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| IIgs battery repair |
Posted by: davidg5678 on 2022-05-13 13:00:22
I'm not sure whether it will apply or not, but here is a potential fix for the no sound issue: I once accidentally plugged my IIgs speaker into a fan header without realizing it. The headers look really similar and I think I remember the speaker making a pop when the power was engaged. The sound didn't work until the speaker was plugged into the correct location on the logic board. |
Posted by: LaPorta on 2022-05-13 21:08:53
Yep, for sure, it is the J1 jack. I also used headphones via the headphone port. Same "pop" when turned on, and then that is it. I suppose one of the caps could be a dud...I guess I could out them one by one and use my ESR meter. I looked under the microscope; no bridges, no cracks, no continuity issues on the multimeter. |
Posted by: LaPorta on 2022-05-13 22:05:25
Ok so the good news is: pulled all the caps, checked them all, all check good. Redid the soldering, made sure to not use too much this time. Sound is loud now! The issue that I have now is that there is a low-level hum, not really perceptible unless close to the speaker, but comes through quite a bit in the headphones. It appears the issue is capacitor SC2: when I push the cap down, it makes the hum much more intense. Maybe the cap isn't working well....not sure. I'll try replacing it tomorrow. |
Posted by: cruff on 2022-05-14 05:11:03
Is it 50/60 Hz hum? Maybe you have other bad solder connections, possibly on the ground plane or a marginal filter capacitor on the primary side of the switching power supply. |
Posted by: LaPorta on 2022-05-14 05:55:07
Wouldn't know what frequency it is at...anything is indeed possible, though I don't know why pressing one solitary sound capacitor would cause it to be worse when moving the others does nothing. There could be crud somewhere from the battery explosion causing the issue...who knows. |
Posted by: LaPorta on 2022-05-14 20:14:11
So, more about this: maybe it is a cap or bad connection somewhere else. I noticed that when the 800k drive is working, if I put my ear right up to the speaker, I can hear the head motor's movements. That sounds to me like some sort of electrical interference as was noted. The question is...where? Might never figure this one out. Lends credence to what cruff said. |
Posted by: Skate323k137 on 2022-05-14 20:54:49
Is it a ROM 01 IIgs? Those have a lot of bus noise no matter what. Booting from slot 7 for example you can hear in the sound output if you have the audio up loud. |
Posted by: LaPorta on 2022-05-14 21:14:36
ROM 3, actually. The volume is loud on here for sure. Maybe if I turned it down the sound would be more normal. But...how does one turn down the volume on a IIgs???
I also found that L17 and some resistors still had nasty battery crud, so I desoldered those and cleaned them up, but no better. I also found that on SC2, it isn't even pushing the cap down, but also coming into proximity to it with a finger that does it! induction by magnetic field? I don't know... |
Posted by: Skate323k137 on 2022-05-14 21:22:09
Humm... the bus noise shouldn't be too bad then.
I use a cheap desktop mixer with mine, something like this:
Moukey Ultra Low-Noise 4-Channel Line Mixer for Sub-Mixing, DC 5V 4-Stereo Mini Audio Mixer, Ideal for Small Clubs or Bars. As Microphones, Guitars, Bass, Keyboards or Stage Mixer-MAMX1 https://www.amazon.com/dp/B08393DLGV/ref=cm_sw_r_apan_i_GBAMSPA90NNAK6C5TXFH
Also, if you really want the best sound experience, I highly recommend https://console5.com/store/darksoun...d-and-digitizer-w-amplifier-line-out-2gs.html
I waited a long time for those to come back in stock; totally worth it, and you can toss it in slot 5 or 6 since it just uses the power pins of the slot, and has a little harness over to the extra multi-pin sound header. The difference is awesome, here is a video I did with recording from one, and also direct from the IIgs.
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Posted by: Simon_Bitdiddle on 2022-05-15 06:37:15
I also found that on SC2, it isn't even pushing the cap down, but also coming into proximity to it with a finger that does it! induction by magnetic field? I don't know... Might be shorting to the RF shield on the bottom of the case? |
Posted by: LaPorta on 2022-05-15 09:32:52
The entire logic board is out of the case on an anti-static mat...otherwise I'd agree it was possible! |
Posted by: Skate323k137 on 2022-05-15 10:03:22
The entire logic board is out of the case on an anti-static mat...otherwise I'd agree it was possible! Is it a silicone soldering anti static mat? I have actually had those cause sporadic issues when running a PCB right on them. |
Posted by: Simon_Bitdiddle on 2022-05-15 10:17:22
Also try checking to see if there's voltage across the speaker's header. |
Posted by: LaPorta on 2022-05-21 21:35:50
So, very good progress: some rotten vias for the card slots touched up by the battery holder, and a new holder installed after verifying traces. Very satisfying to be able to do that.
Now, onto the sound issue. I have a feeling that the sound may have a background hiss because it is loud. When I start up the machine, the startup sound is there, but way, way louder than I remember it. This is with the machine back inside its case, using the original speaker. I am not sure what about the cap replacement could have caused that to occur. I also am not sure how to adjust the volume on this thing, either!
There still is some intermittent crackling as well. I think there probably is some battery goop still somewhere causing havoc with the sound system. Now, where to look...
Already replaced the sound caps and have traced back to the headphone jack and inductor right there and cleaned them up. |
Posted by: NJRoadfan on 2022-05-22 07:42:21
Apple-Control-Esc activates the built-in control panel to adjust the volume. |
Posted by: LaPorta on 2022-05-27 21:36:46
I went through a few resistors on the back side that were tainted with goo. The sound is a little clearer than it was, but it still seems loud. Is the IIgs just loud in general? I used the system control panel, and no matter if I raised or lowered it, it seemed to be just slightly louder or softer. I am somewhat ready to just give it up as the thing actually works both video and sound, and this is getting nitpicky on something that suffered a massive battery explosion. |
Posted by: LaPorta on 2022-05-28 09:06:47
So my kids have been testing it, and it does work, but with time crackling appears in the background of the sound. There must be battery goo affecting the sound circuit somewhere. I wish I could trace it better through the schematics past where it says on the 8th page “4, SOUND H”. Can’t find what page that goes to. |
Posted by: desertrout on 2022-05-28 14:51:43
I'm not finding a '4, SOUND H' on page 8 - I must be missing it? I'm not seeing SOUND H on page 4 either as that suggests. However, I do see a (3) SOUND.H, which goes to Pin 11 of J10 (page 3). |
Posted by: LaPorta on 2022-05-28 15:26:27
Yeah I totally mistyped that! That is what I was looking for. Seems that just goes right to the video connector. I’m basically looking for each and every area of the sound circuit that could have gotten hosed by the battery crud and might have some lurking under it causing this issue. It appears to be two issues:
1. The background noise (which, by the way, will sometimes turn into an intermittent crackling when the machine warms up).
2. The inability to properly modulate the sound. In the control panel, no matter what I set the volume to (outside of mute), it sounds just as loud no matter what…and that means full volume at any setting.
Ill keep looking for any possible common denominator. |
Posted by: desertrout on 2022-05-28 18:43:22
What is the sound like through the audio jack? Same symptoms? I read above that the hum is audible, wondering about the level issues. |
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