208p build thread (papz's PCBs)

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kristop
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Post by kristop » Sun Aug 11, 2019 6:58 pm

Just want to clarify R72 & R73 on the mother board. The layout shows 2 different locations. And the same 10k value for both. The build notes mention 470ohm... The populated photos seem to even show something else.... What should I be putting and where?

Oh there's also 2 extra R69 in that area marked as 470ohm. Populate as indicated on the diagram?
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search64
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Post by search64 » Tue Aug 13, 2019 7:15 am

kristop wrote:Just want to clarify R72 & R73 on the mother board. The layout shows 2 different locations. And the same 10k value for both. The build notes mention 470ohm... The populated photos seem to even show something else.... What should I be putting and where?

Oh there's also 2 extra R69 in that area marked as 470ohm. Populate as indicated on the diagram?
Just follow the diagram.

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search64
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Post by search64 » Tue Aug 13, 2019 7:15 am

Swapped the 4136, no bueno still. No bongos for me.

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papz
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Post by papz » Tue Aug 13, 2019 9:29 am

Double check all components value, perhaps you did the same mistake populating boards 10 and 11 since you seem to notice the same misbehaviour in both LPGs.
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search64
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Post by search64 » Thu Aug 15, 2019 3:32 am

papz wrote:Double check all components value, perhaps you did the same mistake populating boards 10 and 11 since you seem to notice the same misbehaviour in both LPGs.
This'll take a while since I don't read color coded resistor values. Perhaps if someone here feels like helping out, I might be on my way a bit sooner. So to that effect, here are my two LPG cards:

Image
Image

To reiterate the symptom: everything works, but I hear no difference between the combination and VCA modes. No bongo's, so no vactrolly goodness.

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papz
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Post by papz » Wed Aug 21, 2019 1:17 pm

kristop wrote:Just want to clarify R72 & R73 on the mother board. The layout shows 2 different locations. And the same 10k value for both. The build notes mention 470ohm... The populated photos seem to even show something else.... What should I be putting and where?

Oh there's also 2 extra R69 in that area marked as 470ohm. Populate as indicated on the diagram?
Thanks for pointing this, I removed the R69, R72, R73 labeling and updated the archive. Please pay attention to the 470 and 10k value only and populate as indicated on the diagram.

search64 : you can compare the resistors with the pics on Dave Brown's website.
Resistors code is nothing complicated, there are plenty of tables online that will introduce you to the holy secrets of the color lines, it's worth learning if you're in DIY anyway.
Also check the caps value, no color code on those.
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Post by kristop » Fri Sep 06, 2019 4:26 pm

I managed to screw up my switches order and got Taiway sub-mini switches. Anyone know if solder lug mount switches will work on these boards as I found a good price on all of the switches except the most expensive one, CKN1493-ND‎. But can get the solder lug version for the same ~$2 price.
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Post by papz » Fri Sep 06, 2019 5:07 pm

The 208p FAQ is worth a good read. ;)
The enlarged holes for switches allow the use of both PCB mount (with thin lugs) and panel mount (with larger lugs) switches.
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kristop
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Post by kristop » Fri Sep 06, 2019 7:02 pm

papz wrote:The 208p FAQ is worth a good read. ;)
The enlarged holes for switches allow the use of both PCB mount (with thin lugs) and panel mount (with larger lugs) switches.
aha! thanks. i swear i've been through it like 100 times. solved many issues that way, but still managed to get the wrong switches the first time.
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search64
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Post by search64 » Thu Sep 12, 2019 7:43 am

search64 wrote:
papz wrote:Double check all components value, perhaps you did the same mistake populating boards 10 and 11 since you seem to notice the same misbehaviour in both LPGs.
This'll take a while since I don't read color coded resistor values. Perhaps if someone here feels like helping out, I might be on my way a bit sooner. So to that effect, here are my two LPG cards:

[...]

To reiterate the symptom: everything works, but I hear no difference between the combination and VCA modes. No bongo's, so no vactrolly goodness.
Checked the components, still can't find any errors. Which components on the motherboard could be at fault here?

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papz
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Post by papz » Thu Sep 12, 2019 8:50 am

R 65, 66, 67, 68
SW 19, 20

On a 208 partial build that I recently debugged and completed for a customer, R65 and 66 (300k) were missing on the MB, as a result there was no difference between the "combination" and "LPF" switch settings.
If that's the cause of your issue, you can add them to the back, no need to take the panel apart.
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search64
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Post by search64 » Fri Sep 13, 2019 3:00 am

Resistors are there and in situ resistance measurements are as follows for (measurements for both pairs are about the same so only one measurement given):

R66/65:
LPF ~0
Combination 82k
VCA 10.5k


R68/67:
LPF 12.5k
Combination 75k
VCA 3.2k

Could this be bad vactrols? I used dual Xvive 5c3.

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Post by Puzzler » Sat Sep 14, 2019 5:32 am

Hello,

my ToolBox Batch 5 doesnt change "MO Lo" frequency at all. Trimming doesnt help.
The MO LO resistor is 120k? Or should i try another value?

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Post by papz » Sat Sep 14, 2019 11:55 am

Hi Puzzler
This build thread is for the 208p, please start a new thread for your ToolBox question.
Thank you.

search64 your measurements look ok.
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search64
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Post by search64 » Fri Sep 20, 2019 9:23 am

papz wrote:Hi Puzzler
This build thread is for the 208p, please start a new thread for your ToolBox question.
Thank you.

search64 your measurements look ok.
This is quite maddening. I think I'm going to see what happens with different vactrols. Maybe single ones, and excelitas if I can find them.

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Post by search64 » Thu Oct 10, 2019 6:00 am

I found my issue: the Xvive vactrols I used have absolutely no tail whatsoever. I subbed it for a dual excelitas vtc/4 I still had lying around in my parts bin and now I get the correct albeit somewhat too long ringing when I hit the LPG with a very short envelope. So on to look for another excelitas dual for the second LPG.

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Post by boops » Thu Oct 10, 2019 6:05 am

Interesting,is your xvive vactrol used is tested good?
Last edited by boops on Fri Oct 11, 2019 2:23 am, edited 1 time in total.
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Post by papz » Thu Oct 10, 2019 7:59 am

Thanks for the info and glad it's (half) fixed :tu:
I'll add it to the FAQ.

Enjoy bongos (and cowbell of course ;) ) !
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Post by agustindead » Thu Oct 10, 2019 1:30 pm

Hi everyone. I couldn’t find a solution for this, but my pulser stops working at high frequencies. I have to retrigger it and then it’s fine, but it’s kind of annoying. This seems like a common issue from what I saw, is it?? Is there any fix for this? Thanks.
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Post by papz » Thu Oct 10, 2019 1:34 pm

I never met this pulser issue before but IC3 (4001) looks like a good suspect.
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Post by search64 » Fri Oct 11, 2019 2:03 am

boops wrote:Interesting,is your xvive vactrol used are tested good?
I didn't test them, I just plonked them in there to see what happened. I used duals to avoid having to match them in the first place.

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Post by tarandfeathers » Fri Oct 11, 2019 5:30 am

search64 wrote:I used duals to avoid having to match them in the first place.
I think this is probably putting an unreasonable level of trust in Xvives QC procedures. I tested a handful (maybe 10 or 15, I don't recall exactly) and as far as I can tell their dual optos are not matched on any parameter.
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Post by agustindead » Fri Oct 11, 2019 12:24 pm

papz wrote:I never met this pulser issue before but IC3 (4001) looks like a good suspect.
Thanks. I'll try swapping a couple of 4001's to see if it gets better.

Just to clarify and check if anyone has experienced this: it works perfectly fine in the slider range, but at higher frequencies it stops... Like, I have to be careful when modulating it with the random outputs, because it can drive it out of range and make it stop (which of course sucks live).
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Post by papz » Sat Oct 12, 2019 7:55 am

I just tested on my 208, controlling the pulser with the sequencer, all sliders all the way up to drive it to very high frequency, it doesn't stop self-retriggering.
This confirms yours doesn't behalve as it shoud.
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agustindead
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Post by agustindead » Thu Oct 24, 2019 7:55 pm

papz wrote:I just tested on my 208, controlling the pulser with the sequencer, all sliders all the way up to drive it to very high frequency, it doesn't stop self-retriggering.
This confirms yours doesn't behalve as it shoud.
Well, wasn't able to test it just until now.

Tried a couple of TI's 4001's and had no luck. It always stops retriggering at around 2kHz... This doesn't happen when triggered through the keyboard input, just on self triggering. Someone told me he experienced a similar issue with original easels as well, just saying.

Any ideas on what to try next?? Or any schematics for the pulser card?? This page of my scan is almost useless.
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