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Messages - strat68

#31
General Questions / Lab Series Preamp Debug
August 04, 2016, 03:57:34 PM
Finished it and after finding out I had both voltage regulators (7815, 7915)reversed I need to see why it does not work.
Doc: https://www.dropbox.com/s/dnizjzbetec84gu/aion-lab-series-preamp-documentation.pdf?dl=1

1. Since I had the VRs reversed should I expect damage to them or any downstream components.  They got hot when reversed and still get hot when inserted properly.

2. The AC power source measures about 12 volts and not 9.

3. When measuring voltages,  since I'm not a circuits expert, should the meter be set on AC or DC voltage?  The board has  +/- 15v testpoints.  AC or DC?   

Thanks!
#32
General Questions / Re: Resistor/ Capacitor Kits
March 28, 2016, 03:39:55 PM

Quote from: jposega on March 23, 2016, 05:05:08 PM
Thanks everyone. Just started checking out Tayda and their "easy order" resistor page alone has me convinced I should give them a try when their next coupon code pops up. I won't need 100s of them, but just a couple dozen in each common flavor to do a few projects after I finish my undergrad in May.

IMHO, that's the way to go for resistors.    I never buy less than 20 at a time even if I only need 1 of a specific value.
#33
Quote from: jimilee on February 08, 2016, 07:39:09 PM
BLMS is where mine come from, awesome guy, you can stock up and still only pay 5.95 shipping.

I second this one.  On average, the lowest prices I've found.
#34
It was the 2n5457s.  I took a close look and 3565's must have gotten into the wrong bin.  The pedal works fine now.
#35
Tech Help - Projects Page / Re: Squealing LT1054
May 08, 2015, 02:15:10 PM
The resistors are correct.  I'll have to continue tracing the circuit with a probe.  I can't get any sound past Q1.  I've re-flowed solder for the various Q1 parts.  Nothing makes it to the Gain pot.  I'll re-check the voltages since the doc. has a list for each transistor. 

build doc: http://www.madbeanpedals.com/projects/Flabulanche/Flabulanche_2015.pdf
#36
Tech Help - Projects Page / Re: Squealing LT1054
May 07, 2015, 05:03:19 PM
Quote from: midwayfair on May 07, 2015, 03:01:19 PM
Almost guarantee you used 470k instead of 470r for all three source resistors.

That's what I'll check first.
#37
Tech Help - Projects Page / Re: Squealing LT1054
May 07, 2015, 01:28:25 PM
Quote from: midwayfair on May 07, 2015, 03:51:09 AM
Quote from: madbean on May 07, 2015, 01:29:13 AM
You could try bumping up your T2 trimmer to 50k or 100k to see if you can dial in the bias voltage.

No change at all in the bias voltage? That says to me that either the trim itself is faulty or the source resistor is wrong. Very wrong. Like orders of magnitude wrong. A really big trim there like 50k would also be a pretty hefty source impedance to drive the 100k gate resistor that follows.

Correct, with different 5457's the bias voltage does not change regardless of where the trims are set.  For all 3.  I'll check the resistors but more than 1 mistake seems unlikely unless I dropped a whole bunch of the wrong value resistors into that bin.  A definite possibility.

#38
Tech Help - Projects Page / Re: Squealing LT1054
May 07, 2015, 12:12:36 AM
Bridging fixed the squeal but no output past Q2.  I tried 2 different lots of 5457s and the second lot will not bias )but they do pass a little sound)at all.   Shows 17 volts and never changes regardless of what I do to the trimmers.  I'm going to have to study the schematic and see what's up.   I should have stuck out the EE degree in college.
#39
Tech Help - Projects Page / Re: Squealing LT1054
May 06, 2015, 07:10:45 PM
Quote from: rullywowr on May 06, 2015, 06:14:07 PM
It's possible that they may be  counterfeit and actually a 1044 type instead and just labeled lt1054.  If this is the case, bridging pins 1 and 8 should make the squealing disappear as the click will be put in turbo mode.  Did you buy these from a reputable supplier?

I'll try the bridging.  Bought 'em on ebay, so probably not reputable.  My next batch is coming from Jameco.
Thanks Ben!  Anything new coming up?
#40
I'm in the process of checking out a Flabulanche and finding that the batch of LT1054's all cause a squealing noise in the output.  I had tried one of these 1054's in another pedal with the same result but did not get around to trying the other 2 part before I found a different 1054 that was OK.

Is this more likely a bad batch of parts or is there something I can do to alleviate the squeal?
Thanks
#41
Quote from: madbean on March 23, 2015, 01:48:06 PM
I will get that up this week. Thanks for the reminder.

Ping?
#42
General Questions / Re: Chinese footswitches
March 30, 2015, 06:21:14 PM
Quote from: Luke51411 on March 30, 2015, 06:16:07 PM
Don't. or at least be very careful. I bought a lot that was $16 for 10 and they are no good. I have one installed that sometimes decides to actuate and sometimes doesn't and you have to press it again. For what you get, buy from a known source. You won't regret it. The cheaper ones tend to introduce more mechanical noise when switching as well. If you are in the US, BLMS is not much more expensive and definitely better quality.

BLMS is where I buy all switches now, among other items.
#43
Quote from: aballen on March 23, 2015, 11:53:59 AM
Did the "mid-month" signup sheet ever happen?  Not whining here, just want to be sure I did not miss it.... Been traveling for the last two weeks.

Yep.  Wondering the same thing.
#44
I just realized that I had forgotten to pay attention to capacitor voltage and was running it at 18 volts.  What are the symptoms of doing this?  I'm getting occasional sound out of the distortion side that sounds great.  The thing seemed to worked before boxing it and now works sometimes after taking it back out of the box.

Alternatively I also think my real problem is some type of connection issue on the board itself.  I can always trace a good signal to lug 3 of the volume pot.  Only some of the time does it the signal come out of lug 2 and make all the way to the output connection.  The pot is OK as I switched it out and checked the new one before attaching it.    The signal at R23 is also fine (as expected).  I've re-flowed solder on the parts from IC3 to the volume pot.

Here's the schematic:  http://home.comcast.net/~gprause/BuildDocs/T-Wrex_II_V3.2_Build_Doc.pdf

Any info is greatly appreciated.  This things sounds awesome when I can get sound out of it.
#45
Build Reports / Re: Rullywow Vapor Ray
March 03, 2015, 02:36:22 PM
Just finished the Vapor Ray list night.  An excellent pedal.  I like it far better than any of the Timmy boards I've built.