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9
J. HAIBLE Dual WASP Filter (Euro)
Some Troubleshooting Tips
•
First make sure both sides work correctly, i.e. ignore the middle section completely, feed a signal into
each side and listen to OUT A / OUT B.
If only one side does not work: compare both sides, they are iden-
tical, so a build issue is likely on the side not working. If both sides do not work, it seems to be a system-
atic problem, check power, values, op-amp orientations etc.
•
Only deal with the middle section if both sides are OK!
Some quick tests for the middle:
*
Check that you used a BCM8
5
7 (not BCM8
4
7!)? Or, if you used single transistors for
Q1 and Q2, that you used the right ones / inserted them correctly? Note the “
E
” marking
(emitter) on the pcb.
*
Feed an audio signal into INPUT A (only), set both filters to LOWPASS and open filter A
and B (CUTOFF) and listen to OUT (middle). Any signal present? Turn the mode knob (try
both ends) - does the signal change? Play with CUTOFF A, does that affect the output /
do you hear a filtered sound?
*
No sound in the middle? Keep feeding a signal into A, CUTOFF open and check with a
scope using the
test pads
: “
(x) TP IN (y)
” - on (y) you see the signal going into the VCA,
on (x) the output of the first VCA.
If you have a signal on IN (y) but not on (x), swap the lower
LM13700 (near the power connector).
*
Test pad 2 (“
TP2
”) can be used to check the signal coming out of the second VCA (= second half
of the LM13700). However, if you have no signal on test pad (x), there cannot be any on TP2, so x
and y are usually more relevant for spotting any problem with the LM13700.
•
You can also measure the voltages on pins 1 and 16 of the lower LM13700 while slowly turning the
mode knob
- these are the VCA control pins. When turning the mode knob you should see it
moving somewhere near the negative rail, approx. just between -10,5V and -11V (but it should
move). If these pins don’t move (but sit on the negative rail):
*
When you move the MODE knob, the voltage at the 3rd pin from the bottom of the long
(top) pin row on the right of the main pcb (connecting the panel pcb and the main pcb) -
next to the „L“ of the JHAIBLE logo - should change.
if it does not, there could be an issue
with the pot or the connection.
*
If all of that looks OK, the OTA (LM13700 near the power connector) could be dead.
Power Consumption
Power consumption: up to 130mA @ +12V and ca. 40mA @ -12V
Module width: 22HP, depth: < 35 mm
(Version 2. July 2017, 4:20 PM)
