LC II won’t chime

[Challenger 1983]

My LC II wont chime but the hard disk spins up and when i put a floppy in the drive it spins for a second and then stops i can briefly hear the hard drive access before it stops, any ideas?

Edit: the power supply makes a ticking noise when turned on 

 

[MrFahrenheit]

Time for a recap?

 

[bibilit]

the power supply makes a ticking noise when turned on

Probably you culprit here, LC PSUs are notorious for having bad caps.

 

[BadGoldEagle]

Time for a recap?

Or for a mAcTX... A PicoPSU-80 (the cheapest and least powerful one in the lineup) is beefier than the original PSU used in the Q605/LC475, and no soldering is required   

 

[Challenger 1983]

I’ll definitely look into a new power supply, I’m just worried that my logic board might be dead, is there anyway to test? Like with a PC power supply for now?

 

[MrFahrenheit]

My experience buying about 25 different LC/LC2/LC3/LC475 machines is 75% of the time the board needs a recap to work properly. Most also need the PSU recapped or replaced. 
 

I’ve had a variety of issues resolved by recapping including SCSI, sound, ADB, and video not working, as well as machines that just don’t boot. 
 

With machines getting close to 30 years old, it’s shortsighted to avoid recapping. Especially since time causes more damage and 1 year makes a big difference. 

 

[Challenger 1983]

Sorry I really should have mentioned that I completely recapped the logic board a few weeks ago, which brought sound back to the machine, it was just yesterday I went to power it up and got nothing 

 

[Challenger 1983]

Does anyone have a pinout for the power supply, I want to confirm that it is the power supply at fault 

 

[cheesestraws]

Sorry I really should have mentioned that I completely recapped the logic board a few weeks ago, which brought sound back to the machine, it was just yesterday I went to power it up and got nothing 

If the logic board was working, it probably is still; in my experience, at least, those power supplies don't tend to take the board with them if they don't fail dramatically.

Like with a PC power supply for now? 

The LC boards only need 5v, 12v and ground.  There's also a -5v, but for testing purposes you can leave that out.  The pinout is here:

https://old.pinouts.ru/Power/mac_lc_power_pinout.shtml

The connector is compatible with the Molex KK396 (if I remember correctly); when I built a replacement "PSU" I used cheap KK396 clones from eBay.

With an ATX PSU you'd have to manually fiddle with the soft power of course.

 

[Challenger 1983]

Thanks, My only question is why are there two ground wires? 
 

I apologize for asking so many questions 

 

[cheesestraws]

Thanks, My only question is why are there two ground wires? 

I assume to make sure that there's enough current carrying capacity to take all the current back to ground?  There's no point having big chunky voltage wires if the ground connections aren't up to the job .

I apologize for asking so many questions 

No apologies needed, you are in the right place to ask these questions and a lot of them are questions I asked when I was trying to build my PSU-thing.

 

[Challenger 1983]

I assume to make sure that there's enough current carrying capacity to take all the current back to ground?  There's no point having big chunky voltage wires if the ground connections aren't up to the job .

No apologies needed, you are in the right place to ask these questions and a lot of them are questions I asked when I was trying to build my PSU-thing.

Thank you so much, today I’ll hack an ATX power supply to confirm that everything works and I’ll look at getting/building a proper power supply for it 

 

[cheesestraws]

and I’ll look at getting/building a proper power supply for it  

Repairing your existing one may just be a "replace-the-capacitors" job.  That often seems to fix them.

Otherwise if you do need a replacement, I'd look at the macATX LC (I think it's @Compgeke's project), which is a pre-made converter for ATX PSUs especially designed for picoPSU type arrangements.  I don't use one, but that's only because I built mine before theirs came along.  Given how nice theirs looks, if it had been around at the time I probably wouldn't have bothered building one from scratch.

 

[Challenger 1983]

Repairing your existing one may just be a "replace-the-capacitors" job.  That often seems to fix them.

Otherwise if you do need a replacement, I'd look at the macATX LC (I think it's @Compgeke's project), which is a pre-made converter for ATX PSUs especially designed for picoPSU type arrangements.  I don't use one, but that's only because I built mine before theirs came along.  Given how nice theirs looks, if it had been around at the time I probably wouldn't have bothered building one from scratch.

I think I’ll trying replacing caps first, I’ve also heard that sometimes solder joints crack so I’ll reflow everything first 

 

[Challenger 1983]

Update: after leaving it plugged in and turned on for about 15 minutes it suddenly chimed and booted, however the audio is very faint, I’m assuming these are symptoms of bad caps in the PSU?

 

[MrFahrenheit]

Update: after leaving it plugged in and turned on for about 15 minutes it suddenly chimed and booted, however the audio is very faint, I’m assuming these are symptoms of bad caps in the PSU?

I had an issue similar to this on my IIsi that I recapped. I simply removed and resoldered down the caps and it worked after. Perhaps try that on the caps near the sound?

 

[Challenger 1983]

I had an issue similar to this on my IIsi that I recapped. I simply removed and resoldered down the caps and it worked after. Perhaps try that on the caps near the sound?

I’ll try that, did that also solve the booting issue?

 

[MrFahrenheit]

I’ll try that, did that also solve the booting issue?

I had several issues. Video, scsi etc. I removed and soldered again. I was told that even though there’s a solder connection if it’s a cold solder it won’t electrically connect. So attaching caps but with a cold solder joint results in no conductivity. That is possibly one of your problems. Very easy to rule out in a few seconds (heat, remove, clean, resolder). 

 

[Challenger 1983]

I had several issues. Video, scsi etc. I removed and soldered again. I was told that even though there’s a solder connection if it’s a cold solder it won’t electrically connect. So attaching caps but with a cold solder joint results in no conductivity. That is possibly one of your problems. Very easy to rule out in a few seconds (heat, remove, clean, resolder). 

Alright I’ll try that, thanks