transferred sound lab to new case and now it doesn't work

jimmyschaus · Joined: Jul 02, 2006 Posts: 10 Location: syracuse, ny

Hello, I completed my Sound Lab a few months ago and it has worked great up until recently, when I transferred it into a new case. This entailed a new panel as well. After I removed it from my old case I had it sitting around for a few days while I prepared my new case. Once the panel was ready I mounted everything and tested it...everything was fine at this point. Right before I was ready to drill it into the new case I tested it one more time and it sounded messed up, so I jiggled it around a bit and started sounding great again. I put it in and it worked fine. A few days later I played it again and no sound was produced at all. I opened it up and started looking for loose connections and stuff when I realized maybe it needed new batteries...so I put new batteries in and it worked again, but soon thereafter the AR generator stopped working. I began looking at it and trying to find problems , and from that point on everything slowly started to break down...at this point, the only things that work are the second VCO and the LFO and the white noise, sort of. But it's as if the minute I started to seriously look at it for the AR problem things just gradually got worse until it was at the point that it's at now. So I'm just wondering if anyone has had a similar experience after transferring it to a new case and was successful in fixing it, so maybe I know where to start. I know there are loads of general troubleshooting things, but it sort of seems geared towards boards that didn't work in the first place. Everything was fine to start out with, and it worked once it was in its new case, but then something just started happening and now it's all screwed up...I did resolder some things without taking the chips or transistors out, but I was careful that the places I resoldered were not on or near them...they were mostly pots/switches. Can that stuff get damagaed from heat as well? I'm just looking for some general advice here, thought maybe this might be a situation some others have been in. sorry this post is so long...

thanks
jimmy

Uncle Krunkus · Posted: Mon Jul 03, 2006 2:39 am Post subject:

Hi Jimmy,
First of all it is almost certainly not anything to do with the soldering, (unless you accidentally put something back the wrong way) all the components in the SoundLab can stand being re-soldered, hell, even unsoldered/removed/replaced/resoldered wouldn't hurt them unless you were particularly rough in the way you did it, and you got it working in the first place, so I know you're not that rough.
The bit that made me wince was where you said: -
"Right before I was ready to drill it into the new case I tested it one more time and it sounded messed up, so I jiggled it around a bit and started sounding great again."
What do you mean by "drill it into"? and "jiggled it around"? My fear is that you may have turned it on with something shorting on something else when it wasn't in the case.

Anyway,
put new batteries in and find out how much current is being drawn by each of the power rails. (For the +ve rail, only connect the -ve of the +ve side battery, and complete the circuit with a multimeter set to mA. For the -ve rail, only connect the +ve of the -ve side battery, and complete the circuit with a multimeter set to mA. I'll add a pic in case this isn't clear)
Only leave it turned on long enough to get the readings you need.

Once you've found this out let us know what the results are and we'll go from there.

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Mr Swirling Vortex Man · Joined: Jun 13, 2006 Posts: 23 Location: Australia

Hi Jimmy,

This may not help but... I recently experienced some weird problems where one oscillator stopped oscillating and the other still worked. I had brand new batteries in there so I was convinced that there was a component fault. (I even messed around with a lot of component swaps etc. etc. and had no luck). I then measured the voltage of my "new" batteries and found that one was only giving about 8v and the other was something like 6v. Anyway, I changed them again for 2 batteries that were definitely giving 9v and ... hey presto! ... all was OK. So, you never know... your batteries may have been on the shelf for a long time down at the shop.

Good luck.
Adam

jimmyschaus · Joined: Jul 02, 2006 Posts: 10 Location: syracuse, ny

okay, so, for the positive rail (which is the battery snap whose black wire is connected to the ground between the two and red wire goes to the board), i have only the negative half of the battery in the snap and the multimeter hooked up between ground and +9V on the board. for the negative rail (which is the battery snap whose red wire is conneccted to the ground between the two and whose black wire goes to the board), i ahve one end of the multimeter hooked up to ground and the other hooked up to -9V on the board (??) ehh that's what the picture seems to suggest. i've also tried the meter hooked up to ground on one end and the other half hooked up to the portion of the battery snap not being used. regardless, i always get 0 mA, which is obviously wrong since everything but the two vco's and white noise is working (which is an improvement from yesterday, i think i had some shitty batteries on there and in the process of not knowing that and tryhing to fix other stuff i broke some chips by being charged and touching the board?) so yeah, at this point everything but the vco's and noise works, sorry if the picture explained everything easily and i just didn't get it, i think you might have to explain it some mroe for my retarded ass

oh, and by drill into it i meant just drill the panel onto the frame, and yeah, i played around with it a bunch without it in the case touching stuff i probobly shouldn't have...maybe that's what screwed it up..

thhanks for your help

fonik · Posted: Tue Jul 04, 2006 4:31 am Post subject: Re: testing...

Uncle Krunkus · Posted: Tue Jul 04, 2006 4:39 am Post subject:

The multimeter is not connected to the ground at all. It is put "in line" or "in series" with either of the power rails. The current you are measuring has to flow through the multimeter.
Nothing in the VCO or Noise circuits is static sensitive, so you might have shorted something to ground etc.
As I say to a lot of people, all the time, you don't learn anything without doing it. The only reason I know what I'm doing is that I've done it before, and stuffed it up many times!! Laughing

fonik · Posted: Tue Jul 04, 2006 4:46 am Post subject:

jimmyschaus · Joined: Jul 02, 2006 Posts: 10 Location: syracuse, ny

okay, so after doing exactly that my multimeter still reads 0 mA, but the lfo and ar are still working, which does not make any sense. maybe it's my multimeter?

for the positive rail, only the negative side of the battery connected with one end of the multimeter on the positive side of the battery and the other on +9V on the board. the other battery connected as usual.

for the negative rail, only the positive side of the battery connected with one end of the multimeter on the negative side of the battery and the other on -9V on the board. the other battery connected as usual.

still nothing! is there some sort of explanation for this, or am i still doing it wrong?

fonik · Posted: Wed Jul 05, 2006 1:41 pm Post subject:

hmm...

SL working without power consumption? unlikely.
if not already checked be sure to set your multimeter to milliAmpere (some gear provides different plugs for Ampere and Milliampere).

just one more pictorial graphic for verification of wiring to measure the positive power consumption:

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Uncle Krunkus · Posted: Wed Jul 05, 2006 4:40 pm Post subject:

Yeah, and on mine I have to change the position of the lead.

jimmyschaus · Joined: Jul 02, 2006 Posts: 10 Location: syracuse, ny

okayyyy so i found an open, closed it, and now everything works better than ever, except the first oscillator is stuck at a high frequency and won't change...any suggestions?

gosh, thanks for all your help thus far, by the way

fonik · Posted: Thu Jul 06, 2006 1:53 am Post subject:

Uncle Krunkus · Posted: Thu Jul 06, 2006 5:04 am Post subject:

In Fonik's situation: -
Do you have anything connected to the external CV inputs for either Osc1 or 2? If not they should be "floating", ie; not connected to ground or any other voltage. (actually it might be okay for them to connected to ground, check with Mosc, Stein, Tom or Jan.) Something is adding an offset to Osc1's CV and sending that to the CV for Osc2. They should each be pretty much independant of each other unless they have the same CV plugged into their Ext CV or if they are both being modulated by the same internal CV source, eg AR or LFO. If it's an actual fault and not user error I'd almost gaurantee it's some kind of front panel wiring fault.

In Jimmy's situation: -
Again, you need to track down what is supplying the CV to Osc2. Check that the master tuning Pot has +ve(-39K?) on one side and -ve on the other. Trace all the other possible CV in's for Osc2 and make sure they are either not connected (ext CV in) or they are switchable (AR/LFO CV in) you may have inadvertantly wired one of these wrong so that it is held up to the +ve rail all the time.

fonik · Posted: Thu Jul 06, 2006 5:15 am Post subject:

jimmyschaus · Joined: Jul 02, 2006 Posts: 10 Location: syracuse, ny

Okay...so I'm checking the master tuning pot for oscillator two, even though it's the first one that's giving me trouble? Can you explain how the controlled voltage for the second oscillator effects the pitch of the first?

Both master tuning pots have +ve on one side and -ve on the other side. Ext CV is connected from the input jacks to the board for both oscillators, but nothing is connected to the jacks (which is what I assume you meant by ext CV in)...also, the wiring is correct for all the switches pertaining to CV ins. Also, I noticed that oscillator one is audible all of the time, even when down all the way in the mixer, but that changing its "level" in the mixer actually changes it's pitch, all in a very high range of frequencies, though. Again, the tuning pot does not change the pitch at all, and it's stuck at a high frequency, unless you change its level in the mixer. Also, new batteries died in three days, so I'm pretty sure one of the rails are drawing too much current, but I can't figure out which one because whenever i test it with the multimeter it reads O mA! I'm pretty sure I'm doing it right based on both of your guys' explicit diagrams, maybe the multimeter is broken, or I'm a moron and still doing it wrong. Any new ideas, suggestions? The rest of the synth works so beautifully, it's just this one thing...could I need a new chip or something?

Uncle Krunkus · Posted: Mon Jul 10, 2006 12:27 am Post subject:

I think we're getting closer now. Wink

Check that the wires connected to the wipers (centre connection) for the tuning pot and the level pot haven't been swapped.

jimmyschaus · Joined: Jul 02, 2006 Posts: 10 Location: syracuse, ny

nope, both pots are wired correctly

jimmyschaus · Joined: Jul 02, 2006 Posts: 10 Location: syracuse, ny

any other suggestions? i just want it to worrkk!

Uncle Krunkus · Posted: Wed Jul 12, 2006 3:44 pm Post subject:

Nah, I'm all out of RAM at the moment. I s'pose it could be time to start swapping out chips. Start with the Oscillator 444s.

fonik · Posted: Tue Jul 25, 2006 6:00 am Post subject:

any news?
you may forget about that it was once working and start troubleshooting as you have built it new: check via netlist once more, check solderjoints (i once had a bad solderjoint that must sometimes have worked and sometimes not, as soon as i tipped all joints with the hot iron the module worked...) and so on.
let us know as soon as you reanimated your SL.

jimmyschaus · Joined: Jul 02, 2006 Posts: 10 Location: syracuse, ny

soundlab reanimated! i found two tiny little opens that must have chipped off in the moving process or something. thanks for all your dudes' help.

fonik · Posted: Thu Jul 27, 2006 11:40 am Post subject:

good job

, case closed.