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Insides of a 0-18V, 2A power supply, the CSI1802X

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I recently purchased a CSI1802X from Ebay.  Normally I look
for supplies with LED displays, so I put in a low bid on it and
surprisingly picked it up for $26.

Details of the supply are here:

Anyone have experience with Circuit Specialists?  Are they
a surplus dealer and/or OEM?  The supply has their name on
it, with a "Made In China" sticker.  Can't tell if it's their
design or a relabel of someone else (maybe Mastech)?

I ran some tests with my Fluke 87-V measuring voltage and
current.  The power supply displays were spot on, within
+- 1 digit of what the Fluke showed.

I'll attach pics of the inside in another post.


The insides seem surprisingly good.  Not sure if my expectations
are really low, or if this is on par for a supply retailing for $60.

The design is a straightforward linear supply, with a multitap
transformer and a relay that switches taps at certain voltage

The display board is mostly surface mount.  No ECOs are visible.
There is something like silicone RTV on the power switch covering
any exposed metal space where the supply wires are attached.

The regulator board is phenolic, not FR4.  I guess it must save a
penny or two :-)


Wow, thanks for posting the detailed pics.  It looks like an older Mastech [ or Mastech copied them, who knows?] or maybe they all get their 'generic' boxes from the same maker and design the electronics around it.  Mastech lists the 1803 for $64 athough its +1A more than CS, the CS model appears decent, if it checks out spec wise.

Not mentioned in the manuals is that LED annunciator pictured above near the V adjust, its likely in constant voltage mode when it lights, is there another for constant current?

The newer Mastech's have a different look and adjusts, more akin to the GWInstek PSU:

I haven't had time to take photos, but compared to your CS PSU, the Mastech uses through hole components, no SMD, and very much like the photos I posted on this link:

The links you provided include the schematics, what couldn't be better?  Its pretty straightforward too, the LCD readouts are built around the 7106 Intersil DVM, its dual, one for V and A. 

The PCB has QJE on them, and I can track it to a Chinese model PSU with model numbers QJXXYY for XX = volts, YY = Amps.

In China, the model referencing QJE directly are these, but from year 2008 :

and you can see it has the same LCD board as the CS.

QJE direct Chinese links suggeset the parent model is made in the province Guangdong, where a QJE factory exists, but while they say they 'contract' manufacture their parent products are electrical equipment.

The PCB has clear hand soldering and corrections [see the link for the factory pics, lots of hand labor].

In the end, one thing we'd all like to know is how does it perform to spec?  Check the short circuit protection, you can also use that setting to check the constant current adjust.  Check the load regulation, just attached it to a load and put a scope across the power input and look for ripple. 

Once you've spec'd it out, that would be the 'real' specs I'd rely on rather than the rather spartan manual on the website.

Congratulations and enjoy!

slburris you need some training ASAP .. about resizing pictures... or just set your camera or mobile phone to 800x600 .

I like the pics just fine, its a good size until you click it, then you see the details!  It formats nicely until then.

Welcome back K, its good to read your always exciting  ;D remarks  :D

--- Quote from: Kiriakos-GR on August 01, 2010, 02:51:50 pm ---slburris you need some training ASAP .. about resizing pictures... or just set your camera or mobile phone to 800x600 .

--- End quote ---


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