DSOTM Phaser (solved)

[Fabian]

Hello everyone

I recently built the NostalgiTone D.S.O.T.M.. Unfortunately, I seem to have a similar problem to Matt (https://guitarpcb.com/community/topic/dsotm-phaser-rate/) regarding the phaser. WattAmp and LunaFuzz work great, but the phaser just doesn’t phase.

The effect can be switched on and something happens to the sound. But not in the way you would imagine a phaser to be. In particular, the “Rate” and “Intensity” potentiometers have no influence.

Just like with Matt, the LED simply stays on and does not pulse.

In the meantime, I was able to record the following measured values:

Note: This is the first time that I have recorded measured values. I therefore took a measurement with all potentiometers at maximum and a second measurement at minimum.

Do I understand correctly that the problems point to Q1 in particular?

How should I proceed from here? Should I re-flow some joints?

What can you guys recommend as my next step?

Let me know if you need additional pictures or re-measurements.

Thank you already for your much appreciated help.

Many thanks and happy Easter!

Fabian

EDIT: Posted Images of the measurement tables.

[Billy]

I can’t quite see the 4th multiplier band on R20 the bands should be brown green black red brown 15K

 

[Barry]

A quick tip: Watch out for the sharp angles between the foot-switch boards and the main board once everything’s mounted in the enclosure. It looks like the ribbon cable might be under unnecessary strain. This stress can cause connection issues now, or later.

 

With regard to the Phaser foot-switch PCB I am not liking the ground connection pad.

I would carefully re-flow the back side of all six pads.

The reverse side also shows that a re-flow is required.

[Fabian]

Hey Billy,
hey Barry

Thank you very much for your feedback. Due to a heavy workload at the office, I only got round to following up your comments today.

Long story short: the phaser is now working without any problems.

As I wasn’t quite sure myself whether R20 might not be a 15k resistor after all, I quickly desoldered it.

With better lighting, however, you can see that the 4th multiplier band is red after all.

The measurement also gave a proper result of 14.93k.

As Barry suggested, I then re-flowed the six pads of the connection (as well as a few others for the sake of good order).

The result: the phaser works!

Thanks again for your feedback and your help!

Do I have to mark the title of the post as ‘solved’?

Best regards

Fabian

Ps: When reviewing the instructions again, I noticed the following error at the bottom of page 2: ‘D5 requres a Yellow or clear White LED’. In my opinion, this should not be D5, but D4.

[Barry]

Thanks for following up. I appreciate it. Now marked solved.

When I look back through my support history over all of the years I have found that a careful re-flow solves about 80% of problems.

[Author]

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