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Search: Posts Made By: Rainbow
Forum: Troubleshooting Power Supplies and Power Supply Design Today, 01:00 PM
Replies: 23
Views: 1,741
Posted By Rainbow
Forum: Troubleshooting Power Supplies and Power Supply Design Today, 12:56 PM
Replies: 35
Views: 21,918
Posted By Rainbow
Re: Delta DPS-800GB Power Supply No Power

Yes, most server PSUs have fan failure detection and will shutdown instead of overheating and catching fire. The fans are connected using 3 wires: 12V, GND and RPM sense (likely).
Forum: Major Manufacturers Boards 10-15-2019, 03:12 PM
Replies: 18
Views: 8,232
Posted By Rainbow
Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

The C4 (120uF/420V CapXon KM) cap in Acbel AC235AS-00 PSU is known to fail, causing Q3 (SPP11N60C3) to short and F301 (F6.3AH/250V) to burn.
Forum: Troubleshooting Power Supplies and Power Supply Design 10-15-2019, 03:07 PM
Replies: 34
Views: 10,682
Posted By Rainbow
Re: DELL OEM H240AS-00 (HIPRO) ~ major blow up!

Beware, most CP012A on eBay or AliExpress are fake. Before using any of them, check voltage drop from GND (pin 5) to all other pins using a diode test on a multimeter. If any is missing or over...
Forum: Troubleshooting Power Supplies and Power Supply Design 10-15-2019, 02:51 PM
Replies: 23
Views: 1,741
Posted By Rainbow
Re: Dell model L275E-01 pn: Wu142. Optiplex 755 small form factor.

The 180uF/420V cap is known to fail without any visible changes in L275E and also L235P (OptiPlex 780). Desolder it and you will see leak on the bottom.

Then usually IC501 (TNY280PN) shorts,...
Forum: Troubleshooting Power Supplies and Power Supply Design 10-15-2019, 08:43 AM
Replies: 35
Views: 21,918
Posted By Rainbow
Re: Delta DPS-800GB Power Supply No Power

I've also changed KN4401S (ZUA) transistor on control board as seen here:
https://www.rom.by/forum/Problema_s_BP_ot_Delta_Delta_DPS-800GB?page=16
(use Google Translate)

It tested bad (one PN...
Forum: Troubleshooting Power Supplies and Power Supply Design 10-15-2019, 02:25 AM
Replies: 35
Views: 21,918
Posted By Rainbow
Re: Delta DPS-800GB Power Supply No Power

The answer is no. Removed the heatsink (soldered on both ends, also Q804 and Q808 must be desoldered as they're screwed on) only to find that the two hidden caps are not crap. C820 is Nichicon, C904...
Forum: Troubleshooting Power Supplies and Power Supply Design 10-14-2019, 08:07 AM
Replies: 35
Views: 21,918
Posted By Rainbow
Re: Delta DPS-800GB Power Supply No Power

I have this PSU but with a different problem. Standby works but main power does not start. With the PSU installed in a server (2nd PSU removed), power button lights orange. When pressed, power supply...
Forum: Troubleshooting Laptops, Portable, and Mobile Devices 08-26-2019, 11:11 AM
Replies: 5
Views: 952
Posted By Rainbow
Re: Dell optiplex 740 AMBERLIGHT

I've had an OptiPlex 740 with a weird looking problem: after connecting power, power LED glows amber but with reduced brightness, otherwise dead - no reaction to power button. The cause was...
Forum: Troubleshooting Laptops, Portable, and Mobile Devices 02-01-2011, 12:29 AM
Replies: 955
Views: 435,119
Posted By Rainbow
Re: Toshiba Satellite - Locks up when plugged in

Just fixed one Satellite A300. This is caused by a bad cap. A big one - NEC/TOKIN 0E907 (900uF/2.5V) under the CPU. Mine had 900uF but probably lost some of its magic, resulting in >100mV ripple on...
Forum: General Electronics Technical Discussion 08-06-2007, 01:49 AM
Replies: 13
Views: 10,779
Posted By Rainbow
Re: Internal Speaker for DESKTOP

You can use a tiny single-chip amplifier - like LM386 or something like that. They're sometimes intergrated on older mainboards with AC97 sound.
Forum: General Computer & Tech Discussion 08-02-2007, 02:48 AM
Replies: 14
Views: 2,552
Posted By Rainbow
Forum: General Electronics Technical Discussion 08-02-2007, 02:47 AM
Replies: 13
Views: 10,779
Posted By Rainbow
Re: Internal Speaker for DESKTOP

The output signal is line level - you need an amplifier.
Forum: General Capacitor Questions & Issues 07-27-2007, 12:14 AM
Replies: 13
Views: 3,133
Posted By Rainbow
Re: Caps replaced, still a problem!?

If the drive doesn't read DVDs, it's bad.
Forum: Troubleshooting Computer Displays 07-23-2007, 01:46 AM
Replies: 2
Views: 2,488
Posted By Rainbow
Re: Acer 7257c startup issues....

Check the tube heater voltage. It should be 6,3V usually. Bet your is too low. Trace it to a voltage regulator somewhere on the PCB and check nearby caps. I had similar problem with my Iiyama 17" CRT...
Forum: General Electronics Technical Discussion 07-20-2007, 02:36 PM
Replies: 3
Views: 3,095
Posted By Rainbow
Forum: General Computer & Tech Discussion 07-17-2007, 07:06 AM
Replies: 28
Views: 6,271
Posted By Rainbow
Re: Is this bad??

Use ohmmeter to check if the holes are connected in parallel. If they are, it's not problem, just connect the leg to the "good" hole nearby. If they are not, find a nearby point that's connected with...
Forum: Troubleshooting Power Supplies and Power Supply Design 07-16-2007, 05:38 AM
Replies: 53
Views: 15,545
Posted By Rainbow
Re: Dell NPS-250KB caps

The caps are connected in series. They're rated 200V each but about 320V is across them - and the voltage needs to be divided (about) equally. That's why the caps must be equal. And the resistors...
Forum: Troubleshooting Power Supplies and Power Supply Design 07-16-2007, 05:29 AM
Replies: 6
Views: 3,572
Posted By Rainbow
Re: PSU for Compaq Proliant DL360 G1

Do cable colors in the ATX connector match? If they do not, don't power it up - get the original PSU fixed instead.
Forum: General Computer & Tech Discussion 07-16-2007, 05:22 AM
Replies: 28
Views: 6,271
Posted By Rainbow
Re: Is this bad??

You can always use a piece of wire. If the capacitor was connected in parallel with the one next (left) to it, just leave one leg of the new cap longer and solder it to the left. It's not going to...
Forum: Troubleshooting Power Supplies and Power Supply Design 07-05-2007, 09:25 AM
Replies: 53
Views: 15,545
Posted By Rainbow
Re: Dell NPS-250KB caps

Check that two resistors (that are connected in parallel with the caps) too. At least one of them is probably open. Once I repaired a Compaq PSU with one cap blown and that resistors had different...
Forum: Troubleshooting Power Supplies and Power Supply Design 07-03-2007, 05:46 AM
Replies: 53
Views: 15,545
Posted By Rainbow
Re: Dell NPS-250KB caps

The 470uF caps should work. Replace both original caps!
Forum: General Computer & Tech Discussion 07-02-2007, 01:39 AM
Replies: 2
Views: 2,036
Posted By Rainbow
Re: HP Scanjet 4 with ADF

Maybe UMAX needs newer firmware.
Forum: Troubleshooting Computer Displays 06-29-2007, 08:09 AM
Replies: 12
Views: 4,548
Posted By Rainbow
Re: No red suddenly on Envision EN9410e

You might need to check the PCB in the monitor - the input part that begins with the VGA connector.
Forum: Troubleshooting Computer Displays 06-29-2007, 12:30 AM
Replies: 3
Views: 2,875
Posted By Rainbow
Re: Viewsonic VB50HRTV

1) Sounds like bad caps. Might be in the tuner itself or in the power supply.
Showing results 1 to 25 of 500

 
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