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Search: Posts Made By: redwire
Forum: General Electronics Technical Discussion Yesterday, 11:07 PM
Replies: 8
Views: 176
Posted By redwire
Re: Fluke 87 Meter repair

Q8, Q10 are at the power system for the DMM IC, which is never supposed to see any overloads. It could happen if you were running the DMM from a bench power supply instead of the 9V battery and...
Forum: General Capacitor Questions & Issues 08-05-2020, 12:33 PM
Replies: 30
Views: 2,565
Posted By redwire
Re: Panasonic FC series - leaking? quality gone?

The Panasonic FC series also got popular for audio use because they sound fine, not a lot of distortion or dielectric non-linearity.
I have to recap a soundbar and subwoofer, going to use FR series...
Forum: General Electronics Technical Discussion 08-05-2020, 12:19 PM
Replies: 8
Views: 176
Posted By redwire
Re: Fluke 87 Meter repair

Absolute murder to find the part! Q8 N-ch small signal DMOS FET for battery switch.
TEMIC/Silconix SSTVNS009-T1 SOT-23, Fluke 830851 replaced by Fluke 927538. Not in Silconix 1986 FET databook.
...
Forum: Equipment Usage, Soldering, Techniques, and Reviews 08-04-2020, 11:12 PM
Replies: 3
Views: 1,472
Posted By redwire
Re: B&K precision 2190 3 Channel Oscilloscope

B&K Precision 2190B 100MHz analog scope - From that ko4bb schematic, the B+K scopes 2120B, 2125A, 2160A, 1541D are the same chassis but 30MHz. They might match, but 100MHz league uses higher voltage...
Forum: Troubleshooting Power Supplies and Power Supply Design 07-31-2020, 12:52 AM
Replies: 16
Views: 372
Posted By redwire
Re: Jecod DCS3000 marine 24v pump

There are 10 speed LED's on the board but only 8 visible on the front overlay, it's kinda confusing. The bigger pumps have 10 speed LED's visible, so it must be the same board used across the line...
Forum: Troubleshooting Power Supplies and Power Supply Design 07-30-2020, 03:26 PM
Replies: 16
Views: 372
Posted By redwire
Re: Jecod DCS3000 marine 24v pump

The motor power-driver IC's are AO4614B (http://www.aosmd.com/pdfs/datasheet/AO4614B.pdf) dual P+N ch MOSFETs, arranged in a 3-phase H-bridge.

With the motor disconnected and power off, I would...
Forum: Troubleshooting Power Supplies and Power Supply Design 07-29-2020, 12:51 PM
Replies: 16
Views: 372
Posted By redwire
Re: Jecod DCS3000 marine 24v pump

The model is DCW or DCS in your thread title?

It's hard to work with a board that is conformal coated, you need needle probes.
Reading IC numbers takes a magnifier and bright light at a sharp...
Forum: Troubleshooting Audio Equipment 07-26-2020, 09:14 PM
Replies: 23
Views: 425
Posted By redwire
Re: Car radio stopped working

Active antenna pre-amps can get water in or a bad connection on power, and almost a total loss of FM signal. AM makes it through anything.
Or the coax can get water in it, try ohmmeter it.
In the...
Forum: Troubleshooting Power Supplies and Power Supply Design 07-26-2020, 03:24 PM
Replies: 16
Views: 372
Posted By redwire
Re: Jecod DCS3000 marine 24v pump

Jebao/Jecod DCS-3000
Likely the BLDC motor controller has a problem like a failed mosfet or bad capacitors, or the impeller is jammed. Take the controller apart and post pics. I would also check the...
Forum: Troubleshooting Audio Equipment 07-26-2020, 03:06 PM
Replies: 23
Views: 425
Posted By redwire
Re: Car radio stopped working

Does it have an active antenna? I have seen these get water in them and then croak.
Forum: Equipment Usage, Soldering, Techniques, and Reviews 07-19-2020, 02:11 PM
Replies: 11
Views: 320
Posted By redwire
Re: Airgap in soldering iron tip

OP could try even aluminium foil. It's better than air for conducting heat.

Cement has 1/10 the heat transfer, it's largely an insulator so the T12 construction is still not the greatest....
Forum: Equipment Usage, Soldering, Techniques, and Reviews 07-19-2020, 01:28 PM
Replies: 11
Views: 320
Posted By redwire
Re: Airgap in soldering iron tip

I've only seen the airgap issue with Hakko tips for 900 and FX888, whose tips I measured are a few thou smaller ID than 900 series tips. I guess Hakko tried to improve the heat transfer.

The...
Forum: General Electronics Technical Discussion 07-12-2020, 01:41 PM
Replies: 17
Views: 436
Posted By redwire
Re: maybe a job for my 100w iron ?

It's tough because you have to heat up all pins on all four sides. If you heat up only one or two edges, total waste of time.

Another approach I have used is cut the IC's pins off with an Exacto...
Forum: General Electronics Technical Discussion 07-11-2020, 10:02 PM
Replies: 17
Views: 436
Posted By redwire
Re: maybe a job for my 100w iron ?

What's an "as15 ic" ? What package is it
Forum: General Electronics Technical Discussion 07-04-2020, 03:35 AM
Replies: 9
Views: 380
Posted By redwire
Re: Any idea what power adapter this thing uses?

I have an older one (without LEDs) box says AC24V 1.3A and I thought it came with a heavy AC adapter with transformer. Newer ones use smaller 24VDC 800mA SMPS adapter. You can search "12 LED mist...
Forum: Troubleshooting Game Consoles & Other Weird Devices 07-02-2020, 10:35 AM
Replies: 18
Views: 424
Posted By redwire
Re: Handheld vacuum cleaner kills power adapters (With schematic)

Some people run the batteries totally dead - to the point some cells in the pack get reverse voltage across them. There might be weak cells in the pack. Those cells can act like a short and so the...
Forum: General Electronics Technical Discussion 07-02-2020, 10:27 AM
Replies: 8
Views: 275
Posted By redwire
Re: I am looking for a transformer secondary of 60 volts @ 30 amp

Is the brake (current) the same as always? I have seen brake solenoids fail with shorted turns, which causes current to go way high. 1.4kW is a huge brake!

At 23A and 60V whatever is switching...
Forum: General Electronics Technical Discussion 07-01-2020, 09:36 PM
Replies: 8
Views: 275
Posted By redwire
Re: I am looking for a transformer secondary of 60 volts @ 30 amp

Are you sure about your specs? 60VAC 30A output is 1,800VA and about a 45lb beast. That small transformer is probably overloaded and why it is stinking.

1,500VA control transformers are common but...
Forum: Troubleshooting Audio Equipment 06-28-2020, 12:53 AM
Replies: 6
Views: 247
Posted By redwire
Re: Altec Lancing ACS41

I know the LM324 has a gritty sound/mid-range blare to it due to the cross-over distortion so I change them out. Quad op-amp alternates:
LM837 (https://www.ti.com/lit/ds/symlink/lm837.pdf) is older...
Forum: Troubleshooting Audio Equipment 06-27-2020, 08:34 PM
Replies: 6
Views: 247
Posted By redwire
Re: Altec Lancing ACS41

These are good systems and worth repair/recap. I have an ACS48 coming in for repair and it looks really well built.
You can change out the LM324 for a better op-amp with less cross-over distortion,...
Forum: General Electronics Technical Discussion 06-24-2020, 03:36 PM
Replies: 55
Views: 1,682
Posted By redwire
Re: TO-220 exploded...estimated overload?

yes TO-220 fullpacks ran really hot, I tried them(MOSFETs) in mains SMPS instead of all the insulator/hardware to keep it simple. Thermal imaging cam showed over double the operating temp.
MOSFET's...
Forum: General Electronics Technical Discussion 06-24-2020, 12:32 PM
Replies: 55
Views: 1,682
Posted By redwire
Re: TO-220 exploded...estimated overload?

TO-220F has quite poor heat transfer to a heatink, around half that of the TO-220.
I was going to build an audio power amp using them but they can't get rid of heat:
FJPF5200 (TO-220F) 2.5C/W...
Forum: General Electronics Technical Discussion 06-22-2020, 11:33 AM
Replies: 14
Views: 403
Posted By redwire
Re: Can someone confirm these resistor values?

A first-order 6dB/oct crossover like OP's, the resistors are only to pad the tweeter which might have say 100uH inductance so a few uH is not an issue.

My Amrel LCR meter will also give negative...
Forum: General Electronics Technical Discussion 06-21-2020, 11:30 PM
Replies: 14
Views: 403
Posted By redwire
Re: Can someone confirm these resistor values?

I've never seen non-inductive resistors used in a passive cross-over network.
The inductance of ordinary wirewound resistors is very low, at most a few uH which is so small compared to the inductors...
Forum: General Electronics Technical Discussion 06-21-2020, 03:49 PM
Replies: 55
Views: 1,682
Posted By redwire
Re: TO-220 exploded...estimated overload?

You might be over-torturing things using light bulbs as load? Their resistance is non-linear and much lower when cold.
A 100W 120VAC bulb is 144 ohms lit but at 1/2 voltage drops to 124 ohms, and...
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