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Search: Posts Made By: redwire
Forum: General Electronics Technical Discussion Yesterday, 03:28 PM
Replies: 9
Views: 49
Posted By redwire
Re: flourescent ballast resistance

That seems reasonable. You can check if there is a ground fault, winding shorted to case.
If the overall startup current is too low I think the starter will just sit there trying to get the...
Forum: General Electronics Technical Discussion Yesterday, 02:10 PM
Replies: 9
Views: 49
Posted By redwire
Re: flourescent ballast resistance

I would measure its inductance. F14T5 is 14W 0.265A lamp current, need around 900ohms impedance, so 148R from the coil and maybe ~2.5H is needed. Using 240VAC and 40V tube drop for rough math.
Does...
Forum: Troubleshooting Game Consoles & Other Weird Devices Yesterday, 10:46 AM
Replies: 14
Views: 223
Posted By redwire
Re: Graco ST MAX II 495 PC PRO , paint spray machine help

I understand the conformal coating can make the repair extra hell. I use needle probes to poke through for readings, and hot air gun to heat/soften the coating and scrape it off.
TBH the board is a...
Forum: General Electronics Technical Discussion Yesterday, 10:42 AM
Replies: 14
Views: 182
Posted By redwire
Re: Reading input and output of bridge rectifier on the same scope?

OP it's always good to have a fuse/1A circuit breaker because transformers can put out much more current into a short circuit.
Check the scope's internal ground did not melt open, I have seen that....
Forum: Equipment Usage, Soldering, Techniques, and Reviews 06-27-2022, 11:11 PM
Replies: 9
Views: 295
Posted By redwire
Re: Short finder

All that is missing is a PCB layout? It's not that complicated, it's just people wanting changes and complaining etc. that takes away all the fun....
Forum: General Electronics Technical Discussion 06-27-2022, 05:56 PM
Replies: 4
Views: 105
Posted By redwire
Re: Microwave advise please

Last to check is for open filament wiring at the connector/feed-through capacitors or for a bad connection there, or inside the can at the EMI chokes. Magnetron filament is low voltage, high current...
Forum: General Electronics Technical Discussion 06-27-2022, 04:06 AM
Replies: 52
Views: 2,667
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 06-26-2022, 11:20 AM
Replies: 14
Views: 182
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 06-26-2022, 11:17 AM
Replies: 9
Views: 176
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: 180
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: 180
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: 2,667
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: 133
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: 790
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: 14
Views: 223
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: 14
Views: 223
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: 9
Views: 295
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: 158
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: 2,667
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: 2,667
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: 1,709
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: 1,709
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: 258
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: 24,573
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: 123
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...
Showing results 1 to 25 of 500

 
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