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Power supply Kaypro 4/84 [message #10166]

Thu, 24 November 2022 15:35

kurt_z80
Messages: 4
Registered: June 2021

Junior Member

Hello folks,

Does anyone have any info for me where I can get a schematic of the Califonia dc power supply from the Kaypro 4/84.
The power pack has the model no. LR53001-15. On the front of the board is still 60 0205 02.
The power supply has a short circuit and I can't find the fault. My Kaypro now has a MeanWell RT85B power supply.
This works very well.
But I would like to repair the original power supply.
It will benefit posterity.

Greetings from the Rhine
Kurt

/forum/index.php?t=getfile&id=2831&private=0

/forum/index.php?t=getfile&id=2831&private=0

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[Updated on: Thu, 24 November 2022 15:37]

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Re: Power supply Kaypro 4/84 [message #10170 is a reply to message #10166]

Mon, 05 December 2022 06:24

w9gb
Messages: 55
Registered: October 2015
Location: Chicago, IL

Member

Kurt -

For troubleshooting Switch-Mode Power Supply (SMPS) boards, proceed with Caution.
High Voltages (HV) > 300 Volts are present, when connected to AC Mains.
Assure that Electrolytic capacitors are discharged -- when disconnected and on Service Bench.
==
CHECK FUSE -- OKAY ?

Determine the Controller IC used on the board.
A number of manufacturers, thru the years.
https://en.wikipedia.org/wiki/Switched-mode_power_supply

ST Micro L6566B is one example
https://www.st.com/en/power-management/l6566b.html

Control of SMPS (Texas Instruments video)
https://training.ti.com/introduction-control-smps

===
I do not see "Bulged Capacitors, BUT Leakage may be present.
VISUALLY Inspect for Burnt Components and / or Discolored PC board areas/components.

SO, First Test the Transistors -- using a VOM/DVM -- start with TO-220 package on heat sinks.
Than the Diodes.

Many SMPS employ Opto-Isolators (encapsulated LED/Detector) in their designs,
Over Voltage (OV) situations can burn out the internal LED.
https://en.wikipedia.org/wiki/Opto-isolator
--
Replace bad or out of value components found.

Greg
chicago

[Updated on: Mon, 05 December 2022 06:26]

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Re: Power supply Kaypro 4/84 [message #10316 is a reply to message #10166]

Thu, 13 April 2023 04:35

w9gb
Messages: 55
Registered: October 2015
Location: Chicago, IL

Member

Be aware of INPUT Voltage Jumper, on this Swith-Mode Power Supply Board.
On the Right Edge of this PC Board, you will see 230 and 115 VAC marked on board,
Adjacent to a Jumper.

This Selects the INPUT AC Voltage. Very OLD Design (1970s).
LEAVE at its 230 VAC setting (Proper for Europe, where you live).

21st Century SMPS designs are Global with ISO standardized input connectors (C13/C14).
These SMPS Self-Manage the commercial AC Input Voltages from ~100 to 250 VAC Inputs,
with NO Input switches for Voltage setting.

greg

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Re: Power supply Kaypro 4/84 [message #10343 is a reply to message #10316]

Tue, 09 May 2023 04:14

kurt_z80
Messages: 4
Registered: June 2021

Junior Member

Hello folks,

Thanks for the information.

I swapped the power supply for a Main-Well rt85b.
Kaypro 4/84 works great with the new hardware.

greeting
Kurt

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