Sunday, 9 October 2016

Wizboard hoverboard segwway scooter gyro board repair.

Component transfer service: 

I thought I would offer a service to transfer gyro board parts over as I still can't see any Wizboard configured Gyro boards for sale. If you have faulty gyro boards and want your replacements modifying to fit your wizboard, leave a comment below with your email and I will get back to you !

I was passed a Wizboard branded balance board for repair, the first one I had seen.

A quick look on the web showed how it should work, no front lights should come on until you stand on the pressure pad. This one was powering on with both lights immediately on. The motors would not energise at all.

Again the web showed this was a fairly common failure, the solution being to replace the gyro board for each affected side.

I found this a little strange as I would not have expected both to fail at the same time ? and also wondered about the failure mechanism, especially as it is common fault ?

Nothing was showing up about 'repairing' the board, just swapping them out.

I didn't want to spend too much time as the person wanted the board back working ASAP and there was a quick solution but I thought I would at least have a bit of a look into it.

As a quick first check I checked the pressure pad switches were working correctly, they were.(no voltage across the connector, press the switch and it had about 3v across it).

The board doesn't have a great deal on it, a 3 axis chip, a microcontroller, a fet and voltage regulator, some passives.

All the passives, fet and regulator checked out so my money was on the 3 axis chip, the micro second but as there was no way to flash a new one I just went with the 3 axis chip.

I ordered 2 new chips and swapped them out, chips were removed using hot air and flux, and replaced the same way, touching in with the iron afterwards as I didn't want to overheat the chip. What is going on inside a 3 axis chip to sense movement ! its like magic, I will have to read up on it.

Sadly no success, board behaved exactly as before, disappointment.

So two new boards were sourced off ebay, cheapest price was £32 for two delivered.

There were no identical boards, the Wizboard does not have opto sensors mounted on the board, the switches are mounted in the pad and connect via wires, however the layout and components on the ebay boards looked almost identical except for this so I ordered some with a view to swapping parts over.

The boards came and a close inspection revealed a few of the resistors (for LED current limiting) were a different value.

Also although the connectors on the board looked the same the Wizboard wiring would not plug into them as the molding was different.

So as well as swapping the sensor connectors over, I swapped all the other connectors and the SMD resistors for the LED's.

Put it all back together ( had to open up the holes on the new PCB as they were about 0.5mm out of alignment).

Success ! it was nice to see the board back up and running, I had a quick go before handing it back !

I would have liked to have had a proper go at diagnosing and fixing the original boards, but if as I suspect it was the micro, it would have been more work to source the code and flash it (if available at all).

If you have had success actually repairing the boards or why they fail I would be very interested to know !

Wednesday, 3 December 2014

Technics SC-CH900

Not really a repair, but possibly useful info for somebody and an excuse to share some love for the SC-CH900, for me the best, the pinnacle of the mini hifi system in the 90's. Im sure a sony MHC-6600 fan would disagree :-)

So the Technics SC-CH900, I lusted after this baby for 23 years ! I always had a fascination and interest in home electronics, hi fi's TV's etc so back in 1991 after I started work I set about saving for and buying my first stereo. I knew all about HiFi, what cable to buy etc but despite it not being 'HiFi' in the seperates and OFC speaker cable sense I was hooked on getting one of these. I think it was the copious use of VFD displays that did it. So every week I would check out the stereos in the local shopping precinct, It was between the Technics and a Sony MHC3600/5600/6600. So the time came to buy, what I actually bought was a SC-CH700, largely the same system but without Dolby surround capability or the brushed metal finish. Crucially though it was from memory about £200-£300 less than the £1000 of the 900, a lot of money for me in 1992. The CH700 did me many years of good service and I loved it but I always regretted not getting the top of the tree 900. So good old eBay delivered the goods and all these years later I have a pristine SC-CH900 and I love it.

The only issue with it was the display of the main amp unit, the other components looked as new but the amp had 2 issues, the cover / filter over the VFD was cloudy / hazy / dirty. Secondly some parts of the display were significantly brighter than other, some looked over bright, others too dim ? As seen in the picture below from just after I bought it.

I looked into getting a new display and considered swapping the display from my 700. Panasonic UK said that they did not support the unit anymore but armed with a part number from the service manual I inquired in the US and found it was still available, would have cost about £40.

I did a bit googling on VFD's and found some referance to the grid wires oxidising due to lack of use. Either manually powering them and flowing a bit more than normal current through them may help or just leaving the unit in for an extended length of time. Although the clock is lit all the time it didnt seem to be getting any better after a week in standby so I left it fully powered on overnight. Success, the next day the display was bright and uniform.

So I then stripped the unit down to clean the inside of the display, as the amp is on all the time in standby and has a fan running when the volume is turned up I suspect that is why it had got dirty and the other components looked like new.

I wasn't dissapointed with the construction, the service manuals are amazing in quality and the unit was too. It came apart very nicely, lots of screws, no forcing or plastic tabs breaking.

A careful gentle wipe and it was like new again.

All set up with my SL1210 MK3D. A video of it in action.

I knew I had the brochure sat in my loft somewhere so dug it out and scanned it below, ah the memories.

A link to the whole brochure I scanned in.

The only other issues I have come across with these systems relates to the fan, when the volume goes above a certain level an internal fan kicks in, if this fails the unit shuts down. My SC-CH700 did this and I fitted a new, quiter fan. The 900 seems ok so far (and I am actually just useing hte the whole thing as a pre amp currently).

The fan was my only gripe with the 700 as I found it intrusive the way it would come in and out, almost with the beat at the volume levels I listened to the unit at.

Thursday, 30 October 2014

Panasonic SA PT470 dead, no power.

A Panasonic home theatre system, passed to me as dead no power.

A close listen revealed that the unit was not totally dead, pressing the power button the unit would click on then immediately off (but nothing on the display). This could be repeated a second time but then the unit would not respond. Pulling the power lead would allow this sequence to be repeated.

So the unit was alive and intelligent.

A quick google gave me the manual to download from the excellent site, electrotanya.

Panasonic / Technics manuals are absolutely superb.

I may do a post about my beautiful Technics SC-CH900 that I finally bought after 22 years ! :-)  anyway..

So I opened it up and stated to take a look. Nothing obvious so decided the best plan of attack was to take the PSU out to get some proper access.

Admission: I took a stonking 360v dc hit from the main cap, Warning,  always approach with caution, measure the high voltage DC caps, and discharge as appropriate.

This fault will leave the main caps charged. I usually check but got sloppy.

So nothing jumped out visually, the mains went through a hefty filter and feeds standby power section of the PSU, the main psu is switched in through a relay, the relay only stays in if the PSU behaves correctly.

I did some passive checking but again nothing jumping out.

A move not without risks but I decided the best way forwards was to bypass the relay and see what wasn't powering up, the brain was obviously not happy and shutting everything down.

Using the drawings I checked all the rails and found the 18v fan power to be absent. I checked the rectifier diode D5805 and found it short. Fitted a repalcement and all good.

Friday, 22 August 2014

BMW E83 X3 PDC fault finding and sensor replacement. 66206989069

The PDC enables as you engage reverse and you are met by a long tone and then no PDC function, indicating there is a fault.

To check the sensors the engine does not have to be running, just but the ignition to second position so the dash lights up and press the PDC button. The long tone will sound. You can now get out to check the sensors.

Put your ear close to each one in turn, you should hear a very faint ticking sound. Any that don't are bad or have a wiring fault. In my experience the sensors do just go faulty, that is ones that look pristine and have clean electrical connectors can just stop working.

Order a replacement sensor. 66206989069 from ebay, £10 delivered

I had a search of the web about removing and refitting the sensors and didn't find a lot of encouragement, some indication of having to remove the bumper.

I can tell you on a model with unpainted bumpers it is possible to replace the rear inner sensors without having to take the bumper off because this is the one I did.

To replace the RHS inner sensor.

Remove the tow hitch cover.

Reach you hand in the gap to the back of the sensor.

Feel for the plug, squeeze and remove the electrical connector, this is in line with the body of the sensor but at the top.

The sensor can now be removed, tricky working blind but quite doable.

The sensor is held into the bumper receptacle with two fingers. Splay the two fingers downward and pull the sensor out. Theses fingers hold onto plastic pips on the sensor holding it in place. The fingers are quite flexible, my tip is to grip the body in the palm of your hand, splay one finger downward and pull on the sensor at the same time, then while still maintaining a pulling force on the sensor (this keeps the pip out of the finger ), splay the other finger. The sensor should then start to pull out from the rear.

Slide the new one in paying attention to the orientation.

My faulty sensor. New one in and all working ok.

Saturday, 31 March 2012

Pansaonic inverter microwave cuts out, stops, resets: 2M236-M42 NN-A713a

This microwave was not heating food, cutting out after about 10 - 20 seconds.

Trying to use it, all would sound normal for a couple of seconds but then there was a buzzing arcing sound and relays would start to click and finally the microwave would stop and the timer reset itself.

There was some information on the web about Panasonic microwaves showing error codes but it was showing nothing after it cut out.

The microwave was opened up and (carefully) run with the cover off to see if the arcing was visible, possibly see something else ? On initial inspection nothing could be seen, just the original symptoms heard.

The microwave lamp comes on with the power and was making it hard to what may have been arcing so that was disconnected.

I still couldn't see anything so decided to power off and just have a look at the magnetron, there was talk on the web of seeing the magnet had cracked, I could measure the filament too.

Well upon removal I was a bit shocked, the side of the magnetron that could not be seen with it in place looked like this....

Hmm, that doesn't look right ! It looks like it got a bit hot !

Inspecting the rear air vent it was totally blocked with grease and fluff. The picture is after I started to clean it.

So a new magnetron was ordered off ebay, only £28 (cheapest local shop wanted £60).

Here it is next to the old one. All the adverts on ebay say the new one is a genuine Panasonic item sourced from Panasonic direct, just not branded because they are used in many brands of microwave for rivals ? No way to be sure.

In it went and all working again. :-)

Friday, 3 February 2012

Philipos DPV630 faulty power supply.

A DVD player that would not power up, just a flickering red standby light.

A close inspection revealed  a bulged capacitor. A chance to use the ESR meter in circuit, it confirmed the capacitor was bad.

Component out, definitely gone.

New capacitor in and it was working again.

Sky + faulty power supply.

A Sky+ box stuck with a red light, would not power up.

The output capacitors were bulged and replaced but still no boot up. The main input capacitor looked visually ok but was checked with an ESR meter, it did not register a capacitance or a resistance ! totally shot.

New one in (circled below) and the machine was working again.