March 01, 2021, 07:55:20 PM

Sound issues on X68000 Red Zöne

Started by huggyone76, February 21, 2021, 02:38:35 AM

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huggyone76

February 21, 2021, 02:38:35 AM Last Edit: February 21, 2021, 03:37:28 AM by huggyone76
Hi everybody !
After one ACE and one ACE HD, I bought a Compact Red Zöne. :-)
After replacements of some obviously leaking capacitors (PSU was almost dead... but it seems to be good now) and the 74ALS04 (display problems...), the Red Zöne is alive ! ;-)
But... Sound is really, really bad. Nothing from internal speaker, nothing from rear connector and a very low and bad sound from the front connector.
So I looked at this page :
https://gamesx.com/wiki/doku.php?id=x68000:x68000_xvi_compact_audio_troubleshooting_and_repair
But I've a wierd problem. If I test the two op-amps MC3403, I've only 5V on the VCC+ and nothing on the VCC-.
Moreover, I don't understand how to test the test points. Between which points ? I see the 4 points but I don't think I have to test between these points... :-D
If someone can help me ;-)
Thank you !

Edit : the sound is better (really better, louder, cleaner) after ten or fifteen minutes...

kamiboy

Test for continuity between the start of the trace against the end of the trace which runs through each test point to see whether the test point has become corroded and broken the trace running though it.

If you cannot find the start and end point you could scrape away the mask on each trace at a point below, and above the test point and test for continuity between them.

SuperDeadite

If I am understanding the first post correctly, you only replaced the leaky caps?  On a compact you really need to replace all of them.  Even caps that look fine should be changed asap.  If the sound starts working 10-15 mins after the system warms up, that is a classic sign of bad caps.  You still could have other issues too though.

huggyone76

Thank you for your answers. I will change all capacitors and let you know if that's better ;-)

huggyone76

Hi everybody !
After replacement of all capacitors, my X68000 still have sounds issues. But I didn't see the real problem before today. Motherboard traces are cut under pins 3, 4 and 10 of IC7 (MC3403) !
Is that possible to fix ? I've got new MC3403 in my spare parts but I don't have the skills to fix this problem.
So, perhaps I can found someone near where I live (France) but I need to know before if a fix is possible... or not ;-)

Thank you for your help

megatron-uk

Sounds like you may have to desolder the op-amps, repair the traces and then refit.

Have you got a desoldering gun or something similar? You can probably do the job easier without the IC in the way.

huggyone76

Thank you for your advice.
I've found a good friend who fixes a lot of Amiga and Atari computers.
I will let him the X68000 in a couple of week and hé will try to fix the trace. I desolder the MC3403 yesterday with my desoldering gun (hopefully without more damages !)
I will let you know in some weeks if it's a success ! ;-)