what to check when you want to put a different chip in same PSU?
For example replace ob2269 with Sg6846 - the internal schematics look similar enough
there is one diode and divider at FB input , but Zcs and Zfb differ too much between the two ?(12 and 5.5 kohm compared to 40 and 9 kohm so the component values in the rest of the PSU circuit need to be changed?)
[url]https://cdn.badcaps-static.com/pdfs/f9b4daae91fac761db7f652d6a23c015.pdf[/url]
Ld755s is a better match when it comes to Zcs but it has a extra diode at FB inputwhat to check when you want to put
tukidid
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Last Activity: 03-15-2011, 08:38 AM
Joined: 01-25-2011
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notebook needs current mode pwm adapter
is this a rule o a voltage mode ac adapters are used as well? -
Re: bad caps preventing video output?
no shorts on power connector,
swapping 2 other power units,ram or cmos battery makes no difference -no beeps,keyboard flashes, cpu worms up but no video with on board agp or external pci graphics -
Re: bad caps preventing video output?
no video without/with external graphics card ,what are you supposed to get ohming into pwr/gnd pins of good mobo (when off) and is VRM a chip close to cpu(which gets warm)
Caps are LICON throughout but suspect ones are 2 1000mF close to mobo integrated video out(but then again they look visually ok and if external card did not help than that is not it)Leave a comment:
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bad caps preventing video output?
on older mobo will not output display no more ,but cpu,fan seems to be working-
does this sound like a caps around the graphics chip problem or some solder gone bad -
Re: old ibm-6043 switching on?
thanks you probably refer to P9(or p12 -pc could be woken up from lan)Leave a comment:
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Re: old ibm-6043 switching on?
the pinout of the ibm pc300gl mbd connector is
Connector Location Pin 1 Pin 2 Pin 3 Pin 4 Pin 5 Pin 6
P1 System Board PWRGOOD +5 V +12 V -12 V GND GND
P2 System Board GND GND -5 V +5 V +5 V +5 V
P3 3.5" Diskette Drive +5 V GND GND +12 V – –
P4 DASD +12 V GND GND +5 V – –
P5 1 DASD +12 V GND GND +5 V – –
P9 2 System Board +5 V CONTROL GND – – –
P10 Riser 3 V +3.3 V +3.3 V +3.3 V GND GND GND
P11 System Board 3 V +3.3 V +3.3 V +3.3 V GND GND GND
P12 LAN +5 V CONTROL...Leave a comment:
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old ibm-6043 switching on?
how do you switch it on- it has neither computer switch wires(black,brown,blue,white)nor the green one
tnx -
Re: what to check when replacing pwm IC
it is hp 18.5v,3.5a notebook supply and ob is not readily availableLeave a comment:
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what to check when replacing pwm IC
Can you replace bad ob2269(SMPS not clicking any longer and chip has about few V on pin 3 VIN although in front of it there is 310V) with sg6841 or ld7552 or some other without modifying circuit around it(except for the sw. frequency setting resistor) as the one at
What should one check Zfb,Zcs first, or missing leading edge blanking block and one diode after fb input?
(real ob2269 circuit has different component values and in addition resistor divider at MOS gate and one more diode+capacitor in front of VDD)... -
replacing pwm driver
Can you replace bad ob2269(SMPS not clicking any longer and chip has about few V on pin 3 VIN although in front of it there is 310V) with sg6841 or ld7552 or some other without modifying circuit around it(except for the sw. frequency setting resistor) as the one at [url]http://pdf1.alldatasheet.com/datasheet-pdf/view/103294/ETC/SG6841.html[/url]
What should one check Zfb,Zcs first?
(real ob2269 circuit has different component values and in addition resistor divider at MOS gate and one more diode+capacitor in front of VDD)https://Can you replace bad ob2269(S...any longer and
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