Forum: General Capacitor Questions & Issues
Today, 10:17 AM
|
|
Replies: 4
Views: 53
Re: Capacitor Identification
The capacitor is a metallized paper cap Rifa PME285 series, 2.2nF or 2,200pF X2 safety rated 275VAC.
Don't replace with Rifa PME271's they are notorious for cracking and shorting out, they burn up....
|
|
Forum: Troubleshooting Audio Equipment
Yesterday, 04:07 PM
|
|
Replies: 6
Views: 72
Re: Pioneer turntable tone arm adjustment
It's usually due to a bent rod in the mech, or the cam has rotated. If someone was rough with the tonearm, or a kid trashed it. It must be more than a few mm out.
There would be no adjustments...
|
|
Forum: General Electronics Technical Discussion
08-17-2022, 09:25 PM
|
|
Replies: 24
Views: 402
Re: Old analog Power Supply needs your advice
It's your usual chinese dream, you have to derate it a lot to make it last.
Max. is 24VAC input but under a light load transformers put out higher voltage. So say 28VAC which gives around 38VDC, add...
|
|
Forum: General Electronics Technical Discussion
08-17-2022, 05:12 PM
|
|
Replies: 24
Views: 402
Re: Old analog Power Supply needs your advice
It's weird, the board has a 24VDC regulator 7824 for a 40mm? fan yet none of them come with a main heatsink or fan, like in the pic. There is a small heatsink for the driver transistor included. ...
|
|
Forum: General Electronics Technical Discussion
08-17-2022, 10:55 AM
|
|
Replies: 24
Views: 402
Re: Old analog Power Supply needs your advice
The low cost chinese 0-30V 2mA-3A power supply boards do not work if you feed them DC. They only work with a power transformer because they make a -5V rail for the op-amps from the cap+diode AC...
|
|
Forum: Troubleshooting Audio Equipment
08-16-2022, 09:17 PM
|
|
Replies: 5
Views: 147
Re: Power button on mixer dead ?
It's not a problem with the power switch, that is all or none for power. Some power is present if the phantom red LED is on, so the switch is not to blame.
Your electronic expert friend would have...
|
|
Forum: General Electronics Technical Discussion
08-16-2022, 04:40 PM
|
|
Replies: 24
Views: 402
|
|
Forum: General Electronics Technical Discussion
08-15-2022, 09:45 PM
|
|
Replies: 24
Views: 402
Re: Old analog Power Supply needs your advice
It's a 1970's design, the regulator board. Changing over to an IC like LM317 (1A) or LT1084 (5A), along with a big heatsink would be best. Or that chinese power supply board does OK too, it is from a...
|
|
Forum: General Electronics Technical Discussion
08-15-2022, 11:08 AM
|
|
Replies: 24
Views: 402
Re: Old analog Power Supply needs your advice
I'd guess a 20 to 25VAC transformer is missing, would connect to the purple wires.
The regulator is no good - there is no heatsink for the power transistors which will get really hot. I don't know...
|
|
Forum: General Electronics Technical Discussion
08-14-2022, 02:14 PM
|
|
Replies: 32
Views: 469
Re: Help me with capacitors replacement
I can't see upsizing the bridge rectifier because of the high (mains) voltage and the PC board bad design mean the spacings simply are not good enough. You need a couple mm at least or it will just...
|
|
Forum: General Electronics Technical Discussion
08-12-2022, 06:42 PM
|
|
Replies: 32
Views: 469
Re: Help me with capacitors replacement
I would say it's a crappy soft-start circuit, the big resistor gets bypassed by the triac once the main filter caps are charged up, after the delay.
The board does not look repairable - the bridge...
|
|
Forum: Troubleshooting Audio Equipment
08-12-2022, 11:06 AM
|
|
Replies: 2
Views: 94
Re: AU101 Sansui amp schematic please
I find many old grey Elna electrolytics pretty much dead nowadays, they dry out and go low value. I'd replace them all.
You can compare DCV readings between channels. Two transistors are the phono...
|
|
Forum: Troubleshooting Audio Equipment
08-11-2022, 11:07 PM
|
|
Replies: 2
Views: 106
Re: Recapping a Cerwin Vega Crossover help
I see a 1.5uF 200VDC and 3.5uF film capacitors, and another small one underneath, and some others as well.
Those caps look fine and if they test reasonable, I would leave them alone. If they were...
|
|
Forum: General Electronics Technical Discussion
08-11-2022, 03:08 PM
|
|
Replies: 13
Views: 344
Re: Converting +/- 5v to a Usable Hz Signal
I see the wheel has already been invented. There are many aftermarket fan controllers for cars:
Summit Racing (https://www.summitracing.com/search/part-type/fan-switches) has several different makes...
|
|
Forum: Announcements & Related News
08-10-2022, 04:52 PM
|
|
Replies: 4
Views: 1,301
Re: Panasonic exits VRLA market
Panasonic VRLA were top quality, end of an era. There's nothing left but cheap chinese VRLA with not even 1/2 the lifetime. Just look inside, the lead plates look like they were made by kids, all...
|
|
Forum: General Capacitor Questions & Issues
08-10-2022, 04:37 PM
|
|
Replies: 29
Views: 832
|
|
Forum: General Capacitor Questions & Issues
08-10-2022, 04:33 PM
|
|
Replies: 13
Views: 472
|
|
Forum: Troubleshooting & Designing Networks
08-10-2022, 03:11 PM
|
|
Replies: 28
Views: 618
|
|
Forum: General Electronics Technical Discussion
08-10-2022, 02:52 PM
|
|
Replies: 13
Views: 344
Re: Converting +/- 5v to a Usable Hz Signal
You can reverse-engineer what is needed with not so much work. It's kind of two parts - knowing the engine temperature, and controlling the fan(s).
I have a peer who does ECU design and will ask...
|
|
Forum: General Electronics Technical Discussion
08-09-2022, 01:35 PM
|
|
Replies: 13
Views: 344
Re: Converting +/- 5v to a Usable Hz Signal
If I understand you, you want to add a variable speed feature to the older generation ECU on/off fan control?
Most cars use simple on/off control with a relay for the cooling fan(s). In stopped...
|
|
Forum: Troubleshooting & Designing Networks
08-08-2022, 01:08 PM
|
|
Replies: 28
Views: 618
|
|
Forum: General Electronics Technical Discussion
08-07-2022, 06:20 PM
|
|
Replies: 63
Views: 1,482
|
|
Forum: General Electronics Technical Discussion
08-06-2022, 12:43 PM
|
|
Replies: 63
Views: 1,482
|
|
Forum: General Electronics Technical Discussion
08-05-2022, 10:48 PM
|
|
Replies: 63
Views: 1,482
|
|
Forum: Troubleshooting & Designing Networks
08-05-2022, 02:32 PM
|
|
Replies: 28
Views: 618
|
