier in-circuit measurements. After providing some place on my desk for the good old LT344 I could began to analyze the calibration signals during the booting process. It turned out soon, that the negative supply of the ECL chips was significantly insufficient at the beginning and slowly increased after. From this point it was easy to find and replace the corresponding capacitor in the PSU. There are very good quality capacitors in the PSU, I do not recommend changing them all. You'd rather find the defective one if there is any.

Cooling fans

The cooling of these scopes are very important. Much heat produced in a relatively small and crowded box. The fans have to be able to blow out the heat, otherwise the scope may become damaged. Mine had pretty much working hours, and at least some of the fans were probably replaced during it's previous life. However they appeared to be noisy. The noise of airflow is one thing, but I suspected that the bearings also produce extra noise due to their age. I made a simple device for evaluating the fans:
A tube with a passive fan (magnet removed) on one end, and the fan under test at the other end blowing the air into the tube. There is an optical sensor on the passive fan, for measuring something which gives no exact measure but at least somehow proportional to the air blown. I removed the three fans (PSU, acq board, system) and tested on this device. I was surprised at how much the airflow increased when I replaced the bearings in the fans originally found in the scope. It was about 30%! You can see some data in this table. The airflow readings are from my testing device, suitable only for comparison.

I also purchased several types of fans from several sources with theoretically similar specs, but almost all of these new ones produced less airflow comparing to the used ones extracted from scope. The reading of the fans coming from Aliexpress were more or less under 180, so I did not even include them in the table above.
The worse were the ones purchased from aliexpress with different labels. None of them fulfilled even it's own specification. Finally I found ORION FANS OD7015-12HHB01A at Mouser which appeared to be in the same league, so I have put these ones to the scope.

Display backlight

The CCFL backlight had a bit low but still usable intensity, however I decided to replace it with LEDs. It was quite easy. After releasing a plastic lock, the CCFL assembly could be pulled out from the LCD. I had ordered two pieces of suitable LED assemblies from aliexpress to have a spare also, who knows, how long this may last. After removing the CCFL tubes from the metal piece I fixed the LED bar into it using a tiny stripe of double sided adhesive tape, and two drops of silicone adhesive on both ends.
The original inverter received 12V DC supply and nothing else. I could get a connector of the same shape as on the CCFL inverter, and applied it to the LED inverter to be able to connect it without ruining the original cable. The whole thing fits in the place of the original CCFL inverter. Also put a trimmer potentiometer for intensity adjustment and drilled holes for it on the aluminum covers.
The result is an even, intensive backlight, which consumes about half the power comparing to the original. Maybe the color temperature is a bit cooler than ideal, but I do not really care of absolute color fidelity, I have other devices for watching photos...

Front panel

Coming soon


I read somewhere (maybe Steve wrote on EEVBLOG?) that those handlebars which are not black may broke. I was happy with mine, because it was sort of black. But not black enough.

Once when I put the scope into it's carrying box, the handle had just been broken. The scope was almost in the box, which was soft inside, so nothing really happened. I asked my local LeCroy dealer at ELSINCO Hungary, if they could give me a quote on the handlebar. They told they will try but not sure they will succeed. But finally they and LeCroy did.

I received the real black handlebar, which is a cast aluminum piece, and of a very clever design, made of two halves to be installed separately and screwed together in place. And I received it for free. Thank you LeCroy, thank you ELSINCO!