Kikusui PLZ303W fuse repair help

[todd_fuller]

I picked up this rough-looking Kikusui PLZ303W load off eBay recently. A bit of a gamble being it's rough shape. Turns on and appears to work fine, but when you apply a load, it gives a FB2 fuse out alarm. Being that I paid $250USD shipped, fixing a fuse is a minor nuisance. However, the fuse is buried in under a series of PCBs, so I wanted to ask if anyone has the service manual for this unit or knows the best way to get to the fuse?

Thanks!

[coromonadalix]

Ask kikusui directly, they sent me under an NDA (non disclosure agreement)   the PAD series

[todd_fuller]

I actually did that yesterday after I posted this the prior evening. I hardly expected a reply for a hobbyist, but as you've noted, they were able to send me the service manual under NDA. Now I just need to figure out how their fuse detection circuit works. What I thought were the only fuses was totally wrong, they have a bunch of smaller fuses all over the place. Hopefully, this ends up being repairable!

[todd_fuller]

So this unit suffered not only some physical abuse, but electrical abuse as well. 75A main DC+ bus fuse was melted in half.

[coromonadalix]

It was the fuse under the blue shrink tube near the bars ??

[todd_fuller]

It certainly is. 75A is a fair bit of current. I wonder if someone hooked up a car battery or something. Seems to work OK now, at least as high as I can test with my bench power supply, 30V @ 3A. Might pull out one of my HP server supplies which should be able to sink 60ish amps at 12V.

-Todd

[JohnG]

I actually did that yesterday after I posted this the prior evening. I hardly expected a reply for a hobbyist, but as you've noted, they were able to send me the service manual under NDA. Now I just need to figure out how their fuse detection circuit works. What I thought were the only fuses was totally wrong, they have a bunch of smaller fuses all over the place. Hopefully, this ends up being repairable!

Is there any chance the service manual sent also covers the PLZ1003W? I have one in need of repair.

Thanks,
John

[todd_fuller]

John,

Repair manual I received only covers the PLZ153W and PLZ303W. I can vouch that Kikusui was very responsive to my query.

-Todd

[JohnG]

Thanks, Todd. I contacted them, so hope to hear soon.

John

[Johnny10]

Did you contact Kikusui in US or Japan?

[JohnG]

I never heard back, myself. But, I found and fixed my own problem with my PLZ1003, which was a dead NiCd backup battery. It turns out that if you let the load sit for long enough, the battery dies and you loose some settings. I replaced the battery and did a recal based on the regular manual, which had instructions.

Now I make sure to turn it on every week or so.

John

[Johnny10]

Before I start a new thread, I thought I might post a curious problem on a Kikusui PLZ603W I have on the bench.
It is a 603 unit that thinks it is a PLZ153W model.

The load presented at the terminals is about 4X what is on the display and when I go into the Calibration menu same.
I can match differences exactly as per 153 to 603 table.

Tried recalibrating unit but I cannot select the 603W in the calibration mode only the 153W.

My assessment would be the firmware eprom.
This is a unit from unknown history.

As I said, everything works it is simply presenting 603 loads while showing 153 display. i.e. when set for .34A the actual load is 1.26A.

While proceeding to order an eprom programmer and asking around for a download of 603 Firmware (Firmware not available from Company), I thought I would post the problem.

[todd_fuller]

Looks like someone repaired it with an 150W PCB. When I turn my 300W unit on, it gives the right model name, so it's not simply a calibration difference.

Have you tried to recal to the 600W settings?

[Johnny10]

Yes, will only accept 153 as Model number.
When you examine the units they are the same physically except more modules are added for higher wattage.