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VFE Mini Mu

Started by pedalbob, July 08, 2024, 01:59:30 AM

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pedalbob

July 08, 2024, 01:59:30 AM
Hi All-

Just bult a VFE Mini Mu with the included Tru Soft switching board.  I used the latching relay and I jumpered the board approprioately per instruction sheet.

The effect turns on and sounds fine ... everything works in effect mode ... LED lights up.  When I click to bypass LED goes out but I get no sound coming thru at all.  Assume the issue is somewhere on the True Soft Board.

Any ideas on where to start ?  I can post pictures but it is boxed and the True Soft Board is "upside down" (solder side showing).   

madbean

#1
July 08, 2024, 02:55:04 AM
Quote from: pedalbob on July 08, 2024, 01:59:30 AMHi All-

Just bult a VFE Mini Mu with the included Tru Soft switching board.  I used the latching relay and I jumpered the board approprioately per instruction sheet.

The effect turns on and sounds fine ... everything works in effect mode ... LED lights up.  When I click to bypass LED goes out but I get no sound coming thru at all.  Assume the issue is somewhere on the True Soft Board.

Any ideas on where to start ?  I can post pictures but it is boxed and the True Soft Board is "upside down" (solder side showing).   

Just a bit of gentle love here, but this is why I emphasize the goofy "rock it before you box it" mantra. Unfortunately at this point you may be looking at some disassembly and pics before anyone can give meaningful advice. The problem description alone isn't enough to give meaningful feedback. There are just too many factors that could be at work.

pedalbob

#2
July 08, 2024, 01:36:14 PM
No problem I almost always do that (test in my test rig first) but with the 2 boards connected with stiff ribbon cable and 3 pots and 3 switches, integral PCB Jacks etc. it is a bit of a tight squeeze/ alignment trick so I soldered the upper part of the ribbon cable (to the switching board) once I had the effect board in and lined up.

I can easily get it apart.  I forgot to mention above there is also no difference when I toggle the buffer/true bypass switch (no bypass signal).

I also have an extra switch board already built because I was making one of these for myself and one for a friend at the same time.  I may just swap that to eliminate that.  I reflowed all the solder joints I did on the installed switching board as step one last night but still nothing. 

pedalbob

#5
July 09, 2024, 07:14:53 PM
 So I changed out the switching/power board for a second one that I had built at the sme time with identical components and I am getting the same result (no bypassed signal) but effect on is fine. No bypass signal with buffer/true swicth in either position.

pedalbob

#6
July 10, 2024, 10:41:00 PM
 Worked on this some more today with no change ...

The only parts I didn't get from Mouser besides the resistors (which I checked with my Peak passive component tester before installing) was the 2 transistors ... I pulled the BS170 and the J175 and installed sockets ... put in some others that I had that tested fine on my PEAK DCA55 ... still no by pass signal just effect.

I guess next step is to get out my signal probe ... unless somebody has a better idea ??

I've built multiple VFE pedals (Blues King, Choral Reef, etc.) with the old style switching relay boards and never had a problem.  Frustrating since the effect itself is working great.     

madbean

#7
July 11, 2024, 12:21:38 AM
Sorry, a little sick today. I'll take a close look at your posts tomorrow and respond.

pedalbob

#8
July 11, 2024, 12:39:13 AM
No problem. Get well. This can certainly wait. 

pedalbob

#9
July 28, 2024, 01:46:05 AM
If I wanted to just make this a plain true bypass with a 3PDT the old fashioned way I assume I would :

1) Wire In & Out on mini-mu board directly to 3PDT
2) Leave +9v, -9v and GD connected between Soft Touch and Mini-Mu board
3) Wire up LED old fashioned way with 3PDT and CLR
4) Wire the board mounted input and output jacks directly to 3PDT
5) Leave the BU and Hi and FS pads empty on both boards

Anything I would need to remove or clip on the Soft Touch Board ?   

jwin615

#10
July 28, 2024, 12:51:39 PM
There look to be 2 components that are unpopulated compared to beans photo in the minimu build doc. I can't seem to find a sps v3 build doc so not sure what they are or their function. Maybe this is nothing...

pedalbob

#11
July 28, 2024, 01:37:32 PM
Hi -

Thanks for the reply.  The one in the upper left is a jumper if you use the non-latching relay and since I used the latching relay it doesn't get poulated (but two other jumpers do which I have populated).  The one to the right of the relay is a transistor which is shadowed by the relay in the photo so hard to see (i.e. it is populated)
   

madbean

#12
July 29, 2024, 05:25:09 AM
I'm on vacay right now but if you can hold off another week or so I'll dig into this.

pedalbob

#13
July 29, 2024, 12:19:37 PM
OK thank-you.
I have a 2nd Effect board that I have populated with everything except the pots and switches. Reluctant to go further and get same result.
I used the original Softtouch board and tried the one for the above with the 1st effect board with same result.
I tried disconnecting the IN/Out from the Softtouch board and just going direct to the mini-mu thru my test rig (i.e. using its in/out jacks and bypass switch but still using Softtouch power supply).  Now I'm just getting loud hum so afraid I messed something up.
I'll hold off doing anything else.

pedalbob

#14
August 04, 2024, 02:23:06 PM
Update -

We've had a few rainy days here and this project has been on my bench for weeks so I went ahead and built the 2nd one I had.

1)Plugged in for 1st time and it was in Bypass mode ... clean guitar signal came thru fine.
2)Press switch and effect came on ... effect and all settings work fine
3)Press switch and no sound
4)Little switch on relay board was at "buffer" setting originally ... un powered pedal and switched to bypass but still can't get it to pass clean signal.

Seems like something latched in the bypass leg of the circuit and it won't unlatch.

Only difference with this build from my other was that I socketed the transistors on the relay board (J175 & BS170) and I used TL074 on effect board instead of TL034.(and I haven't hooked up indicator LED yet).   
 
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