eprom is out of a '7747. I like to zero out them out before they go into my eraser. However this one cannot be written to, which leaves me afraid that if after it is erased, it will not be writable. (currently it has has factory 1990 5.0L TBI image)
When flashing these 7747's 27c32, any special voltages needed? Never had this issue before but I know there are some older eproms who require high voltage to burn.
Any thoughts?
1990 GMC C1500, 5spd, 1993 LT1 (ECM 16159278 $DA3)
Why not try erasing it first, then read it, to see that it is erased?
The man who says something is impossible, is usually interrupted by the man doing it.
Well right now it's a working computer/eprom that I'm selling here on the forum. I'll ask the buyer if he's ok with me trying this, with the warning that I might not be able to write to it again.
I dont have another 27c32 to spare.
1990 GMC C1500, 5spd, 1993 LT1 (ECM 16159278 $DA3)
Ok, if you're selling it, why are you trying to erase it? huh.gif
The man who says something is impossible, is usually interrupted by the man doing it.
He asked to make a small change and trying to be nice, I stupidly said no problem. I'm communcating with him now though and it doesn't seem to be deal breaker.
Just seeing if there was anything special to know about for these particular eproms.
Last edited by bentrod; 08-08-2013 at 09:05 AM. Reason: added the trying to be nice part O:-)
1990 GMC C1500, 5spd, 1993 LT1 (ECM 16159278 $DA3)
How do you zero them out first before erase? Didn't think you could change anything without UV erase?
I'm not familar with 27c32? I use 2732a chips from ST which need 21 volt. I forget what stock chips are? AMD? Voltage? It's always best to have the data sheet for the chip to get specific voltages.
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
What programmer are you using? I know the Willems software warns that external power supplies need to be used for certain EPROMs.
The man who says something is impossible, is usually interrupted by the man doing it.
My Gq-4X does say external power is needed, although Willems/reseller says it does not, it's a software issue? It did work without power for a long time but then burns started to fail? I added the power and always a clean burn again?
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
a blank PROM will read FF in all locations(all bits are set(changed to 1, not 0)). IIRC, you can change a bit from 1 to 0, but you can't change from 0 to 1 without an erase. so you could technically change all values in the PROM to 00 without an erase happening first. decent way of checking if all bits are capable of being set to 0.Originally Posted by EagleMark
or something like that.... been a while since i've messed with a UV PROM.
http://wiki.xtronics.com/index.php/H...mming_an_EPROM
that seems to agree with the above statements. guess my memory is a bit better than i thought.
1995 Chevrolet Monte Carlo LS 3100 + 4T60E
Sure glad your memory is still good at your age!
There was some other good info on that link about the C in chip number and voltage!
The Difference Between C & Non-C EPROMs
The only difference between a 27256 and a 27C256 is that the 27256 uses NMOS while the 27C256 uses CMOS technology. CMOS only consumes appreciable power when a signal is switching. NMOS uses N-Channel FET's with resistor elements while CMOS avoids the power wasting resistors by using both N and P-channel FET's. Thus CMOS avoids the production of heat allowing tighter placements of transistors than NMOS is capable of. The high density placement of CMOS reduces the interconnect path lengths and thus increases the speed. CMOS also shines when there is limited power such as in a battery system.
Some people have problems when programming CMOS EPROMs on older programmers because of the differences in programming voltages (CMOS has a 12.5V Vpp). CMOS EPROMs also require a supply voltage (Vcc) of exactly 6 Volts. CMOS parts are easier to erase but prone to die if over exposed to UV light.
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
neat info.Sure glad your memory is still good at your age!
There was some other good info on that link about the C in chip number and voltage!
and i tend to go on learning "binges" and tend to stuff too much information in at one time. things get jumbled around and incorrectly remembered.
1995 Chevrolet Monte Carlo LS 3100 + 4T60E
Well at my age when I go on learning binges it all sticks, but my head hurts and it takes a few days to let other memory banks back...
Maybe my hard drive is full and I'm clearing cache? Just can't remember...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
i may be outta place here but i think if i remember correct that the 27c32 is the eeprom version(or was it of the 2732(2732 being the uv type which is used in the 870 ecm)although i could be wrong on this.either way i think i have the chip info and voltages somewhere.. i will try to look and find them...
ok The 27c32 uses a programming voltage of 25volts. hope that helps
Last edited by xtreamvette69; 08-08-2013 at 11:23 PM.
What make chip? If you have the make as well as number you could google for the correct data sheet.
The info I quoted above said C (CMOS version) needed 12.5v VPP and 6v VCC from burner...
1990 Chevy Suburban 5.7L Auto ECM 1227747 $42!
1998 Chevy Silverado 5.7L Vortec 0411 Swap to RoadRunner!
-= =-
2732c, 2732a, 27c32 i was lead to belive that letters at end ment cmos type and letter in middle ment eprom type but again ya i could very well be wrong
i do recal reading there were cmos and eprom versions of the chip designated as
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