Yaesu FTDX-400

Discussion in '"Boat Anchor" & Classic Equipment' started by AF6LJ, Aug 18, 2011.

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  1. W5WPL

    W5WPL Ham Member QRZ Page

    Have you found anything new? How did a coil seize up? Did it have an adjustable core?

    No such thing as a stupid question.
  2. K9STH

    K9STH Platinum Subscriber Platinum Subscriber QRZ Page

    The manuals and, especially the schematics, on some of those early Yaesu radios were horrible! I got the "twins" in a trade deal and actually obtained the original manuals. The schematics were not only condensed so small that it was very difficult to read them even with a magnifying glass, the entire manuals, including the schematics, were printed using the old alcohol spirits purple printing process that they used when I was in elementary school! Even a mimeographed manual would have been easier to read!

    Glen, K9STH
  3. AF6LJ

    AF6LJ Ham Member QRZ Page

    The coil slug was cracked.

    If you look at the above picture that shows the top side of the radio you will notice a pot mounted on a bracket, behind the front panel, next to the S-Meter. That pot is the relay sensitivity control for the VOX circuit. Not to be confused with the VOX Gain. I haven't completely worked out the circuit I found it in the schematic Thursday Night.

    I have been busy and have not had the time to get back on the radio, I should have some time tomorrow.

    I forgot to mention on Thursday that I made some power supply measurements and It looks like there are filter caps in my future. The high voltage supply is running just over 3% ripple and there is about 90 volts sag in the power supply, this doesn't surprise me.
    The 350V supply also has ripple in excess of 3%, recapping the power supply is beginning to look like a good idea. If I go through with that I'm also going to replace all the power supply diodes.

    I still have to get a gob & bunch of slip on tube shields.
    This one is going to be a longer term project, but well worth it.

    Stay tuned.
  4. W5WPL

    W5WPL Ham Member QRZ Page

    And yous is single!!!?
    Yous noes I's gots mosts of mind on teeths
    And ok sumtimes withs ma depends
    Yous willn't hast to chang me moe than twoths a day.
  5. AF6LJ

    AF6LJ Ham Member QRZ Page

    Mouser seems to have filter caps and should have some new diodes, I haven't looked for them yet.

    Over the next month there is going to be a lot of cleaning and some disassembly.
    I'm still trying to decide if I want to pick up a bottle of white lacquer and replace the inspection paint or not, that is really minor.....

    One of the owners was a smoker, albeit not that bad.
    I have decided that before I continue with any alignment and repairs filter caps and tube shields need to be replaced and the radio needs a good cleaning. Before I can begin I must provide a place for the radio to sit idle while I'm waiting on parts. Where it's sitting now isn't acceptable.
    I guess I'll have to clear some space off to the right there.....
    Stay tuned.

  6. W5WPL

    W5WPL Ham Member QRZ Page

    I see you like your curiously strong mints

  7. WA6MHZ

    WA6MHZ Premium Subscriber QRZ Page

    I use those here at work too. Excellent for holding small parts. I also score HOT SAUCE Cups for SMT parts, as I don't feel like getting up and walking to the Stockroom every time I need a part. Hot Sauce cups stack easy if not too full. If they get too full, then you just score another cup. The boss complains about all these cups and altoids tins, but that is his job: Just like a WIFE, her job is to COMPLAIN!
  8. AF6LJ

    AF6LJ Ham Member QRZ Page

    The hot sauce cups are great, I have given serious thought to buying a package of them from CostCo, but the Altoids boxes work great.

    Meanwhile back at the bench.......

    I put together a parts order from Mouser;
    25 1KV 3Amp diodes
    And two new electrolydics for high voltage supply.

    Sorry for the slightly blurred picture

    One of the things I'm going to do and there has been a considerable amount of discussion about this to the point of fights breaking out.........
    I'm going to remove the equalizing resistors and caps. My reason for doing so has to do with the forty year old diodes are being replaced and there is no need to keep parts that no longer preform a purpose. So this board will be a lot less cluttered.

    Also in the coming weeks the PA is going to get a good cleaning and going over.
    There is some tobacco residue and I'm going to take the time to clean things up starting with the rear half of the radio and working forward.
  9. AF6LJ

    AF6LJ Ham Member QRZ Page

    It's been a while and the week has been busy.
    I had some time today and spent it on the FTDX-400.

    As we last left off I had ordered some parts both by way of Ebay and Mouser Electronics.
    The parts arrived and are waiting....

    I had planed and started to remove the PA cage to do some intense cleaning however that became impractical due to the location of the front two PA shield screws. The screws are under a harness shield that runs parallel to the last bandswitch shield. As a matter of fact the shield is anchored to the shield in question and under that section of wiring harness are the two PS shield screws. I'm not going to risk breaking forty plus year old bandswitch wafers that I may not be able to get except out of a parts radio. So I put in the screws I took out and went about cleaning the upper PA compartment which was in need of some cleaning. I'll post a couple of pictures later as there is something I noticed today that I found rather interesting and goes far to explain why this radio is built the way it is.

    One of the mildly frustrating issues involved in working on this radio and the Tempo-One is the use of non magnetic screws. Removing screws is easy but getting some back where they belong required some sticky grease which will have to be cleaned out when I continue that process later in the week.

    My tube shields came and I'll have a few dozen left over.
    I selected the ones I wanted to use in the radio, I'm making a trip back to that box on Thursday because I have one that I chose that I want to find one that is a better fit. I looked at proces for NOS tube shields and the ones I needed were about four bucks a peace, I needed eleven.
    So for $52.00 I bought off E-Bay a box of ninety-six tube shields.

    My Mouser parts arrived along with the shields on the day the lights went out.
    Because of mechanical considerations I didn't get exact value caps.
    They are rated at 500VDC however instead of 100MF I picked up 200MF caps, shouldn't be a problem. The 100s were too small to fit where the existing caps are and I don't see any problem with inrush current since I'm going to replace the diodes also. I ordered and received 1KV @ 3A diodes for the replacements. As I said above the equalizing resistors for the diodes are going to be removed from the diode board along with the caps that are across the existing diodes.
    I do have an issue there and it gives me an excuse to buy another tool to add to the collection. I have to drill out the holes on the diode board and need a pin vice for that task. So later this week we shall pan a field trip to one of the big box stores. for that item.

    I found some 470K 2W resistors rated at 500V to replace the two equalizing resistors for the new caps, so I'm good to go there.

    I keep seeing in my mind a perforated shield where the large caps and one of the power supply chokes are now. inside that shield would be a PCB with all the power supply caps on it. This is one of those "if I get really motivated" kind of projects. For now we need to get the power supply rebuilt and deal with any other issues that crop up.

    Well that's all for now, more work on Thursday.
    Stay tuned pictures to follow in a day or so.
  10. AF9J

    AF9J Ham Member QRZ Page

    Very cool Sue!! :cool: I'm glad I passed the radio on to you.
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