Vsv Posted October 14, 2020 Share Posted October 14, 2020 (edited) Its my first post, so hello everyone. I found many helpful guys up here helping each other, so thought I could get some help with my problem as well. Recently I bought a RSW15 to be paired with the RB75s that I already had. I bought the sub in not working condition thinking I could repair if something minor is wrong, otherwise use it as a passive subwoofer it it doesn't work out, especially that I plan taking it to EU, where we have 220V instead of 110v. After opening up the sub, I see that it can be rewired to 220V, so it makes even more sense getting the original amp to work. So THE PROBLEM: the amp does power on, and stays on, but the internal protection starts cutting out the power when the volume reaches speaking level of sound (I assume it's like 1/10th of what it should be able to produce). Increasing the volume the protection keeps triggering on and of, however I cannot hear any distortion or other problems in sound quality during the second it works, except it keeps turning on and of (the clicking sound is heard in the amp circuit board when it turns on and of). First I have expected to have one of power transistors blown or out of specs, but after testing all of them (without removing them) I found the same readings for all of the kind, so either all of them are out of specs, or all are good. Since they don't produce almost any heat, sound good I would say they should be fine. Thought perhaps the audio input level can be too high, but when the speaker is disconnected, I can go with volume all the way up with no clicking sound in the amp board. So the signal is fine. Then I thought, perhaps the power supply gets overloaded (its the only part that gets worm playing even at low power level) I tested the amperage draw in the main input (~160V DC), but it's very marginal, like ~30mA, when I increase the volume to get the power cut out I can see no more than 50mA draw from the power supply. So I assume there's no real overload condition happening. The last thing I would think the problem occurs should be the overload sensing circuit (?). Anyone has experience with such a problem? Any advices? Thank you in advance for any thoughts. Edited October 29, 2020 by Vsv 1 Quote Link to comment Share on other sites More sharing options...
Ken Uridge Posted October 18, 2020 Share Posted October 18, 2020 I am having the same issue, just posted and later read your thread.. Not sure what to do.. looking to buy a new one. 1 Quote Link to comment Share on other sites More sharing options...
ngen33r Posted October 22, 2020 Share Posted October 22, 2020 RSW's start with the caps and start tracing the circuits. These are not easy. Quote Link to comment Share on other sites More sharing options...
Vsv Posted October 29, 2020 Author Share Posted October 29, 2020 I have solved the issue. It was the 3 small caps in the power supply board. They were totally dead (no capacity left). My advice for the owners of RSW15 maybe it applies to the other RSW as well - keep the power of when not listening, because the power board in sleep mode is still producing the heat, so its only a matter of time when your caps will fail. IMHO they are even rated to low for this application (85C, when the big caps have 105C rating) and staying under the heatsink they are all the time in heat. No surprise it will dry out, especially if unit is always on. 1 Quote Link to comment Share on other sites More sharing options...
billybob Posted October 29, 2020 Share Posted October 29, 2020 Welcome to the forum! Others may be helped by this information... thanks. Quote Link to comment Share on other sites More sharing options...
babadono Posted October 29, 2020 Share Posted October 29, 2020 @Vsv Which caps? I've got my service manual out to make notes of what you found. Please come back. Did you replace with 105 C parts? 1 Quote Link to comment Share on other sites More sharing options...
Vsv Posted October 31, 2020 Author Share Posted October 31, 2020 Yep, i have picked the 105c rated. The caps from poweboard that stabilize the +25v -25v and +30v (c415,416, 418 if i remember right). But there are only 3 little electrolythic caps there, so you woun't mistake them. Quote Link to comment Share on other sites More sharing options...
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