Notes on FT

Repaired by Yaesu March 2003 because of blown out front end. Returned to PJ2 on 10 July 2003.

Followed the directions below and found not the thermal fuse, but the other small 50 micro amp fuse open. Wired a short across it and the display came back to life. See micro fuse photo and inverter board photo.

We should consider ordering a spare inverter board as well as a new fuse for the one that I wired shorted.

Filters in this radio:
XF-100 CN 455 KHz
Collins XF-115C 455 KHz
Collins XF-114CN 250 KHz
XF-114CN 250 KHz
XF-8.2M-501-03 8.215 MHz
XF-8.2M-262-01 8.215 MHz
Collins XF-115C 455 KHz
No 2.0 KHz filters

Disassembly:
Remove six screws in black tabs
Remove two brass screws in top tab, two in side, then loosen hinge screws
Unplug P5501, then hinge panel down, unclipping white wires from top of inverter power supply, remove case covering power supply, including wire lead-keeper on right side.

Installed INRAD roofing filter 9 Sept 2005. K9AN audio filter mod is already installed (by W8TK).

Brought out of closet 27 October 2006 to put at Station # 2 when FT 1000 there became partially mute. Failed after about an hour with main RX dead, transmit dead, sub RX 100% good. I opened the case and it started working. Buttoned up and stopped again. After the contest I tested it and all was 100% good. Line voltage during contest was 104 volts with room ambient temperature of 99.8F.

Returned to States 30 Jan 2007 by W8WTS because of reports of badly distorted transmit audio. Also main RX was intermittent and TX sometimes intermittent.

Tests at W0CG confirm RX sounds desensitized and TX is inop both modes. Keys in both CW and SSB, but no power out. No SSB sidetone heard except for low level crackling when driven with speech. After about half an hour the RX woke up and TX was fully operational.

XCVR was shipped to WA4GEG, our new repair shop. Here is his message from 29 September.

I have your transceiver repaired, and also went over the alignment of all critical sections to bring the unit up to OEM specs. All work is covered in detail on your service invoice.

The intermittent RX/TX problem was a hairline fracture in an 0605 size SMT resistor on the RF Unit board. An unrelated issue was found in that the quad J-FET RF amp. / stage was overheating, and I've corrected that with the addition of a bias shunt resistor. I also replaced the display micro fuse.

Your total which includes return insured FedEx shipping is $198.96, payable via personal check*, certified check or money order to my AD below. I also take PayPal (good for cash, credit and debit) to recipient.

XCVR will be shipped to W0CG on 16 October for transport to Curacao in November 2007.

XCVR received from WA4GEG. Checks out perfectly. Click here for service invoice. (XCVR will be retained at W0CG until we rotate another one out of Curacao. All six are working at present.)

XCVR transported to Curacao by W0CG. Passes operational check at Station 3. Main tuning knob is slightly loose but operates OK. In service at Station 3.

Question: The display on my 1995 vintage 'MP went dark tonight. The rig still > seems to function (I can computer control t)...and the front panel indicator lights are working. I tried resetting the CPU...no luck.

Question: Sometimes when I start my rig, the display takes up to 15 seconds to come on, what is the problem?

Solution/Response: If the problem is what I had, it's on the inverter board that provides some rather high voltage - a few kV? - to the display. The inverter board is not manufactured by Yaesu, so there's no schematic for it in the manuals and they do not repair it (at least based on my phone call to them a few months back) and so have no components for it. They will sell you an entire board (I don't recall the price).

The inverter is behind the front panel. You need to remove at least the top cover (and I believe the bottom as well) in order to get access to the screws that hold the front panel on the main chassis. (No need to take the front panel itself apart - just disconnect it physically from the MP's main chassis.) You *can* get it to kind of hinge down on two screws though not enough, if I recall, to get full access to the inverter.

The inverter is a board about 25mm x 75mm (under a metal shield) mounted on the far right as you are looking at the MP from the front. It's not on the front panel assembly, but on the front surface of the main chassis. If I recall correctly, a couple of screws hold the cover on - remove these and then you can get to the screws that hold the board to the chassis.

There's not much to the board - just a few components. There are two fuses - a leaded over-current type (looks like a resistor) in series with a thermal fuse (mine looked like a square-package capacitor - about 5mm x 5mm x 2mm thick with radial leads). The thermal fuse proper is mounted between and thermally coupled to two transistor (or FET) devices. My fuse was open circuited - I simply bypassed it and the display started working. I am still looking (albeit less enthusiastically) for a suitable replacement. It says 2A 102°C.

In addition, apparently lots of folks have seen this happen (and I have as well): You turn the radio on, and the display takes an inordinate amount of time to come up (many seconds) but it does light up. Next time you power it up, it may come up much faster. No solution has been offered for this problem as far as I can tell.

Hope this helps. (Next time I open the MP, I'll try to think straight and shoot some digital photos.)

Subequent Posting: Mike... Got the radio apart...found the board...even found the fuse...it's late...it's been a tough day...but after awhile...I realized that TF stood for thermal fuse. There seem to be six pins soldered into the board from the bottom of the fuse and two black wires that extend out of the side of the fuse that are soldered into the board. My initial guess was to cut the two wires...and solder them together. Is that anywhere close to correct? Ray ND8L
Response: The two black leads coming out are the fuse (the 6 pins going straight down are the leads for the two transistors I mentioned - the transistors whose temperatures are monitored by the TF.) Pls note that the fuse is a separate physical device, that is bonded with some goop to the two transistors it is supposed to protect. THe 2 transistors have 3 short leads each going into the board. The TF is "sky-wired" - the body is glued into the space between the two transistors and the TF's leads gently folded over and soldered to the board.

NO, don't cut the leads. You should first verify that the TF is the problem. So unsolder one of its leads from the PC board, and then run a continuity (ohm meter) check on the two leads (one still soldered on the board, one you just unsoldered). The TF should measure a VERY low ohm value. IF it's working properly. If, however, it's blown (as we suspect) then it should measure open (Megohms). If it is open, then place a jumper of wire on the board between the 2 pads that the TF was soldered to. You do not *have* to remove the TF physically from the transistors (it is "glued" in) for this "bypass" to work - only if you want to or want to replace it. But you probably should anyway just to get it out of the way. If the TF is not an open, then this will not work of course. Check the other fuse as well -it's wired in series right next to the TF - looks like a resistor on my board - a little brown leaded part. Test/bypass the same way if needed.

Hope this is clear. 73 Mike N2MG

K8LEE and K6AM performed XCVR triage of all radios. Found that this XCVR RX 10 dB down on 80, no IPO, same on 40, - 6 DB on 20, 10 OK, 15 OK. TX power out good all bands. Put back in storage in a new bag.

Used in CQWW SSB at Station 3 on 15. No problems. Some days later the display would not come on, but I tested it today and all is good. Put in storage in a bag.

Main receiver way, way down in sensitivity. Sub RX is good. Removed from service.

Verified main RX sensitivity very low, sub RX OK, TX OK. Opened radio and rattled all the obvious places. Wiggled filters. No change. Set aside for repair. Cannibalized display inverter board to put in (7), but this did not fix the problem in 7.