A1200 audio connector replacement

warci · 24 May 2014, 15:55

Hello guys,

one of the connectors on my mainboard had snapped off, so i soldered a dual cinch cable straight to the motherboard.
So far so good, i bridged the internal connectors on the + of each cinch (each plug has 3 connections, i guess so the amiga can 'detect' if something is plugged in?) Anyway, i bridged those because a cable has 2 connections in stead of 3.
On my old amplifier all is fine and dandy, but now i connect my amiga to a mixer and the sound is very strange. If i plug in only one cable, i have sound but rather low in volume. If i connect both cables the sound is really crappy and even more quiet.
What gives? Is it because i bridged the connections and somehow the mixer has trouble with it? The mixer transforms the 1 channel to stereo, so maybe it has trouble with my crappy fix? How should i solder up the connector?

Arnie · 24 May 2014, 17:39

I have some spare audio connectors here, what colour do you need?

warci · 24 May 2014, 23:03

thanks for the offer! But i can maybe solder off some connectors of a broken A500 if i can't get the new cable to work

hooverphonique · 25 May 2014, 01:04

are you sure, 2 of the 3 conections on the socket is aren't both ground?

what do you mean by 'the mixer transforms the 1 channel to stereo' ?

sounds to me like you hooked something up wrong, causing a short between the channels..

ajk · 25 May 2014, 06:24

AFAIK the idea with the original connectors is that if only one plug is inserted, all four channels will be sent via that side. If you use connectors without the internal switches, you will lose this feature and only hear two channels using a single cable. But if you connect both plugs, there should be no difference. Just don't bridge anything, connect both plugs, and see how that works out.

hooverphonique · 25 May 2014, 11:02

Quote:

Originally Posted by ajk

AFAIK the idea with the original connectors is that if only one plug is inserted, all four channels will be sent via that side.

oh, so the a1200 has a built-in cross-channel mixer? didn't know that...

BigFan · 25 May 2014, 19:14

Quote:

Originally Posted by ajk

AFAIK the idea with the original connectors is that if only one plug is inserted, all four channels will be sent via that side. If you use connectors without the internal switches, you will lose this feature and only hear two channels using a single cable. But if you connect both plugs, there should be no difference. Just don't bridge anything, connect both plugs, and see how that works out.

Well, well, this is just weird guessing.

RCA jacks got 3 connectors, signal, shortbar and shielding. Both shieldings are grounded.
I'm convinced warci wrongly soldered shielding to shortbar or something else (

) and now having sort of lowered output on the second jack.

The jacks are soldered this way:

-----> signal
-----> shield
-----> short (this is done on the pcb, stereo signal output is wired to both jacks, 2 channels combined in one signal, so 4 channels give to 2 stereo outputs)

If the jacks are off, then circuitry may be incomplete.

I hope this info is a bit of help.

BigFan · 25 May 2014, 19:59

Quote:

Originally Posted by warci

Hello guys,

(each plug has 3 connections, i guess so the amiga can 'detect' if something is plugged in?) ?

Sir, no Sir, never meant to work this way
See above.

ajk · 25 May 2014, 20:17

I was talking about replacing the missing connectors like the thread title is, not soldering a cable to replace them - I assume the cable is only a temporary solution

But the A1200 does indeed go mono-only if only one cable is connected. The Amiga doesn't actively "detect" anything but the left and right connectors are shorted together when there is no cable plugged in. See the schematic here for example, or check continuity between the channels with a multimeter.

Older style A500 connectors (metal frame) essentially have only two pins so they don't have this feature.

warci · 25 May 2014, 20:39

ok, so first of all, thanks for all the reactions.
My idea was: i don't care about the 'mono mode', so i bridged the points as if there's alway a cable connected. I am correct in presuming when you plug in a cable, those two points are bridged, no? When i measure with a multimeter on my other A1200 i get all kinds of funky readings, so i don't really get what's going on.
Anyway, i'll do some more tests tonight... funfun

ajk · 25 May 2014, 20:44

I think you have it the wrong way around. The channels are shorted together when there is no cable, and when the cable is plugged in, the connection opens. Perhaps you are now listening to the Amiga as it would sound without cables, an unusual situation

BigFan · 26 May 2014, 12:43

The linked schematic from above makes me wonder what model is shown and what kind of addition has been suggested (light blue).

I found this page, it may provide some more information.
http://www.amigawiki.org/doku.php?id...ice:schematics

ajk · 26 May 2014, 14:11

That schematic I linked to is probably from an A4000, but I looked through the A600 and A1200 schematics also and they have the same arrangement with the connectors.

warci · 27 May 2014, 19:36

You guys were 100% correct: desoldered the bridges and voila: perfect sound!
and to thing i used that machine for years like that!

and yes: i think the schematic is not from the A1200 as the wireing is slightly different

thanks guys!!

24 May 2014, 15:55	#1
warci Registered User Join Date: May 2014 Location: Belgium Posts: 38	A1200 audio connector replacement Hello guys, one of the connectors on my mainboard had snapped off, so i soldered a dual cinch cable straight to the motherboard. So far so good, i bridged the internal connectors on the + of each cinch (each plug has 3 connections, i guess so the amiga can 'detect' if something is plugged in?) Anyway, i bridged those because a cable has 2 connections in stead of 3. On my old amplifier all is fine and dandy, but now i connect my amiga to a mixer and the sound is very strange. If i plug in only one cable, i have sound but rather low in volume. If i connect both cables the sound is really crappy and even more quiet. What gives? Is it because i bridged the connections and somehow the mixer has trouble with it? The mixer transforms the 1 channel to stereo, so maybe it has trouble with my crappy fix? How should i solder up the connector?

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24 May 2014, 17:39	#2
Arnie R.I.P Smudge 18-08-16 Join Date: Aug 2005 Location: Leicester/UK Age: 66 Posts: 3,968	I have some spare audio connectors here, what colour do you need?

24 May 2014, 23:03	#3
warci Registered User Join Date: May 2014 Location: Belgium Posts: 38	thanks for the offer! But i can maybe solder off some connectors of a broken A500 if i can't get the new cable to work

25 May 2014, 01:04	#4
hooverphonique ex. demoscener "Bigmama" Join Date: Jun 2012 Location: Fyn / Denmark Posts: 1,624	are you sure, 2 of the 3 conections on the socket is aren't both ground? what do you mean by 'the mixer transforms the 1 channel to stereo' ? sounds to me like you hooked something up wrong, causing a short between the channels..

25 May 2014, 06:24	#5
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	AFAIK the idea with the original connectors is that if only one plug is inserted, all four channels will be sent via that side. If you use connectors without the internal switches, you will lose this feature and only hear two channels using a single cable. But if you connect both plugs, there should be no difference. Just don't bridge anything, connect both plugs, and see how that works out.

25 May 2014, 20:17	#9
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	I was talking about replacing the missing connectors like the thread title is, not soldering a cable to replace them - I assume the cable is only a temporary solution But the A1200 does indeed go mono-only if only one cable is connected. The Amiga doesn't actively "detect" anything but the left and right connectors are shorted together when there is no cable plugged in. See the schematic here for example, or check continuity between the channels with a multimeter. Older style A500 connectors (metal frame) essentially have only two pins so they don't have this feature.

25 May 2014, 20:39	#10
warci Registered User Join Date: May 2014 Location: Belgium Posts: 38	ok, so first of all, thanks for all the reactions. My idea was: i don't care about the 'mono mode', so i bridged the points as if there's alway a cable connected. I am correct in presuming when you plug in a cable, those two points are bridged, no? When i measure with a multimeter on my other A1200 i get all kinds of funky readings, so i don't really get what's going on. Anyway, i'll do some more tests tonight... funfun

25 May 2014, 20:44	#11
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	I think you have it the wrong way around. The channels are shorted together when there is no cable, and when the cable is plugged in, the connection opens. Perhaps you are now listening to the Amiga as it would sound without cables, an unusual situation

26 May 2014, 12:43	#12
BigFan Registered User Join Date: Feb 2014 Location: Germany Posts: 261	The linked schematic from above makes me wonder what model is shown and what kind of addition has been suggested (light blue). I found this page, it may provide some more information. http://www.amigawiki.org/doku.php?id...ice:schematics

26 May 2014, 14:11	#13
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	That schematic I linked to is probably from an A4000, but I looked through the A600 and A1200 schematics also and they have the same arrangement with the connectors.

27 May 2014, 19:36	#14
warci Registered User Join Date: May 2014 Location: Belgium Posts: 38	You guys were 100% correct: desoldered the bridges and voila: perfect sound! and to thing i used that machine for years like that! and yes: i think the schematic is not from the A1200 as the wireing is slightly different thanks guys!!

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