Question about Pyramid 10 AMP 13.8V POWER SUPPLY Car Audio Amplifier

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Pyramid PS-21K Power Supply HELP!

I replaced the four 2N3055's in the back of unit but now instead of 13.8 volts its doing 19-21 volts. What did I do wrong? Something in the wrong Place?

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Check the resistors that bias the transistors, and also any zeners connected to them.

Posted on Jan 02, 2009

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Pyramid PS-52KX. Getting 24 volts DC on my output. I am knowledgeable in this department. I need to know what ac voltage should I be reading off of my transformer? I can't find a good schematic...


Sounds like the regulator goin. I've read when they go bad it will go full voltage which is 37vdc.
Looks like they use the LM723 regulator. I'm no expert, but may be that simple.
Here's a link to a schematic. Hope it helps
http://www.pyramidcaraudio.com/manuals/PS52K.pdf

I have a PS14KX. It won't handle any load. If you have any ideas let me know

Mar 05, 2011 | Pyramid - PS52KX 40 Amp Power Supply Car...

1 Answer

20-Volt DC Power Supply instead of 12-Volt amp


Here's a few things that come to mind. An auto charging system will operate normally from about 11 Volts to about 14.5 Volts, depending on what is operating (lights, blower,etc), and whether the vehicle is at idle or not. Most car amps will operate from about 10.5 to 16.5 Volts, and outside that range, they will probably shut down.
Another consideration is your 20 volt power supply. You didn't mention if it is a DC power supply, but it needs to be. The other factor is its output, meaning its amperage rating. I'm figuring it will need to put about 5 amps, at the least, for the Sony to put out some watts. I think the line fuses of the Sony are rated @ 25 amps each.
I don't like this type of situation, because I want to say 'try it and see what happens" and I want to say 'don't do it, something may blow".
If you decide to try the 20Volt power supply, maybe if you put smaller rated fuses (say 10 amp) in the Sony amp, they will act as a fail safe. Good luck!

Jul 26, 2009 | Sony Xplod XM-554ZR Car Audio Amplifier

1 Answer

Ps 52 kx power supply will not hold load


thank you for your help . I have already fixed the power supply I double checked the transisters and found three bad so I replaced all the power transisters and it is fine . thanks again bob

Nov 17, 2008 | Pyramid - PS21KX 20 Amp Power Supply Car...

1 Answer

Pyramid ps-36kx


Generally, the fuse only blows when the rectifiers fail. In other Pyramid supplies, they use a square, 4 terminal bridge rectifier. They probably use the same thing in your supply.

Let me know if you have any other questions.

Nov 15, 2008 | Pyramid - PS21KX 20 Amp Power Supply Car...

1 Answer

Pyramid Power Supply PS 52KX


I have used this tech for repairing some of my radio equipment and found him to be honest and dependable A rare thing now days. check with him at rmauro218@aol.com. Unless you are wanting to take a shot at repairing it yourself if so I will do some searching myself to see if I can give you a hand on it.

Sep 10, 2008 | Pyramid - PS21KX 20 Amp Power Supply Car...

1 Answer

Hello, I have a pyramid power supply(PS-52KX), that recently started with a overvoltage problem. I run a Galaxy DX94 HP 10 meter transceiver, and just recently, when I key up the radio, the...


I'm not sure what you mean by 'wide open voltage'. If it's over 17v, the supply may have multiple problems. I don't have the 52kx schematic but other Pyramid supplies have over-voltage protection. There is an SCR that is triggered when the voltage gets to ~17v. This should clamp the output and trigger a shutdown. You should check the 16v Zener diode and the SCR. If the SCR or the Zener is defective, that would prevent the over-voltage from clamping the voltage. Also confirm that the SCR has a solid connection to the ground terminal of the supply. If it's open, that could prevent the clamp from shutting down the supply.

If the voltage is going high, measure the DC voltage from pin 4 to pin 5 of the LM723. It should remain the same at all times. Also measure the voltage from pin 5 to the ground terminal of the supply. That should also remain constant at all times.

Aug 20, 2008 | Pyramid - PS21KX 20 Amp Power Supply Car...

1 Answer

Pyramid ps-21k power supply


you need to get the voltage regulator circuit checked in your ps-21k

Jun 13, 2008 | Pyramid 10 AMP 13.8V POWER SUPPLY Car...

4 Answers

Pyramid - PS21KX 20 Amp Powersupply overload


The problem I have had with a PS-20 is a blown capacitor. Hooked to a radio, would allow radio to receive fine, but when trying to transmit, amperage would bottom out. Behind the transformer is a large circuit board. UNPLUG POWER SUPPLY, remove cover, Undo the two nuts, flip board over, and gently rock the 4700uf capacitors side to side. If they move more than 1/16th of an inch, chances are they are blown. Remove/replace and should be good to go...

Jan 10, 2008 | Pyramid - PS21KX 20 Amp Power Supply Car...

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PS36K power supply overload problem


Most of Pyramid's supplies are based on the LM723 voltage regulator. The DATASHEET should tell you most of what you'll need to know to repair it. THIS is the schematic diagram.

If the output voltage drives the voltmeter to the end of the scale, it likely has one or more shorted power transistors.

Dec 21, 2007 | Pyramid - PS21KX 20 Amp Power Supply Car...

2 Answers

PB1500 no diag. lights - Power - OK


I don't know how you checked the fuses but if you didn't use an ohm meter, you need to confirm that you have B+ and remote at the amplifier.

With your multimeter set to DC volts, the black meter lead on the ground terminal of the amp and the head unit on (so the amp will have remote voltage applied), touch the red lead alternately to the B+ and remote terminals of the amp. If the voltage is below ~11 volts, you need to check the wiring feeding whichever line is too low.

If the voltage is sufficient at the remote and B+ terminals, the switching power supply has probably failed in the amplifier.

Dec 20, 2007 | Pyramid PB1500 Car Audio Amplifier

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