Someone modded my FDS?!

[FoxNtd]

Today I got in the mail a new FDS belt. I got to work on my FDS to clean out the remains of the old one (it broke apart into many pieces and, oh joy, scraping the remnants off the motor's pulley...) and while I was working on this, I noticed a red wire was soldered onto the circuit board. The pictures and other documentation I've seen do not show such a wire existing.

Click this to see a photo.

My camera isn't very good at showing things at short and small distances so it does appear a little blurry. I never heard of any mods for FDS or what they might do. The left solder point should be obvious but the other one is one the top row, five pins in. Does anyone know why this is here? Should it be here?

To backtrack a bit, I tested the FDS when I got a working Famicom and it powers up and quickly goes to "Now Loading..." even without a disk card in it. Now that I have the FDS open, I see the little metal switch that triggers whether or not there is a disk card is fine, it's not stuck. So I'm not sure why, unless this soldered wire explains that odd behavior?

I'm still busy cleaning the broken belt out so I will not be back to testing for some time. Hopefully I can get an answer about this red wire before I will reassemble the FDS. If this wire needs to be taken out, now's the time to do it.

Thanks for the help...

[madman77]

Possible repair of a broken trace? It doesn't relate to any of the FDS write mods, so that's the only other thing that makes sense.

[FoxNtd]

Possible repair of a broken trace? It doesn't relate to any of the FDS write mods, so that's the only other thing that makes sense.

Thanks. I figured that might very well be true.

I have completed my repair! Success on the first try! I watched the FDS head move nice and smooth and I hear the parts smoothly rotating the disk card. Very glad to see this thing working!

....But one issue remains. The FDS thinks there is ALWAYS a disk card inserted. When I power on the FDS, it will jump to NOW LOADING... almost immediately and if there is no game in there it will either keep trying to read or throw Error 21. Now, if I power up with a disk card actually inserted, I get expected behavior. After the game loads it will stop reading and the LED goes off. But since the FDS always thinks a card is inserted, I can't play a game. I have to go to Side B but the system thinks I am never removing the disk in order to flip it.

I have tried to find info about the disk card sensor being always on, including checking these forums and didn't turn up anything. Found info related to head alignment but I don't have an issue there as all my FDS games (except for one which must be a bad disk, Error 22 twice in a row) loaded perfectly each time.

Can someone explain to me what controls how the FDS hardware knows if there is a disk card inserted or not? I need to locate it and adjust it so that when there is no card, it actually is signaled that the slot is empty. Until this is fixed I can't play anything; all my games require Side B to be loaded.

I'm wondering if that soldered wire is the problem but I can only count on someone who is familiar with mods and/or knows how the sensor operates to eliminate that variable.

[madman77]

If you have a multimeter, I would start by checking the switch. It should have infinite resistance in one position and 0 in another. If not, the switch is faulty. Very doubtful that that wire has anything to do with the switch.

[FoxNtd]

I would start by checking the switch.

I'm trying to find out where it is. When I go back inside the FDS, I want to know what I'm looking for. At first I thought I knew which it was, but the switch I had in mind seems to be the one that tells the FDS the head is already at the end of its track and should not continue to back away from the center of the disk card. (Well, it may or may not be that particular switch's purpose, but it appears that way.) Since the tray itself moves when a disk card is loaded, finding exactly what I need might be tricky.

I can't seem to find anything that describes this issue or where the switch is located. If I can't get any info on what I'm looking for, I'll have to play with the disk tray and loading a disk card and try to figure it out. Hopefully it's something I can correct by hand so this thing will be as good as new.