so i got a 4pm soldered and working… i played with it a little and having fun with the filter. i was using the selector to change patches and i couldn’t figure out how to get back to the main menu, so i pulled the power and turned it back on. now i get a white bar for the first line of the lcd… and the 1,3,5,7 led’s are lit…
any ideas…? i would hate to have bricked it after a minute of playing with it… 8\\
Just got it all desoldered, awaiting the replacement from Mouser currently. desoldering wick is magical!
True, in which case, I will add a small dab of solder to the joint.
The solder sucker also works better when there’s a nice blob of solder to remove. Too little and it doesn’t really work.
I have yet to use a solder wick. The best technique I use is apply some flux to the pad you want to desolder, heat it up with the iron and have a solder sucker ready. As soon as you pull away line the sucker up the the hole and suckitout! Works like a charm. The extra flux really helps to pull it all out. I did this wen I removed a SID from my old C64 the other day. Came right out without a hitch. If you have an old PCB with through hole, practice a bit first.
Of course! Clearing the solder out of the holes can be a serious pain as well, though. I need to get the technique down with the solder wick before I try it on the shruthi board.
Repeatedly: Cut the Legs and desolder one by one. This way you put much less stress/heat to the Board.
I’m dreading the desolder process for the component. That beautiful white board is going to look gross and yellow by the end of it.
Edit: meant to say white, not wide.
Isopropylalcohol (or just plain H2O) to the rescue!
The heat sinks on voltage regulators are usually not isolated, therefore bleeding lots of voltage/current to anything that touches them - this normally isnt a problem(its part of the design anyway), unless you somehow short something to it, which very well could kill the part
That’s exactly what I did. Oh god. This sucks.
Pulling the plug shouldn’t affect anything. If you haven’t installed a power switch you always pull the plug to turn it off. I would look to something else. Stuck button maybe? Disconnect all cables and try again.
Most of the experts are on European time. Give it a few hours and they will be here to help.
Try to check S6 switch (look like it boots into bootloader mode) also check MCU socket.
What you see (first line of display blank and leds 1, 3, 5, 7) indicates that the unit is in firmware update mode. One usually needs to press S6 to enter this mode.
Things to check:
- no mechanical problem on S6
- no soldering problem on the resistor network and the 74hc165
- no bent pin on the MCU (pin 7)
ahhh… so it’s not a fancy paperweight… that’s good… a problem with S6 makes sense to me, because its pins were really close to the 7805/7905 and i was afraid it would accidentally ground it or bend it. i’ll double check everything and let you guys know how it went.
btw…it sounded REALLY awesome before the “incident” 8)
okay… here’s what i’ve done
- de-soldered S6. continuity test checks out fine. it’s a working switch. since it’s a n.o. switch i didn’t solder it back in to help simplify this problem.
- check across S6 pcb pads 2 and 4 indicate it’s an open circuit
- checked S6 pad 2 to the 74HC165 and that’s fine
- S6 pad 2 to ground is open circuit, pad 4 to ground is low resistance
- pin 7 of cpu shows low resistance to socket pin. there is low resistance to pin 1 of the avrisp header pads. i’m pretty confident the cpu is properly and securely in the socket
- resistor network has the dot pointed toward the LCD screen, which i believe is the proper orientation.
maybe this is the problem… i just measured the resistor network… and common to 1…5 show ~10k… but common to 6 shows a very low resistance…
is this the problem? the data sheet seems to indicate that it should be 10k as well…
i’ll try to unsolder just that pin and replace it with a 10k resistor i’m sure i have lurking somewhere… i’ll let you know if that fixes it…
also something interesting… so i have a cheap radio shack multi-meter, but it works well for the simple stuff i do… anyway… at the 200 ohm setting it’s showing an open circuit between pads 2 & 4 of S6… but when i bump it up to the 2K and higher setting, it’s not showing an open circuit, but ~500 ohm. wondering if its just that i have a cheap meter… or if it’s an indicator of something…
ugh… well my research thus far has lead me to conclude i blew up the 74HC165 somehow…
yup… blew up the 74HC165… replaced it and everything is working fine now
Glad you’re sorted aberant - it’s a good feeling isn’t it?