Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Messages - Cybercow

Pages: [1] 2 3 ... 5
Tech Help - Projects Page / Re: Mandroid Static
« on: January 16, 2021, 03:12:08 PM »
Have you resolved this yet? I'm beginning three different Robot circuits (just to note the differences) and was wondering where you are on the "static". My first build used the Robot Voice kit using the HT8950A (16-pin version), and it seems to be noisy as well. I've got three HT8950 (18-pin version) builds I'm about to begin and hoping to share some info.

Coupe of points . . . .

1) eBay specialized IC purchases, (especially from China), are a crap-shoot at best. They could very well be fakes or bad pulls and cleaned up. China sellers have been known to sand off the markings and re-ink them for whatever they want.

2) But let's assume they are good and\or genuine MN3102 + MN3207 chips . . . . if they are the real deal and in working order, those trims pots for setting the bias each have a very narrow sweet-spot. And according to the Aion BlueShift builddocs, an o-scope is needed to get those trimmers dialed in correct. Kevin also states that it can be done (near-passably) by ear, recommends an o-scope. I didn't see in your post that you had tried setting them in any fashion, so I have to ask: Did you try adjusting the trimmers to acquire a proper bias for each chorus section? He has a full description of biasing with your ear and o-scope on page #7 of the build docs.

Short of a biasing issue, when the new chips arrive, they will need to be re-biased when you swap them. If the new one(s) work, at least you can request a refund on the ones you got from China.

Good luck!

Tech Help - Projects Page / Re: Pork Barrel 2019 Help Request [SOLVED]
« on: August 11, 2020, 07:11:55 PM »
1 & 5 are fine (power is switched for the MN3207 vs. MN3007) pin 6 should be the same as pin 2, there's a problem with your 3102.

As Scruffie said, Pin 6 of the 3207 is tied directly to Pin 2 of the 3102. If Pin 2 of the 3102 is good (as you mentioned in your post) then you need to find out what is causing that voltage to drop at the 3207.

Thanks guys. I didn't have another V3102 handy, so I swapped out both the clock chip and the BBD for an MN3102 & MN3207 and the chorus came to life. A little trimpot tweak and it sparkled just like a great chorus pedal ought.

I then got curious and swapped out the working MN3102 & MN3207 for the original V3102 & V3207 and it worked just as well with the 'MN' chips. (After another quick tweak of the trimpot.) The best guess I can make of what the original "problem" was, is that the clock IC was not seated well enough and . I poked and prodded around with a plastic chopstick and could not get any faults or intermittents.

Played thru it for a good hour (with original 'V' chips) whilst fiddling with the controls & bypassing \ re-engaging several times and it seems solid now. Electronics truly is a fickle mistress.

On further consideration, (while I've not yet tried it), I'm guessing the CoolAudio V3102 & V3207 are interchangeable with their counterpart MN3102 & MN3207 versions. (?) Based on their respective datasheets, it looks like one chip can be the CoolAudio 'V' and the other chip can be the 'MN' version. Conversely, the MN3101 & MN3007 are NOT equally compatible with the MN3102 & MN3207 or the CoolAudio versions. (Following the schematic more carefully and noting the orientation of the jumper requirement differences.)

Thank you for your suggestions, time and consideration.

Thanks for the helpful posts already, and any other help will be icing on the cake!!

Thanks for the kind words. You're welcome.

1) The LDR's are oriented at a 90 degree angle from the board. Is this how they are supposed to go? I initially just assumed they were tacked down straight to the board and would catch ambient light within the light shield.

The positioning of the LDRs was just a choice. They work fine either way. The light shroud is important.

2) This is more out of curiosity, but is there a reason you left C33 open? You may have just been waiting for a part to make it through the mail, but maybe you have discovered some mod that I should know about. :D

I noted in the build docs that no value for C33 was given in the BOM. In fact C33 was not even listed in the BOM - but it is shown in the schematic. Also, the build document shows a photo of a 9v build that excluded C33 as well. Also, I know the LT1054 charge pump is pretty stable and the datasheet for it demonstrated no need for that 100nF cap in that position. The final result of my build sounds great with no chargepump buzz and the 15v supply is clean. So I just followed the build document. I also don't believe it would be harmful to use it.

VFE Projects / Re: VFE Choral Reef Build - Distorted Output - [SOLVED]
« on: August 08, 2020, 09:28:25 AM »
May I ask what brand it is and where you got that resistor?

That's an extremely good catch

Don't remember the brand - but I know I got it from Mouser. When I do VFE builds I get all my parts from Mouser and SmallBear.

VFE Projects / Re: VFE Choral Reef Build - Distorted Output - [SOLVED]
« on: August 07, 2020, 06:19:02 PM »
Daaaaamn nice job.
Sent from my iPhone using Tapatalk

Thanks JimiLee !

VFE Projects / Re: VFE Choral Reef Build - Distorted Output
« on: August 07, 2020, 01:42:19 PM »

To cut to the chase - it was the 2M2Ω resistor off of pin 12 on the TLE2074. When measuring from pin 12 of the empty socket to the 2M2Ω resistor, I got continuity. When measuring across the 2M2Ω resistor I got 2.2M Ω resistance. When measuring the from VB board input to the 2M2Ω resistor I got continuity. That is what told me the 2M2Ω resistor was good.

HOWEVER . . . ..  with the TLE2074 still out of socket, I should have been able to measure 2.2M Ω resistance from pin 12 to the VB input - but it read open. That should have been my troubleshooting "AHA!" moment. But I overlooked it because all the other readings suggested all was well.

As it turns out, the pressure of applying the DMM probes to each side of the 2M2Ω resistor was putting enough pressure to make the resistor measure properly. Without any pressure, it measured 'open'. I had reflowed that resistor twice and all the above measuring and testing remained true. So, I pulled out the 2M2Ω resistor and put in a fresh one and THEN I could read continuity from pin 12 to the VB input. I then replaced the TLE2074 chip and pins 12, 13 & 14 then gave correct voltage measurements. After which I hooked it up to my amp and guitar and VOILA! I had crystal clear chorusing with all controls doing fantastic things to the chorus settings.

Finally, I went back to the 2M2Ω resistor I had pulled and gently connected alligator clips to the leads and re-measured it. It read 'open'. I took the gator clips off and applied the DMM probes to either side and it measured 2.2M Ω. Apparently, that specific 2M2Ω resistor has an internal micro-fracture. It's in the bin and I'm happily onto finishing the enclosure for my new VFE Choral Reef pedal.

Thank you to everyone who participated.

VFE Projects / Re: VFE Choral Reef Build - Distorted Output
« on: August 07, 2020, 07:53:11 AM »
Here are the build photos . . .

During the build process, I carefully examine the progress with a strong light and magnifying visor - double checking for any bridges and\or solder splashes. Especially before soldering the pots into place; as they cover up much of the work. I suspect there may a micro fracture (possible a scratch) through a trace near the first opamp section.

Thanks for all the suggestions thus far.

VFE Projects / Re: VFE Choral Reef Build - Distorted Output
« on: August 06, 2020, 11:24:51 AM »
Bench update . . . .

With the TLE2074 removed:
1) pins 12 & 13 now read 4.88 volts - but pin 1 reads only 1.2v.
2) unable to measure the 2M2Ω resistor between pins #12 & #5 of the socket - but there is continuity between pin 12 and the 2M2Ω resistor; there is also continuity between pin 5 and VB - AND continuity between the other side of the 2M2Ω resistor and VB.
3) the 2M2Ω resistor measures 2.2M Ω (with the TLE2072 out of the socket.

On the SB3 board:
1) R5 & R6 are in place
2) C6 is installed reverse of the PCB markings (as per the build doc)
3) there is ~4.88 volts on the V- point and ~9v on the V+ point

Other points:
1) all 3 16mm pots have SmallBear pot condoms on them
2) with all chips in place, powered up and plugged in, all the controls have functionality. The output is just quite distorted. (The first opamp [TLE2074] section has a low-voltage condition on pins 12, 13 & 14.)
3) C18 (.22µF) is not leaky (from Mouser)
4) C12 (10µF BP) is not leaky (from Mouser)
5) Tried a few different quad opamps (TL074, TL084, OPA4134 & OPA4132) and all exhibit the same low voltage on pins 12, 13 & 14 - and all the pots still have functionality - just dirty output
6) With all chips in place and the circuit powered up, there is 4.88v at the VB points, including pin 5 of the TLE2074

I've not started pulling my hair out yet, but it's close to that pointless prospect. Clear photos coming shortly.

Any further suggestions or things to check will be appreciated.

VFE Projects / Re: VFE Choral Reef Build - Distorted Output
« on: August 06, 2020, 10:55:51 AM »
Did you add the 2 resistors and reverse the one cap on the switching board? This is part of the "choral reef" difference on the switching board.

Yes - R5 & R6 installed and C6 installed reverse of the polarity markings on the SB3.

VFE Projects / Re: VFE Choral Reef Build - Distorted Output
« on: August 06, 2020, 09:38:35 AM »
That'll do it, I was expecting that the BBD output op amp was going to be the problem, given how close to the rails it ends up biased.

What doesn't make sense is why all the other voltages are correct. I even swapped the TLE2074 with a fresh one - same result. (I got both TLE2074 chips from Mouser, so I should be able to assume they're both good. Or at least one of them.)

I'll look closer at the SB3 switching board to see what I can find. Without a schematic for it, I'm left to tracing from the layouts in the SB3 build doc. And I did catch the bits in that build that are exclusive to the Choral Reef.

Back to the bench . . .. .

VFE Projects / Re: VFE Choral Reef Build - Distorted Output
« on: August 06, 2020, 09:34:22 AM »
Remember that for the Choral Reef the VB source is on the switching board. This is explained in the SB3 doc. It's the only project that requires it.

I just sorted that bit out. And I did carry over the -V line from the SB3 to the PCB. I also followed the explicit instructions in the "In the Choral Reef the following exceptions are applied" section, leaving off the charge pump IC and C5.

VFE Projects / Re: VFE Choral Reef Build - Distorted Output
« on: August 06, 2020, 09:07:37 AM »
What sort of pickups are you using? It's not exactly designed for high headroom.

Could you please also post your MN3008 voltages regardless, just so I can double check them.

Thanks Scruffie . . . . I use a '79 Strat, so the pups are not hot. I remeasured all the voltages as shown in the chart, and the MN3008 is spot on. However, I think I've found the source of the distortion.  Pins 12, 13 & 14 of the TLE2074 are reading much lower than they ought. Instead reading 3.86, 4.88 & 4.88 respectively, they are at 0.93, 1.04 & 1.04 - also respectively to pins 12, 13 & 14 of the TLE2074. That's the first opamp section in the circuit. All other voltages are within 5% of the voltages listed in the build doc. Except pin 2 of the 4047 which measures 34mV instead of 115-118mV.

When I try to measure the 2.2MΩ resistor on pin 12 of the TLE2074 (with the TLE2074 removed) I cannot get a reading between pin 12 and the VB. Theoretically, with the TLE2074 removed, I should be able to read 2M2Ω between pins 12 and 5 on the TLE2074 socket. But it reads as 'open'.

Also, there seems to be no source of "VB" on the schematic and as such I have no reference for what VB is supposed to be. I can only guess it's supposed to be 1/2 of the supply voltage. I can easily find 4 locations on the schematic where "VB" connects to specify points, but no reference to a "VB" in the power distribution section.

VFE Projects / VFE Choral Reef Build - Distorted Output - [SOLVED]
« on: August 05, 2020, 07:59:23 PM »
Got the Choral Reef up and running today but I cannot seem to ditch the distortion. All the voltage measurements seem to match the build document voltages. And I've gone back and forth between the two trimmers to try and get rid of the distortion. No parts substitutions - except that 65K resistor where I tented two resistors that equal 65K in series.

I followed the build docs for adjusting the BBD, but it sounds very distorted. There is a sweet spot at just about midway on the BBD trimmer where the distortion is at a minimum. But I don't believe it should be that distorted.

All parts were sourced from SmallBear and Mouser.

Does anyone have any experience with the VFE Choral Reef that has a distorted output? Or are the trimpots just that fussy with only a tiny sweep section of each of the trimmers? I spent over an hour already futzing with them in very tiny increments.


Tech Help - Projects Page / Pork Barrel 2019 Help Request [SOLVED]
« on: August 01, 2020, 09:23:41 AM »
Just finished wiring up a Pork Barrel 2019 and have an issue I was hoping some kind soul may have encountered and can pass along a solution. Bypass works just fine. When engaged, I have to swing the "Blend" control all the way over to get any sound. The "Rate" LED pulses and changes speed with a change in the 'Rate' control - suggesting the LFO section is working as it should. I'm using the V3102 & V3207 clock and BBD combination.

As I adjust the trimmer towards one extreme, I can begin to hear some distorted sound and modulation, but no chorus effect.

All the voltages  - EXCEPT on the V3207 BBD are correct. Here are the voltages on the V3207 BBD:
1) 0.002 (effectively zero - supposed to be Vcc [9v])
2) 4.2 (seems to be correct)
3) 3.4 (supposed to be ~4.8)
4) 8.1 (supposed to be ~0.61)
5) 8.8 (supposed to be ~0)
6) 0.008(effectively zero)
7) 4.65 (seems to be correct)
8) 4.65 (seems to be correct)

I suspect a bad BBD, but would like to hear of any other insights or obvious blunders on my part.

I have NOT installed D5 (as per the build docs) and am using the vertical jumper configuration for the clock/BBD combo (also as per the build doc). All socketed devices are securely seated. All components acquired from SmallBear and\or Mouser.

Thank you for your time and consideration.

Pages: [1] 2 3 ... 5