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Search: Posts Made By: redwire
Forum: Troubleshooting Audio Equipment 01-22-2022, 12:14 AM
Replies: 19
Views: 236
Posted By redwire
Re: Thorens TTA-2000 DC offset

I think you need a speaker relay to stop the huge thump until the output caps charge up. Not for (shorted output transistor) protection.
There are pics of TTA-2000 with and without one. It might be...
Forum: Troubleshooting Audio Equipment 01-21-2022, 03:03 PM
Replies: 19
Views: 236
Posted By redwire
Re: Thorens TTA-2000 DC offset

As others have mentioned, this amplifier is not DC-coupled to the loudspeaker. It uses a large coupling capacitor C1 10,000uF
So your DCV reading is likely due to small leakage currents in the big...
Forum: Troubleshooting Audio Equipment 01-20-2022, 09:26 PM
Replies: 19
Views: 236
Posted By redwire
Re: Thorens TTA-2000 DC offset

zoldi, can you download the schematic (https://www.analog-forum.de/wbboard/index.php?thread/122403-thorens-tta-2000-schaltunterlagen/&postID=1538721#post1538721) from that forum and post here?

Do...
Forum: General Electronics Technical Discussion 01-20-2022, 09:19 PM
Replies: 9
Views: 163
Posted By redwire
Re: Inductor or resistor

That DC resistance is too high at 25Ω, and the current-rating 100mA is too low. You need something with lower resistance and higher current rating.
Forum: General Electronics Technical Discussion 01-19-2022, 06:51 PM
Replies: 9
Views: 163
Posted By redwire
Re: Inductor or resistor

The part is a ferrite-core inductor used for a differential-mode filter, roughly around 1-5mH. Purpose is to lessen the EMI and RFI noise from the SMPS primary that radiates out to mains. You could...
Forum: Troubleshooting Audio Equipment 01-16-2022, 04:07 PM
Replies: 13
Views: 235
Posted By redwire
Re: My grandma's Vintage Speakers Winson SB 300 A (1979)

It depends on what you want to keep vintage. It's in a nice stand. For all the room it takes up, why not have it be able to play mp3 from bluetooth? Or just add a box outside if the unit has AUX or...
Forum: General Electronics Technical Discussion 01-16-2022, 04:03 PM
Replies: 23
Views: 432
Posted By redwire
Re: can a flyback transformer for USB charger isolate?

What voltage do you need for the LED string you are testing?
In Sweden they have many isolation transformers but developing countries they are too expensive.

For high voltage strings like in TV's...
Forum: Troubleshooting Audio Equipment 01-16-2022, 01:16 PM
Replies: 13
Views: 235
Posted By redwire
Re: My grandma's Vintage Speakers Winson SB 300 A (1979)

From pics of the board, audio amplifier IC HA1338 is rated 6W at 24VDC power and 8R load. So the power level is not enough for a party ;) Grandma need to dance
For modifications I would add a low...
Forum: General Electronics Technical Discussion 01-16-2022, 12:22 AM
Replies: 23
Views: 432
Posted By redwire
Re: can a flyback transformer for USB charger isolate?

The term came from CRT's, AFAIK. When the B-field in the transformer quickly collapses, it made the HV spike and the beam quickly "flies back" (blanked) back to the left edge.
Forum: Troubleshooting Audio Equipment 01-16-2022, 12:19 AM
Replies: 13
Views: 235
Posted By redwire
Re: My grandma's Vintage Speakers Winson SB 300 A (1979)

It looks like a low cost china or taiwan speaker. These were sold out of vans by guys in parking lots... or sometimes just fake that everyone thought was a real hifi speaker because they had the...
Forum: Troubleshooting Audio Equipment 01-13-2022, 05:39 PM
Replies: 11
Views: 202
Posted By redwire
Re: Monitor Audio RSW-12 Plate Amp Popping/Crackling

Q10 if it tests OK I would leave alone then. It supplies 15V for the power-on circuit and relay on that board, I don't see it powering anything in the audio sections.
The voltage regulators appear...
Forum: General Electronics Technical Discussion 01-13-2022, 05:31 PM
Replies: 3
Views: 112
Posted By redwire
Re: (Multiple Spark Discharge) MSD 6AL Q204 required

From another (https://nurciq.blogspot.com/2009/06/repairing-msd-6al.html) MSD 6AL repair blurb:

TC4627 (https://ww1.microchip.com/downloads/en/DeviceDoc/20001426D.pdf) has voltage-doubler 2.2uF...
Forum: Troubleshooting Audio Equipment 01-13-2022, 12:29 PM
Replies: 11
Views: 202
Posted By redwire
Re: Monitor Audio RSW-12 Plate Amp Popping/Crackling

If a new problem shows up after replacing capacitors, it means I've made a mistake doing that.
I would double-check the replacement electrolytics are installed good, no solder bridging or reverse...
Forum: General Electronics Technical Discussion 01-13-2022, 12:04 PM
Replies: 4
Views: 182
Posted By redwire
Re: Thermal Cutoff/Fuse ID -Surge Protector

I would match the fusing temperature 109C. This is a power strip so it is supposed to prevent fire when the MOV's overheat.

If it was a food cooker that goes unsafe just above boiling temperature...
Forum: Troubleshooting Game Consoles & Other Weird Devices 01-11-2022, 04:35 PM
Replies: 21
Views: 532
Posted By redwire
Re: bad linear compressor on my LG fridge

You're also paying for the fridge to run and pump out the light bulb's heat. There's three 40W bulbs in the Whirlpool (one in the freezer too). Not a lot of money of course.

It just seems silly...
Forum: Troubleshooting Game Consoles & Other Weird Devices 01-10-2022, 07:56 PM
Replies: 21
Views: 532
Posted By redwire
Re: bad linear compressor on my LG fridge

It's when I'm unpacking groceries that the door is open for more than a few seconds. I'm paying twice - electricity for the light bulbs, and for the fridge to remove that heat.
If you put a...
Forum: Troubleshooting Game Consoles & Other Weird Devices 01-10-2022, 03:17 PM
Replies: 21
Views: 532
Posted By redwire
Re: bad linear compressor on my LG fridge

I put a power meter on my Whirlpool refrigerator and was shocked the power drain was 0.2W jumping to 90W when you open the door! Turns out it's got two 40W incandescent light bulbs :facepalm: These...
Forum: General Electronics Technical Discussion 01-10-2022, 12:24 PM
Replies: 21
Views: 653
Posted By redwire
Re: Neighbor has a constant drain on his car battery...

Acura is Honda, Lexus is Toyota.

Acura/Honda 4-cyl do use the smallest car battery group 51R which really belongs in lawn tractors lol. It's at best 35-40Ahr.
I'm a bit suspicious the system...
Forum: Troubleshooting Power Supplies and Power Supply Design 01-10-2022, 12:10 PM
Replies: 18
Views: 1,862
Posted By redwire
Re: 12V 2A battery charger/maintainer

Thanks for the schematic, I forgot to finish mine. It looks almost identical to the one I have. This charger is really good for the car, I don't like the brittle cables when it's cold out or the hot...
Forum: General Electronics Technical Discussion 01-06-2022, 11:26 PM
Replies: 11
Views: 356
Posted By redwire
Re: Wirewound Cement Resistor Ceramic explanation

Modern resistors and capacitors follow the EIA standard (https://en.wikipedia.org/wiki/E_series_of_preferred_numbers) for values. Example is the EIA-12...
Forum: General Electronics Technical Discussion 01-01-2022, 11:02 PM
Replies: 10
Views: 311
Posted By redwire
Re: 7 segment LED display with different pinout

I see nothing like that, even going back to the 70's. Maybe post pics of the display.
It would be very odd to break conventions and use that nutty pinout.
Forum: Troubleshooting Game Consoles & Other Weird Devices 01-01-2022, 10:45 PM
Replies: 21
Views: 532
Posted By redwire
Re: bad linear compressor on my LG fridge

Appliances are very big money, every household has several $1,000's worth of them. They are mission-critical too. Food spoilage or you can't cook dinner or do laundry when they aren't working.
...
Forum: General Electronics Technical Discussion 12-31-2021, 09:13 PM
Replies: 21
Views: 653
Posted By redwire
Re: Neighbor has a constant drain on his car battery...

The limit is about 125mA for automotive parasite draw.

Although you see 300mA, give it 5 minutes or so. After key-off an ECU does some house-keeping before it goes to sleep. So it might be stuck...
Forum: Troubleshooting Power Supplies and Power Supply Design 12-31-2021, 01:39 PM
Replies: 25
Views: 4,169
Posted By redwire
Re: APC BACKUPS-RS550 not charging battery

For your 550, I only find bits pieces here: https://www.elektroda.pl/rtvforum/topic3529704.html
I have this schematic for APC 640-0259_REV05 which is I think is Back-UPS RS500, BR500i. No charging -...
Forum: General Electronics Technical Discussion 12-30-2021, 01:53 PM
Replies: 10
Views: 311
Posted By redwire
Re: 7 segment LED display with different pinout

Usual Fairchild-style, pin 5 is DP and pin 6 is B-segment, with 3,8 common.
I did see an alternate pinout, for the 10-pin (across the top and bottom) LED display.
There is common on pin 5,10 which...
Showing results 1 to 25 of 500

 
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