Hi all!
I recently replaced the belt in my FDS, which went suspiciously smoothly. I was right to be suspicious.
Now, the drive always thinks there's a disk inserted. Tries to read constantly as soon as it gets power.
Did I break something? Can you think of anything I might have done that would cause that?
The thing hasn't been used in about 12 years, but it worked when the previous belt was installed (around 2012). It only works with batteries, so I assume it needs a voltage regulator. I thought it best to identify the other problem before buying one, but I'm happy to go ahead and get one if you think that could somehow be the issue.
I'm not *completely* incompetent with respect to electronic repair, but I know enough that I can confidently say that I'm *mostly* incompetent. Even coming away from here with a better understanding of the device would be a small victory.
Thanks for any help you can offer!
Check whether you haven't jammed any of the sensor switches in the drive; particularly the on the side:
(https://i.imgur.com/9ha8u68.png)
If they're fine (i.e not always shorted), then measure the 2SB1009 transistor on the power board:
(https://i.imgur.com/c1BoKJU.png)
Quote from: Skawo on April 09, 2024, 11:31:29 amCheck whether you haven't jammed any of the sensor switches in the drive; particularly the on the side:
(https://i.imgur.com/9ha8u68.png)
If they're fine (i.e not always shorted), then measure the 2SB1009 transistor on the power board:
(https://i.imgur.com/c1BoKJU.png)
The switch LOOKS fine - I'll check it with my multimeter when I get home. What should I see from the 2SB1009? Would you consider that to be a "novice-replaceable" part?
It's no different than replacing a voltage regulator. Very similar sort of package.
Unscrew the transistor, blob solder on all three pins to heat them up all at the same time, pull the transistor out. Clean up excess solder with soldering braid, put new transistor in.
Just check what each pin reads and report here.
Middle pin is ground. Both pins on the sides should read ~1.5V when the drive is meant to be running and ~7.5V when it isn't.
Quote from: Skawo on April 09, 2024, 10:29:11 pmIt's no different than replacing a voltage regulator. Very similar sort of package.
Unscrew the transistor, blob solder on all three pins to heat them up all at the same time, pull the transistor out. Clean up excess solder with soldering braid, put new transistor in.
Just check what each pin reads and report here.
Middle pin is ground. Both pins on the sides should read ~1.5V when the drive is meant to be running and ~7.5V when it isn't.
Will do, and thanks! It looks like I'll have to wait for my new multimeter to arrive. My old one gave up on me (it's not the fuse) and all I need to diagnose its issue is... another multimeter. Never a dull moment!
Quote from: Skawo on April 09, 2024, 10:29:11 pmIt's no different than replacing a voltage regulator. Very similar sort of package.
Unscrew the transistor, blob solder on all three pins to heat them up all at the same time, pull the transistor out. Clean up excess solder with soldering braid, put new transistor in.
Just check what each pin reads and report here.
Middle pin is ground. Both pins on the sides should read ~1.5V when the drive is meant to be running and ~7.5V when it isn't.
Finally got myself a new multimeter! Looks like the 2SB1009 transistor may need to be replaced. Both sides read 8.7V when in use, which I would guess is well outside of the acceptable range.
Now that RadioShack is gone, where can I find one of these?
Well, online is your best bet.
There's this aliexpress listing (https://aliexpress.com/item/1005005724793292.html), but the seller doesn't have the best feedback.
You can definitely substitute this transistor with a 2SA1217, 2SB1217 and BD376.
2SA1359 should also work.
I
Quote from: Skawo on April 14, 2024, 06:22:01 pmWell, online is your best bet.
There's this aliexpress listing (https://aliexpress.com/item/1005005724793292.html), but the seller doesn't have the best feedback.
You can definitely substitute this transistor with a 2SA1217, 2SB1217 and BD376.
2SA1359 should also work.
I found one through a (somewhat) local seller. I try to buy things like that locally, since my motivation to repair the machine is on the same level as my motivation to clean the oven. I have to strike while the (soldering) iron is hot!
Thanks so much for your help, and I'll update you once I get the new part in place.
Nice.
There's a slight chance it's one of two other components, but hopefully it'll work.
Quote from: Skawo on April 17, 2024, 12:07:17 pmNice.
There's a slight chance it's one of two other components, but hopefully it'll work.
Got the replacement transistor installed! On the bright side, the FDS now runs via the AC adapter. Unfortunately, it's still experiencing the same issue...
You mentioned two other possibilities?
*edit* Possibly related: The FDS only displays on my TV when running via batteries. When on the adapter, my screen stays black.
Welp, yep, so the transistor WAS bad, but there are multiple faults.
Hm, just to check - you're using a negative center AC adapter, right?
The other two possibilities are:
More likely: the dual operational amp chip
(https://i.imgur.com/9RbnCCU.png)
Very common, cheap part; can be replaced with any other dual operational amp, for example an LM358N
Less likely: Q2 and Q3 transistors (both C2021).
Quote from: Skawo on April 20, 2024, 08:39:14 amWelp, yep, so the transistor WAS bad, but there are multiple faults.
Hm, just to check - you're using a negative center AC adapter, right?
The other two possibilities are:
More likely: the dual operational amp chip
(https://i.imgur.com/9RbnCCU.png)
Very common part; can be replaced with any other dual operational amp, for example an LM358N
Less likely: Q3 transistor (C2021).
Yes, the AC adapter is center negative. It's a daisy chain situation, powering both the main console and the FDS.
It looks like you replied before I could edit my previous post, so I'm pasting it here: Possibly related: The FDS only displays on my TV when running via batteries. When on the adapter, my screen stays black.
Well, that sounds like there's a short to ground.
Incidentally, could you take a picture of your work having replaced the transistor?
If you make the FDS run for a minute or so, do any of the components get very hot when touched?
Here's a picture: https://postimg.cc/9R5JQzFQ
I know, there's plenty of room for improvement. It's just so rare for me to get a chance to practice...
I'll check for hot components shortly.
I don't feel anything getting hot, but my old, calloused fingertips probably aren't the best for that purpose.
I'd try to reflow that left leg, at least, but if it's making contact, shrug.
Do you get continuity between ground and 5V when power is not connected?
Try checking between these legs
(https://i.imgur.com/9dNZT6Y.png)
Yeah, it looks like there's continuity there. I guess that's the short you suspected?
Yeah, there should not be any continuity there.
The proble is which component that short is in. It could be the chip itself, but it could also be any of the transistors or caps on the board :s
I guess I'd try taking out the chip next and seeing if the short goes away.
Will do. I'll let you know once I get the replacement in place.
I mean, you could check the short before you put the new part in.
If the short is NOT caused by the amp then it could even damage the new amp you put in.
Haha, that would have been a good idea. The amp just got here and I just finished installing it. Guess I might have a spare. I'll check the short before anything gets power.
Didn't find a short, but the issue persists. C2021, I guess?
So, wait, you changed the part and the short went away, but it still acts the same, or is the short still there?
The short went away, but it still acts the same. I quadruple-checked the switch (again) but it's working perfectly.
Does it at least let the console start up now when connected to the AC Adapter?
And, well, yeah, I guess the next step would be the C2021. I hope the first transistor didn't get cooked by the short :s
I didn't check whether the console sent anything to the TV, but I'll do so this evening.
Even if the chip DID get fried, no big deal. I bought 2,just in case.
Still no display/audio with the ac adapter, but it has both with batteries.
My C2021s are taking forever to get here. Are there any alternative parts? I have an original NES that could function as a donor, if it has any parts in common with the FDS?
BC107, BC171, BC183, BC207, BC237, BC547 are alternates of C2021, but they might be different packages;
you'd need to check datasheets for which leg is which.
For example, between the C2021 and BC547 two of the legs are swapped:
(https://i.imgur.com/GG0fKgG.png)
(https://images.theengineeringprojects.com/image/webp/2017/06/BC547-Pinout.png.webp?ssl=1)
I am really confused why there would be no video now if the short is gone, though. Unless the legs on the chip aren't making good connection and there is still a short, or the DC barrel jack itself is faulty?
:s
Thanks, I'll check if I can find any of those outside of China.
I'll also redo the points on the chip and try to verify that the barrel is good. At this point I'm invested, and I've honestly enjoyed learning about this stuff.
I finally received and installed two 2SA937-R in place of my 2021s, and I'm now getting audio and video when on the adapter!
Incidentally, does the "R" in that part number stand for reverse? It's powering on when the console is off, so... probably need to flip them.
All that aside, it's still trying to read when nothing's in the drive. I reckon the tall limit switch behind the header must be damaged, but I can't see anything wrong. Is there a good way to check it? Maybe while the machine is running?
See which points on the circuit board the switch belongs to and see if there's continuity when you click the switch, I guess.
As far as I can tell, 2SA937-R is a PNP transistor while the 2SC2021 is NPN... that's not going to work.
Ha, I actually expressed concern that the part number wasn't one I'd seen listed. His response: "It's definitely an interchange." Either his eyes are failing or he was desperate to sell $5 worth of transistors. Probably the former, as he's pretty advanced in years.
On the bright side, I'm getting good at soldering/desoldering components that go through the board.