Jaycar MP3086 30 Volt PSU Teardown and testing

Old MP3086

Okay so I bought a 30VDC Variable 3 amp PSU from Jaycar a few weeks ago. It is model MP3086 with CV and CC modes. I was expecting the one shown above with 3 pots, one for amps, and coarse and fine ones for volts.. Instead I got a new improved model, unless you like the coarse/fine pots!

New MP3086
So of course with anything new you need to follow Dave from EEVBlog’s advice.. Don’t turn it on tear it apart so that’s what i did..
Cover off, transformer looks nice doesn’t it ?
Okay so first impressions from the photo above.. Nice secure soldering on the mains connections, shake proof washers on the earth wire and extra covering on the mains feed, see that black rectangle on the right centre ? Here it is closer up…
Switch Close-up
It is a real clunking power switch on the mains, so no standby current usage, Yay a thumbs up..
IEC socket with integrated fuse holder, nice one !
Shake proof washer a point for Jaycar
Spring washers on transformer mounts with intake vent for fan, there is also vents on the sides with exhaust at the rear of the unit
Terminal block for permanent connections say a bench Multimeter and banana sockets

Okay now for the close-up internal shots, there are five boards

  • Rectifier board Power transistor board with Relays to switch taps from transformer to transistors
  • LCD Display board
  • Keyboard Board for buttons
  • CV/CC Control board
  • Connection board for front panel outputs with current shunt for amps readings

Rectifier Board with room for two more transistors


Is this a real Japanese Rubycon or a copy ? 
The Main Power board looks like it has a real Rubycon capacitor, the screen printing looks good and it does not look like a rip off

LCD Control Board all SMD, the bodge wires on the right run to the back light, keyboard board bottom left with ten turn pot for volts selection underneath
The Voltage and Current control board, there is nothing on the other side apart from a few through hole caps and a voltage regulator on a small heat-sink, notice the flux residue on the through hole hand soldered joints, not good how hard is it to clean a a board ? Here are some close ups of the cruft left behind after soldering. But hey the Ningbo QJE company gave us their phone number if you want to call and complain to them about it :p

NXP Chips a counter IC and a logic gate, some more quality parts to go with the Rubycon cap…

Nice SMD soldering, re-flowed not hand done ! This is one of the trimmers to calibrate it all
Nice thick bus bars to the connections on the front panel with shake proof washers as well, excellent job.
Thermal switch for the fan, wired in series with fan it is rated at 5 amps and 50 C cut in temperature but cuts in before that, 
Okay now for some testing…. 
The test set-up consisted of the following.
  • RS232 connected DMM logging temperature
  • Galaxy Note 2 Smartphone for dB readings (Not real accurate but okay) 
  • Incandescent 12V globe as resistive load
  • Digitech QC1932 25MHz DSO
  • Supply set at 6.9 Volts, this just switched to the second tap (6.8V) so max heat from transistors

12 Volt Light globe pulling 1.33 amps at 6.9 volts, this tested at about half of the maximum amps and the second tap on the transformer had just switched in at 6.8 volts so I was dissipating the most heat for this amperage in to the heat-sink. 
The test set-up, I connected the scope probe to the terminal block on the front directly, I just hadn’t done it here yet
Below is the capture of power on unloaded, there is a small HF ripple at power on then ramp up to full voltage (5VDC) with no overshoot, there is a small amount of ringing when it reaches the set voltage, from power on to stable voltage is about 10 milliseconds.
This is a close up of the spike at power up unloaded, about .5-.75 volts lasting 206 microseconds
Here is a capture of a loaded supply at 7VDC from turn on to full output is 76 milliseconds with no overshoot to speak of.
1.6mV ripple at 7 volts under loaded conditions
dB levels with phone acting as meter with smart tools app. The first bump is me pressing the power switch, the second is the mechanical temp switch clicking in, then you can see the fan ramp up to 69dB. the phone was sitting 10cm behind the PSU with the microphone sideways to the fan, the power switch click is quieter as it is at the front while the temp switch was closer to the rear. The ripples in the graph is just background noise in the shack.
If you look between the cursor marks on the timebase below you can see two little ripples lasting about a second, this was when the fan switched in but was brief and low in amplitude. It may have just been induced noise from the arcing in the mechanical temperature switch for the fan as its contacts closed.
Here is the temperature run at 7VDC 1.33 amps from cold (I did this test first after leaving it off overnight) Starts at about 26c the shack temp, ramps up to 43.9c in about 2 minutes then settles to around 34c and stays there. I ran it longer then this graph loaded and the temp was stable and didn’t run away at all which it shouldn’t pulling 9 watts from a 90 watt supply.

 All in all for the price I am very happy with it, well built steel case, the front panel is plastic but has steel rails running from it to the back panel for support.

So what don’t I like ? Well not much the only things are as follows.

  • Earth Connection is in the centre, so I cant plug a standard spaced dual banana plug adaptor in to the – and + rails, I may re arrange the banana sockets and move the earth to one side.
  • You need to short the rails to set the required amperage for CC mode, I am going to put a NO momentary switch on the front so i don’t need a lead to do it
  • Switching on CC mode is a bit hit and miss, I dont know if it is key bounce or a slow micro but you have to press the CC button a few times before it locks in to CC mode, it is a soft switch
Apart from that i really like it and it actually goes to 31.5 Volts
MP3086 Regulated lab Power Supply 30VDC at 3 AMPS
List price $199 AUD

Photos of the shack all setup

The Twisted Shack
The twisted Professor

Shack mascot Tux and Mr Bean teddy
My Pulse Jet

Tools in filing cabinet

Power tools in Filing Cabinet

Close up of my books

More books

Even More Books

Bits and bobs on display

A few more knick knacks and a dummy load project DC-1GHZ 250W

VIC Royal mail Service Morse Key circa late 1800’s

Small hand tools

More Small hand tools

Pocket Digital Scope and Function Gen from Velleman

Keyboard and mixinf desk at workstation side

Fishtank and tablet

Loose tools behind Drillpress

Storage bins

12VDC Shack battery backup

Gas storage Mapp/propane

Microscope, ultrasonic cleaner battery Charger, Pestle & Mortor and telescope optics

Flatbed scanner I get out as needed and storage draws

Breadboarding

Labeller, tacho and camera

Dremel and Hot Snot

Gaming PC in old 19inch Rack case and Fan/heater on top under the desk 
Air COmpressor Oiless with water trap for dusting electronics

Tool Bag for field work

Inside tool bag, I add the pocket scope and sig gen when i go out with the bag

Swing out lead rack

Test leads for field bag

Network cable tester and resistor/capacitor sub boxes

2nd Dremel and drillpress stand

Air tools

Measuring and scraping draw

Spanners

Metal Working, files snips reams

Screwdrivers

Drillpress

Hammers clamps and random tools

larger pliers, side cutters allen keys

Sockets

Handmade clock from old 240VAC clock that had broken glass and burnt out Mistral Desk fan

More Sockets Taps/Dies Drifts Wad punches

Under workbench storage and solder dispensper Atten Digital iron and Compressed air outlet

Digitech 2 Chan DSO, Powertech 30VDC 3A PSU Tek 314 Scope GW Freq Counter DMM with Cap/Ind/Tran test and cordless power screwdriver

Main Shelving with video feed from driveway and frontdoor so i dont miss the postie with goodies from eBay

Atten Iron (Base under desk) Digitech SMD rework station (air and iron) and small PCB hand tools in old makeup case with USB outlets to left and Power fail torch (Comes on when power goes out)

Drill press and visitor chair with storage bins, resistors in drawers to left

Asst small parts Caps/Semis/Screws etc

Overview of workbench side

Panning to left of workbench

Workstation, Desktop PC at top laptop with 2nd screen center and tough book laptop right, all linked with synergy remote software to use one keyboard and mouse to run it all as one virtual PC

Ham radios Mindisc recorder, 10 band graphic equalizer transmatch and 13.8PSU with 24VAC for weller iron (So I can solder power etc at radio side)

Sign my son made me for Christmas, just hung it up for the pics 🙂

The entry to the shack

Old fridge outside shack to use for chemical storage

The 2.4×2.4Mt (8×8 foot) garden shed that is the shack

The wire bin for scrap wire

Around the back of the unit is bins of larger parts and some tools

CB250N Cafe Racer The Hornet and the 5K wall

Here is a photo taken by the seller of me riding away from his house..

So now the saga..

Well I have spent the last few days rebuilding the carbs on the bike, had them off about 15 times, checking and rechecking cleaning and checking again.

A photo of my work area, I am in a small unit with no space..

I spent a lot of time reading blogs, forums and tuning guides and kept coming to the 5K wall that honda twins of this vintage had. This was the problem I was having with the CB250N it would not rev past 5k  and I now was pretty sure it was not the carbs.

Okay this led me to electrics, COOL…. I know but in a past life I did this as a job and my hobby is Ham radio and electronics so now I went from an area i was okay in (Mechanics) to an area I actually loved electrics.

I was able to get the bike running so the first thing i did was put a timing light on it to see if the high RPM pulser was triggering the advance, it was advancing but I noticed that as the bike surged and lost power it lost spark, okay so it really is looking like an electronics problem.

Okay next I pulled the wiring to the CDI on the left hand of the air box… WTF I just noticed that the frame has been resprayed with the bloody wiring loom on the bike, there is paint in the connectors, there is paint on the earth points and paint everywhere it should not be….

So out came the dremel (mini grinder) and I started to sand all the paint of the earth points for the coils and CDI. I removed some extra wire that had been spliced between the CDI and the stator and reran the loom to get an extra two inches to rejoin the loom.

A photo of the “new” rewired loom you cant see much but I replaced connectors in the harness and removed a 6 inch splice someone had added to the stator wiring (blue white CDI voltage wires) and reran the loom to allow for the shorter length

Gapped the plugs and cranked it,…. Its alive its alive it is revving to red line and just sounds heaps better.

I hosed the stator with with a dry silicon lube I use that repels water and doesnt harm wiring to protect it and stop corrosion.

So I have been over the bike and so far have a small list of things for RWC (MOT) they are as follows…

Replace Brake Lever (I broke it putting the bike in the car)
Re wire front brake switch
Plastic weld LH side cover crack
Lube Clutch and Throttle cables
Pull apart RH switch block and clean Hi/Lo switch
Replace Fuel line and add inline filter
Sync Carbs
Reweld header it has a small crack near the muffler

On the plus side the previous owner who could not get it to run well had done the following already…

New chain and sprockets
New Rear Indicators
New Brake pads and bleed brakes
Replacement seat from wrecker
New brake light

Anyway that will do for this post… but for those that didnt see the last post in the welcome section here is a rendering of what I want the bike to look like when done

My New Project CB250N Superdream

I decided I needed a project bike as the XJ is getting tired and I didnt want to do it up as it is a bit heavy for me as I have a back injury (From a stack at 18 years old on a CX500 shaftie at 186 KPH or about 115 in the old currency) and I wanted a lighter bike.

Today I sealed the deal on a 1980 CB250N for AU $800 and went to pick it up. I got an unregistered vehicle permit to allow me to ride it home, this is a temp permit for moving a vehicle to a new home or to a mechanic etc for repair.

I got 1.5km or about a mile from the sellers house and that was it the needles in the carbies got shit in them and it started flooding, what to do, what to do…. I had my wife following me in the car a Ford Falcon station wagon as she had driven me down to pick it up. I was about an hours ride from home and not going anywhere fast, top speed I could get was about 20kph.

Okay pull the bike on to the verge on the side of the road and drop the few litres of fuel I had put in to ride it home it will evaporate off the road and I didn’t do it on a drain or anything like that, I didn’t want to but had no jerry can to collect it.

Next I had to lift the rear wheel in to the back of the wagon with a snatch strap attached to the rear wheel, the strap was so my wife could pull it from the front while I lifted the bike, with my back I could not lift the dead weight and push it in to the car at the same time. Between dropping the fuel and wrestling the bike we blew an hour on the side of the road.

The tailgate would not quite close so I strapped it closed and set off home but hey I got the bike up to 100kph. better then the 20kph it was doing earlier even if it was in the back of the car.

Well now it is home and out of the car, I forgot to take a photo of it in the car, oh well you can all imagine that. So now it all begins. The bike is not in to bad condition it has an oil weep from the rocker cover, the carbs need work and the muffler weld is cracked at the headers, oh and as I found out it starts in gear so will have to sort that out.

The course of action is to repair the small things I need for a road worthy and get it registered. Then I am going to attack it and I really do mean that…. This is my mock up of what I want to do with the bike.

It may not be exactly the same when finished but I mocked this up as a guide of what I would like it to look like when finished, I am going to do what I call a rolling resto in that I will be riding it and taking it off the road for a week here and there to do it in stages

The first photo is how it was when I picked it up, and the second is the mockup i did

Looking forward to your ideas and input on the project as it moves along

My Swag and Hootchie Shelter

Jo-anne bought me for my Christmas present a New Oz Trail Swag the other day for when I go camping. I wanted to add to my gear and was lucky today. I was at the op shop earlier and got three hootchies (Real army ones not copies) and two aluminium snow skiing poles that i cut the handles off and used as really light weight tent poles. The two auscam hootchies are used for the tent the drab green is the floor, canvas swag with oz trail sleeping bag rated to -5 degrees C a wool blanket, pillow, mattress, nylon mattress cover. I had to buy some pegs and I already had 25m of paracord.

The reason for the extra tent coverage over the swag and extra blankets is I go camping in the Alpine High Country, -2c in November up there

I have also got some other gear for camping as listed below.

So price breakdown is as follows…

Oz Trail Wentworth Swag $100 off bought for $149 (NEW)
Oz Trail -5 degree Jumbo Sleeping Bag 50% off $59 (NEW)
3 Genuine Army Hootchies and small ground sheet $10 (OP Shop)
2 Ski Poles(Tent Poles) $6 (OP Shop)
2 x 2m Ocky Straps $5 (NEW)
10 Meters Para-cord $12.50 (NEW)
Heavy Duty Tent Pegs x 10 $7 (NEW)
Doona Cover to cover mattress $5 (OP Shop)
Wool Blanket $5 (OP Shop)
Pillow (FREE) Already Had
Sleeping Bag Liner $2 (OP Shop)
Genuine Trangia Hiking Spirit Stove Set $2.50 (OP Shop) Retails at $125
Camel back Olive Green Hydration Pack $4 (OP Shop)
Extra Mattress for swag (FREE) Already Had
1 liter Aluminium Bottle for Metho for Stove (FREE) from free box at op shop
Camp Cookware $1 (OP Shop)
1 Army issue Angle Torch (Free) from friend
4 Ever Ready Electric Glow Sticks $8 on special at supermarket
Collapsing Table Lightweight $20 (NEW)
Folding Stool $5 (OP Shop)
Cooking Utensils including 100+ year old carbon steel carving knives

I have a friend building a trailer to go behind my motorbike to carry my camping gear so am well on the way to being mobile and the bike can go most places a 4×4 can go so I will be camping off the beaten track

I also need to get a small (12 inch) chainsaw for firewood collection and a few other bits of kit

My Portable Gadget Collection

So what portable gadgets do you have ? I have a smallish collection of gadgets that I use when out and about as well as at home, I do not take all of them out all of the time it just depends what I am doing, so here are my go to gadgets sort of in the order of most use…

Galaxy SIII in pebble blue 16GB with 16GB Memory card

Plantronics Discovery 975 bluetooth headset for phone calls with my Galaxy SIII

Kindle Keyboard WiFi version with 3GB of storage

Yaesu VX-6R VHF/UHF 5watt Handheld HAM radio

Galaxy TAB 10.1 Ver 2 16GB WiFi with 32GB Memory Card

Bluetooth Keyboard/Stand/Cover for Galaxy Tab 10.1

Nokia Stereo Bluetooth Headset for music

Varta V Man 3 USB lithium battery pack to charge phone etc on the go

Pentax K100D DSLR this is in a waterproof tough case with heaps of lenses and  other stuff
including Memory Cards, Batteries, Filters, Remote’s, Time lapse controller etc
Goal Zero Nomad 7 Solar panel with AA USB battery pack/charger for
solar charging  of phones and other devices