Yellow Magic sort of works. (Resolved)

yes i’ll do that. it often helps. the ones i built for others all worked first try :wink:
shit happens sometimes. of all pads i had to rip off one of an ic of course. but i managed to get a socket on there (the 4822)
but i resoldered a lot of other joints and now there’s even bad distorted audio with changing volume, haha.
i must say on this board i cut all component legs damn short. it’s good possible that there’s not enough contact somewhere who knows.

How come your component legs are so short ? Are you cutting through the soldered joint (assuming you cut after soldering the component) ?

yep exactly, i was trying that. i normally only do it as short as possible below the Shruthi LCD. well that won’t become a habit

Good news is that the delay totally works now. Bad news is that the 39K resistor suggested above is way too much. Makes some cool sounds but the delay is so late and distorted.

Eidt: One other thing. The output seems to be really hot with this filter board, is there a way to adjust that ever so slightly?

You can replace R6 by a lower value (say 10k) to get a lower output level.

I just added a 27k resistor and the delay is still way too long and distorted sounding, but it didn’t work with a 22k resistor at all. What?

Quite possibly the New problem you describe is related to something other than the R58 value. I’ve had to use that value (39k) several times and haven’t had that issue. As long as its starting up consistently, the 27k value should be ok to leave in.

I don’t have much experience with Debugging this board yet so I can’t really offer much more insight.

Spent some time with this today. It was acting really strangely when I plugged it in last so I decided to resolder some of it. While doing so something weird has happened. I suddenly got no sound output. The first thing I decided to do was to take my multimeter and check the red points and blue points like in the guides. Interesting.

EDIT: Let me clarify that the unit wasn’t turned on when I was soldering. :stuck_out_tongue:

I get 5 volts for red, and -0 volts for blue. Interesting. Something is obviously wrong here. Odd that it powers up and I can move through menus. Any ideas?

I’m thinking the LT1054 burned out… I want to try and swap one from my other shruthi-1 into it but I’m scared it will burn it up. :o

EDIT: Tried it out. It’s not the LT1054. I’m confused.

have you tried the supposedly fried 1054 in your working Shruthi or how can you tell?

I put my good shruthi-1’s chip into the “bad” shruthi-1 and there was no change. This is so odd because it was working today…

Edit: oh and vice versa of course…

The Digital Board doesnt require -+5V so it will well run without the LT1054, only the OpAmps on the Filter Boards need negative Rail. Check if you dont have accidentially shorted the negative rail to GND.

Readings for LT1054 in case this helps. Also, the chip itself is getting very hot.

pin 1: 1.10v
pin 2: 2.48v
pin 3: 0v
pin 4: -1.1v
pin 5: -2.47v
pin 6: 2.6v
pin 7: 1.4v
pin 8. 8.23

I’ve resoldered everything several times now… could this be a faulty 7905?

there’s probably a short in your negative rail. the voltage at pin 5 should be the negative equivalent of pin 8

There are no visable shorts. Thinking of just scrapping the filter pcb and starting over. Not super expensive, ill at least have all the chips and i can do a clean run. I got the pcbs on ebay so they could have been faulty. (They were really cheap.) Lesson learned.

There was never a known faulty PCB from MI, the are all factory tested. Measure for a short between the rails.

“Only visual inspection misleading can be.” - Master Yoda

"Got the PCBS from eBay"
So from that other guy, who sold assembled units for far too cheap, without adding anything to the community… His PCBs having a fault wouldn’t surprise me, since I don’t know anything about his testing procedures…
EDIT after attempting to use my brain - He didn’t offer YM version PCBs though, did he?

Success!

Sorry to resurrect the thread, but I’m having issues with the delay as well. I tried replacing the 22k with a 27k and then a 30k, and I can’t hear a difference. The Eq and feedback work, just not the delay it seems. Is 39k the magic number then?

For me it was 33k. I think it really depends on the chip. I added 1k resistors in line until it worked and then bought the right resistor.