Do you have an HP 4261A LCR meter with a bad ROM? If so, this is the part you need. The ROM chips in this popular LCR meter have a nasty tendency to fail and until now no replacements have been available, but with this part it is a simple matter of unsoldering the original and soldering in a replacement. Absolutely no modifications to the instrument are required.
Please specify during checkout if you want the replacement display ROM, P/N 1818-2271A or the replacement control ROM P/N 1818-2272A so I can program the replacement correctly.
If you are not sure if your LCR meter has a bad ROM you can easily test the original ROM chips in your meter using my EPROM programmer universal adapter. For more information, please see the product here.
If you are interested in the story behind the development of these parts you can read my blog post about it here.
Download the schematic and PCB layout for this product here. Note that these files are available for PERSONAL, NON-COMMERCIAL USE ONLY. In short, you are welcome to use them to build this product yourself, but you must contact me to work out a commission if you wish to sell anything derived from them. This product was designed in ExpressPCB so you will need to download a copy of that software from expresspcb.com before you can view the files.
CHAN WENG CHOY –
Great job after reading your post “Developing reproductions for the ROM Chips in the HP 4261A LCR Meter”
I wonder you could help me fix my HP 4261A LCR Meter .. it displays fixed garbage on the 7 seg display upon power up.
I believe 1 of both the display ROM (1818-2271A) and the control ROM (1818-2272A) . Used to have Apple 2 rom programmer card .. had discarded .. Would you able to program these 2 chips at your convenience .. The meter has been dead for many years .. no hurry .. I’ll compensate for your time & parts.