EPROM 27XX 25V and 21V VPP adapter for TL866II Plus TL866A & TL866CS

This adapter allows you to program old 21V and 25V  2716, 2732, and 2764 EPROMs using your cheap TL866II Plus USB programmer. You can use also for 25V EPROM with your TL866A and TL866CS.

Other programmers may work also, but I have not tested.

As you know TL866II Plus has a limit Vpp voltage of 18V (the older TL866A and TL866CS 21V), so you may have many old EPROMs that need 21 or 25V for programming. With this adapter and a external power supply (NOT INCLUDED) you can do it using your programmer.

Simply insert this adapter into the TL866's 40pin ZIF socket and select the device to be programmed with the 2 slide switches. Insert the EPROM, plug USB cable and connect the external Vpp power supply. You may need to try selecting different devices in MiniPro software, but always ensure that Vpp is at least 18V.

Be aware of fake cheap EPROMs remarked, I have found many EPROMs marked 2732A-2F1 21V that are really Fairchild NMC2732 or similar and need 12.5V for programming and Vdd write of 5.5 V.

Only compatible with JEDEC pinout EPROMs, for old not JEDEC like 2532 you need also and adapter. Texas TMS 2516 have JEDEC compatible pinout, but TMS 2716 has a different pinout and 3 different power supplies, so it is not compatible.

With some EPROMs you may need to disable the “Check ID” in the MiniPro software, others may trigger Overcurrent Protection.

New firmware versions of TL866II plus  (4.02.128 with Mini Pro v.11.90 and others) may not work with this adapter.

NOTE: Listing is for the adapter only. TL866 programmer, EPROMs and external power supply and cables are not included, shown for reference only.