Gen8-180 power supply repair

[era007]

I have this issue in GEN8-180 power supply. When I turns ON the power supply the voltage display shows "OFF". If I tun ON output then Voltage display shows "OUP" and Alarm LED blinks. I have checked the AC input board and two power side boards but I couldn't find any faulty item except this shorted 5 pin .V8E (looks like TSOT-23-5 package) component on main control board. Can you guys identify this component ?

[Jay_Diddy_B]

Hi,

I happen to Lambda Genesys GEN60-25 power supply on the bench at the moment. Here is a better photograph:




I am not sure what the IC does. I tried various things but I could get any of the pin voltages to change.

Jay_Diddy_B

[Roehrenonkel]

Hi era007,
 
check your setting for OverVoltageProtection.

Good luck

[fzabkar]

V8x = MC74VHC1G86 - Single 2-Input Exclusive OR Gate

https://pdf.datasheetcatalog.com/datasheet/on_semiconductor/MC74VHC1G86-D.PDF

http://markingcodes.com/search/c/v8

[Jay_Diddy_B]

It could be, but it would mean that that my unit and the original posters, have the same date code.

The date code on the op-amp, OP2177 is 0939, thirty-ninth week of 2009.

I have a few more of these power supplies, I could check another one.

Regards,

Jay_Diddy_B

[MathWizard]

Yeah just from working on a few motherboards and GPU's, I was thinking it could be a logic gate. They usually have a positive feedback resistor network around them. They are used in the power-up sequence, like for power good signals, reset signals, etc. The circuits around it will probably lead back to the power good pin, or reset or enable, or the output of some voltage regulator IC or switching controller IC.

[era007]

Hi era007,
 
check your setting for OverVoltageProtection.

Good luck

Actually I did. OVP =10V(max)

[era007]

V8x = MC74VHC1G86 - Single 2-Input Exclusive OR Gate

https://pdf.datasheetcatalog.com/datasheet/on_semiconductor/MC74VHC1G86-D.PDF

http://markingcodes.com/search/c/v8

can it be 74LVC1G08GW ?

[era007]

Hi guys. I received the replacement component SN74LVC1G86 today. Unfortunately it didnt solve the OVP + Alarm LED issue. The output doesnt turn ON. So I opend the top cover and probed the DC output . Surprisingly the Vmax on my DMM showed 11.8V . Its more than the maximum possible OVP voltage of the device (set to 10V). Then I unplugged the output sense wire from the control board and it bypassed the OVP protection and  output turned ON. When I measured the output voltage it showed 13.187V    . It seems like the power boards are running at full voltage. As I understand the control board has failed to adjust the output voltage at least it its previous values. Actually I am not familiar with this type of power supply operation.

I am expecting help to repair my Gen 8-180 from those who has experience with these power supplies.

[era007]

Output voltage when the sense cable unplugged from the control board

[era007]

The output turned ON when I pulled out the internal sense wire from the output.