Server chronicles - another repair (UPDATED)

 The entropy can only increase, so after some time I had the server shut down, when I restarted something went wrong.
I didn't notice any problem until I did walk close to it.
I did see the Red LED blinking, indicating a problem.

Server chronicles - testing fan proposal

The HP ProLiant DL360p Gen8 has 8 fans to cool down the two CPUs and other hardware.

These fans are high speed PWM controlled and are prone to fail over time.

The only thing to do is to replace the defective fan with a new one, but it would be nice to understand exactly what the problem is and check if the replacement fan is working before to open the server.

Eton American Red Cross SOLARLINK Portable Radio ARC FR600

On an antique mall I did find this nice radio, little bit dirty but otherwise in good shape.

Some cleaning notes.

Repair - UV insect trap (UPDATED)

Funny story of a trivial repair attempt over an electronic ballast used to drive a fluorescent UV bulb for an insect trap.

DISCLAIMER !!!
This stuff is connected DIRECTLY to the power grid and the fluorescent bulb emits dangerous UV !!
Working on these type of circuit REQUIRES knowledge and precautions !
DON'T ATTEMPT ANY REPAIR UNLESS YOU KNOW WHAT YOU ARE DOING !

Repairs - Mazda 5 Aux input

 

This time I spent some resources to fix the AUX input on my Mazda 5 2012.

Repairs - attic fans

Arkansas is very hot place in summer, so basically every roof has one or more fans to help to reduce the accumulation of heat and humidity.

It is very important structure for the health of the house.

Repair Roomba 5th gen brush block

UPDATED !

Roomba is a very good brand of home robotics, I own one Roomba 6 and one old Roomba 5th generation (560).

In these years of use of course I had to repair it sometime.
The battery of course usually last about 1 to 2 years, I had a wheel unit broken, had to clean the sensors, a couple of lateral brush motor broken and now, a main brush defective.

3D Printing - repairing a Jlab headphone

For many years I did buy a headphone from a company called Jlab.
They are cheap (< 30$) and very good sound quality and comfort.

I think I did buy so far 4 or 5 headsets and the reason is because after a while they broke down.

Finally I was able to repair one !

Texas Instrument TI Programmer

Often during the week ends we love to visit antique malls and similar places, looking for something to adapt to other uses or just strange things.
Sometimes instead I found things that .. well, something I can not just leave there.

Repairing a GoldStar microwave

My old microwave started to have a problem lately.

Sometime when turning ON the oven, only the light works, the blower and the magnetron remains turned OFF.

Raspberry Pi - broken micro SD card reader

One of the Raspberry Pi I have around has now a broken micro SD card reader.
The micro SD card is not retained anymore, thus the options are :

a) trash away the Raspberry and buy a new one
b) try to repair it

Repairing a zapper

In the springtime, summer and fall, there is an appliance that works almost 24 hours a day, at least in my garage.
A zapper.
This one, a PestiTech, did work all the last summer and fall.
Really, in Arkansas is not an option to have a zapper to limit the "things" that can fly and bite you !
The garage is the main entry for these pests, so a good zapper is really the first protection.
Now it was time to restore it and ... of course dead !

Roomba 5xx - repairing a power supply

Time ago I had a Roomba 560 with an Error 5.
The problem was the power supply used to charge the battery.

Time to try to fix it.

Repairing my Craftman electric lawn mower - UPDATE !

Scroll at the end for the update !

One of the things that really irritate me, is the noise and the smell of a gasoline lawn mower.
The tranquility  of a beautiful place is always destroyed when a gasoline lawn mower is turned on.
It's incredible how much pollution and noise one small contraption like that can generate.
Very very annoying.

Roomba repair - common problems

It's quite a while I play with Roomba.
Here a list of the common problems for these little robots (3rd and 4th generation) placed in the most probable happening order.

Battery

THE Roomba common problem is of course the battery.
On average, at least once per year, the battery dies.
It depends about the use of course, and contrary to the common sense, more a Roomba is used, more the battery last.
But as said, on average the battery last about a year.

NiCd batteries are lasting even less, mostly due to the "memory effect".
NiHi batteries are better.

Deck/motor

The second typical  problem that can happens to your Roomba, is in the deck motor or in the deck gearbox.
The deck motor is the electric motor that drives the brushes.
Typically the problems in these areas are happening when the Roomba entangle in wires or thick carpets.
When trying to remove itself,  more trust is placed on the brushes and if this happens often, after a while the mechanic can be damaged.
Actually there are different kind of problems that can happens to that area  :

1. broken motor gears
   The motor has a gearbox used to increase the torque.
   There are 3 gears inside the motor and they are made in teflon or plastic.
   The typical problem is that one or two of these gears, broken up, losing one or more "teeth".
   The final result is to have the motor spinning and  the main shaft not moving.
   It's enough to replace the gears to fix the problem.  Unfortunately  a new set of gears can cost more than the motor ... so often is more cheap to buy a new motor with a new gearbox (they come as single piece).
   
2. broken motor
   More rare but it happens that some internal connections broke.
   In this case the only thing is to replace the motor.
   
3. broken electronic
   The motor is driven by some electronic. Specifically a Mosfet is feeding the motor.
   Sometime, even more rare than the broken motor, is the electronics that fails.
   In this case "in theory" is enough to change the mosfet to fix the unit.
   Unfortunately it is extremely difficult because you need to take TOTALLY apart the Roomba in order to extract the electronic.
   Then you change the component and in order to test if the repair is correct, you need to put back totally the unit !
   It's about 2 hours work and if something goes wrong, you need to do it again !
   Unless to have a Roomba simulator , in order to test the electronic without the need to put it in a Roomba, is one of the worse case scenario for repairing a Roomba.

Also the deck gearbox can have problems :

1. broken gears
   Like the gears in the motor, the gears in the deck gearbox can loose teeth or broke down.
   Having other broken decks is possible to substitute the broken ones.
   
2. broken gearbox cage
   A couple of times I had to repair a gearbox deck cage broken.
   The gearbox cage is screwed to the deck and if broken can not keep the gears in the right place.
   Change the gearbox deck cage or the entire deck.

Wheels

The third typical problem with Roomba are the wheels.
The Roomba wheel is quite complex object. It is composed by four parts :

1. electric motor
2. planetary gearbox
3. sensor
4. tire

Each one of these elements can develop problems, but the most recurring problem is on the sensor.

The sensor is used to determine the speed  of the wheel and is very simple.

A special wheel with some openings is mounted on the main shaft and the light from an infrared LED can reach a photodiode only when an opening in the wheel happens.

The problem is that dust can, and does on time, cover the photodiode, so that become insensitive to the infrared light.

The result is that Roomba loses feedback from the wheel, starting to act crazy.

The phenomenon is well known as circle dance and usually cleaning the sensor solve the problem.
With some luck can be cleaned with compressed air, otherwise the wheel needs to be taken apart.

In all these years I own many Roomba, I never saw a planetary gearbox broken.
It is rare, but is possible to have tires used so much that the rubber is incredibly thin or the electric motor defective.

Repairing a Mickey Mouse Lamp - UPDATED !

My daughter has a nice Mickey Mouse lamp.
We bought it years ago and it worked nicely for many years, until "somebody" connected it to an X10 Lamp module.
After few times, the lamp stopped to work completely.
In this article I'm documenting the repairing process.

X10 - notes about the CM11A

WARNING !   X10 stuff is connected to the power grid !
If you don't know what you are doing, don't do it !!

YOU are responsible for your safety !

The CM11A 
 
The CM11A is a controller, one of the first controllers, used to create scenery and macro with X10.
Has a RS232 interface, to allow a PC to program the unit or use it as "interface" toward the X10 plant.
Was part of the CK11A kit, one of the first ActiveHome kits.

The problems

The CM11A always had some problems.
The most famous was (or is) the overheating.
There are tons of material about this problem, and also some solutions, like the one on the Ido Bartana website, devoted to X10.

Another intermittent problem, is related to some internal failures over the years.
Usually, every 5 or 6 year, a unit is expected to die.
Few years ago (was the 2002) one of my unit died, so I decided to repair it.
Now, few days ago, the unit I put to substitute the one broken years ago died as well.

So in this article I'm trying to collect the information to repair the CM11A.

The overheating
Sometime the CM11A suffer of a problem that become apparent with the total stop of any activity and a overheating of the unit itself.
Here an article that describe in detail what happens and a possible solution.


Unit receive, connect to the PC but not send any X10 signal
The problem, is related to a transistor that is connected to the transformer.
Since the unit is capable to receive X10 signals, we have to assume the transformer and passive components are alive.

Basically Q7 is the transistor that receive the X10 signal from the microcontroller and drive the transformer.
If this transistor is dead, no X10 transmission happens.
The transistor originally was a 2SD667 (Japanese transistor).
I replaced it with a normal high voltage NPN (I used a MPSA44 Motorola).
Open the box is extremely easy, is enough to unscrew the 4 screws at the bottom with a small Philips and gently separate the two plastic shells.

Here some pictures to help to identify the transistor in the circuit.

The transistor is close to the transformer metal enclosure, the one that became hot for the overheating problem.
I suspect that the cause of the death of such transistor is due to the overheating and the time.
The PCB close to the transistor is well cooked (not easy to see from the pictures, just believe me).

There is no need to detach the cables. Just gently extract the circuit bending the cables.

After the fix the unit restarted to work as usual.