A Most Bizzare Indivision AGA 1200 Problem

Fingerlickin_B · 02 March 2009, 12:28

Ok, this has me stumped.

Since installing my Indi, pretty sure I#ve not cranked up the audio volume beyond "not at all loud", but tonight was listening to some music on my A1200 & up the volume went.

What does audio have to do with the Indi? I#ve no idea, but it#s related...let me explain...

When the volume on my amplifier is turned up I get MAJOR humming & when HDD is in action it even seems to beep!

BUT, only when the Indivision output is connected to an LCD, if using a CRT there is no significant humming.

I tried 2 of each (LCD & CRT), only get the noises from the A1200#s native audio output when using the LCD monitors (well, one is a TV with VGA input, but you know what I mean).

Potential problems checked:
Monitor/amp/miggy/indy grounds (audio or otherwise) all referenced individually & in any combination, no luck.
All...that#s ALL connectors in miggy cleaned & re-attached, no luck.
LCD monitor & miggy on different mains sub-circuits, no luck.
Checked & tested different power leads to miggy & LCD, no luck.
Changed VGA cables, no luck.
Tested miggy PSU, all voltages perfect, no luck.
Booted 3.1 & some games from floppy just in case it#s an OS issue, no luck.
Disconnected PCMCIA ethernet card, turned off router & ripped all cables from the room, no luck.

Any ideas?

PZ.

p.s. Sorry about all the "#S"...if you know how to fix the iBrowse keymaps I#d love to know!

TheCorfiot · 02 March 2009, 12:41

@FLB

Have you checked the -12V supply is OK ?????

TC

Loedown · 02 March 2009, 12:43

Quote:

Originally Posted by Fingerlickin_B

Ok, this has me stumped.

Since installing my Indi, pretty sure I#ve not cranked up the audio volume beyond "not at all loud", but tonight was listening to some music on my A1200 & up the volume went.

What does audio have to do with the Indi? I#ve no idea, but it#s related...let me explain...

When the volume on my amplifier is turned up I get MAJOR humming & when HDD is in action it even seems to beep!

BUT, only when the Indivision output is connected to an LCD, if using a CRT there is no significant humming.

I tried 2 of each (LCD & CRT), only get the noises from the A1200#s native audio output when using the LCD monitors (well, one is a TV with VGA input, but you know what I mean).

Potential problems checked:
Monitor/amp/miggy/indy grounds (audio or otherwise) all referenced individually & in any combination, no luck.
All...that#s ALL connectors in miggy cleaned & re-attached, no luck.
LCD monitor & miggy on different mains sub-circuits, no luck.
Checked & tested different power leads to miggy & LCD, no luck.
Changed VGA cables, no luck.
Tested miggy PSU, all voltages perfect, no luck.
Booted 3.1 & some games from floppy just in case it#s an OS issue, no luck.
Disconnected PCMCIA ethernet card, turned off router & ripped all cables from the room, no luck.

Any ideas?

PZ.

p.s. Sorry about all the "#S"...if you know how to fix the iBrowse keymaps I#d love to know!

Audio isn't really my thing, but it sounds like some form of ground loop, or definately an Earth issue of some kind. I did hear, personaly, when my wife was in Hungary and her flatmate turned on his laptop, the M-Audio box had a fit, unbelievable static and noise. The solution there was to run his laptop off a different circuit. I know you already specified that, but I would be inclined to check the Earth pins of the power points, in reference to each other, use a DMM set on AC 500 / 750 range and start checking all the points, run extension leads if you have to so that the DMM is in reach of both / all points. I reckon you'll find a dodgy ground, but AC theory is a long gone memory. One final thing, check the grounding points Vs. the cold water tap.

TAP --> wire <-- DMM --> wire <-- power point Earth

Anyone with better AC theory, feel free to correct me.

Paul

Fingerlickin_B · 02 March 2009, 12:58

@TC - Yep, that#s actually the very first thing I checked

@Loedown - The house doubles as a recording studio, so any grounding problems were addressed by myself a long, long time ago...but thanks as I appreciate any input

PZ.

*edit*
Never used an LCD with my Winblows or Mac recording setups...maybe that should be checked too...very drunk now, watching 5th Element, maybe later

Loedown · 02 March 2009, 14:29

Greetings,
Filter cap in Miggy gone dry, plugging in leads to the 1200 is enough to break the circuit, flexes the PCB?

Subtle and broken ground off Miggy audio connectors?

Cordless phone sub harmonic of 2.4 GHz, ok it's clutching at straws?

Chain · 02 March 2009, 15:16

Ill bet on caps too, not onyl in miggy, but in that lcd too

Fingerlickin_B · 03 March 2009, 00:16

All connections checked & good.

Must be capacitors then...but...why do I only get this when using an LCD?

Remember, 2x LCD (one almost brand new) make it buzz, 2x CRT don't make it buzz.

PZ.

Peter · 03 March 2009, 00:54

It strikes me that there are clear issues with LCD TV's with Monitor input and Indivision - Individual are looking into my situation...

02 March 2009, 12:28	#1
Fingerlickin_B Amiga Nut Join Date: Oct 2006 Location: Belco, Australia Posts: 2,242	A Most Bizzare Indivision AGA 1200 Problem Ok, this has me stumped. Since installing my Indi, pretty sure I#ve not cranked up the audio volume beyond "not at all loud", but tonight was listening to some music on my A1200 & up the volume went. What does audio have to do with the Indi? I#ve no idea, but it#s related...let me explain... When the volume on my amplifier is turned up I get MAJOR humming & when HDD is in action it even seems to beep! BUT, only when the Indivision output is connected to an LCD, if using a CRT there is no significant humming. I tried 2 of each (LCD & CRT), only get the noises from the A1200#s native audio output when using the LCD monitors (well, one is a TV with VGA input, but you know what I mean). Potential problems checked: Monitor/amp/miggy/indy grounds (audio or otherwise) all referenced individually & in any combination, no luck. All...that#s ALL connectors in miggy cleaned & re-attached, no luck. LCD monitor & miggy on different mains sub-circuits, no luck. Checked & tested different power leads to miggy & LCD, no luck. Changed VGA cables, no luck. Tested miggy PSU, all voltages perfect, no luck. Booted 3.1 & some games from floppy just in case it#s an OS issue, no luck. Disconnected PCMCIA ethernet card, turned off router & ripped all cables from the room, no luck. Any ideas? PZ. p.s. Sorry about all the "#S"...if you know how to fix the iBrowse keymaps I#d love to know!

02 March 2009, 12:58	#4
Fingerlickin_B Amiga Nut Join Date: Oct 2006 Location: Belco, Australia Posts: 2,242	@TC - Yep, that#s actually the very first thing I checked @Loedown - The house doubles as a recording studio, so any grounding problems were addressed by myself a long, long time ago...but thanks as I appreciate any input PZ. edit Never used an LCD with my Winblows or Mac recording setups...maybe that should be checked too...very drunk now, watching 5th Element, maybe later Last edited by Fingerlickin_B; 02 March 2009 at 13:36.

03 March 2009, 00:16	#7
Fingerlickin_B Amiga Nut Join Date: Oct 2006 Location: Belco, Australia Posts: 2,242	All connections checked & good. Must be capacitors then...but...why do I only get this when using an LCD? Remember, 2x LCD (one almost brand new) make it buzz, 2x CRT don't make it buzz. PZ. Last edited by Fingerlickin_B; 03 March 2009 at 00:24.

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02 March 2009, 12:41	#2
TheCorfiot Amibay Senior Staff Join Date: Feb 2008 Location: Cardiff / Wales Posts: 1,302	@FLB Have you checked the -12V supply is OK ????? TC

02 March 2009, 14:29	#5
Loedown Precious & fragile things Join Date: Feb 2009 Location: Victoria, Australia Posts: 1,946	Greetings, Filter cap in Miggy gone dry, plugging in leads to the 1200 is enough to break the circuit, flexes the PCB? Subtle and broken ground off Miggy audio connectors? Cordless phone sub harmonic of 2.4 GHz, ok it's clutching at straws?

02 March 2009, 15:16	#6
Chain A-Collector, repairments Join Date: Jul 2001 Location: Czech Rep. Age: 50 Posts: 1,536	Ill bet on caps too, not onyl in miggy, but in that lcd too

03 March 2009, 00:54	#8
Peter Still an Amiga user Join Date: Nov 2006 Location: Kent Age: 55 Posts: 2,715	It strikes me that there are clear issues with LCD TV's with Monitor input and Indivision - Individual are looking into my situation...

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