The Lemon Mishap

[HennessySlick]

Alright fellas I screwed up. Tl;dr; I need to know how to fix a specific trace (4th from the bottom on the IC in the middle) and was wondering if you could help me.

Following a guide from this lovely website I decided I'd try out a different way of getting an access LED on my VA7 motherboard. It involves tapping a pin on the CD drive ribbon connector and a power source. I only had 3.3v LEDs to hand, and the PSU only has 5v and 9v, so I figured I'd whack out the ol' multimeter and find a 3v point or something in that ballpark, and I found a point near the power/video/crosslink connectors with about 2.5v.

I turned it on, and sure enough I got an access light. I connected it up to my TV to make sure everything on the console was working beyond powering up, and sure enough I got Earthworm Jim 2 working, but the top and bottom of the screen were getting a rainbow effect. I resolved to find another point, but when desoldering, the iron took the pad with it (I held it on for a couple of seconds at most - must've been running too hot). Everything works fine, but this point was, of course, the Blue point for the RGB signal, leaving it all yellow, hence the title.

I've successfully fixed traces before but this time it doesn't seem to go anywhere. Can anyone help?

[zyrobs]

The VA7 doesn't have access led in the ribbon, they took that out from VA6 and upwards. But the pins are still on the cd drive somewhere, including premade traces for the smd resistor and the LED (it's the lone diode symbol on the front).
That guide... lists the C2 error flag (it shows read errors) as the one to use for access led. Well I guess it lights up usually when the drive is making reads, but it's not the access led line.

For your blue problem, pin 4 of the video encoder connects to pin 84 of the VDP2, through a 0.1p cap (marked C39) and with an 1k pulldown resistor (marked R32). But you should double check the schematics for this - the video encoder stayed the same for all but the last few boards.

[HennessySlick]

It did work as a kind of stand-in, and lit up most of the time - I guess it's an alternative to a proper access LED if you have one of these models and also happen to have a Phoebe, since I don't think they use the trap board.

Great, thanks for the tip! Do you happen to have any schematics? Searching the forums I found your post for the VA0 schematics, but haven't been able to find any others.

I'll follow the traces from the components you've mentioned and confirm if they lead there.

[HennessySlick]

Solved!

Zyrobs, what can I say, you know what you're talking about. I really appreciate it - my baby is no longer sick!

I followed the trace and C39 was on the underside of the board. Small piece of kynar wire between the two and we're back in business.