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[CLD-92] Audio Noise https://forum.lddb.com/viewtopic.php?f=53&t=8635 |
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Author: | cplusplus [ 17 Sep 2019, 00:02 ] | ||
Post subject: | Re: CLD-92 Audio Noise | ||
Diodes and filter caps:
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Author: | rein-o [ 17 Sep 2019, 00:44 ] |
Post subject: | Re: CLD-92 Audio Noise |
Wish I could help more. The only thing I know is if you are doing caps that you can use a larger voltage but you must use the same microfarad. Hope someone else can chime in. Also if you are buying from an electronics person who knows their stuff they should be able to answer, the guy I used to buy caps for my arcade machines would help me with questions back in the day before the interweb. |
Author: | krbahr [ 17 Sep 2019, 00:47 ] |
Post subject: | Re: CLD-92 Audio Noise |
If your only issue is audio then you either need to focus on the +/-15V power outputs or verify the RF level is not weak. +/-15Vlines are mainly for the audio decode/output sections. RF levels getting a little weak will produce dropouts in the digital audio before the level gets low enough to affect the Video and Analog audio tracks. |
Author: | krbahr [ 17 Sep 2019, 00:52 ] |
Post subject: | Re: CLD-92 Audio Noise |
I’d actually re-flow the solder at the droid first if you thing that is the problem. I’d recommend GI851 Fast switching rectifiers as they will also help lower the noise floor over the conventional rectifiers. |
Author: | cplusplus [ 17 Sep 2019, 03:40 ] | ||
Post subject: | Re: CLD-92 Audio Noise | ||
rein-o wrote: Wish I could help more. The only thing I know is if you are doing caps that you can use a larger voltage but you must use the same microfarad. Yep Nichicon makes the exact ones that I need thankfully. 2200uf 35v. Should fit well physically too. I've recapped with Nichicon's UKA line before to nice results. Thanks for your response Kurtis. I was concerned about a weak laser before purchase, especially after reading your post here: Pioneer CLD-92 Distorted Digital Audio The audio sounded great via TOSLINK, so that should mean the RF level is good right? No notable issues with video. I should have checked the RF level anyway, but the overheating was so severe I was afraid to power it on again. Pulling the diode from the board and testing it shows it is bad for sure though. Continuity in both directions. I will check for the +/-15V after replacement. I'll order GI851 and replace all four.
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Author: | cplusplus [ 17 Sep 2019, 03:47 ] | ||
Post subject: | Re: CLD-92 Audio Noise | ||
Here's a photo of how the audio board is powered. I've never seen this before- wiring coming out of the top of a transformer.
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Author: | krbahr [ 17 Sep 2019, 22:05 ] |
Post subject: | Re: CLD-92 Audio Noise |
The +/-15V also feeds the DAC so yes that could cause the bad digital audio while the TOSLINK is good. |
Author: | cplusplus [ 22 Sep 2019, 15:35 ] |
Post subject: | Re: CLD-92 Audio Noise |
I replaced the rectifier diodes and the filter caps. Now there is now power at all. The wires running from the top of the transformer to the audio board show no voltage and the secondary side of the power board seems dead as well. Time to pull the power board so I can get a better look. I'm thinking the transformer cooked itself when one of the rectifier diodes died on the audio board? |
Author: | cplusplus [ 03 Mar 2020, 05:09 ] |
Post subject: | Re: [CLD-92] Audio Noise |
Update on this. After a lot of more or less hopeless pondering, I figured out how to get this back up and running. The thermal fuse inside the transformer was for sure blown. I am unable to simply replace the fuse because this is a laminated core transformer that has been welded together. I also looked under the tape and saw no signs of a fuse. Additionally, I could not find a suitable replacement for this transformer. After removing it from the power supply board, I saw what appeared to be the legs of a fuse wrapped around two posts on the primary side. I jumped these, presumably bypassing the fuse, and power came back on the secondary side. Voltages looked good and my repair on the audio board worked great. I ran a full LD and the only issue I noticed was the transformer was a little warm afterwards. Not a good sign, so I'll need to look into why that is happening before I consider this repaired. Additionally, I'll need to see about getting a low threshold thermal fuse to put on the side of the transformer for safety reasons. Other than that the picture looks great and the sound is back to normal. |
Author: | rein-o [ 04 Mar 2020, 00:49 ] |
Post subject: | Re: [CLD-92] Audio Noise |
I know you always go super far into repairing your players, thanks for posting the pics and details. |
Author: | cplusplus [ 05 Mar 2020, 01:49 ] |
Post subject: | Re: [CLD-92] Audio Noise |
Thank you for the comment. I'm trying to do my best to document my adventures in repair and laserdisc hardware in general. The efforts to revive fallen players will have to go further as time moves on, especially when dealing with good ones. |
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