Easyvibe not 'vibing'

[mat]

Hi There! (first post)

I just found the wonderful hobby of building your own effects on this summer ! I read a lot on a net of the subject and the more I read and learn the more I am hooked  :shock:

I've learnt what the basic parts do and how to wire them and my soldering technicue is getting better and better all the time.

I've built so far the 'Jack of all boosters', 'Fetzer valve', 'Phozer - not working currently', 'CabSim', 'Little Gem', 'EH LPB-1 booster', 'Eighteen' and the 'Brown sound in a box'. I also have components for about dozen effects waiting the hot iron. I have liked all of them very much. I have the Banzai Fireball 2  :

http://www.banzaieffects.com/europe/products/fireball2.htm  

and liked it a lot but the Eighteen gives me similar results (with the JOAB as a boost channel) plus clearer bottom end which I seem to be fond of.

I read all I found of the easyvibe on this forum and cannot solve the problem I'm having.

Here are a few facts:

The sound is not 'vibing'
The leds are oriented like this forum advices
I've checked the copper traces again and again
the electrolytis caps are as the layout shows
ic's are as the layout shows (TL072CN's by the way)
The bypass works
The sound changes slightly when engaging the effect, very minor phasing effect
the vibrato/chorus switch changes tone noticeably
two leds on the bottom are on all the time (while bypassing with 3PDT)
the four leds with LDR's are not flashing (I think that's it)
the pots seems to do little for the sound

I love the vibe effect and been strugling with this for a week so I'm kind of desperate what to do.

If some one could point me where to check voltages or something else, I would be very greatful ))

Thank You All,
Matti Tiilama (mat)
Helsinki, Finland

[Branimir]

have you tried tweaking the trimmer on the board?

i think it controls the current in the diodes or something...

(don't shoot me, this is from memory)

[RDV]

Welcome Mat:  :wink:  I couldn't resist.

Your oscillator is not working. I assume you've tried adjusting the 1k drive pot? Some have troubles with TL072, some don't. I used TL062 so I could be sure. Make sure all your diodes are correctly polarized also.

Good Luck

RDV

[mat]

Hi Branimir and RDV  

Wow! This was very quick responce !

I forgot to mention that yes I did also try to adjust the trimmer with no luck. The diodes are also right way.

mat

[JohnM]

You need to get those 4 LEDS flashing...  Are they on at all?  I noticed on mine that a bad connection to (or in) the speed control pot would cause it not to oscillate (stay frozen at a certain brightness).

[jrc4558]

Hey there! One more thing.
All the LEDs have to be same. And yes, TL062 should be used. There's something with biasing that calls for that particular chip.

[mat]

Hi!

they are not on at all - I'll check the speed pot.

What kind of voltages should the led+'s have from left to right ?

mat

You need to get those 4 LEDS flashing...  Are they on at all?  I noticed on mine that a bad connection to (or in) the speed control pot would cause it not to oscillate (stay frozen at a certain brightness).

[mat]

Hi!,

The led's are same, but they are 5mm I think. I'll buy 3mm/low current as the instruction says (just noticed that) and see what happends.
There stands in the part list that TL072 works. After all I'll start to hunt the TL062.


Thank You for the advice,
mat

Hey there! One more thing.
All the LEDs have to be same. And yes, TL062 should be used. There's something with biasing that calls for that particular chip.

[Torchy]

No need to hunt ... ask TI for some samples  :wink:

[mat]

Hi Torchy!

Thanks for the VERY good tip  

mat

No need to hunt ... ask TI for some samples  :wink:

[mat]

Hi!

No succes yet  

I chanced the leds for the 3mm low current and checked everything again. I cannot get the leds to flash. The led voltages are from left (-,+)
LED1 02.15mV,   0.3V
LED2 0.343V,   1.457V
LED3 02.15mV,   0.355V
LED4 0.350V,   1.457V

The two leds on bottom are on all the time (even when bypassing the effect) - is this how they should be ?

I'm waiting to the TL062's to arrive but I think that the leds should be blinking by now - the error lies on somewhere else.

The upper leftmost leg of the TL072 on the left goes on the left led has voltage of 02.1mV. In fact all the TL072's upper leftmost legs show that low value.

Any ideas ?

mat

You need to get those 4 LEDS flashing...  Are they on at all?  I noticed on mine that a bad connection to (or in) the speed control pot would cause it not to oscillate (stay frozen at a certain brightness).

[Torchy]

Have you used the pcb or perfboard ?

I ask because my first Easyvibe was a dud ... I had connected the lfo leds to the bias rail instead of 0V ... just a thought  :wink:

[mat]

Its pcb. What are the bias rails ? Are they those long lines under those IC's ?
Sorry, im that novice  :oops:

mat

Have you used the pcb or perfboard ?

I ask because my first Easyvibe was a dud ... I had connected the lfo leds to the bias rail instead of 0V ... just a thought  :wink: