That 3 legged device has markings: KA6 50 (or could be "SO"). I did try to search it up, but turned up nothing useful.
And thanks for the alternative service manual. That's from a unit in the 90's of which the circuitry appears to be completely different than the AM10 IV. I've already tried sleuthing through Elektro Tanya for anything Bose in the hopes the schematics for similar products of this era may yield some details. I also contacted Bose and they would not disclose any service manuals.
EDIT: WOW..nevermind. Thanks for pointing me in the right direction!...
nobbnobb1
Senior Member
Last Activity: 02-08-2025, 05:18 PM
Joined: 11-16-2019
Location: BC
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Where is this SOT23 you are talking about?
I did try to clean/scrape things off...no markings legible at all. Also, per the above schematic for the similar AM10 III, I'm noticing that the two transistor/bridge rectifier sets (top row vs bottom row in the board pic) have very similar components. I thought that in theory, if I could find the similar resistor on the bottom bank in my unit...that it should be the same as the burnt one I'm trying to identify. However, no luck as it seems the AM10 IV is different enough to the AM III that I am unable to find it....Leave a comment:
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Thanks. So per the above circuit, I was trying to trace it and was under the impression that it was the resistor labelled R73 which is a 2Kohm resistor. But the schematic doesn't line up exactly based on me trying to trace it from pin #3 on Q209, to Q213, then to R73.
So if I'm measuring 50 ohms right now, by that logic I may be safe just ordering a 2Kohm resistor and seeing what happens?...Leave a comment:
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Dang, so I just discovered that small SMD resistor below the "O" in "BOSE" may also be blown. It's testing ~50 ohms, but I'm guessing there's almost no way to verify what it should be without the schematic?
I found a similar Acoustimass 10 III schematic (attached), but upon further tracing it's not 100% the same, so I'm a bit lost on how to identify this resistor.
[URL=filedata/fetch?id=3509270&d=1731861276][ATTACH=JSON]{"alt":"Click image for larger version Name:\tbose_acoustimass_am-10_series_mk3_amplifier_sch.png Views:\t0 Size:\t290.8...Leave a comment:
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Bose Acoustimass 10 IV Subwoofer No Sound. Help with burnt component identification?
I picked up this used Bose Acoustimass 10 IV speaker system. Speakers seem to work fine, but the subwoofer does not make any noise. So I took apart the unit and found some obviously failed (burnt) components:
- 1x 3.14 A @ 250V main circuit fuse
- 1x bridge rectifier GBU601. there's actually two of these on the board, one is obviously burnt and the other does not seem to have any anomalies like shorts. However I figure may as well replace both.
- 2x diode. This is tricky because the only markings I see on it are: "617 402". No current rating or anything else.... -
I picked up a top of the line LG plasma for free which was in mint condition, but had a failed chip on the mainboard. All I did was reflow the BGA with a heat gun, and added a fan to the chip which I found a 12V take off point somewhere off the power supply. The BGA problem is well known on this TV, but after the heatgun trick it's been holding just fine for the last 4+ years. So well worth it to add the extra cooling IMO as it minimizes the thermal stresses on the chip on each on/off cycle....Leave a comment:
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TVs vs Computer Monitor Reliability & Failure Rate
Anecdotally, it seems to me that TVs fail much more often than computer monitors judging from personal experience and looking at the classified where people are getting rid of broken/malfunctioning TVs all the time.
So I'm just wondering if this is the case? Is there something inherent in the design of monitors that makes them more reliable? I would've thought they'd be operating under more severe conditions than a TV. For a typical family, a TV may only be on for a few hours every day. Whereas a monitor could be on 8+ hours, along with countless power cycles turning on/off as power... -
They are "ChongX" and says "VEHT" and "low ESR". Is it supposed to say "VENT"? In hindsight, I'm guessing I shouldn't risk it. Didn't realize knock offs of even Chinese capacitors is such an issue....Leave a comment:
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Cheap Aliexpress Capacitor: Much smaller than original. Safe to use?
I am trying to get a set of Creative T40 computer speakers to work again of which I believe the problem is bad caps (470uF @ 35V). So I get a generic set off Aliexpress. The brands are meaningless, but if anyone cares it's a "Chongx"
When they arrive, to my surprise it's much smaller than the originals. These are 8mm x 15mm whereas the OE is 10mm x 20mm. Unfortunately my meter does not test capacitance but I'm guessing there's no way this meets spec at 80% the size.
​​​​​​Thoughts? Is it still worthwhile or safe to try and install these to see if... -
Laptop LCD Panel Upgrade (HP Elitebook G8 845)
Hello,
I have an HP Elitebook G8 845 with the base 14" 250 nit LCD screen which looks terrible. I believe the base unit is a B140HAN04.6 (but not 100% sure). From looking at some part interchange numbers, I believe this is the 400 nit upgraded panel which came as an option (not 100% sure...just based off an Aliexpress listing):
B140HAN05.3 [URL]https://www.panelook.com/B140HAN05.3_AUO_14.0_LCM_overview_42334.html[/URL]
Then looking at the same family of panels, this unit appears to be a version with better specs:
B140HAN05.9 [URL]https://www.panelook.com/B140HAN05.9_AUO_14.0_LCM_overview_44257.html[/URL]... -
That's not a bad price. For me, I wanted somwthing high current and the cheapest way was to just build out an old ATX computer power supply. You can buy a cheap DC-DC adjustable regulator, a small voltage/current display, and some knobs....Leave a comment:
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Re: Onkyo NR609 usual Dolby/DTS DSP failure
I didn't know people go through the effort of reballing! Since I don't have the tools or skill, I've just been doing the heatgun trick. I shield the chip surroundings with some tinfoil and blast the heatgun until I measure 200C on the chip. I then let it cool slowly and naturally, then stick on a heatsink to the chip. I also modified the onboard fan to run all the time (there's a spare connector somewhere that puts out a constant 12V). Has seemed to holdup for the last year so far.
I've also done this to fix a Toshiba plasma...Leave a comment:
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Re: DIY NAS Service Life (Hardware)
I'm curious what kind of problems do you notice beyond that in terms of reliability issues? Hard drive and fan failures are fairly easy to work around. This is the only machine that I've really ever ran for such long periods. Even then, it's not a 24/7 machine. It auto powers down from midnight to 6am everyday.
I would also maybe attribute my reliability to the fact that I built it to be a pretty low power machine. ~50 watts on idle with 1 drive. Was very surprised to see the infamous yellow glue in the power supply...Leave a comment:
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DIY NAS Service Life (Hardware)
So I'm probably a decade behind on this, but my current NAS is a low power machine I built in 2009. It was originally running Windows Home Server, then eventually I migrated to Windows 10 using Storage Spaces for my drive expandability and redundancy. Despite being slow for W10, I love the familiarity and functionality so I never bothered getting into NAS specific OS.
Hardware wise, it's got 4x drives but the hardware is all super low draw, so the Antec EarthWatts EA380D power supply is barely above ambient. This PSU is apparently known for capacitor issues but when I went in to... -
Re: Onkyo TX-NR609 Sound only on USB/Internet Radio/DLNA Input
These series of Onkyos were notorious for the no sound problem, but it was almost always that chip of which you are saying you reballed already. Did you remove the chip entirely to reball or did you just do the heatgun trick? Also I believe it's called the DTS/HDMI chipLeave a comment:
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Re: Fix for Logitech Z906 speaker erratic function
Was there yellow glue inside which turned brown? This similar thing happened on some other computer speakers and turned out to be the culprit, not the caps. Strange that the Z906s would have bad caps already because I would've thought this model is relatively new.Leave a comment:
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Re: The Real Dangers of conductive glue.
It's disappointing to see that even in the modern day, that manufacturers are still using this glue despite a 20+ year history of this stuff causing problems.
I now make it a habit to open up any electronics that I moderately care about that is 10+ years old to check for this stuff. Usually it's only an issue on parts that run hot. If the area is cool running, this stuff will almost never degrade so I just leave it as is because it's super hard to remove. Chipping away too aggressively just risks damage to the circuit board....Leave a comment:
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Re: Panasonic TC-P50U50 Powers Off - 8 blinks
Just replaced the 5.6 ohm resistors. No luck, still the same problem. Pretty darn close to just giving up on this SS board now.Leave a comment:
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Re: Question about common symptom in repaired subwoofers
I'm still a super beginner but it's hard to say. With capacitors, I've had units that looked perfectly normal with no bulges/leaks and yet it was still bad enough to prevent the amp from functioning. The capacitors that are most likely to fail seem to be the large ones on the power supply, and any unit near heat sinks or other heat sources. Always good practice when replacing caps to try to bend/point them away from nearby heat sources if possible.
After that, definitely test each diode/transistor...Last edited by nobbnobb1; 03-29-2023, 05:48 PM.Leave a comment:
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Re: Panasonic TC-P50U50 Powers Off - 8 blinks
I have replacement 5.6 ohm SMD resistors (R041 and R051), but then I just noticed the ones I bought are physically too small! I could probably be creative in using a blob of solder to jumper it together. A little tough getting the right size because I got these off Aliexpress and seemingly none of the sellers list out the dimensions!
In the meantime, I powered on the TV with SS33 disconnected and TPVe tested 170V as per the service manual. Those other transistors I tested in-situ and they don't seem to have...Last edited by nobbnobb1; 03-28-2023, 08:03 PM.Leave a comment:
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