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Syncrowave 300 problems

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  • #16
    That would be great.

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    • #17
      OK, finally got to study the diagrams a bit. Difficult problem to troubleshoot long distance due to lack of info on TD1 and TD2, and documentation conflicts. The problem area is likely around PC2, but you already know that. The fact that you are having both flaky HF and postflow problems leads me to question if there could be something common, which could be several things on and associated with PC2. I would first clean all of the connections on the plug that connects to PC2 with electronics contact cleaner, and pull the plug on and off a few times. Also look at wires/pins in the plug that connects to the board for loose connections or corrosion, and associated traces on the board for opens, cold solder joints, etc.

      There is a discrepancy between the schematic in the front matter errata sheet for SN HF884575 and on, which should be correct for your machine, and the one in the main body of the book in the back, which is what was published when the machine was first sold. The errata sheet diagram, which should be the latest, shows four contact pairs on CR2, while the one in the back of the book, and the description on the parts list, both say it has three contact pairs. So, to begin, have a look at CR2 and see how many pairs of contacts it has, and post the answer.

      Since I have never seen the inside of a Sync 300, what do TD1 and TD2 look like? Are they mechanical or electronic? Any part numbers on them that might lead to, say, a Potter-Brumfield diagram? Those guys made a lot of time delays back when, and still do, for that matter.

      TD1 is the postflow timer, and TD 2 is the HF Start timer. It appears that the gas flow sequence is: hit the pedal, CR2 energizes, its contacts tied to wires 2 and 23 energize the solenoid on the gas valve and open it. If I'm guessing correctly, TD1 contacts also close, and now CR2 and TD1 contacts are both feeding current to hold the gas valve open. Now at a steady state until you let off the pedal. When you let up, CR2 opens, but TD1 contacts should stay closed until the timer runs out. So, it seems most likely that TD1 is bad, and not holding the contacts closed after releasing the pedal (or they are never closing in the first place). If you can see mechanical contacts on TD1, see if they are closed when you hit the pedal, and staying closed when the pedal is released. You could verify that by connecting an AC voltmeter between wires 1 and 13 (If I'm reading the correct schematic). If the contacts are closed, you should read 0 or a very very low voltage during what should be the time-out period after releasing the pedal; if not, you should see 115 VAC, give or take. Don't get zapped! TD1 is the obvious culprit, but in my experience there are many times that if you just change the obvious part, that wasn't it. :-)
      If you can find a TD1 at a reasonable price, you might what to try replacing it, but obviously no guarantees.

      Please post what you find out about CR2 and the voltage across the contacts on TD1. Hope we can get this figured out.
      Last edited by Aeronca41; 12-10-2016, 11:45 PM.

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      • #18
        Thanks a ton for taking the time to investigate! I'm going to sit down and go through your post and get back to you in the next couple days. Really cant thank you enough. Im going to get some shots of the circuit board to post. Although Im having alot of trouble posting pictures.

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        • #19
          Glad to help-although we're not sure if it was any help yet. :-)

          Pics are hard-just snapping with a phone and posting often leaves them too small to read anything in them. You can resize with Photoshop, per H80N, but I don't have it. See what you find out, and how the pics come out when you post them.

          Besides TD1, the trouble could be CR2 (or something else) but we really need to understand CR2 and which diagram is correct.
          Last edited by Aeronca41; 12-12-2016, 11:24 PM.

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