Just yesterday assembled my new Joshua Tree attenuator and today build it in my tube preamp with an extra line buffer at the input side. On turning the pot there is no reaction at all, nor any clicking of the relays (should I hear these?) nor any sound on the output side. Checked nearly everything; there is power on the driver, all the VCC lines and the volumite; input signal present coming from the line buffer. Checked every single cable core connection, all dip switches are of, using the J2 connection, installed the zero ohm jumper and the resistors on the volumite. Cannot see if the volumite is sending any I2C signals (no scope).
Please advise me.

Send some more for details:

amp_klein.jpg (232kb) downloaded 29 time(s). att_klein.jpg (183kb) downloaded 30 time(s). IMG_20160610_182639.jpg (117kb) downloaded 26 time(s). IMG_20160610_182651.jpg (112kb) downloaded 25 time(s).

Dear Brian,

You noticed it quite good; but thats for the photo. In all my amps I use star grounding, meaning all ground wires go to a central star ground. This is to prevent earth loops. So the input grounds go to the star as does 1 ground line (black wire) on the relay board. Because of the J1 connection all ground lines on the PCB go over that one ground line. Tomorrow i'll send a picture of the star grounding.

Dear Brian,

The resistor pairs have a ground reference over the star grounding, as my "old" ladder attenuator had.
Tomorrow I hope to control the I2C lines over a scope. Let you know the outcome.

Marnix

I believe you have hit on the problem. The volumite should be used at 5V because the target MCP23008-E/P IO expander is running at 5V. That means the volumite should have the on-board reg removed and bypassed so that it is directly powered by the relay driver board.

Cheers!
Russ

Hi Russ/Brian,

Tried your last solution and removed and shortened the regulator on the volumite. No effect, still the volumite is dead in the I2C lines on the scope. Already wondered that this solution would helped. My test on the volumite before showed a dead volumite I2C signal, apart from the fact if the pic was fed with 5V or 3.3V. Russ’ advice concerns the effect of the signal on the MCP23008-E/P IO expander and not on a dead volumite.

I have the following solution: I order a complete new volumite with JT attenuator firmware in it. I’ll set it up with a shortened regulator (so the IC2 on the PCB shortened). I’ll pay for it, but when this brings the solution (a complete working attenuator) you reimburse me the cost for the new volumite. Meaning I’ll take the risk.

Hope you support my proposal.
Marnix

One other thing just to double check is that you have good continuity on all wired nets - including the headers for the ribbon cables between the JT and the Driver board. Sometimes IDC cables don't make great contact and have to be worked with a bit.

Cheers!
Russ

Hi Brian,

Did not receive any reaction after the statement of Russ... I hope you are able to send me a new volumite or at least a new ATtiny85 chip (with firmware for the JTA) asap.

Marnix

Hoi Russ,

First, I hope Brian gets well soon, always nasty the flu....
On you question; can't do it myself but i will ask my brother in low, he's a professional software developer for industrial control units based on Raspbery pi's. Maybe for him your question is a piece of cake. Let you know. Otherwise i'll have to wait (unfortunately) on Brians recovery.

Marnix

Excellent - thanks for the update. :)

Edited by moderator Thursday, July 7, 2016 6:11:33 PM(UTC)  | Reason: Not specified