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Search: Posts Made By: redwire
Forum: General Electronics Technical Discussion Today, 04:06 AM
Replies: 52
Views: 2,632
Posted By redwire
Re: Fixing a multimeter based on VC9805 schematic

Display shows 1___ with those readings?
Pin 40 COM voltage is too low, it needs to be at least 1V above V-. On the schematic it would be QC4,QC3 to check- that would short COM below 1V. On your...
Forum: General Electronics Technical Discussion Yesterday, 11:20 AM
Replies: 3
Views: 74
Posted By redwire
Re: Reading input and output of bridge rectifier on the same scope?

Fixed: just as well oscilloscopes are sold in packs of 10 on aliexpress! :D
Forum: Equipment Usage, Soldering, Techniques, and Reviews Yesterday, 11:17 AM
Replies: 9
Views: 169
Posted By redwire
Re: Buy a Agilent U1242A or Fluke 179 DMM?

I'm repairing three old American-made multimeters, but I might have maxxed out at having 10 lol I've got no Flukes, just HP, Beckman, Wavetek.
I hate Taiwan-built multimeters, either they blow up...
Forum: General Electronics Technical Discussion 06-25-2022, 02:11 PM
Replies: 11
Views: 162
Posted By redwire
Re: Conversion of Anolog Voltmeter into Ammeter

"the meter still needs to be touched to work".
Find the bad connection, then worry about the design issues.
Forum: General Electronics Technical Discussion 06-25-2022, 10:29 AM
Replies: 11
Views: 162
Posted By redwire
Re: Conversion of Anolog Voltmeter into Ammeter

Your test setup looks good, I think there is a poor connection or maybe a switch is inside the meter so you must press it down to take a reading.
Usually panel meter specs are two things - the coil...
Forum: General Electronics Technical Discussion 06-24-2022, 09:54 PM
Replies: 52
Views: 2,632
Posted By redwire
Re: Fixing a multimeter based on VC9805 schematic

Post #28 I said to use a multimeter and measure some voltages "On DCV 20V range, measure the A/D voltages: IN HI, IN LO, REF HI+, REF LO-, COM wrt V-"
That is 5 readings to take.
Forum: Troubleshooting Game Consoles & Other Weird Devices 06-24-2022, 09:51 PM
Replies: 7
Views: 121
Posted By redwire
Re: Turbo Start QPET 16V/25A racing charger repair

It looks like a typical battery charger using phase control. The SCR's gate is driven by the H11 opto-couplers U4, U5. There's a current-transformer so it must do CV/CC control.
The only scenario...
Forum: General Electronics Technical Discussion 06-24-2022, 12:41 PM
Replies: 18
Views: 764
Posted By redwire
Re: Using car key fob as generic remote control

Check the RXB6 pinout, it has an enable pin 6 which floats high to enable data, not power save.
Some of those 433MHz RX modules have extremely weak data output 10uA (!) so a low value pullup or LED...
Forum: Troubleshooting Game Consoles & Other Weird Devices 06-24-2022, 12:26 PM
Replies: 12
Views: 184
Posted By redwire
Re: Graco ST MAX II 495 PC PRO , paint spray machine help

D16 is usually a SOT-23 diode like BAV99, BAS16, MMBD4148 etc. I think BAT54 (https://www.vishay.com/docs/85508/bat54.pdf) at 30V is too low. Around 10R looks reasonable for the resistor. C20 must be...
Forum: Troubleshooting Game Consoles & Other Weird Devices 06-23-2022, 07:17 PM
Replies: 12
Views: 184
Posted By redwire
Re: Graco ST MAX II 495 PC PRO , paint spray machine help

C20 looking preggo, D16 pin not soldered, was a gorilla inside trying to fix this?
Forum: Equipment Usage, Soldering, Techniques, and Reviews 06-18-2022, 10:39 PM
Replies: 6
Views: 254
Posted By redwire
Re: Short finder

I think you'd need the compliance voltage-limited to say 0.2V to not damage anything. That pretty much rules out the LM317, have to use an op-amp and power transistor.
I also do well with a good...
Forum: General Electronics Technical Discussion 06-18-2022, 10:34 PM
Replies: 4
Views: 151
Posted By redwire
Re: SMD marking 2290?

Looking at the board, my guess is an RF Amplifier MMIC or LNA IC.
Forum: General Electronics Technical Discussion 06-17-2022, 04:51 PM
Replies: 52
Views: 2,632
Posted By redwire
Re: Fixing a multimeter based on VC9805 schematic

Ok, that transistor matches the schematic for Tp2, controlling battery power to the multimeter, for the auto-power off.
If it was shorted, the multimeter would stay powered on, it would not...
Forum: General Electronics Technical Discussion 06-17-2022, 01:20 PM
Replies: 52
Views: 2,632
Posted By redwire
Re: Fixing a multimeter based on VC9805 schematic

Which transistor is shorted? poker, do not confuse the power-on transistors with the protection transistors.
On OP schematic for VC9805+ Tp1, Tp2 are for battery power switch. SMT marking L6 (is...
Forum: General Electronics Technical Discussion 06-17-2022, 10:46 AM
Replies: 41
Views: 1,698
Posted By redwire
Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

The Blue ESR Meter works very well, you can check the calibration with a resistor.

It's odd the 10uF cap keeps having a short life.
I would say Milwaukee's CM either forgot a resistor or used a...
Forum: General Electronics Technical Discussion 06-14-2022, 03:58 PM
Replies: 41
Views: 1,698
Posted By redwire
Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

KZE (https://chemi-con.com/wp-content/uploads/2021/05/KZE-Series.pdf) is low ESR (but no 10uF 50V offering).
KY (https://chemi-con.com/wp-content/uploads/2021/05/KY-Series.pdf) 10uF 50V is ESR 1.5Ω...
Forum: General Electronics Technical Discussion 06-14-2022, 03:35 PM
Replies: 6
Views: 252
Posted By redwire
Re: resistors in parallel ?

The heat to be dissipated would be shared over two parts, each one dissipates a ratio of the value a single part would. Regardless of whether the two are in series or parallel.
50-50 split so 1W...
Forum: Equipment Usage, Soldering, Techniques, and Reviews 06-14-2022, 01:05 PM
Replies: 301
Views: 24,529
Posted By redwire
Re: Soldering station thoughts and guidelines

JBC C210 cartridges (https://www.jbctools.com/c210-cartridge-range-product-18-design-iron.html) there are two knife blades 2.5, 3.4mm.
How about the chisel (screwdriver) tips? The spoon/hoof is...
Forum: Troubleshooting Audio Equipment 06-13-2022, 11:52 AM
Replies: 4
Views: 116
Posted By redwire
Re: TC158R , Sony cass deck schematic please

Check your work- either you didn't put it back together properly or there is a (new) broken connection, bad solder joint, cable connector etc.

Sometimes working on the motor can cause a short with...
Forum: General Capacitor Questions & Issues 06-12-2022, 10:05 PM
Replies: 5
Views: 241
Posted By redwire
Re: Identifying capacitor type (Laserdisc PSU)

To me they look like polyester mylar film capacitors similar to Nichicon QXY. I would replace with Panasonic ECQB (although obsolete) or anything with the same lead spacing and ratings. Polystyrene...
Forum: General Electronics Technical Discussion 06-12-2022, 08:02 PM
Replies: 41
Views: 1,698
Posted By redwire
Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

I wouldn't scope that cap, it's hazardous live on the hot side and sam might have a bad day.
The 10uF 50V caps don't last because they're made in the bowels of guangdong and can't take much of...
Forum: General Electronics Technical Discussion 06-12-2022, 04:29 PM
Replies: 41
Views: 1,698
Posted By redwire
Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

Many people having problems with Milwaukee M12/M18 chargers and tossin' them in the garbage.
They seem to be from some contract manufacturer "professionally made in china" with quality all over the...
Forum: General Electronics Technical Discussion 06-11-2022, 06:30 PM
Replies: 41
Views: 1,698
Posted By redwire
Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

I would not have replaced those based on ESR, it still looks reasonable? I measure their capacitance as well. I wonder about the bigger output caps too. Maybe the heat is too much for the smaller...
Forum: General Electronics Technical Discussion 06-11-2022, 06:22 PM
Replies: 4
Views: 166
Posted By redwire
Re: Looking for fuse specs HRC , Fuse Link, Type A350/5

That might be better, no idea what "British Style BS 88" means, it seems to be a size 47mm end-end and 38mm between the bolt holes.
Littelfuse KLC is Imperial sized, 73mm 2-7/8" end-end.
Forum: General Electronics Technical Discussion 06-11-2022, 02:45 PM
Replies: 4
Views: 166
Posted By redwire
Re: Looking for fuse specs HRC , Fuse Link, Type A350/5

I think it's a specialty fuse for protecting semiconductors? 2014 Infineon bought International Rectifier, so I would expect that fuse is obsolete and you'd have to find a substitute.
In the low...
Showing results 1 to 25 of 500

 
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