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thanks dude that's a really cool answer,

Since the roms are now out of order I guess I will try and retry what you just said about cleaning, I have already sanded every pin, and yes I have an chinese cheap eraser, and the window of the rom is pretty full of glue I will do everything you said.

Whenever I get it to work again I will come back to you with screens of this behaviour.
 
Regarding cleaning pins on chips and even fingers on JAMMA edges, I find a fiberglass pen works wonders and you don't have to worry about some spinning mechanical device accidentally hosing your stuff.
 
after trying a lot of things today, my bet is the top3000 is not compatible with writing these old eproms, I ordered 27c128 and 27c256 from buyicnow
 
after trying a lot of things today, my bet is the top3000 is not compatible with writing these old eproms, I ordered 27c128 and 27c256 from buyicnow
I've never had any issue burning any kind of 27Cxx EPROMs with my TOP3000.
Now with all the problems people have with this programmer when others have no issue at all I wonder if there are faulty batches or even worse fake units on the market.
I paid ~$200 for mine when I see some have bought one for ~100.
 
it is possible that I am still missing something, tried to polish the pins, clean with alcohol, erase twice during 40 minutes, changed usb port, even the capacitors inside the top3000, changed the software... these 3 eproms still don't want to cooperate

I have read in the specs that they need 21v to get written, is a 5v powered device able to handle this ?
 
I have read in the specs that they need 21v to get written, is a 5v powered device able to handle this ?
Absolutely, it can generate higher voltages, 21V is for older EPROMs (pre-mid 80s) then it's 12.5V for most on them for Vpp (programming mode).
 
I had some bad experiences with eproms coming from China. They called them "refurbished" and it's a kind of lottery. -Sometimes you cant erase them no matter how long you leave them in the eraser. or they erase but when you write a couple of bits wont change state. Unfortunately in many cases you have no other choice as these are since looooong ago not anymore being produced.
 
@Darksoft they look exactly like the original ones, but they have been rewritten for sure because they were labeled by hand, I know it's possible to buy them refurbished yes, it could be that. The behaviour after erasing is this, it gets full of FF, but sometimes, one of them has F7, and when I try to write only first bits are written on one of them and the others get some weird patterns.

What makes me think it could also be my setup is there are 2 brands on the 3 eproms and these have the same behaviour, but everything is possible.

Toshiba MM27256-15 (150ns) for Rom 3
Toshiba MM27256-20 (200ns) for Rom 5
Mitrsubishi MM27128K for Rom 4

Are these references really the original ones, if I replace them does it matter to take same speeds or same size or can I get one model of 27C256 for the 3 with 200ns and don't care about the 128k ?
 
I had success writing the roms with buffer starting from 8000 for the Toshiba TMM27256D and buffer 4000 for the Mitsubishi M5L27128K but it doesn't seem to work on the pcb. From what I understood data begin to write at 8000 and 4000 ? I just noticed that the software was saying buffer 0000-7FFF and 0000-3FFF then guessed it should start from that point ? I think it doesn't make much sense data should start at 0000 and finish at 7FFF.
Programmer buffer settings are fine, you must leave them as is.

7FFF is 32K, the size of the 27256 while 3FFF is 16K which is the size of 27128.So programming must start from 0000 and finish to the end (7FFF for the 27256 and 3FFF for the 27128)
 
yes that's what I realized after, it's later that I understood that the progress bar was doing no error because it was writing notihng I was starting outside the buffer, programming should start at 0000.

the chips must be bad, some of them has F7 instead of FF after erasing process.
 
these are 3 chips actually from 2 different brands, new chips are on their way.

out of curiosity, do you know guys if the Japanese G version needs 5 eproms instead of 3 ?

is there any data on how this can work ? is it just adding 2 additionnal sockets or there's a deeper modification ?
 
^after trying a lot of things today, my bet is the top3000 is not compatible with writing these old eproms, I ordered 27c128 and 27c256 from buyicnow
That^
I have the same issues with the TOP 3000 programmer.
 
^after trying a lot of things today, my bet is the top3000 is not compatible with writing these old eproms, I ordered 27c128 and 27c256 from buyicnow
That^I have the same issues with the TOP 3000 programmer.
Can you take pictures of your programmer (both sides)? It can only work with something as simple as 27C128s or 27C256s, I burn them all the time with the same programmer.
 
after trying a lot of things today, my bet is the top3000 is not compatible with writing these old eproms, I ordered 27c128 and 27c256 from buyicnow
I've never had any issue burning any kind of 27Cxx EPROMs with my TOP3000.Now with all the problems people have with this programmer when others have no issue at all I wonder if there are faulty batches or even worse fake units on the market.
I paid ~$200 for mine when I see some have bought one for ~100.
Maybe you are on to something here, i paid around 100 for it.
 
@Trol thanks for the pictures, looks identical to the one I've got.

@archimage Topall Ver8.25 (2015-07-31)

Can you guys please do a test for me? Go in "Cofig" tab and change parameter "delay" to 1ms and try burning a 27C128/27C256/27C512 again.
 
in my case it's not 27C128 and 27C256 but 27128 and 27256
 
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