Any experiences here with failing 28F010 28F020 flash memory

[prutser]

I was applying a well known software change to an 1995 HP network analyzer, which has an AM28F020 flash chip. Bought a TL866ii plus programmer (not used before)
I had to reprogram the chip a couple of times, to try something and after approx. 10 times, I experienced verify errors at various places.
Later the programmer even reported "programming errors" before the verify. I would not expect this, because at least 1k erare cycles must be possible. Ok
maybe chip is bad after so many years for some reason.

Ordered another chip (CAT29F020) programmed it, the first time verify errors. Always the same bit (byte LSB b0) which stays at '1'
The address is kind of repeating.

0x7C
0xFC
0x17C
0x1FC
...

Might be something wrong with an address line (programmer or PLCC adapter)

Programmer selftest: OK

PLCC 29F010    No problems
AT28C64          No problems


Is this really bad luck, both 28F020 flash chips having issues ?  Any experiences here with failing flash behaviour ?

[amyk]

If there's a way to slow down the programming speed, I would try that first.

You can use an oscilloscope or logic analyser to look at what the signals are like.

[TheSteve]

I would bet on it being a bad contact on the adapter.

[prutser]

Today I received 2 new flash chips.

1st  The programmer reported "pin error" and could not read device ID
2nd  I was able to program it 2 times, after that the same as with the first one

The flash chip from 2 days day before: I could still to program it, but with verify errors at fixed address offsets.

Then I hooked up the programmer to a laptop, so  it was battery powered. Measured Vcc and Vpp with scope.

Vcc 5V and Vpp 12V, which is according to the datasheet. Vcc was a bit noisy during programming. I added 100NF capacitors between Vcc/GND and Vpp/GND on the PLCC/DIP adapter. 

After this I was able to program the flash which had the verify errors at least 3 times (did not try more, because I had what I wanted)

So the reliability seemed to be related to poor decoupling.

Left me with the other issue, which bothers me:

1. CAT28F020 which at first use in the 'TL866ii plus' reported pin error and could not read ID  (tried/swapped several times)
1. CAT28F020 which was programmed 2 times successfully, after which it came into the same state as #1
1 AM28F020   which was programmed 3 times successfully, after which it came into the same state as #1

So those 3 devices look un-usable now.  I have a feeling that the programmer does something the IC's do not like.

[gmilliorn]

I have one, and gave up on using it to program GAL22V10's.  It ruined several of mine to the point where
they were un-erasable, while others were fine.  Some people report no problems at all, others report
the same, which leads me to conclude it is one or all of:

- The SW has data-dependent bugs,
- The SW doesn't/can't handle minor process variations (22V10A vs. 22V10D vs. etc)
- The HW has subtle voltage/timing issues

There's probably a good reason DataIO had close ties with vendors and issued updates far more
frequently than Autoelectric can.

I got a Wellon VP299, which is a lot more expensive than the TL866, but it hasn't given me problems yet and
it was cheaper considering how many 22V10's I wasted.
--
So, rant aside:
1) do you have access to any other devices, particularly DIP w/o an adapter needed, that work
   when programmed?
2) Is the USB cable decent?
3) Reading the ID value requires high voltage, you mentioned VDD was noisy but what about 12V?

[narkeleptk]

Maybe your tl866 is a bad one. I have an original tl866 and a newer tl866II and they have never let me down or had any issue's like what your experiencing.

[BrokenYugo]

Maybe your tl866 is a bad one. I have an original tl866 and a newer tl866II and they have never let me down or had any issue's like what your experiencing.

These things are supposedly heavily counterfeited, not saying the genuine ones are perfect, but it's something to consider. I made a point of buying mine from a factory recommended source and the only problem it's given me for the couple dozen chips I've run through it (various flash and 12 volt eproms) is it occasionally spits out a pin detect error if the chip is centered in the obviously and understandably fake 3M socket, slide to one side before locking down and it's all good.

[CaptDon]

Recently it seems many people have bought the cheap chinese knockoffs from ebay. They are junk and absolutely don't function correctly. I guess there is a reason why the ebay price varies so much.