Tonepad FSH-1 voltage request

[Govmnt_Lacky]

Just built the Tonepad FSH-1 from an etched board and it is giving me fits  

Link: http://www.tonepad.com/getFile.asp?id=138

Mods: I included the S&H/Filter via a DPDT stomp and the Up/Down mod via a DPDT toggle.

Also used multi-turn trimmers for the 10K and the 100K.

I am wondering if someone could post some voltages from a working unit. Here are mine:

Input voltage = 9.0 Regulated

MAX1044
Pin1) 9.1
Pin2) 4.5
Pin3) 0
Pin4) -4.3
Pin5) -8.6
Pin6) 4.3
Pin7) 6.6
Pin8] 9.1

JRC13600D (IC1)
Pin1) -7.1
Pin2) -0.2
Pin3) 0
Pin4) 0
Pin5) -1.3
Pin6) -8.2
Pin7) 0
Pin8] -1.3
Pin9) -1.1
Pin10) 0
Pin11) 8.6
Pin12 thru 14) 0
Pin15) -0.1
Pin16) -7.1

IC2 (4558D)
Pin1) 0.4
Pin2) 0
Pin3) 0
Pin4) -8.6
Pin5 thru 7) 0
Pin8] 9.1

IC3 (4558D)
Pin1 thru 3) 0
Pin4) -8.6
Pin5) -4.6 to -4.9 flux
Pin6) Fluxuated too fast
Pin7) -6.8 to -7.2 flux
Pin8] 9.1

Q1 (3904)
C) -8.6
B) -8.0
E) -0.13

Q2 (BF245A)
D) 0
S) 8.6
G) -1.34

Q3 (3906)
C) -7.1
B) 0
E) 0.13

Q5 (BF245A)
D) 0.02 to 0.15 flux
S) 0
G) -6.5

Q6 (BF245A)
D) 9.1
S) 1.54
G) 0.02 to 0.15 flux

I DID reverse the BF245A trannys from what they are on the Tonepad layout (as per build reports and schematic)

This effect is just not right when compared to other demos I have seen/heard. If someone could post voltages of a working unit it would be much appreciated.

Thanks  

[chromesphere]

Hey Govmnt_Lacky,

Sorry to hear your build isnt working.  Heres the voltages as per your PM.  I typed them up in a doc file, ill just wack them in here:

Readings for IC's start on pin one and go around in order
Trannies have 'gate' or 'arrow' mentioned.  Refer tonepad parts layout.  Next reading is middle, and then the last pin on the trannie.
Readings taken in 'filter' mode.
Also checked what trannies i've used and listed accordingly.

4558
.12 - pin 1
0
0
9
4.7
1-1.3
6.6-6.9
9

13600
6.8 - pin1
0
0
0
0
0
0
1.65
6.8
.8
0
0
0
8.4
0
1.2

4558
1 - pin 1
0
0
8.6
3.6
3.6
1.9
9

q6 - j201
0-1 gate
0-1.7 middle
9.3 last

q5 - j201
6.6 gate
.01 middle
.2-15 last

q4 na

q3 -  2n3906
6.5 arrow
0 middle
.6

q2 - j201
0 gate
9 middle
0

q1 - 2n5088
.1 arrow
8.6 middle
.1

[chromesphere]

Answers to your questions as per PM:

Furthermore, i personally found i could not get this effect going with the listed fets on tonepad, and posiibly even q1 2n3904, from what i remember, sorry it was a while ago...maybe i got duds...i dont know, but the j201's in combination with the other trannies i used worked.  I found, once i had the correct combo on trannies, it all just worked the way it should.  

I recall, one of the trimpots seemed to adjust the range of frequencies the sample and hold effect selects from, sort of like...its range?  if that makes sense.  at minimum, you only get 2 or 3 frequencies, but at the other end of the scale, you get alot of frequencies, as heard in my youtube video.  If you adjust it too far though it starts distorting.  I cant remember what the other trimpot did sorry.

You should also be getting a fluctuately voltage on q3 (not the arrow pin, or the middle, the other one) in sample and hold mode (my is 9-10v). i remember one of the trimpots makes the range of this voltage wider.  Mine sounded best at this setting (9-10v).  My FSH q3 also doesnt fluctuate in filter mode as confirmed by the volt readings. but if your not getting fluctuating voltages in S&H mode on this pin, S&H wont work.

The dials shouldnt make much different to this varying voltage reading on q3 in S&H mode.

The key to getting mine working was the trannies. Could be different for you, but 'eureka' was heard from the study when these trannies were correct.  Before than, i was just getting weird stuff.

Sorry the info is a bit sketchy, it was a while ago...but i hope it helps all the same!
Paul

[Govmnt_Lacky]

Hey chromosphere,

Thanks for the post with the info. I have a question for you though.

I noticed that you don't list any negative voltages in your post. Was that intentional or was it just a mistake? When I took readings on my FSH, some of the ICs and trannies had negative voltages on the pins. Could you elaborate on which voltages were negative?

Also, could you post which 4558s are which? (IC2 or IC3)

I appreciate all of the help. I think I am going to try the J201/5088 combination that you have and give it a go.

You are right that there is not a lot of info on this effect. This may be a good place to start! 

[chromesphere]

No problem.

Sorry polarity was left off of the voltage readings accidentally.

I'm also not sure which 4558 is which.

Paul.

[Govmnt_Lacky]

No problem.

Sorry polarity was left off of the voltage readings accidentally.

I'm also not sure which 4558 is which.

Paul.

Any chance of clarification on these? 

[Govmnt_Lacky]

OK. I have learnt a few things since yesterday. Here are two:

1) This circuit works MUCH...MUCH better when you actually connect the Resonance pot 
2) I was able to get much more volume and response by following what chromosphere said and replaced the FETs with J201s and the noise transistor with a 5088.

It seems that now I am getting closer to a good working unit however, I still have a few bugs to work out.

I was able to see a voltage swing on the COLLECTOR of Q3 as in other threads that I have read. I adjusted the 10K trimpot until the Q3 collector was wobbling between -7 and -6.5V. This was with a 9.0V regulated input.

The S&H bee-bop (what I call the computer-like tones that it outputs.... which I THINK is right  ) is CLEARLY audible even when I do not strum the guitar.... kinda like bleedover. I think this may be due to the Q1 Noise transistor but I am not sure. Will need to do some swapping to find out.

Seems that the Filter only works when the Range pot is almost maxed. Is that normal?

Still a ways to go but at least there is some progress 

[liquids]

Hope this post/thread helps:

http://www.diystompboxes.com/smfforum/index.php?topic=69381.msg633193#msg633193

[Govmnt_Lacky]

Hope this post/thread helps:

http://www.diystompboxes.com/smfforum/index.php?topic=69381.msg633193#msg633193

Hey liquids! Thanks for the response.

Could you possibly clarify what it is you were saying in the linked post above? I have read it about 20 times but.... is there any way you could "simplify" it for an FSH newbie? Especially the parts about reading the voltage swings, how to adjust to get them right, and what you meant when you said "And FYI, if you aren't already getting a continually variable voltage at the chips in the appropriate pins, as documented by gigimarga, than the S/H side is certainly not going to work, so continue debugging until you get those variable."

I think I have mine "almost there" but like I posted above, the S&H just does not sound right after seeing chromosphere's demo. Also, I get the S&H bee-bop fairly LOUD even when not playing.

Thanks 

[liquids]

You're voltages don't look bad at all really.   Some places they should be fluxuating and they may be, but possible the DMM is too slow/speed is set too fast to read the variations cleanly.

Turn that speed pot down till its working right.

And turn the resonance down when you do audio test it.  More resonance will yield more volume.  And if you are prototyping it on a breadboard (should with this kind of circuit), adding a volume control should be easy enough...

Keep looking over it for errors.

Did you get the Envelope portion to work?

Multi turns trimmers shouldn't be necessary.

try other types of FETs, other people have had issues in the past...at least compare voltages around those areas if you swap.

[Govmnt_Lacky]

You're voltages don't look bad at all really.   Some places they should be fluxuating and they may be, but possible the DMM is too slow/speed is set too fast to read the variations cleanly.

Turn that speed pot down till its working right.

And turn the resonance down when you do audio test it.  More resonance will yield more volume.  And if you are prototyping it on a breadboard (should with this kind of circuit), adding a volume control should be easy enough...

Already in the enclosure...    However, as mentioned above, the only Volume problem that I have is that I hear the S&H frequencies fairly loudly even when NOT playing.

Keep looking over it for errors.

This is what led me to the head slapping moment where I realized that the Resonance pot was not even connected  

Did you get the Envelope portion to work?

I think it is working properly. The controls are very picky (as mentioned above, the Range pot has to be almost maxed out to get and envelope filter operation.

Multi turns trimmers shouldn't be necessary.

Already soldered in. They work great, just more turns needed. I actually found that I get the voltage swing at Q3 with almost the entire pot span. The only thing that changes is the centerpoint of the swing and the amount of swing. I tried to get it to -7.5 +/- 0.5V like in your post on the other thread, but I could only get it to swing between -7.0 to -6.5V. Maybe due to a difference in PS voltages??

try other types of FETs, other people have had issues in the past...at least compare voltages around those areas if you swap.

I definitely plan on trying different Q1s to try to get rid of the S&H bee-bop when not playing but I will also try different FETs and maybe even a different Q3.

Thanks for the help Liquids... if you think of anything else.... please post  

[Jmkrull]

Hey,

I just checked all my voltages and I'm getting 8.6~8.9v across every point on the board. Pardon my stupidity, but does anyone know why this would be?

I remelted all the joints and am going to replace all the ICs, Transistors and Diodes as well as scrape around to dislodge any shorts. Besides that, does anyone know what else I should be looking for?

Thanks,
John