Again questions on TL866ii Plus !

[Wawavoun]

Hello there,

I'm trying to do a cool little trick to program the 2716s with the TL866II Plus.

First point with an eprom directly in the device everything is fine:
1) reading ok, pin detect ok etc ...
2) writing ok by applying an external 25 V on pin 21 (pin out of the support of course), the pin detect and verification must be deactivated but after returning to 1) reading is perfect

Bend pin 21 :  it's ok once, it's ok twice ... but quickly it breaks ... hence the assembly, see pictures.

It's not complicated. We shift everything directly to a zif next to it except pin 21 which goes through a jumper that we can put in read (connected to the programmer) or write (connected to VPP). The 0V and VPP pins are used to connect the external 25V. No need to bend the leg anymore ...

Well simpler there is not ... but it does not work !!! Already pin detect not ok and fanciful eprom reading if ignored ...

I had already tried with a more complicated assembly (see here https://www.dr-bosch.com/volker/umbau/index.html) and which did not work either ... Well I said to myself there are diodes, not exactly the same references, ditto for the transistors etc... in short I did not insist ...

But there ... I tell myself that I understood nothing...
Of course everythins has been check, continuity and zif ok and no short !

If you have any ideas i'm listening.

Regards
Philippe

[Wawavoun]

Well it's always the most unlikely thing that we do not test that is at the origin of the problem !!

I first tried inserting a support (double lyres) between the assembly and the TL866 history to have more flexible pins ... Same problem!

But I observed that the faulty pins at the "pin detect" were different each time I mount - unmount the assembly from the programmer ...
Obvious sign of false contacts ...

So I sent contact deoxidizer in the zif of TL866 ... and everything works!

Also the more complicated system with diode and transitors works !!!

Here it is ... conclusion the metal of the contacts of the TL866ii Plus zif oxidizes quite easily!

Good evening everyone.
Philippe