Reply
 
Thread Tools Display Modes
  #1   Report Post  
Posted to rec.audio.pro
Richard Crowley Richard Crowley is offline
external usenet poster
 
Posts: 4,172
Default Deaf Alesis HD24

As I was setting up to record a ~100 voice choir and ~50 piece
orchestra last weekend, I discovered that my HD24 (which I had
converted to XR a few years ago) was deaf as a post. Everything
else appeared to work just fine, but no analog input or output.
(I don't have any way to test digital in/out).

I unplugged everything and removed it from the case and opened
it up (with my trusty Leatherman tool which hangs from my belt).
The daughter-board that plugs onto the interior ends of the analog
input and output boards was "hanging by a thread". Of course, there
is no mechanical support for this board. It hangs off the lever-arm
ends opposite from the input connectors (which are all that hold
the analog boards). Now I know why people recommend more gentle
transport practices and methods. :-(

Alas, after re-connecting the daughter board, the HD24 no longer
even recognizes the XR upgrade. In fact it acts exactly the same
as if the whole analog section weren't even connected (I tried it).
The daughter board powers the analog boards, and the power supply
cable to the daughter board appeared to have the voltages that we
would expect (although I don't know that it is actually documented
publicly?)

I re-seated all the ribbon and power connectors. I triple-checked
to see that the daughter board was properly lined up with the input
and output boards (as cautioned in the XR upgrade instructions)

Someone brought a Zoom R16 which records 8 channels to an SD
flash memory card. It worked OK, but the metering is really primitive
and it was difficult to set decent levels.

Dunno what I'm going to do about my HD24. I guess I will try putting
the old (non-XR) boards back in to see if I can make a differential
diagnosis of the problem location.
  #2   Report Post  
Posted to rec.audio.pro
[email protected] sound.service@btconnect.com is offline
external usenet poster
 
Posts: 3
Default Deaf Alesis HD24

On Dec 24, 8:17*pm, "Richard Crowley" wrote:
As I was setting up to record a ~100 voice choir and ~50 piece
orchestra last weekend, I discovered that my HD24 (which I had
converted to XR a few years ago) was deaf as a post. Everything
else appeared to work just fine, but no analog input or output.
(I don't have any way to test digital in/out).

I unplugged everything and removed it from the case and opened
it up (with my trusty Leatherman tool which hangs from my belt).
The daughter-board that plugs onto the interior ends of the analog
input and output boards was "hanging by a thread". Of course, there
is no mechanical support for this board. It hangs off the lever-arm
ends opposite from the input connectors (which are all that hold
the analog boards). Now I know why people recommend more gentle
transport practices and methods. :-(

Alas, after re-connecting the daughter board, the HD24 no longer
even recognizes the XR upgrade. In fact it acts exactly the same
as if the whole analog section weren't even connected (I tried it).
The daughter board powers the analog boards, and the power supply
cable to the daughter board appeared to have the voltages that we
would expect (although I don't know that it is actually documented
publicly?)

I re-seated all the ribbon and power connectors. I triple-checked
to see that the daughter board was properly lined up with the input
and output boards (as cautioned in the XR upgrade instructions)

Someone brought a Zoom R16 which records 8 channels to an SD
flash memory card. It worked OK, but the metering is really primitive
and it was difficult to set decent levels.

Dunno what I'm going to do about my HD24. I guess I will try putting
the old (non-XR) boards back in to see if I can make a differential
diagnosis of the problem location.



The first thing I would do is to check the analogue power supplies,
which should be something around +15v and -15v. (possibly as high as
+- 18v) If one or both voltages are not present in the analogue
section, the machine may well behave as though there is no analogue
circuitry present, while the computing section, running on 5volts,
will be unaffected and even unaware the analogue section is not
working.

If the analogue section uses 8 pin DIL op-amps, this is the easiest
place to check - select a convenient chip and carefully meter each of
the 8 pins in turn, with the negative meter probe on a ground point.
Make sure you don't short 2 pins together with the probe, or you could
kill the chip.



Gareth.

  #3   Report Post  
Posted to rec.audio.pro
Richard Crowley Richard Crowley is offline
external usenet poster
 
Posts: 4,172
Default Deaf Alesis HD24

wrote ...
The first thing I would do is to check the analogue power supplies,
which should be something around +15v and -15v. (possibly as high as
+- 18v) If one or both voltages are not present in the analogue
section, the machine may well behave as though there is no analogue
circuitry present, while the computing section, running on 5volts,
will be unaffected and even unaware the analogue section is not
working.

If the analogue section uses 8 pin DIL op-amps, this is the easiest
place to check - select a convenient chip and carefully meter each of
the 8 pins in turn, with the negative meter probe on a ground point.
Make sure you don't short 2 pins together with the probe, or you could
kill the chip.


Thanks, Gareth. Alas, the analog I and O boards are all small-pitch
SMD components, so the trusty method of checking VCC and VDD
for +/-15V isn't quite as convenient. Now that I have it back home,
I'll do some better troubleshooting ("fault-finding" has a different
meaning over on this side of the Pond! :-) I'm going to try to see if
I can discover what the nominal voltages on the power harness are
supposed to be.

The HD24 worked great on the 230V 50Hz in Romania, but now that
it is back home here in 120V-land, maybe it has become wimpy? :-)
(The switched-mode PS runs on 100-240v, no user control, so I
didn't forget to set the power back.) The digital parts of the unit
work perfectly, which would appear to indicate that the +5 is good.
  #4   Report Post  
Posted to rec.audio.pro
[email protected] sound.service@btconnect.com is offline
external usenet poster
 
Posts: 3
Default Deaf Alesis HD24

On Dec 24, 9:22*pm, "Richard Crowley" wrote:
wrote ...

The first thing I would do is to check the analogue power supplies,
which should be something around +15v and -15v. *(possibly as high as
+- 18v) *If one or both voltages are not present in the analogue
section, the machine may well behave as though there is no analogue
circuitry present, while the computing section, running on 5volts,
will be unaffected and even unaware the analogue section is not
working.


If the analogue section uses 8 pin DIL *op-amps, this is the easiest
place to check - select a convenient chip and carefully meter each of
the 8 pins in turn, with the negative meter probe on a ground point.
Make sure you don't short 2 pins together with the probe, or you could
kill the chip.


Thanks, Gareth. *Alas, the analog I and O boards are all small-pitch
SMD components, so the trusty method of checking VCC and VDD
for +/-15V isn't quite as convenient. *Now that I have it back home,
I'll do some better troubleshooting ("fault-finding" has a different
meaning over on this side of the Pond! :-) *I'm going to try to see if
I can discover what the nominal voltages on the power harness are
supposed to be.

The HD24 worked great on the 230V 50Hz in Romania, but now that
it is back home here in 120V-land, maybe it has become wimpy? :-)
(The switched-mode PS runs on 100-240v, no user control, so I
didn't forget to set the power back.) *The digital parts of the unit
work perfectly, which would appear to indicate that the +5 is good.




Well in that case you should measure every pin coming off the Power
Supply. If you don't find + and - something around 15 volts, then
you have found the problem. I wouldn't even bother trying to establish
the exact nominal voltages, they will either be present or absent.

Good luck!



Gareth.

Reply
Thread Tools
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Syncing Alesis HD24 [email protected] Pro Audio 11 December 12th 05 06:27 PM
Alesis HD24 JM Pro Audio 5 October 5th 05 02:56 PM
FS: ALESIS EC-2 96k upgrade for HD24 James Reynolds Pro Audio 0 March 5th 04 09:02 PM
RME 9652 AND ALESIS HD24 John Pro Audio 1 October 20th 03 03:22 AM
Alesis HD24 LeBaron & Alrich Pro Audio 10 October 16th 03 10:33 AM


All times are GMT +1. The time now is 04:53 PM.

Powered by: vBulletin
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AudioBanter.com.
The comments are property of their posters.
 

About Us

"It's about Audio and hi-fi"