Gen8-180 power supply repair - Page 1
Forum section: electronics / repair

author: era007
author_rank: Contributor
timestamp: August 10, 2024, 03:37:08 pm
content: 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 ?

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: August 11, 2024, 01:02:43 pm
content: 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

author: Roehrenonkel
author_rank: Frequent Contributor
timestamp: August 11, 2024, 01:59:26 pm
content: Hi era007,check your setting for OverVoltageProtection.Good luck

author: fzabkar
author_rank: Super Contributor
timestamp: August 11, 2024, 03:57:32 pm
content: V8x = MC74VHC1G86 - Single 2-Input Exclusive OR Gatehttps://pdf.datasheetcatalog.com/datasheet/on_semiconductor/MC74VHC1G86-D.PDFhttp://markingcodes.com/search/c/v8

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: August 11, 2024, 04:47:40 pm
content: 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

author: MathWizard
author_rank: Super Contributor
timestamp: August 12, 2024, 05:05:29 am
content: 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.

author: era007
author_rank: Contributor
timestamp: August 13, 2024, 03:03:24 am
content: Quote from: Roehrenonkel on August 11, 2024, 01:59:26 pmActually I did. OVP =10V(max)

author: era007
author_rank: Contributor
timestamp: August 13, 2024, 03:08:38 am
content: Quote from: fzabkar on August 11, 2024, 03:57:32 pmcan it be 74LVC1G08GW ?

author: era007
author_rank: Contributor
timestamp: August 30, 2024, 04:39:16 pm
content: 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.

author: era007
author_rank: Contributor
timestamp: August 30, 2024, 04:45:46 pm
content: Output voltage when the sense cable unplugged from the control board

author: era007
author_rank: Contributor
timestamp: August 30, 2024, 04:49:01 pm
content: The output turned ON when I pulled out the internal sense wire from the output.

author: era007
author_rank: Contributor
timestamp: April 04, 2025, 04:28:32 am
content: I was able to repair the power supply. It was a faulty LM324 on the control board. I hope this information will be helpful for some one who has similar issue.

author: era007
author_rank: Contributor
timestamp: April 04, 2025, 04:30:07 am
content: https://youtube.com/shorts/LGmfzvwCoXA?si=yMtkOXOMaY6sN33Y