Briggs and Stratton 21HP Won't Crank Over

My Grandparents new lawnmower refused to start, it would crank part way over and the compression stroke would stop it. It was under warranty, so Sears sent a guy out, it wasn't the valve adjustment, starter, or anything simple, so he came back and put a new engine on it. We've got a broken cub cadet, also my grandparents, that had a Kohler Courage which cracked the engine case after 2-3 years! I told them not to buy another one of those! But the Briggs didn't survive 6 months! The repairman didn't need the old engine, so he didn't mind leaving it for me to try to fix.

Specs

• 21HP Briggs and Stratton
• MFG in 2012
• 331877 - 2371 - G5

Pictures!

Top

Insides

Here's the problem, the compression release weight has failed.

Camshaft and compression release weight

It's made of some sort of cast metal! The hole for the shaft is 1/2 the thickness of the actual weight! What are you thinking Briggs? At least machine it from mild steel, then it wouldn't snap!

Broken compression release weight

Well that's the problem, a new camshaft will cost ~$80, but if it has the same cast weight on it I don't know that I want it! I'm not sure how to proceed at this point. I could try grinding one out of steel, but that's going to be a job.

UPDATE: We decided to go ahead with the new camshaft. It's installed on the Cub Cadet and still working as of April 2015.

Linux Mint 15 and Amazon Video (This also affects other video sites)

I just bought a new drive for my HTPC, A 3tb WD Red, but that's for another post. I had Amazon video working on Mythbuntu (just had to install HAL) but installing HAL on my (fairly) fresh new Linux Mint 15 install didn't work. I finally figured it out, with some help of course

What I've found:

1. Amazon's error is completely useless. It makes you think that you have the wrong version of flash.
2. If you haven't already, you need to install hal and libhal1 "sudo apt-get install hal libhal1"
3. Adobe has a guide for sorting out these problems once you figure out it's DRM related. Here the test page was the most helpful.
4. The test page gave me the cryptic error 3322 - device binding failed. 
5. I tried the solution found here, "rm -r ~.adobe/Flash_Player" it didn't work, but was needed later, after I actually fixed the problem
6. It turns out HAL wasn't starting, I ran "sudo hald --daemon=no --verbose=yes" it spat out a bunch of errors and died. I found the solution here, I'm not sure it's a perfect solution, but I ran "sudo rm -r /etc/hal" then "sudo ln -sn /usr/share/hal /etc/hal" and HAL runs! I think I will copy rather than link it at some point, but that's what I did.
7. I rebooted and the test page still doesn't work, I had to do step 5 again, now it works.

Whew, only took me half the night to figure that one out.

Notes:
I tried this on Linux Mint 14.1 and just installing HAL worked, I couldn't reproduce the problem on 15 by removing the /etc/hal directory. It's possible I corrupted something at some point, I'll try on a clean Mint 15 install sometime and report back.

I also got a 3323 error while HAL was broke, also fixed with #5.


Update: Only steps 2, 5, and 6 are necessary to solve the problem, the others are either diagnostics or irrelevant. (Thanks Douglas Roberts!)

Update 2: This affects other sites (Thanks NikAmi!), I don't really have the time to determine which ones myself, so I'll do a list and update it if anyone finds one that needs it (Post it in the comments). It may help someone else.
Known Sites Also Affected:
NBC Sports

Update 3: There is a package available (at least in Arch Linux's AUR) called HAL-Flash that lets you play DRM Flash content without needing the HAL package / daemon. I'm using it on both my laptop and HTPC and it seems to work fine.

Update 4: Chromium no longer supports NPAPI (netscape plugin API), pepper-flash doesn't work with protected files. Firefox still uses NPAPI and works with Amazon Prime Video. HD doesn't seem to work for me, but SD works fine. I'm not sure why.

RobertShaw HS780 Teardown

I recently replaced a old furnace with a 90+ for my father, I don't recall the make or model of the old furnace, but I salvaged some parts from it to look at. Today we have a Robertshaw HS780 Hot Surface ignition control. The furnace was working, so there wasn't a failure to fix, but it may be of some interest.

RobertShaw HS780

If you watch the video be warned, It's my first attempt at an ad-lib teardown. I kept talking as I figured out the board and was a bit off. It's not bad, hope to do better next time. I think the left small relay is the gas valve, the right one powers up this board when the thermostat closes.

Top

Bottom

By far the most common failure on HSI ignition systems is the ignitor (not this control). They are fairly fragile. Never touch the heating part, it could cause early failure.

Diagnosis would go like this:

• 120VAC present at terminals labeled 120 and NEUT?
• 24VAC present at TH and TR? (thermostat calling for heat?)
• When calling for heat is 120V present at  IGN terminals AND HSI not glowing? (if yes replace HSI, if no suspect large relay)
• HSI Glows and 24VAC present between VALVE and GND? (if yes, suspect gas valve / safety switches/wiring, if no suspect outer small relay)
• Failing all that test the inner small relay, inspect all solder joints for failure and caps for leakage. (if you can't find anything at this point consider replacing the control.)

Sometimes a relay will actually fail (shorted coil, open coil, or bad contacts) and they can often be sourced for $5-10 from digikey or a similar company.

Video Notes:

1. The fan/limit control won't come apart easily.
2. Typical setting are ~100 fan off, ~120 fan on, ~180 high limit.
3. You shouldn't be bouncing off the high limit, if you are you have an airflow problem, oversized furnace, etc.
4. Flame sense is through the ignitor.

Lead Acid Battery Desulfator

UPDATE 2:
My parts have arrived, I've got the schematic sorted out (I think). I think I'm going to do a start to finish post on my current PCB fab procedure and make a new board, even though the other one seems to work. I've got the correct parts and the other pcb is together and working. I'd like to see if they work differently.

Desulfator-RevB - KiCAD 3D Render

The Theory:
When a lead acid battery sets discharged sulfate crystals form on the  plates, reducing the surface area and thus potential capacity of the battery. A desulfator pulses a high voltage / current spike into the battery that causes vibrations that knock the sulfate crystals off the plates.
The usual frequency is around 1khz, though the vibrations are usually in the mhz range. It's described as ringing a bell. The desulfator rings it a thousand times a second and the harmonic vibrations actually do all the work. Therefore the actual frequency doesn't seem to be particularly important.
It would probably be best to remove the battery from the vehicle so we don't pulse high voltage through computers, regulators, etc. It may take a week to several months to restore a battery anyway, so doing it out of vehicle is preferable anyway.

Desulfator Rev. B - Top

The Specs:

• Unit is controlled by the venerable 555 timer, although an attiny would work and allow more control / monitoring of progress.  (Possible future design)
• Should work on many voltages
• May work on nicad's too.
• This is basically a reference design. I want to see if (and how well) it works before spending a lot of time designing my own system (if I even need too, let's not go reinventing the wheel right?)
• I'm trying for a compact design, altoids tin or smaller. preferably 50mm x 50mm, as if it works well I may get a batch made and try to sell them.

Desulfator Rev B - Bottom

Limitations:

• As the battery size increases the amperage needs to increase. Two resistors can be replaced with pots to adjust the frequency and duty cycle of the 555, but this results in increased heat on the inductors. (we'll try the default settings to start)
• Increased amperage requires bigger, more expensive inductors.
• It's not self-powered, so a trickle charge is needed for operation.
• No reverse - polarity protection, hook it up backwards and you will probably destroy it. (I'm going to look into this, doesn't seem it would be too hard to prevent this, definitely looking into this before selling any)

Notes:
I'm basing this on Ron Ingraham's design, I don't think he followed the component numbering of the original, so if they say you can substitute something for R1, it may not be R1 in the schematic.

Update 1:
My parts haven't arrived and I've run out of patience. So I scrounged some inductors (about 600uh and 180uh) substituted some other parts and it seems to work.

Only found two problems:
1. I  missed a trace (somehow missed it in the schematic) and that prevented the duty cycle from dropping below 25% and caused the frequency to change with it. it was really frustrating. I eventually found it and added a bodge wire. Now RV2 adjusts frequency and RV4 adjusts duty cycle. I also added a 180K resistor to RV2, but that's just because I only had 100K pots (should have been at least 300K+. I highly recommend using pots for these. Then you can just dial it right in. (with a power supply and scope or by ear and watching that nothing gets hot)
2. Stupid (me) used non-polarised caps (C) instead of polarised caps (CP) in the schematic, so 3 caps were backwards.

I've corrected all these things in the schematic. I need to clean up the schematic and get it uploaded. I'm not sure if I'm going to roll all this into Rev B or go to Rev C. I have made a number of minor changes, but it's not a redesign by any means.

Rev. B Changes:
1. Replaced R2 & R4 with Pot's for adjustment. Resistors should fit instead, so it's optional
2. Added C41, C43 for more options on the low esr cap.
3. Noted in schematic different options for assembly.
4. Has component locations for several variations on the circuit. Board shouldn't be completely populated.
5. Might have placed the power connector on backwards. Oops.
6. PCB layout is Copyright for now. Free for Personal Use. I may release it to public domain eventually. I just don't want anyone selling these untested boards yet.

Links:
KiCAD + PDF Files

Make sure you add the cache library at the very top of the KiCAD libraries for the schematic. It's a PITA it doesn't do this automatically. The PDF's may or may not work, they gave me a fit. Make sure you print at 100%, no scaling.
Pictures of latest board in my PCB Fab post

Desulfator Information (mine is based on the low power - Ron Ingraham design)

Drill Press Chuck Repair

I've been thinking about starting on another 3d printer, I have some spare time and I gave the one I started last year away. I have some angle iron and a bunch of 608ZZ bearings, so what's stopping me?
The chuck on my drill press broke. At first it just wouldn't tighten up, then it fell apart (some time ago, I hadn't gotten around to replacing it yet).

Note: Picture taken after I started on the repair.

From what I can tell the ring shaped piece is supposed to be one piece and the outer piece is held to it by a tight fit. I tried heating the outer piece and shrinking it onto the broken ring without success, undoubtedly it's worn and there is just too much force from the chuck key. At this point I priced a new (cheap) one at $25. Not bad, but I have one more last ditch effort before I buy it.

Plan B

I took an angle grinder and ground a hole on each side through the outer piece aligned where the ring sets (with it disassembled). I aligned my hole with the crack in the ring and touched it with the grinder to clean for welding.

Prepped

I heated it with a propane torch prior to welding, I've found this helpful when welding heavy steel with a small MIG.

Welded

Ground Smooth(ish)

It seems to work, tightens and loosens freely, doesn't slip when reefing on it with the key either. It's a quick, cheap fix, so if it fails I haven't lost anything and I'll have to buy a new one.
Now I have to find my drill bits and make some slides.

My Failed Fan Controller Design

I've spent all the time and resources I'm willing to on this project for now. I may complete it at a later date. It all works except the input voltage from the furnace transformer is too high after rectification (38-40v).  The 78M05 I'm using is 35v max and it doesn't tolerate any more. It doesn't seem to damage it, as even after testing as bad on the furnace it works fine on 18v (max on my lab PS) I tried to build a SMPS replacement based on Roman Black's design, that also worked fine on 18v and blew at least a zener diode when on the furnace. I used parts I had on hand, so sometime I will get precise values and try again. For now I'm ordering a snap-disk. Perhaps some of this design may be useful to someone for other purposes. It really sucks, as the controller works fine, I just can't get the voltage regulated to 5v. If you have any ideas feel free to comment. It's probably easy and I'm just not seeing it :)

My Dad's woodstove is ducted into his furnace. It works OK, but he has to manually turn the blower fan on to circulate the air through the house. This is OK when they're up and keep the fire going, but if they don't get up during the night the fire burns down and it circulates cold basement air. Brrrr

I realize I could just use a therm-o-disk, but what fun is that?

Plus I get a bit more practice making boards. NOTE: I bumped the zone fill clearance from .020 to .025, that definitely helped me not bridge pins to ground. It's a simple board and I used mostly .025 traces with a few .012 and .080 ones as needed. I can etch .012 very consistently, even .008 fairly well, but I keep tearing pads off drilling. The extra copper seems to help considerably. Extra copper around pad make things much easier drilling and mounting. Essential for wire connections. My first board's traces got torn up where wires mounted (all .012 traces). Notice the pads across the top of the following image compared with the bottom of the board above:

 Requirements:

• Run off furnace power (28VAC)
• Switch fan on at approx 120F, off at 90f
• Make sure fan runs at least 10 minutes when turned on.
• Cheap, hopefully less than a $15 T-O-D

Specs:

• Controlled by a attiny85
• PCB was done for a full-bridge rectifier, but we may use a half-bridge to keep the voltage under control. (use 2 diodes instead of 4) (Note: Didn't Work)
• Used Salvaged Components where possible

Parts List:

• Attiny85 ($1.30) 
• lm335a Sensor ($1.00) (I had some of these, I would use a mcp9700-e/to($0.25) in the future. the board supports it, just omit the 2k resistor)
• lm7805 Regulator ($0.50)
• 2n7000 mosfet ($0.60)
• 2x 1n4007 diodes ($0.50x2)
• 330u 50v cap (salvage)
• 10u cap(salvage)
• 0.1u cap
• 10K resistor
• 2K Resistor (omit for mcp9700)
• RY5W-K Relay (salvage)(you can get ones with ~30ma coils for less than $2.50 and drop the mosfet, though a mosfet does make it more robust IMO) You could also try a solid state relay

Schematic

The 7805 was a bit close to the cap, that will be fixed in the linked files. I intended to use a to-92 regulator, but the one I had was rated for 100MA. I thought my relay was 150MA. It was a last minute change. As it turns out it uses about 9MA idle and 54MA with relay powered. I could have used the to-92 after all.Total cost was under $5, though to buy all the parts would be more like $10, the cheapest T-O-D I found was $8. If I have the wrong temp with this I just reflash the chip, with a T-O-D I buy a different one.

Code is in Arduino, you will need the attiny85 hardware files, a programmer or an arduino, some wires and bits. See this guide for more information. I may redo it in AVR C sometime, I just wanted it up and running. I didn't need to do anything special.

 /*  
  Fan Controller intended for a attiny85, but takes ~3k, change pins below for arduino and uncomment the serial for debugging on the arduino.  
  it's intended for a furnace, so no fancy pwm or anything, thought it wouldn't be hard to add.  
  Stephen Evans - stevesfixitshop.blogspot.com  
  */  
    
 #define INPIN 3  
 #define OUTPIN 2  
 #define ONTEMP 48  
 #define OFFTEMP 32  
 #define DEL 600000  
   
 unsigned long wait = 0;  
 int avread = 0;  
 int ain[10];  
 int i = 0;  
 void setup() {  
 // Serial.begin(9600);  
  pinMode(OUTPIN, OUTPUT);  
 }  
   
 void loop() {  
  //make 10 readings  
  while(i<=9){  
   ain[i] = analogRead(INPIN);  
   delay(10); // wait for adc to stabilise  
   i++;  
  }  
  i=0;  
    
  //average the readings  
  avread = 0;  
  while(i<=9){  
   avread = avread + ain[i];  
   i++;  
  }  
  i=0;  
  avread = avread / 10;  
    
  //Convert reading to degrees C  
  float sensorValue = ((avread*4.8)/10)-284.15;  
 // Serial.println(sensorValue);  
    
  // turn fan on  
  if(sensorValue >= ONTEMP){  
   digitalWrite(OUTPIN, HIGH);  
   wait = millis() + DEL;  
  }  
    
  // turn fan off if below set temp and delay has passed.  
  else if (sensorValue <= OFFTEMP && millis() >= wait){  
   digitalWrite(OUTPIN,LOW);  
  }  
  // every 50 days millis rolls over to 0, this makes sure it doesn't mess things up  
  else if (millis() <= (wait-DEL-50)){  
   wait = millis();  
  }  
    
 }  

ATX PSU Repair

As noted in the HTPC build I used a repaired Ultra D0408 ATX PSU. I was using it in the P4 and it would work fine for a long time, then just start randomly rebooting, then it would be fine again. At first I thought it was the motherboard or ram, but then discovered if i bumped the desk or case it would almost always start acting up. Of course that screams "Something's Loose!".

So I had the opportunity to remove it and inspect it as I did my upgrade. Here's what I found:

Caps all look ok, no bulges, etc.

Cover Off

Be very careful when taking these apart, Voltages may remain for a very long time. I held it by the wires to remove the board, flipped it over and checked those 2 big caps (upper left). They had less than 2VDC in them, but depending on the failure it could be over 300VDC.

Bottom of board

Now we can see something, I don't know if you can see it in the above picture but in the lower right corner there is a capacitor that has come loose from the solder. It is on the 12V rail. The heatsink on the left of the unit also has a bad solder joint, but it appears to be isolated.

Bad solder joint (about in center)

So I soldered it up and will try it out. These units are cheap, so it doesn't pay to spend much time fixing them, but sometimes it's something simple like this. It's also practice for things like the Parrallax. Time will tell if that was the problem or if it's something more serious.