Pyramid PS-26KX power suply
Hello I have a power supply thats not working. The needle jumps from 6 volts up to 15 back and forth. I put a load on it and it stays at 6 volts. The relay clicks when it jumps. I don't know where to start trouble shooting. Can anyone help??
-
-
Re: Pyramid PS-26KX power suply
These Pyramid PSU’s really suck balls. Is the fan still working? What does the amp meter say? Can you put a small load on it like some car headlight bulb? Sounds like a regulation problem of some sort. Is the regulator LM723 IC in a socket? Remove it and put it back in.
Check the 12V regulator (7812) and it’s capacitors, as it supplies the voltage to the relay and other IC’s. There is a 16V zener diode, that makes the SCR fire. Download the manual, the schematic is in it.
Usually with these linear PSU’s the fan fails (pass transistors get too hot), pass transistors fail because the heat or some other unfortunate event (mounted on a large heat sink), the regulator IC LM723 and a bad SCR. The TIP41 rarely goes bad. I’ve seen bad meters on them too, but that is besides the point.Last edited by CapLeaker; 04-26-2020, 09:29 PM. -
Re: Pyramid PS-26KX power suply
Pyramid Power Supply schematics here: http://www.repeater-builder.com/pyra...mid-index.html
The common problems are failed pass-transistors. I would see why the output voltage is too high at no load- it might be a damaged pass-transistor. If the output goes way too high over ~17V the SCR crowbar trips which should blow the fuse.
If the power supply collapses, i.e. output voltage does not keep up to the setpoint, it activates the protect buzzer and LED.
The transformer tap-change relay activates when output is above some voltage so this is normal that it is clicking.Attached FilesComment
-
-
Re: Pyramid PS-26KX power suply
Okay that gives me a place to start. Thanks for the input. anyone out there have one of these??Comment
-
Vizio e601i-A3 - Has Sound and Display, But No Backlight - Bad Power Supply Board or Bad LED Bulbs ?I was given this TV from my great uncle. He said it just wouldn't turn on one day out of nowhere, replaced the TV, and gave it to me to possibly fix and use for myself.
Upon bringing it home and plugging it up, it showed a standby light.
I powered it on and without a flashlight, the display showed the "V" but the lighting is very dim, but visible.
The screen seems to blackout and stay black, but with a flashlight I can see the display.
With my Playstation 4 connected via HDMI, and running a game I can hear sound.
Assuming... -
Hi all!
I'm trying to troubleshoot a Microsoft Surface Pro (5th gen) model 1796 that won't power on. Motherboard model is M1007506-015. My priority is retrieving data, but the SSD is integrated so it looks like if I can't repair it it'll need to go to a data recovery company. I've done a little basic board repair before, but nothing this advanced until now. So please forgive my ignorance in advance. 😅
I found the boardview for this laptop in the forums here, and am able to open it on my PC with FlexBV.
https://www.badcaps.net/forum/troubl...-hardware-devi... -
Hi all,
TL;DR - this laptop is driving me nuts with the oddball power-related behaviors. Appreciate any insight you can provide!
I'm experiencing a power issue on an Asus Probook P5440UF-XB74. Although I've worked with electronics and computers for decades, this is my first attempt at getting into motherboard-level component troubleshooting. Any help the community can provide is greatly appreciated!
A few weeks ago I was using the laptop (on battery power) for a Zoom meeting. The battery was running very low (long meeting) but I wasn't worried about... -
I was working on this CNC machine today found no keyboard functioning no control relay powering on
The screen powered on and was giving an operation error but the manual was not very clear about what the error exactly was but with a little bit of troubleshooting and finding out that the control relays not powering on and no keyboard functions we narrowed down to this one switching power supply which of course does not have any indicator LED light they are on the keyboard interface/relay controller board
Found shorted diodes on main controller relays there are 3 of them that... -
Hi All,
First time posting here ... my name is Kevin but my friends call me Journey.
I have a Samsung 75" LCD model UN75RU8000FXZA that I don't remember the original fault other than it wouldn't power up anymore.
After it sat for many month's I decide to look at it again. The motherboard seemed to have power regulation issues. After much fussing I decided to just get a new MB.
It came a few days ago and I installed it now just cycles the power relay on and off ... when on the backlights light up and then dim and then relay kicks off and the whole things starts again....
Comment