Hi Gabriele, I had not seen your comment until yesterday when a good old friend asked about where he could find my repair article about the DY294 meter. About Diodes D4-D8, if they are not drawn in the circuit they probably were not there in the device. But keep in mind that I did not draw the complete circuit. Almost everything but mainly the most important part of the DY294 circuit to be able to fix most defects and to understand how the device works. It indeed looks like you first need to replace your Q1 transistor to test if that makes your LCD come to life. If it does most likely your 44 pins DMM chip is still fine and you again are a happy working DY294 owner.

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I wasn't sure that the device would be very sensitive to the voltage, but I didn't want to take a chance. That's why I passed on cheaper wall warts and chose the ones that I bought(not to mention how hard it was to find 6V chargers). Then I checked them to make sure when they arrived in the mail. I've bought 4 of them, and they all check good. I gave one to my friend Michelle for her blood pressure monitor.

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Understood Robert. The Wall Adapters (2A and 3A DC) I bought from Ebay and Aliexpress were a bit higher in Voltage. Even with the DY294 attached as load. But it seems the DY operates without problems at higher voltages around 6.5 Volt DC.

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I'm glad the scopes have worked out well for you! The wall warts that I bought for my tester, and to use with other devices, are regulated pretty good and only output 6.24V with no-load. So far they have worked very good.

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The Dremel Tool is also usable like my Kinzo for grinding off the smd chip I think. But this as I wrote only needs to be done if the V+ and V- voltage checks out fine and the SC9013 transistor is not defect by an unattended overvoltage on the 6V DC input powerjack on the DY294. In case the Chip still would not work and the LCD would not display it could be the SC9013 that normally provides the V+ and V- to the chip. But in case of the 4 tested replacement AME7106ackw QFP44 chips in my article it was of course the defect or fake chips themselfs! I was glad to mention your very well documented and correct described Tektronix 2465a Lithium Battery replacement article Robert! (And thanks to your good article I now own a Tektronix 2465a and also a Tektronix 2440 500Ms/s Memory scope! Because after repair I bought the 2440 from my good friend Frans).

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No worries Robert. Understood ! My fault. I wrote so much to read and show I guess it is harder not to miss the little details.

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Thank you Yogesh! Indeed a hobby always involves a lot of time and also some money. Especially in the Electronics Department so to speak. But in the end the effort was all worth it.

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