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NEC TG-16/TE/TurboDuo => TG/PCE Repair/Mod Discussion => Topic started by: D-Lite on March 22, 2010, 07:13:29 AM

Title: Duo showing the solid color screen instead of the Super CD screen
Post by: D-Lite on March 22, 2010, 07:13:29 AM

Know how your system shows the blue/orange/whatever solid color screen when the HuCard is in and not reading correctly?  Yeah, I'm seeing that with no HuCard on a Duo, instead of the normal Super CD Rom "Press Run" screen.  But the system boots HuCards fine.  So is it not seeing the System 3 on chip?  I just finished a cap overhaul on it and the sound is fine.  I haven't tried putting a system card in the Hu slot, probably try that later tonight.  Any idea?  What IC is responsible for the system so I can track down any pulled/crossed traces?

Title: Re: Duo showing the solid color screen instead of the Super CD screen
Post by: nat on March 22, 2010, 07:34:45 AM

I wonder if something in the HuCard port is f--ed up and it thinks there is a HuCard in there when there really isn't, thus it's not even trying to boot from the on-board BIOS. I'd check that first...

Title: Re: Duo showing the solid color screen instead of the Super CD screen
Post by: D-Lite on March 22, 2010, 10:11:26 AM

Quote from: nat on March 22, 2010, 07:34:45 AM

I wonder if something in the HuCard port is f--ed up and it thinks there is a HuCard in there when there really isn't, thus it's not even trying to boot from the on-board BIOS. I'd check that first...

Good idea.  What's the "detect" pin on the slot?  Is there one that just checks for feedback or is it merely a completed circuit that signals presence?

Title: Re: Duo showing the solid color screen instead of the Super CD screen
Post by: Charlie on March 22, 2010, 08:38:04 PM

To the best of my memory:
Pin 1, tied to ground (pin 18) on card = card present; therefore, should be high w/o card.

Might also want to check the Reset, pin 36; low for reset, high for run

Charlie

Title: Re: Duo showing the solid color screen instead of the Super CD screen
Post by: D-Lite on March 23, 2010, 04:09:24 AM

Quote from: Charlie on March 22, 2010, 08:38:04 PM

To the best of my memory:
Pin 1, tied to ground (pin 18) on card = card present; therefore, should be high w/o card.

Might also want to check the Reset, pin 36; low for reset, high for run

Charlie

Fantastic, I'll check that first, thanks.

Title: Re: Duo showing the solid color screen instead of the Super CD screen
Post by: blueraven on March 23, 2010, 01:18:30 PM

I had something similar happen a few months back on a PC Engine Duo (Black);

I was getting an alternating beige and magenta screen with no hucard, and a black screen with a hissing noise with the hucard in. One of the 90 degree angle pins that connects from the card port to the board had a rust deposit that ran down to the motherboard from something (condensation? errant electrolytic fluid? i have no idea). I carefully removed the deposit and cleaned the pin as thoroughly as possible, and re-flowed the solder to the pin, which ultimately fixed the problem. 

Connection to the hu-cards resumed on boot, the CD-ROM screen is accessible but the drive/HOP-M3 has been and is still dead at the moment.   

Title: Re: Duo showing the solid color screen instead of the Super CD screen
Post by: nat on March 23, 2010, 01:37:43 PM

Yeah, it's much more likely a HuCard port problem than a problem with the System 3 BIOS chip. Of course, anything's possible, but I've never seen a bad BIOS chip before.

Title: Re: Duo showing the solid color screen instead of the Super CD screen
Post by: D-Lite on March 23, 2010, 03:23:01 PM

Had a chance to do a quick test and so far it doesn't seem to be pin 1 grounding.  Need to keep plowing through.

Title: Re: Duo showing the solid color screen instead of the Super CD screen
Post by: esteban on March 27, 2010, 07:11:36 PM

Quote from: D-Lite on March 23, 2010, 03:23:01 PM

Had a chance to do a quick test and so far it doesn't seem to be pin 1 grounding.  Need to keep plowing through.

Clearly, this is a case of phantome hucarde.

I suggest an exorcism.