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I have just complete maintenance of first one DC motor and I thought to share few pictures of the internals and mechanical details.

I had to perform some correcting actions (treatment) at motor collector and brushes, I think that I did remarkably well made job.  ;)
2
(For Firmware downloads from GW Instek web site you need to register for VIP account.)
Latest Firmware Version 1.14  11-1-2017  For GDS200 & GDS300 series.

http://www.gwinstek.com/en-global/products/Oscilloscopes/Digital_Storage_Oscilloscopes/GDS-300_Series


Changes Log

Version 1.08
1.Russian language support.
2.Fixed a Korean input method bug.
3.Fixed a calculator app bug when tap ΅§ = ΅¨ key at first.

Version 1.09
1.Added environment temperature  parameter adjustment function for the DMM temperature measurement
2.Added DMM division switching safety mechanism
3.Added the "Cursor Link" function

Version 1.10
1.Modified the DMM maximum/minimum calculation mechanism.
2.Fixed the DMM trend plot display issue.
3.Improved the response time of the DMM Continuity function.

Version 1.11
1.Fixed the remote command for the save waveform file format

Version 1.12
1. Fixed the trend plot update issue

Version 1.13
1. FT5x46 touch panel controller supported

Version 1.14
1. Added Advanced DMM screen lock function.
3
Double horse 7000 7004 7008 receiver circuit board PCB which I have, this must be one of the very first produced ones at about 2010.
My transmitter PCB this has stamped the date of 2010  :) 
Therefore both has identical age.

Receiver PCB this is named as CL-SM024R and this is compatible for DH 7000,7002,7003,7004,7006 .... DH7008 was a later and last production.

Hopefully for me, specific PCB this is made by thru hole parts, and this detail makes it easily repairable.
I did discover that this boat it did had an electrical issue at left turn command, both motors was operating with out the second to lower it speed as much as needed.
At right turn (transmitter) command, the second motor it did lower it rpm (we can turn)  ;D.
My inspection show water damage, one inserted water drop this shorted temporarily one 1N4007 diode at the top side of PCB, and this event caused permanent failure at the diode.
No I am aware of why this boat was sent to trash by it first owner ...  ;)

Also I did noted that at End-stage MOSFETs, nearby resistors and capacitors was undersized regarding Watts and precision, and I am now replacing them with better ones.
Old resistors are now replaced by Vishay Film metal at 0.1% ( 100 Ohm & 10K Ohm).
Generic 104 ceramic capacitors was also replaced by higher quality ones.
Practically I am aiming about getting true equal power from both MOSFETs, by all these component level improvements. 
At my pictures I did upgrade components around first MOSFET and the second still has stock components (Before - After comparison).

Now due the fact that named as 380 type DC motors that SYMA was delivering with the boat, they are not up to specifications of RS380 vacuum cleaner motor, what they did was to use on their first receiver-controller MOSFET parts of medium wattage.
Later on they did produce for these boats a newer version of receiver-controller this having higher power MOSFETs (last picture), even so there is not stock available even from that.
 
Practically it is possible to increase power output of any older SYMA receiver-controller by using MOSFETs output (as is) so this to drive two other higher power N-type MOSFETs (at additional PCB circuit), and these will feed any better higher-power DC motors.
 
My own goal for now this is to keep all electronics as is, but perfectly working.  :)
4
Before I get to more technical details regarding maintenance, I like to say few things about these boats.

First of, I did verify that entire series of such  7000 double horse RC boats this is discontinued from China, and few warehouses they still have some stock.
Therefore I am not recommending to any one about making a buying decision because of this topic, this topic is here about actually helping the stubborn people  :) whom refusing to trash there boats and they seek some ideas of repairing them.

Common complain of other owners and I am included, this is that most to all DH7000 boats they suffer from serious product design issue regarding waterproofing at the top cover.
Practically these top covers they are made by thin plastic, this could easily deform due heat (my own it is deformed too), deformed top cover creates caps which them will allow water to get in and cause corrosion at metal parts and motors.   

Metal screws in these boats these are: M2.6mm Pan Washer Head Flat Tail Phillips Self Tapping Screws.
All screws at my boat were rusted and I did order from China replacement ones of 304 Stainless ones and 100% identical regarding screw design with the old ones.
 
Propeller axle issues: propeller axle this is 3mm but at the end point (screw for propeller installation), axle becomes even thinner and it can easily deform in case of an accident mostly in the land, if the boat has a free fall over the floor (careless handling).
Such spare-part they are not easily available, eBay it is almost empty, and even if such spare parts are found in China, they are extremely overpriced at 25 Euro, when entire boat this has a pricing of 50 Euro. 

Electric motor 380 type:  All descriptions about this motor they refer to 380 Type simply because this is not a regular RS380 motor.
Actually they are at least seven variations of RS380 motors with different specification.
In China they are at least ten factories making copies of RS380 motor that possibly first product designer this could be MABUCHI MOTOR CO., LTD in Japan.
How ever,  SYMA or Shuang Ma they did their shopping from unidentified factory, and at such DC motors: speed - torque - consumption, they are very specific. 
About DC motor details I will write a specific (chapter) in this topic, because a wrong motor replacement it would burn the electronics inside the RC receiver.   


Bellow they are pictures of entire DH 7000 series of boat models.
5
This a quick presentation of my own project, this based at this battery holder design at 4x version.  :)

I wanted to have one test bed for capacity testing of new and used 18650, and I made this DIY design.
a) This is able to use simultaneously four 18650 connected in series for DC Load tests (capacity inspection). 
b) By the use of eight switches at my circuitry I am able to charge all four cells by them be connected in parallel.
c) Wiring and switches are capable to handle up to 6~8A with out issues (specific switches has double set of contacts which I did bridge them).
 
The benefit by adding these eight switches, this is that you do not need any special charger with balance r circuit, in parallel connection changing this easy by any reliable single rail PSU this having CC  ( constant current) mode.

Naturally I could add one Lithium 18650 controller,  but I did made such a power bank at 2014.
Kiriakos New Project: 14.4V 4S 12A Lithium Battery PCB with SII IC

Therefore this is strictly an 18650 test bed.   ;)
6
Double Horse 7008 - RC boat – Engineering and Technical introduction

DH 7008 RC boat Engineering principal this is that driving and maneuverability it would be performed solely by motors thrust.
Such design requiring both motors to be in identical condition and regarding delivered performance.
Regarding electronics product age, my own 25MHz remote control PCB this was produced at 2010.
And now I can assume that also receiver PCB (inside the boat) this has similar age, this information does not translates that this is a bad thing, I am just recording here history facts.

Practically they are several reasons that would influence equal delivery of thrust at those propellers.
a)   Mechanical condition of both motor
b)   RC receiver PCB and actual delivery of power (electrical issue)
c)   Problems caused due propeller shaft condition – corrosion damage (mechanical issue)
d)   Uneven lubrication inside its one propeller shaft tube
e)   Poor assembly at the factory of end piece of (propeller shaft tube) holder.
f)   Damaged propeller

Now all technical information that I am going to add here over time (please bookmark this page) will be for the Dad or any person that he likes working and restoring RC models by having an large tool box, lots of patience, plus he is able to do precision work regarding parts assembly and him is also aware of basics about electrical circuits and electronics.

I am Kiriakos Triantafillou from Greece, I am 48 years old industrial electrician, and in my youth I did have experiences about flying models (airplanes) made of wood.
Therefore I am not a total stranger to RC modeling world.

You are now at ITTSB Blog.
This is an internet project that I am performing evaluations of best electrical test and measurement equipment's.
Due the fact that I own a huge quantity of high quality multimeter and even oscilloscopes,  and due my significant  skills in electronics, I am capable to diagnose any electrical issue that an RC model could have,  RC model this is a scaled down in dimensions electrical machine.
I am more than good at working with machines’, and electric motors they are my children’s that I look after all my life.

Double Horse 7008 - RC boat this EOL (End Of  Life) product, Shuang Ma or Syma or what ever this factory in China it is called, they have abandoned these products.
Therefore I am willing to offer a bit of professional help to anyone whom likes to restore and bring back to life such RC boats. 
Therefore please consider to make a PayPal Donation at my Blog if you do get helped by all those posted information’s.

 
Today I am posting pictures those demonstrating details relative to propeller shaft tube.
7
We use to say Think Green but few ideas comes in mind about reusing old items by converting them to something useful. 

Today I am going to present an exclusive Made in Greece  by Kiriakos, a new product design.  8)
This is a DIY converter for charging TAMIYA 7.2V RC battery or 9,6V or 12V  NI-CD packs of RC models.

Bosch AL60DV this is an remarkable True Pulsing charger for Ni-CD and major advantage this is that cells remain cooler at charging duration in comparison to constant current chargers (CC mode).

Pictured Bosch battery this is now an empty box, internal cells came to their end of life, but the box as you can see in the pictures below, it was converted in to a adapter this be compatible to old TAMIYA charging system.

Bosch AL60DV has thermistor sensing capability and if this charger sense that there is no thermistor inside the battery pack, then there is no Go about charging.
Therefore I did kept original thermistor in place,  then I added one cable with TAMIYA 7.2V RC connector, and additionally I did added two spring loaded contact points ( 2mm hole diameter) and this is a voltage measuring point, or alternatively this can be used as another DC volt output, and connection will be made by simply attaching wires.
 
Personally I am very happy, because very recently I got as gift a used  RC racing speed boat and this came with out charger.
Now I am able to use my Bosch AL60DV for both, and my rechargeable drill and also my boat  ;D ;D
 
8
Very nice deck. I have a similar model (AIWA AD-F810) full functional, since 1993.
The only trouble it has , all of those years was an idler replacement and a belt set too.
Unfortunately its hard to find nowdays service parts for cassete decks, so I must be lucky because I own a spare idler (I had bought 2 pieces)
Ιn my opinion , 90s was the "golden decade" for HiFi equipment.
9
Double Horse 7008 by ShuangMa or SYMA - RC Boat, this is economy version but Fast RC Boat made to please mostly dads.  :)

I got as gift from a friend one Double Horse 7008 boat this be also known as Bluestreak (Blue streak) due the name written over the decoration decals.
At past 10 days I did a very in-depth research, so to discover any related information about the whereabouts of these brands and also about spare parts and technical documentation about proper maintenance of this RC model.

This topic expected to become quite long:

a)  I am going to share history facts about DH 7008 ( This seems now to be an 10 years old production ).

b)  Maintenance information for this DH 7000 family of boats ( 7008 7007 7004 7002 RC Speedboat )   

c)   Detailed analysis of electrical circuit - DC motors consumption - Over all consumption.

d)  Correct DC motor replacement type, by one from the real RS380 motor from Mabuchi product line.

e)  My own pack of suggestions for any one interested to for improvements which them will increase such products life cycle.
 
For now I am going to demonstrate few pictures of my own Double Horse 7008, and of my new DIY home made ( dry parking ) spot for maintenance - repair and storage.  ;)
10
This is one follow-up regarding thermistor sensing ability of AL60DV:

By using 1051 Resistance Box (Times Electronics UK) as this to behave as thermistor resistance simulator, I did manage to discover Low & High limits.
Low or High limit, this is a resistance value that internal battery thermistor could be at, and also here is where AL60DV this gets alerted and refuses to operate ( start charging).

Overheat alert: This found to be approximately at 2.1K ~2.2K and I am using the word approximately because there is small influence from the actual temperature of the charger it self.
I do not keep my chargers plugged at Mains when they are not needed, therefore when I am up to using them they are cold, from the other hand when a charger is plugged all day long, internal temperature could be 10C above ambient. 

Frozen battery alert:   This found to be at 23K Ohm.
I am mentioning this just for the fun of it,  I am not living in Siberia to worry about : Frozen battery alert  ;D

By all this knowledge that I have now, I can safely come in a conclusion and this is that any thermistor when this is at working temperature of 50C and this can have 2.2K of  resistance, then this is suitable for operating with an AL60DV.   :)

More Bosch thermistor comparisons will follow later on when I will receive new PHILIPS thermistor's from Taiwan and also two genuine Bosch batteries (with dead cells) that I got from Germany. ;)
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