Service Forum

pokin5 · Interesat Joined: 15 Nov 2005 Posts: 10

I have been trying to unlock my IBM for awhile, but my circut never seems to read the EPROM. I have tried the new "itester" program and what happens is: 5 seconds after hitting connect SDAin turns to 1, another 5 second later SDA/SCLout turns to 1. After another 5 seconds SDA/SCLout turns to 0, and keeps alternating every 5 seconds. SDAin always stays at 1.

Are these proper readings for a correctly working driven circut?

pokin5 · Interesat Joined: 15 Nov 2005 Posts: 10

I also forgot to add that I am using the directions to build the circut from:
hxxp://www.rkawakami.net/ibm_600x/max232_if/

I have also uploaded pictures if anybody can help. They are 4 MB and can be downloaded from:
http://w11.easy-share.com/659932.html

The plus and minus over the holes in one picture is where I connect the + and - from the batteries.

Any help would be greatly appreciated, as I have been trying for atleast 8 months to get this thing working.

Thanks

victor · S.F. Boss Joined: 07 Mar 2004 Posts: 2581 Location: Staff

The circuit is correct, I saw that you got MAX232ACPE and 100nF capacitor which is correct.

I think the problem is with the COM port connections, I can't figure out how you used the DB9 connector. Which is the front end? Could you post a detailed picture of it, it seems to be a DB9 female but if the picture shows the front end, then is wrong.

pokin5 · Interesat Joined: 15 Nov 2005 Posts: 10

I used a gender changer for the serial port. That way I can have the proper wires connected to the gender changer, then when I am ready to use it I can plug my serial cable into it. The serial cable I am using is about 6 feet long. Here are some pictures of the serial connecter and cord.

The pictures are about 3.6 MB
http://w11.easy-share.com/659974.html

The gender changer is the same on both sides.

So if the circut is correct, and it is connected to the computer properly, are those readings in the first post correct for a good circut? I have built and re-built this circut several times, all with the same results. When trying to read the EPROM I get the EPROM not found error. If the circut is working correctly then I can rule out the circut being the problem, then the only thing left are the solders on the chip.

Thank you very much for your help victor.

PS - The capacitors I used are "Ceramic-Disc Capacitor" 0.1uF, 50WVDC max, High K dielectric, and a tolerance of +-20%.

I hope 0.1uF is the same as 100nF.

victor · S.F. Boss Joined: 07 Mar 2004 Posts: 2581 Location: Staff

I didn't say that your circuit is working correctly, itester shows that it doesn't work at all violin

I only say that the breadboard part "looks" OK.

Well, I saw the pictures, and I would say that the solution you chosen can get you a lot of problems. My suggestion is to buy a DB9 female and SOLDER the wires to it.

1uF (micro) =1,000nF (nano) =1,000,000pF (pico)

So, your circuit is not working, itester must show the same value for SDAin and SDA/SCLoutputs. I vote for a COM connector/cable issue

pokin5 · Interesat Joined: 15 Nov 2005 Posts: 10

With some tinkering I have finally been able to get the itester program to switch both SDAin and SDA/SCLout from 0 to 1 at the same time and back to 0. Are these the results which would indicate a working driven circut?

I tried reading the EPROM again and I get the same error "EPROM not found". If the circut is now working correctly, wouldn't that only leave the solders on the EPROM chip?

Again, thank you for your help Victor.

lnd54321 · Nou Venit Joined: 23 Mar 2007 Posts: 9

Hi Victor,

Where can I download the itester ? I need to verify my circuit. Thank you

bob · Posted: Wed Mar 28, 2007 12:47 pm Post subject:

Itester.zip

Is also included in the R24RF08 package.

lnd54321 · Nou Venit Joined: 23 Mar 2007 Posts: 9