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Search: Posts Made By: kaboom
Forum: General Electronics Technical Discussion 10-09-2018, 10:25 PM
Replies: 35
Views: 615
Posted By kaboom
Re: Possible ground loop

Yes.



Also, yes. :smile:
For fun, put an AC ammeter in series with this jumper- you should read no current. Well, maybe a few milliamps from the line-GND Y-caps in any noise filters...


...
Forum: General Electronics Technical Discussion 10-09-2018, 06:31 PM
Replies: 35
Views: 615
Posted By kaboom
Re: Possible ground loop

240V as in the two 120V outside legs of a single-phase distribution transformer?
If so, and they're straight-240V (not using the neutral or no neutral current) ground on the supply side isn't...
Forum: Troubleshooting Game Consoles & Other Weird Devices 08-23-2018, 09:46 PM
Replies: 36
Views: 744
Posted By kaboom
Re: Treadmill DC Circuit no motor start

Disconnect all power, and remove the three leads going up to the pot. Check the pot.

From black to red, I'd guesstimate 1-10k for the element, maybe as high as 25-50k.
From white-black, 0 full...
Forum: General Computer Discussion 08-23-2018, 09:24 PM
Replies: 3
Views: 136
Posted By kaboom
Re: steam for linux: steam play on proton (wine) to play windows games on linux

It's a "steaming pile," yawn...

As far as the "runs on linux" bit, that many titles are claiming as of late, if it needs a DOS/win emulator hosted by the native OS, that doesn't mean "thousands of...
Forum: General Capacitor Questions & Issues 08-13-2018, 06:58 PM
Replies: 11
Views: 446
Posted By kaboom
Re: Fake Panasonic cap?

Who likely sourced a "standard" design someplace, and had it branded/customized with their name. Or was semi-legit, and the fake parts got subbed in after the initial samples/prototypes arrived and...
Forum: Troubleshooting Power Supplies and Power Supply Design 08-13-2018, 06:55 PM
Replies: 14
Views: 265
Posted By kaboom
Re: LED Shop light - EMI problem - Chip info needed

Needs common mode chokes (and film caps), on both line input and LED output.

Look at the input section of any legit SMPS for examples.


Without the filters, one should expect severe RFI...
Forum: General Capacitor Questions & Issues 08-10-2018, 09:44 PM
Replies: 11
Views: 446
Posted By kaboom
Re: Fake Panasonic cap?

Fake for sure...

No T vent, and I've never seen Panasonic caps with that seal.
Print is off and there's no stamped date/lot code.

Looks like some "Hermei" or similar trash...
Forum: Troubleshooting Power Supplies and Power Supply Design 07-22-2018, 09:53 PM
Replies: 54
Views: 1,045
Posted By kaboom
Re: Converting Spotlight Power Supply

You can't do this with the adapter you have now. It's not even remotely adequate.
Forum: Troubleshooting Power Supplies and Power Supply Design 07-22-2018, 09:51 PM
Replies: 88
Views: 2,367
Posted By kaboom
Re: Bench PS Problem (Volteq HY3010D)

yes



Ok. Try putting each wiper in the center of its rotation. Then check from 1-wiper and 3-wiper. Each should measure 1/2 of what 1-3 reads.

ASSuming linear taper, a 10k nominal should be...
Forum: Troubleshooting Power Supplies and Power Supply Design 07-22-2018, 08:46 PM
Replies: 88
Views: 2,367
Posted By kaboom
Re: Bench PS Problem (Volteq HY3010D)

Because you're checking them in ckt. Pull em and try again.
Forum: Troubleshooting Power Supplies and Power Supply Design 07-22-2018, 08:42 PM
Replies: 54
Views: 1,045
Posted By kaboom
Re: Converting Spotlight Power Supply

Yes, 9v under load! 18V unloaded/9 under load suggests a 12v transformer which is severely undersized= cheep junk.
Even under load, this one's 3v too high!

A 7806 with a 1N4004 elevating the...
Forum: Troubleshooting TVs and Video Sources 07-20-2018, 02:58 AM
Replies: 11
Views: 381
Posted By kaboom
Re: sansui dvd combo tv, brand new from 2013

As it should be with nominal 115-120 line voltage.



This is a Funai product, it's called "buy up old reputable brands so we can sell junk."
Forum: General Electronics Technical Discussion 07-08-2018, 11:34 PM
Replies: 12
Views: 575
Posted By kaboom
Re: Improvised surge protection

When it involves comms, either POTS or CATV and other equipment with a three wire cord, and there's no bonding jumper (NEC 820.100, 250.94 and related), these independent common points (NOT grounds...
Forum: General Electronics Technical Discussion 07-08-2018, 09:41 PM
Replies: 12
Views: 575
Posted By kaboom
Re: Improvised surge protection

Other than power, what is the RPi connected to?
Forum: Troubleshooting Power Supplies and Power Supply Design 07-04-2018, 05:39 PM
Replies: 88
Views: 2,367
Posted By kaboom
Re: Bench PS Problem (Volteq HY3010D)

check 3 opamp supplies, using out + for DMM negative lead:

+12V at pin 8 of M1 & M2, pin 4 of M4
-15V at pin 11 of M4
- 6.2V at pin 4 of M1 & M2

also check at junction of R2:V6 and R39:V21
...
Forum: Troubleshooting TVs and Video Sources 07-02-2018, 05:08 PM
Replies: 15
Views: 210
Posted By kaboom
Re: Trying to fix VCR...

Well this is expected.

Those time-lapse machines were run to the ground.

Often rewinding & reusing the same tape- the main problem was they usually never got the maintenance required.

If it...
Forum: General Electronics Technical Discussion 06-30-2018, 09:30 PM
Replies: 19
Views: 677
Posted By kaboom
Re: Linear PSU Pass Transistor Question.

As for most TO-3s and some of the "flatpacks," which are usually 125c.

But this is without dissipation!

At TjMax, devices are derated to zero watts on the collector.
Forum: General Electronics Technical Discussion 06-28-2018, 08:10 PM
Replies: 102
Views: 2,578
Posted By kaboom
Re: An idiotic question about AC and shocks.

No problem if ya twist first. They call it "pre-twisting" nowadays; supposedly you can put the wires in loose, twist the cap and like magic the splice is made up.

No way! It was my understanding...
Forum: Troubleshooting Power Supplies and Power Supply Design 06-28-2018, 07:37 PM
Replies: 5
Views: 261
Posted By kaboom
Re: Allied AL-D500EXP (SL-8500BTX) blown primary side

Don't forget to check both sets of base drive components for the switchers.
There's two small caps (I use 4.7/50) that back-bias those BJTs during the "off" time, ensuring they switch off quickly....
Forum: Troubleshooting Audio Equipment 06-28-2018, 03:16 PM
Replies: 15
Views: 434
Posted By kaboom
Re: Luxman L-80V DC Offset a bit too high ~150mV

You can use a pair 4148s for D102. There should be approx .6V across R120. Q105 is a constant current source for the voltage amp stage Q103.

The CCS sets the current thru the bias string and...
Forum: Troubleshooting Audio Equipment 06-28-2018, 03:41 AM
Replies: 15
Views: 434
Posted By kaboom
Re: Luxman L-80V DC Offset a bit too high ~150mV

DO NOT USE varactor diodes! Those are for RF tuned circuits which have ZERO resemblance to an audio amp.

Two 1N4004s will work for bias temperature compensation.

Change these three...
Forum: Troubleshooting Power Supplies and Power Supply Design 06-26-2018, 11:46 PM
Replies: 54
Views: 3,431
Posted By kaboom
Re: Altec MX6021

I saw the dust. It looks like there's a central blister, or at least former hotspot.
I've "peaked and tuned" the image, and uploaded it...




:d
Forum: Troubleshooting Power Supplies and Power Supply Design 06-26-2018, 09:15 PM
Replies: 54
Views: 3,431
Posted By kaboom
Re: Altec MX6021

Just posting quick here...

That driver IC is directly connected to the MOSFET gate, via JMP2. If/when the MOSFET shorts, IC must be replaced.

I see a crater on the 1351 on lincolnkorg's board....
Forum: Troubleshooting Power Supplies and Power Supply Design 06-22-2018, 08:00 PM
Replies: 2,974
Views: 700,426
Posted By kaboom
Re: Power supply build quality pictorial. part 2

IOW, you mean Bambi's mama is EOL?? :tongue:
:group:




Not only can it run away, Bestec-style, the caps go bad resulting in extreme ripple. I've noticed a trend with Deers- +5VSB usually...
Forum: General Capacitor Questions & Issues 06-22-2018, 01:10 PM
Replies: 21
Views: 886
Posted By kaboom
Re: another stupid polymer question (can going REALLY high ripple be bad?)

Ya mean I'm not the only one who does that? :goofy: :tongue:

As in the phrase "that escalated quickly," I tend to go "George Patton" when it comes to software/malware issues- to the point I can't...
Showing results 1 to 25 of 500

 
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