I think my slightly older Sony SA-WM40 powered subwoofer has the same input solder issue. For the past few years it intermittently works but I could convince it by wiggling the RCA input wire. I took the amp off the back of the cabinet and all of the insides look just like this SA-WM500 so I bet the same defects would be present in it too. I'm going to look closer for those rings you mention and see what I can determine. Thanks for putting this video up for us home-gammers!
Great job as usual, just thinking on some of those ESR readings were a bit high, wondering if it would have helped changing them as far as the filtering in that regulator circuit. However, you did say its running as good as the day you bought it, so, what do I know..lol...!!! Have always enjoyed your videos, in fact the 35 yrs I spent in the tv repair bizz, having your videos a few years back were a big help on many repairs.... It's to bad our repair industry went south... It was a great business and I enjoyed it, at times it was frustrating, but, everything in life changes and the service business was not immune to change.
Do you happen to know where I can get parts for the SA-WM500? The RCA male end of my cable broke off in the female end on the sub input, so I'd like to replace the in/out RCA pair. Also, are the speaker inputs truly speaker level? Thanks in advance.
Mine just died after speaker wires touched the the metal cover of hifi where L and R are. And was still connected while on...? What could be the problem?
After changing the STK404-140S on my Sony SA-WM500 the sound relay is not switching or responding when I switch the power button on , but the subwoofer switches on but no sound , I even switch the auto standby on & the system response very well but still no sound ... please help how do I get it to work .
Mine did the same thing. After STK404-140 replacement. Check out the last few videos I posted on that unit. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-uv27Q7mx1vo.html ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-JRvVNQ1cn1U.html ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-JAiUiHntXtk.html
I think this recurring problem comes mainly from improper use, indeed this sub works on a wide spectrum, and therefore must be used at low volume. For more responsiveness in the bass I had to couple it with a passive sub, and indeed, it fills the lack of this big sub, which is effective for very low frequencies and its wide focal length. I was lucky to find a new one in its packaging last year, I did not see any problem, but since it is sensitive and saturates at high volume I imagine it must work on the welds and components ... It is always necessary to stay at the limit which should not be exceeded, but this sub alone is not a good choice, unless you know how to recognize its qualities and back it up with a sub that fills its gaps.
In the back of a TV cabinet, locked up, it heats up a little more than normal. Also i don't think the best seat is at the front with the audio system either for better sound distribution. But thank you for this information, in case mine breaks down.
Just a thought. If I'm reading the video correctly, the Sanyo application note didn't make use of the on-board thermister but the Sony circuit uses it to pull up a line through an NPN that feeds into what they call overload detect. The overload seems to be temperature based with no detection of residual DC on the output. Looking at the schematic, you should be able to add it in pretty easily to kill off the output relay power. A simple missing zero crossing detector circuit on the output set to about a fifth of a second should do it. One side of the speaker drive is to the centre tap of the incoming power transformers (power earth) and the other is to the emitter resistors, so there's no H bridge drive going on here.
Ahhh I See it in the internal block diagram and I see that Sony is using it in their design. I f the temperature gets over the preset design of the resistance network it will turn on the protect transistor and protect the unit. Good eye!
@@norcal715 Love discussions like this, but stop me if it's off track. The type of circuit protection here always acts slower than the SOA requirements of the output darlingtons for short circuits. The tranies will die. In a sealed unit like this sub-woofer, it shouldn't be an issue because the load is permanently wired, but never in an amplifier where the user wires it themselves. This type of protection is mainly for way too much sound for way too long. Instead of cutting power, you can also use the thermister to turn on a fan (or run a fan proportionally) to cool the module, or even use it as a resistor and just lower the size of the incoming signal to reduce the power dissipated.
Hi @NorCal715 Great Video! I have the same subwoofer. Mine decided to stop working at all this week. The green light on the power switch works fine but I do not hear the relay click on anymore. Any ideas? Is it that blue relay inside? Any help is greatly appreciated. Thanks! - Cody
Hey... I notice your TV is a TCL.... who makes that one? I see them at the bargain stores all the time but I know nothing about them.... you have the skills to repair them ... so I guess the brand don't matter to someone like you...
Most likely the standby power supply is the issue. As far as a new board, it would me almost impossible. Maybe you can find a used one out of a scrap unit. email me norcal715videos@gmail.com
My future son-in-law has the board and he'll be leaving for California in the morning he got the tools to check on the power system as soon as I find out I will contact you again
@@norcal715 I know what you’re talking about. Any time if powered up my sub, I’d hear that initial click, then a second a few seconds later. Now when I power up, I only hear the first, no second “click”, and the power indicator on the front isn’t lighting up. What can cause this and how can I repair it?
Cool stuff though I comprehend not a lick. I just fixed I think my Sony sa wmsp87 active woofer had a like three inch board with a tape like strip to it. It was out of the groves that it appeared to slid into. Had it been anything else I would not be jamming cause we need bass currently I’m listening to journeys first album which I feel is there only good one. I saw Steve perry at a gas station in Orinda cal in 7 th grade with my buddy’s. He was with a tall blonde Scandinavian looking gal in his 450 sel convertible ? And we all yelled at him saying journey sucks things. U know he wasn’t on the first album so maybe anyway. Take a rip on me. Shit I’ll send ya a nug if ya want
Nothing lasts forever. Come to think of it everything I have bought from Sony has failed with 3 exceptions... A 1967 AM cube radio, and a 1991 AM only radio, and my two ICF-2010s shortwave radios. They still work perfectly. I guess their radios are the only thing thats lasts.
