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MarnixM  
#1 Posted : Friday, June 10, 2016 3:43:11 PM(UTC)
MarnixM

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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.
Brian Donegan  
#2 Posted : Friday, June 10, 2016 3:54:42 PM(UTC)
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Can you post a picture? This can often help spot problems.
MarnixM  
#3 Posted : Friday, June 10, 2016 5:55:59 PM(UTC)
MarnixM

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Send some more for details:

amp_klein.jpg (232kb) downloaded 26 time(s). att_klein.jpg (183kb) downloaded 27 time(s). IMG_20160610_182639.jpg (117kb) downloaded 22 time(s). IMG_20160610_182651.jpg (112kb) downloaded 21 time(s).
Brian Donegan  
#4 Posted : Friday, June 10, 2016 7:20:42 PM(UTC)
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First thing I notice is no audio ground connected to the relay board. That is required. It would not affect the relays clicking, but it would prevent audio. Still looking...
MarnixM  
#5 Posted : Friday, June 10, 2016 8:19:21 PM(UTC)
MarnixM

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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.
Brian Donegan  
#6 Posted : Friday, June 10, 2016 9:22:03 PM(UTC)
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As long as your ground is connected to the relay board when operating. It needs a ground reference for the resistor pairs to shunt to.
MarnixM  
#7 Posted : Saturday, June 11, 2016 7:30:42 AM(UTC)
MarnixM

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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
MarnixM  
#8 Posted : Sunday, June 12, 2016 9:38:21 AM(UTC)
MarnixM

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Hi Brian,
This morning I tested all three boards of the JT with a scope (borrowed one) and the volumite seems to be the problem. There is 5 volts at the VCC, 0 V at ground but no burst signals at the I2C lines (both SCL as SDA) when turning the pot. As if there was no firmware in the PIC.

To be informative to you as possible to solve my problem:
I installed all components on the volumite as were present in the package you send me; meaning both 3.3K resistors (R1 and R2) and the regulator IC2. The last one I fond remarkable, because the ATtiny85 can work on 5V. It also says on the PCB “See manual”, which isn’t there. I indeed measured 3.3 volt on pin 8 after the regulator.

I also checked all 10 pins on JT2: 5 and 6 are 5V, rest is 0V.

Hoping to hear from you any suggestions to solve my problem.
Marnix
Russ White  
#9 Posted : Sunday, June 12, 2016 12:26:35 PM(UTC)
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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
MarnixM  
#10 Posted : Sunday, June 12, 2016 1:42:18 PM(UTC)
MarnixM

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Hi Russ,

Gonna try that and will report on the result!
MarnixM  
#11 Posted : Sunday, June 12, 2016 3:02:56 PM(UTC)
MarnixM

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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
Russ White  
#12 Posted : Sunday, June 12, 2016 5:01:32 PM(UTC)
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The relay driver is intended to work at 5V - you did nothing but what is normal for that setup. :)

You may need a new firmware chip there may be a wrongly set fuse or something. I am sure Brian will have one out to you soon.
Russ White  
#13 Posted : Sunday, June 12, 2016 5:08:47 PM(UTC)
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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
MarnixM  
#14 Posted : Monday, June 13, 2016 2:46:33 PM(UTC)
MarnixM

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Hi Brian,

Russ wrote:"I am sure Brian will have one out to you soon". Hope you can state this, I got a non working pre-amp now, meaning no music from my streamer.......

Marnix
MarnixM  
#15 Posted : Tuesday, June 14, 2016 3:02:53 PM(UTC)
MarnixM

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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
Russ White  
#16 Posted : Wednesday, June 15, 2016 3:22:26 PM(UTC)
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Brian has been sick with the flu - I am sure he will get with you. If you have a programmer like an AVR Dragon I can get you the firmware hex and you can program it yourself as well.
MarnixM  
#17 Posted : Wednesday, June 15, 2016 3:44:47 PM(UTC)
MarnixM

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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
MarnixM  
#18 Posted : Thursday, June 16, 2016 2:24:23 PM(UTC)
MarnixM

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Hi Russ,

YES! It's working after a long afternoon testing on analyser software. It finaaly went clear that the soldering of the both pull-up resistors had a failure (my failure!). Attached the image of the signal now. attiny85.png (92kb) downloaded 30 time(s)..

Thanks also to Brian for all the work done! And wish Brian to get well!

Marnix
Russ White  
#19 Posted : Wednesday, June 22, 2016 4:46:29 PM(UTC)
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Excellent - thanks for the update. :)

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

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