RE: Analysis of Hobbyzone/Parkzone electronics
There's a limit to temperature. I doubt if you should go much above 800 degrees (F). The pc board will cook, and so will the components. I use a 700 degree tip. I don't think the solder goes completely liquid, but I have seen it look like it has sagged or wicked a bit. It looks dark or dull. But I see a lot of burned out FETS, so I might be looking at the remains of a smoke job. Still, constant vibration & heat can cause copper traces to come unglued from the circuit card at the feed through where the wire is. Then the feedthrough break off from the trace. I use a stiff resistor lead to patch this, bridging the trace & the feedthrough. A side note, re: FETs. I looked at all that ringing of the switched signal on the scope, and thought I could decrease FET switching losses by adding some resistance in the gate circuit. I put in 100 ohms, but it smeared out the waveform too much, so that was a bust. I doubt if a critially damped circuit would really help that much, anyway. I suspect there are much greater losses elsewhere. -n
Posted on: 12/5/2007 3:27 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=6717561

RE: Analysis of Hobbyzone/Parkzone electronics
My theory about why they goop it is that the solder joints around the FET and diode get hot, and the vibration from the prop could cause the wire's solder joint to fail prematurely. They form cracks, develop higher resistance, which generates even more heat, accelerating the failure. As far as healthyfatboy's question about a buddy box, I think I'll tear into one of the 5-AP radios & see how it differs from their older units. I've never had a buddy box, so I don't know what the connection is. Just the joystick pots? Maybe someone could help enlighten me. Re: learning to fly, I just got one of those Esky $20-$30 USB-based boxes running FMS. I added more models than the ones that come with. I now have the Aerobird Xtreme in simulation. I think it's harder to fly the sim model than the real thing! But I do a lot less running after it :)
Posted on: 12/5/2007 1:01 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=6717079

RE: Analysis of Hobbyzone/Parkzone electronics
Hello! After kicking off this thread a while back, I never imagined it would gather so much steam! Sorry, I've been offline for a while. Glad to see that Clint took the reins (quite capably). Clint, did you figure out you Aerobird 3 crystal problem? I'd like to do a tear down on on of those Aerobird 3's. Also, the Cessna, with it's new radio system. Anyone tackled that yet? Looks to me, from the pictures, that they went back to an integral servo/rx board, where the raw servo components are on the pcb. Just like the earliest Commanders! I also noticed that means if you get one off Ebay with a bad servo, you're not likely to be able to buy parts for it, but will have to buy a new rx. My last tear down was of a Megatech radio system. My write up of it on the forums was met with a big 'who cares?' :) As far as the Xtreme mentioned above, I have seen that problem before. But in my case, moving the wires was actually flexing the pcb, and that either opened or closed a connection on the board somewhere. Either a hairline crack on a trace, or a hair line of copper from an under-etched pcb, or a solder bridge, or a surface-mount component that looked fine but was making intermittent contact. My strategy was to look at the power going to the CPU and trigger my scope if it dropped out. If that looked OK, then I would look at the demodulated signal coming into the CPU and see if it was dropping out. Often, that signal would get garbled because of bad signal filtering at the last stage of demodulation. A solder touch-up usually fixed it.
Posted on: 12/4/2007 6:11 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=6713762

RE: Analysis of Hobbyzone/Parkzone electronics
That makes sense. The cap on the comparator positive input discharges after a second or so, drops to below 0.6V and the unit fires.
Posted on: 2/14/2007 4:59 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5419107

RE: Analysis of Hobbyzone/Parkzone electronics
I have a reverse-engineered schematic of the circuit, and yes, they do use an LM339 comparator. Pin 1 -GND Pin 2 - output signal Pin 3 - n/c Pin 4 - +Batt The output signal (connector pin #2) charges a 10nF cap through a 3.3K res. That signal connects to pin #5 of the LM339, the +input of a copmparator. The -input, pin #4, is held at 0.6V (the trip voltage) by a diode to ground and 4.7K pull up. The output, pin #2, discharges a 4.7 uF cap that recharges through a 2.2M resistor. So the circuit takes about a second to charge up to 0.6 volts and switch, then holds the output low for for about 10 seconds. The other 3 comparators in the LM339 are tied in parallel, buffering the signal and driving the coil (actually, pulling it to ground. The other side of the coil is at +Batt).
Posted on: 2/13/2007 3:28 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5413811

RE: Analysis of Hobbyzone/Parkzone electronics
I thnk the X-port signal is open-drain and just pulls a coil low that has the other end at +V. I'll see if I can find a schematic. I'm pressy sure you can do what you want to do with a PNP transistor.
Posted on: 2/12/2007 1:53 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5407917

RE: Analysis of Hobbyzone/Parkzone electronics
Re: There are framing pulses, data pulses, and an overall framelength. Are these parameters conserved across 3-ch hz/pz radios? It would be a good thing to know. From the transmitters I've looked at, I've seen little if any difference in circuit boards. Until you get to the Typhoon. That appears to be a 'standard' radio. Has anyone seen the latest Stryker? Does it use the old PZ radio or the Typhoon one? When PZ went brushless with the Typhoon, they broke out the ESC onto another pc board, so I was wondering how they did it with the brushless Stryker. I'd be surprised if they redesigned the regular PZ rx to handle brushless. BTW, when those Typhoon brushless ESCs blow, it's quite a scene. Components (like the CPU) get desoldered from the glowing pc board and fall into the fuse.
Posted on: 2/7/2007 7:01 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5385760

RE: GS Rasing r25mt Sut Engine specs
I found my answer on Radio Control Zone: from: nitro syco Member Join Date: 12-19-2004 Location: santa barbara Posts: 171 For things other than piston and sleeve, check the were the rod connects to the crank, if it has lots of play, it should be replaced. to take out the piston/sleeve take off the head, first take everything off such as exhaust, head, and pullstart, carb, and clutch assembly can stay. now that you have all that off it is time to take the sleeve out, some are easy, some not first try to pull it out by putting your finger in the sleeve and pulling it out, if this does not work rotate the flywheel so the piston is at BDC (bottom dead center) and stick some zipties or something else soft and clean into the exhaust port and rotate the flywheel so the piston pushes up on the sleeve untill you can pull it out. now take the rod off the crank by wraping the zipties or somethng else behind it and pulling, some come out a lot easier and this is not needed. then the piston and rod can come out the top of the motor. I do not think I missed anything here but I may have, if something is not working, do not force it, nothing should be forced, if something is not working post here again, note the way everything comes out, note on the hole in the bottom of the rod, everything should be clean, dont let any dirt into the motor.
Posted on: 2/7/2007 6:43 PM by Author "khalsans" in the forum "RC Monster Trucks"
http://www.rcuniverse.com/forum/fb.asp?m=5385651

RE: GS Rasing r25mt Sut Engine specs
I just got on of these engines, and it need rebuilding - almost no compression. I'm not sure how I pull the sleeve, and I could use tips on what else I should replace besides piston & sleeve. Any instructions on how to rebuild this engine? I could not find any at the SH site. Thanks. -NSK
Posted on: 2/4/2007 11:04 PM by Author "khalsans" in the forum "RC Monster Trucks"
http://www.rcuniverse.com/forum/fb.asp?m=5372212

RE: Analysis of Hobbyzone/Parkzone electronics
I have not seen a Super Cub on my dissecting table yet, but it's a pretty safe bet that the radio the same basic circuit that HZ/PZ uses everywhere else. I have only seen one instance where a really old Aerobird (pre-ABC era) did not work properly with a PZ transmitter. In this case, the data pulses where a bit too long and the Aerobird got confused. Note that the 2-channel HZ radios are never compatible with HZ/PZ 3-channel ones, but that's not your situation. And when I flip the toggle switch on top of the PZ transmiter (if it has one), the HZ ABC/ABX receivers don't like that - I used a P-51 transmitter with an ABC but I had to keep the Rate switch off. Then, there is the issue of V-tail vs rudder/elevator. The PZ receivers I've seen hae a jumper on them to select between the two. The microprocessor in the receiver will do the V-tail mixing. I'd say your chances are good unless the Super Cub is some new generation in HZ/PZ radios. But they usually just build on the old. Anyone else looked at the Super Cub? -nsk
Posted on: 1/28/2007 2:42 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5335950

RE: Analysis of Hobbyzone/Parkzone electronics
RE: SMT soldering I use a lot of body English, and I have to hold my tongue just so. Actually, I usually don't hold my tongue well enough after an attempt! I do work under a magnifier light. My iron is just an old Weller contant-temperature model with a fine tip. I use my regular 700 degree tip, but I wonder if I should change that for SMT? I use my regular resin-core solder, 63-37 (eutectic). -N
Posted on: 1/25/2007 3:45 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5321966

RE: Analysis of Hobbyzone/Parkzone electronics
Not bad looking at all! I had a board with 2 bad servos and I replaced all transistors with TO-92 parts. They just don't fit - I ended up with so many shorts that I'm stripping them off and going SMT. The Transistor Santa sent me some SMT parts (thank, Clint!) so I might as well give it a shot. -Noor
Posted on: 1/21/2007 11:44 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5303337

RE: Analysis of Hobbyzone/Parkzone electronics
Thanks, Clint, for taking over as chief mentor. I don't get online here as ofter as I'd like. As far as using PZ/HZ electronics in other birds, here's some examples that I submitted: http://www.rcuniverse.com/forum/m_4426802/tm.htm Just remember that you can't use regular servos, only PZ servos. Unless you gut the servo and run the wires from the motor and potentiometer back to the receiver. This has worked for some servos. It's a pain. And, as Clint suggested, test the electronics before installing! Throw it on the bench, make the servos move and run up the motor using the transmitter. After a crash, servos can have stripped gears, and as Clint pointed out, a stuck servo can take out the servo drive electronics. I've done this more than once. Once should have been enough, but some of us are a bit slow... In regard to the dead receiver (servos not centering), this still might be a crystal, but the CPU's crystal. Actually, it's a ceramic resonator, but I've heard of it failing in a crash. These are available from Digikey, I believe. A bad ceramic resonator would be hard to determine with just a DVM, though. So Pilotchipmunk will have a tough time on his own, I'm afraid. Just send it to Clint :) -Noor
Posted on: 1/14/2007 11:36 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5266949

RE: Analysis of Hobbyzone/Parkzone electronics
If it crashed hard and is now dead, there's a good chance that the crystal is bad. They often fail when thumped hard enough. But mucking with the little silver box probably made your job harder. - you'll need to set back the way is was, if you remember. I've been told that the the ceramic filter (the little black box with the number 455 written on it) can also fail on impact, but I have not seen one do that. And I agree with Clint - darn hard to find a bad crystal without looking at it with a 'scope. The only way I can think of is to use a trick I used as a kid - set my shortwave radio to the crystal frequency (it's in the CB band), put the radio's antenna wire on the circuit and listen for a carrier signal coming from the crystal oscillator. I've not tried this with these Hobbyzone radios, since I'm old & rich now, compared to those days: I own my very own scope.
Posted on: 1/9/2007 11:42 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5240617

RE: Analysis of Hobbyzone/Parkzone electronics
Hard to believe that they cram all code in one chip! The signal encoding is PFM vs PWM for 2-channel vs 3-channel. A little more history: The early Commander pcbs had a different CPU, narrower than the present package. They also had a 3rd IC that I never made effort to identify. Then they redesigned to use the CPU used in the ABC, but still retained the old open servo design of a large plastic gear assembly and an uncased motor. Newer Commander 2 uses a regular servo. Now they use the extra CPU pins for their ACT. I wonder how they differentiate now between Commander 2 and Freedom, which has the same pcb. Perhaps they look for the presence of the second servo.
Posted on: 12/26/2006 12:04 AM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5161732

RE: Analysis of Hobbyzone/Parkzone electronics
I tried replacing servo transistors with regular 2N22, 2N2907, but I can't sqeeze them in without creating solder shorts, so I'll try SMT parts next. I still have a Freedom with a bad CPU. The failures that I have seen lately run like this: 2 ABXs with bad solder joints around the FM detector 1 Commander 2 with a mis-soldered battery wire 1 Commander 2 with a bad battery connector pin 1 Freedoms and 1 ABX with faulty servos and blown servo transistors 2 ABX with burned Motor FETs or diodes 2 Typhoons with ESCs melted down to mush 1 Stryker with a bad crystal 2 Freedoms with bad CPUs -Noor
Posted on: 12/20/2006 12:11 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5139204

RE: Analysis of Hobbyzone/Parkzone electronics
"They basically had no idea what these extra switches and outlets can be used for and supplied me with zero answers." All PZ/HZ planes sold in the US come from the importer, Horizon. They are nices folks, but there's no tecnical assistance available from them; they are purely administrative. The DOAs go to HobbyDealsUSA. Nothing gets repaired at Horizon. HZ/PZ is market-savvy - they hire consultants to do market research. You may have seen one of their surveys. I have received two this year already. But they are not appoachable beyond a certain point, technically speaking. But they keep on their toes: If you list one of their planes on Ebay and copy text from their website such as plane specs (admittedly, violating thier copyright), they will have Ebay pull the listing and you will not be asked about it first. So I have a love/hate relationship going with them :) The manufacturing is done in China. Where is the engineering done? Is it done here, contracted out, done overseas? I think it is done in Hong Kong or China. So I think we're on our own. Keep on hacking!
Posted on: 12/17/2006 3:59 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5127198

RE: Analysis of Hobbyzone/Parkzone electronics
Well, I guess it's time I cracked the cover of the Typhoon tx in the pile of projects. My guess is that the extra switch on the tx works the aux output of the rx. I don't see PZ implementing a trainer mode, but sometimes they surprise me.
Posted on: 12/15/2006 6:21 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5120670

RE: Analysis of Hobbyzone/Parkzone electronics
THere are 4 pins for 2 jumpers and on the newer board, a 2 pin jumper behind it for LiPo battery cutoff. The jumpers are documented in the P-51 manual: J1 [closet to the board edge]- Flight Trak (slight mix of elevator & aileron (beginer mode) J2 - V-tail mixing J3 - [second row] LiPo cutoff. If you notice no difference on J2, then perhaps the Slo-V firmware is different. I would be surprised. But if you change the jumper, you probably have to cycle power before the CPU will read it again.
Posted on: 12/12/2006 10:09 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5109167

RE: Analysis of Hobbyzone/Parkzone electronics
Clint, I think you ought to share here what you found out and PM'ed me about the servo drive 'FET's. -Noor
Posted on: 12/7/2006 11:46 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5089271

RE: Analysis of Hobbyzone/Parkzone electronics
Yes. the FET does go 100% on at WOT , and at 65mV drop acros the FET, I'd think you would do better by improving the batt. conn. or wiring. Is there a brushed motor with less mechanical friction or more efficiency that's worth using here in place of the stock motor? I had a Freeedom that came in with a bad motor. Winding resistance checked out fine - no shorts. But the thing just ran hot & slow. I couldn't feel any drastic increase in mechanical resistance, but when I swapped the motor, the smoking stopped. I asume it was crappy bearings. BTW, the armature only has 3 poles. So I can believe that timing adjustments make a big difference.
Posted on: 12/6/2006 11:29 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5085262

RE: Analysis of Hobbyzone/Parkzone electronics
I tried an NM3357 for the RF IC once. It did not fix the problem, so I can't say for sure that it works, but it looks like it should. The IRL2203 could work, but make sure it is low-threshold. If the gate is being driven high by the CPU instead of a pull-up resistor to battery, then it might not turn on hard. The technical term used is 'hard on', (really), but this is a censored site :)
Posted on: 12/5/2006 5:53 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5079443

RE: Analysis of Hobbyzone/Parkzone electronics
Turns out it was not the FETs as far as I can tell, but a bad pin on the CPU - no drive signal to the FET. So perhaps it not so uncommon for these chips to lose I/O pin functionality. And yes, no stall detect. If you get a plane from HobbyDealsUSA that's listed as having a bad servo (I have), expect the FETs to be damaged as well (I have). This scenario is just as frequent as having a stripped servo from a crash, but a lot more work.
Posted on: 12/4/2006 12:28 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5074103

RE: Analysis of Hobbyzone/Parkzone electronics
I had assumed that they only used one mask, but if they only have 2K ROM, and they are using a chip that has no bit-boolean instructions, then they may well need all 2K for each type of plane. Even with hand-crafted assembly code, they probably had to jump up & down on the chip to stuff all that code under the hood of a 2K chip. I have a Freedom with almost the same symptoms & I'm stuck. I think I'll put an ABC rx in it. Critterhunter sent me some bad ones & I salvaged one. I also have one from that batch with a servo that turns only in one direction (CW). Now I have to figure out which FETs are bad.
Posted on: 12/3/2006 8:22 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5071602

RE: Analysis of Hobbyzone/Parkzone electronics
[quote]Interesting long term solution for the lack of replacement CPUs would be to replace the proprietary microprocessor with a flash programmable PIC [/quote] I was thinking the same thing, but I'm no PIC person. I'd do it with the TI MSP430. It's 16 bit, has register-to-register ops (basically, 16 accumulators), super low power (sleep mode is like 1 uA). Hard to back to 8 bit, too spoiled now:) But all the code I've gleaned from the web for ESCs is all written for PICs. One of my coworkers burned code into a PIC and made his own ESC a couple years ago. I remember seeeing some interesting timing tricks in the source code. I thought I had some servo FETS, but I can't find them. I guess I sneezed the last time I had them out. So perhaps I could use a few. So I suppose I could part with my Freedom rx. PM me an address & I'll get it out. -NSK
Posted on: 11/28/2006 10:58 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5051973

RE: Analysis of Hobbyzone/Parkzone electronics
[quote] All the signals look OK but it does not respond to PWM signals. All signs obviously point to bad CPU but at least in my experience, internal CPU errors are relatively rare except on I/O lines Small brain flash - the PWM signal is brought out directly to the XPORT connector - which also has +B. If +B got connected to the PWM signal line it may have fried the PWM input on the CPU.'[/quote] I would bet that there's a bad I/O line - on the rx that I have with the Parkinson's disease in the servos, I see a trace that looks like it got hot, & it goes into an A/D line. I think it was a dumb idea to run an unprotected I/O line to the XPORT. Cheap, but risky. At least the CPU looks easier to rip out that the RF IC.
Posted on: 11/28/2006 6:50 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5050810

RE: Analysis of Hobbyzone/Parkzone electronics
2. Do you need any small parts from DigiKey? (I am about to place an order for some P and N channel FETs for a receiver that has valid gate drive signals but the servo motor is not being energized. I will also pick up one of the motor FETs) I'm well-FETted at this point, thanks. Now, a source for crystals would be a big help! As you might have noted from my Megatech analysis entry, not all rx xtals w/455 KHz IF are the same. I don't know if it's a series vs parallel xtal problem, or what.
Posted on: 11/28/2006 6:43 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5050774

RE: Analysis of Hobbyzone/Parkzone electronics
I just finished putting an ABC rx in the Freedom that I have been working on. No ACT, but I'll just have to live with that...(sniff) The original is missing the FM demod IC. I stuck in what I thought was a replacement, still got no mixer signal out. I was waiting to get up my nerve to replace it one more time. Perhaps I should give it up so you can rip out the CPU. Also, I fixed an ABC once with a Parkzone rx. I cut out a pc board (protoboard) to hold the 2 servos, and ty-wrapped the rx onto that board. I little bit heavier, but not too bad.
Posted on: 11/28/2006 6:35 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5050732

RE: Analysis of Hobbyzone/Parkzone electronics
Perhaps I have the wrong jumper. There is a jumper for LiPo on the Parkzone rx, but it is documented as such. But the same board is used in the Commander 2, so maybe they just use a different firmware? And yes, the pin with the RC on it is reset. If you pull it low, the servos will recenter as on power-up. At least, that's what I found on the old 2-channel boards.
Posted on: 11/28/2006 12:29 AM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5047858

RE: Analysis of Hobbyzone/Parkzone electronics
RE:HMS87C1104A . I looked more closely at the data sheet for this chip and I think I figurered out it's lineage. Long time ago when 8-bit dinasours like the Intel 8080 ruled the earth, Motorola came out with the 6800, and Rockwell followed with a similar chip, the 6502. It was popular in the late '70s in the KIM-1 and SYM-1 kits. Rockwell apparently licenses the core cheaply, because years later I saw it being manufacturered by Winbond, a Singapore company. Hynix apparently made a microcontroller using this core. It makes sense that a Chinese company like Parkzone would use a chip made in the Far East rather than Chandler, AZ (PIC HQ). And Parkzone is definitely an off-shore company - I've never been able to get technical assistance from them. I don't think they ever answered an email from me! Their exclusive importer, Horizon Hobby, is full of nice folks, but they are not techical, just administrative. THis stands in sark contrast to my experience last week with Megatech. I was being brutally honest in an email conversation with one of their staff about their products. Turns out I was talking to the president of the company. Oops.
Posted on: 11/26/2006 8:06 PM by Author "khalsans" in the forum "Park Flyers & Backyard Flyers"
http://www.rcuniverse.com/forum/fb.asp?m=5042300