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Inside the Hitec HSR-5995TG
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m_kanter



Joined: 19 Apr 2006
Posts: 31

PostPosted: Wed Jun 14, 2006 8:13 pm    Post subject: space between motor and housing? Reply with quote

some servos have their pcb directly soldered to the motor leads.
my question now ist if we can solder the pcb on any ""servo-style""
(my question aims to hs 645 and to hs 5995) where on the fotos on this page it looks like the motor leads will touch the bottom of the case (at the first foto of the hs 645 the brown cable is squeesed (flatened))

is there space the place the pcb there? then we get about 3mm pcb length...
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mpthompson



Joined: 02 Jan 2006
Posts: 650
Location: San Carlos, CA

PostPosted: Wed Jun 14, 2006 8:26 pm    Post subject: Reply with quote

Did anyone notice anything peculiar about the RX/TX line.

Colin, it is an interesting circuit. Obviously it's to use the RX/TX lines in the USART over a single line, but I don't have enough analog circuit experience to understand how it works. It looks like it would be simple to build a quick prototype to understand the nature of the circuit. Also, I would be curious to see what hardware assist (if any) they get from the AVR to measure PWM width when operating in PWM mode.

I've heard about people putting these servos in serial mode to control their operation. I'm not sure if they are designed with this in mind or what limitations there are. Here is a document that discusses what has been learned about operating these servos in serial mode.

I'm still partial to using I2C for OpenServo control. It's simple to interface to, support is built into the AVR and it has some nice characteristics. However, it would be fun to build a serial, PWM or analog version of the OpenServo as has been discussed in other threads.

-Mike
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m_kanter



Joined: 19 Apr 2006
Posts: 31

PostPosted: Thu Jun 15, 2006 7:56 pm    Post subject: rx/tx line Reply with quote

waiting for an answer to my previous post, i'm trying to explain the RX/TX circuit:
* to receive the transmitter has to be disabled and the transmitter line has the be pulled manualy high.
- then if the rxd input (at the header) is low, then current flows trough the basis of the transistor resulting in opened collector - emitter direction pulling the rxd of the avr low
- then if the rxd input (at the header) is high, the transistor is closed, but the internal pullup and the diode between collector and basis pulls the rxd input of the micro high
* the transmit the receiver has to be disabled and the reciver pin has to be pulled low manually. then the same happens as above

at the other end of the line there should be an pullup of about 10k. the zener-diode d1 may has an value of 5.1v or 5.6v to protect the ports of the avr.

in hope for some more pics (with measurements) of the servos
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mpthompson



Joined: 02 Jan 2006
Posts: 650
Location: San Carlos, CA

PostPosted: Thu Jun 15, 2006 8:59 pm    Post subject: Reply with quote

my question now ist if we can solder the pcb on any ""servo-style""
...
is there space the place the pcb there? then we get about 3mm pcb length...


The current OpenServo PCB as shown here is best suited for servos where the PCB is soldered directly to the motor. In the case of the HiTec HS-645MG that board won't work. However, it is very easy to modify the PCB layout as shown below to fit into a halfsize board suitable for the HiTec HS-645MG.



The ExpressPCB file on the Hardware page does include the half size boards. Because there are so many different potential servo hardware that can be used, I really intend for the current PCB design to be a reference design that is custom tailored by the end user for the specific servo hardware they is using. For instance, in my robot I'll be using HiTec HS-475HB servos and I'm making minor changes to the PCB to better fit that specific hardware.

Note: To my knowledge the HiTec HS-645MG has not been tested with the OpenServo hardware and I cannot vouch that it will work with the current OpenServo hardware design. Note the motor on this servo has three leads, but the motors I have tested with the OpenServo with so far have only two leads. I presume the black lead from the motor is connected to ground, but I can't be entirely certain without trying it out myself.

-Mike
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kombos



Joined: 26 Oct 2009
Posts: 1

PostPosted: Fri Oct 30, 2009 12:02 am    Post subject: Hitec 5995 Failure Reply with quote

I have two 5995s that have failed.

The first uses the IRC7389 ICs and it looks like one of the ICs is overstress damaged at the source1 aand gate1 pins (or that corner of the part).

The second uses the 9958 ICs and the metal power PCB trace leading from the red wire is fused open.

Can anyone comment on these failures and suggest the cause. I understand from Richard Ibbotson that the 9958s will usually fail secondary to the motor overheating and shorting.....but what about the metal trace fusing?

Are the IRC7389s prone to failure while the motor is still ok?

I appreciate any info you may be able to provide. Was hoping I might be able to repair one or both of these.

Thanks......
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