deveng

Allen Heath Zed 22 FX repair *Solved*
« on: September 28, 2020, 10:33:26 AM »
I'm repairing a Zed 22 FX for a friend and when I opened it up I found an unconnected brown wire going to the FX pcb.  I traced the connection on the FX pcb and it goes to 2 series 47 ohm resistors then to pin 1 (input) of a ST L7805CV regulator.  The problem is the other end.  It looks like it was never actually soldered to the power supply board!  The end is tinned but obviously never fully soldered.  I have the power supply schematic but it doesn't indicate which point is for the FX board.  The power supply schematic only has +/-15V, +48V and a +10v labeled pad (which actually measure 19.8V).    The ST L7805CV spec sheet states for 5V regulator the input can be up to 35V.  I assume the FX supply wire goes to the "+10v" pad with the series resistors used a dropping resistors. 

I found an image on the internet of someone doing a direct out modification to a Zed 12 FX.  One of the pictures does seem to confirm my assumption on connection.  That picture shows the brown wire connected near or at the 10V labeled pad.

Can anyone confirm this?

 
« Last Edit: September 29, 2020, 12:30:07 PM by deveng »


deveng

Re: Allen Heath Zed 22 FX repair *Solved*
« Reply #1 on: September 29, 2020, 12:33:20 PM »
Confirmed FX board power wire goes to P7 pad on power supply.  Allen & Heath technical support returned my call this morning.  I had already wired it to P7 as it was the only logical choice.  Powered up and everything works. 

ruffrecords

Re: Allen Heath Zed 22 FX repair *Solved*
« Reply #2 on: September 29, 2020, 03:36:45 PM »
When you had it open I don't suppose you noticed which FX chip(s) it uses?

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'

deveng

Re: Allen Heath Zed 22 FX repair *Solved*
« Reply #3 on: September 30, 2020, 11:06:36 AM »
Ian,

No but I did take a picture of it! 

Looks to be a NXP/Freescale DSPB56371AF180, a Cirrus Logic CS4271 Audio Codec and a NXP/Freescale LPC1227F microcontroller.


ruffrecords

Re: Allen Heath Zed 22 FX repair *Solved*
« Reply #4 on: September 30, 2020, 12:32:37 PM »
Not a bad implementation the.

Cheers

Ian
www.customtubeconsoles.com
https://mark3vtm.blogspot.co.uk/
www.eztubemixer.blogspot.co.uk


'The only people not making mistakes are the people doing nothing'


 

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