No cursor when testing video section after initial assembly

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No cursor when testing video section after initial assembly

Postby Ckelly » Feb Tue 24, 2009 9:35 pm

After some delay, I've just finished soldering all components in my Replica I TE. After connecting the ATX power supply, the LED lights up, and all GND and +5 voltages listed in the 'testing' section on page 18 in the manual are confirmed. But after connecting (only) the P8X32A-D40 and 24LC256 EEPROM chips and connecting the RCA cable (trying two different monitors and two different cables), I don't see any output--no cursor or anything else.

Any other suggestions for pin connections I can verify?

Thanks,
Christiaan.
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Postby Kallikak » Feb Tue 24, 2009 11:19 pm

Take out the ROM and RAM chips, and check the corresponding address and data sockets for continuity and shorts.

Ken
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Postby vbriel » Feb Wed 25, 2009 7:55 am

Ok, how about 3.3V that the Propeller and the EEPROM run on. What you need to do is remove all the chips except the propeller and the little 8 pin EEPROM. Test pin 8 on the EEPROM to make sure it is 3.3V. These are the only chips required to get the cursor. Check solder connectors, make sure chips are installed correctly.

Vince
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Postby Ckelly » Feb Wed 25, 2009 8:43 am

I've verified all data and address lines on the 27C64, 62256, and 6502 connection pins, and there is continuity among the corresponding pins (e.g. d0 with all other d0 pins, a1 and a1, etc.) and no shorts anywhere (e.g. between d0 and d1, etc.)

Interestingly, though, I don't see any continuity between the Propeller and the above-mentioned sockets on any lines. FYI--I do see, though, continuity between the 8 Propeller pins and the 1k resistors which are alongside it, and I see continuity between the three lower Propeller pins with resistors and the video connector.
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Postby Ckelly » Feb Wed 25, 2009 9:08 am

I've verified the +3.3V to the Propeller and pin 8 on the EEPROM. But I just realized (thanks to your post) that I misread the manual and inserted the wrong EPROM for testing (the larger 27C64 instead of the smaller 24LC256). I'll test it again in a few hours. Thank you.
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Postby Ckelly » Feb Wed 25, 2009 7:47 pm

Yes, putting in the smaller EEPROM (see last post) resolved this issue.
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Postby vbriel » Feb Wed 25, 2009 10:32 pm

So, can we assume the rest of the replica 1 is functioning as well?

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Postby Ckelly » Feb Wed 25, 2009 10:42 pm

Unfortunately, no. But the new problem is the same as in another thread, so I posted my new problem there. Please see my post in the "Blinking "@", No Reset" thread.
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