MSM5564 datasheet and a Yasue FT-225RD Counter fault.

[EI0DB]

Found this community and "Hardware Hackin' the oldies". It came up in a Google search for MSM5564. While searching for a datasheet for the MSM5564 clock chip in the Ft-225RD counter. If anyone has the datasheet would appreciate a copy and any comments on my problem.

I have a FT-225RD that has been off the air for a "few" years after I was in an accident, I am attempting to bring back to life and spec as I could find no repair outfit in the UK who was prepared to sort it for me. :(

The transmitter is on frequency and stable reports say mod is OK, but the built-in counter display is free running on switch on, before settling either on the correct reading or some 2300 Kcs low/high more often low and will stay like that for hours steady.
I now have a DFM and with the Tx on 145.000 (R0), checking around the counter I can see the crystal is oscillating but on 1.310678 Mhz (TP1) (not 1.31072 even when locked, TP2 shows a variable squarish wave 1 to 9 Hz and 5 Hz when locked. At this point I suspect either the MSM5546 or the crystal. Also wonder how critical the 5 volt voltage is, I read 4.8 volts on pin 8 of the MSM5564 ?

Anyone who has seen this fault, has the datasheet please. regards, Dave.:)

[N8YX]

Dave,

Welcome!

I'm going to save you a bit of trouble re: that counter. There's a JA who has developed a PIC-based replacement for the MSM5564 as used in the FT-902, FT-101ZD...and one might be able to retrofit it to the FT-225/625 lines. Let me do a little digging...

[WØTKX]

Hey, here's a linky... http://www.nam-arc.org/cms/index.php...4&changelang=2

[EI0DB]

Hi, Thank you for the replies and the link. The fixes shown will not solve my problem as the MSM5546 (my problem) is providing the gate signal. Once my 225RD locks all digits are displayed OK. I have a replacement chip "on the shelf" for the decade counter the PIC chip fix is for. I found a better explanation of the counter internals in the YC-601 Handbook located this evening, looks as if there should be a 5Hz pulse Have tried all the datasheet sites Google has turned up and have found "zero" on the MSM5546 as if it never existed. I have even found a source for the chip in the far east, but no data sheet. I have not got much hair left, but I am pulling it on this one (hi!). Thanks again, Dave

[N8YX]

A bit of decompress and thought on the matter:

It sounds like the 1.31072MHz crystal (which determines the reference oscillator/gating frequency) has drifted and its load capacitance is changing with heat. Not uncommon with these, it seems. Does the 225's counter circuit incorporate a trimmer and/or a padder capacitor (of around 6-20pF) across the crystal? If a trimmer, can it be adjusted sufficiently to net the oscillator properly?

[WØTKX]

That's a good call John-Fred. ;) And likely that "disappeared" chip is OK, which is a good thing. I saw the Fox Tango website had the YC-601 using that chip as well. Wondered if it used a similar circuit. There are data sheets out there, for $32. Bastids.

Have you tried asking at the Fox Tango Forum? http://www.foxtango.org/phpBB2/index.php

[N8YX]

Belay my PIC comments - I got that part confused with the OKI LSI counter chip which was used in the 101ZD/902 series.

The '5564 is present in the FT-901's counter circuit and I know that one all too well.

It's a CMOS binary up counter which has a max modulus of 524K and is used to divide the reference oscillator signal down to 5Hz. 4.8V on pins 7 and 8 should be fine. The crystal and/or the two capacitors associated with it (typ: 51p to ground on the clock pins 1 and 2) are suspect.

Look at pins 3, 4, 5,6, 9 and 10 with a scope - what do you see, and is it stable?

ETA:

Pin 8 looks to be the divisor setting pin, if chip lead convention is any indication. Tied to 5v it configures the chain as /4. Grounded, /2. (The only other option is Pin 7, and I strongly suspect it's for the +5v supply.)

[WØTKX]

That chip is in the FT-902DM as well?

[N8YX]

That chip is in the FT-902DM as well?

No - the '902 uses a custom Oki counter/display driver chip. The '901 and '225/'625 implemented their readout with discretes, and one of them happens to be the '5564. I thought Yaesu had switched to the single-chip solution in their VHF equipment but it now appears that the counter assembly is almost identical to that of the earlier rigs.

[EI0DB]

Looks like my post from last night failed to complete. First can I have the URL where the MSS5564 datasheet is found I am happy to pay for the info if that is the only source. I spent time yesterday going over the pins of the MSM5564 with DFM and scope. The 5 Volt line reads 4.78 volts steady (measured with Fluke 77 Multimeter), on pins 7 and 8 as was suggested. The oscillator on pins 1 and 2 read consistently (for an hour) 1310.67 KHz. The frequency on the other pins all vary. Pin 10 4-6 Hz, pin 12 10-13 Hz, pin 13 20-23 Hz. I have ordered a pack of replacement 51pF disc ceramics 5% 50V, and ordered replacement MSM5564 chip as I would like to bring the counter back to original as far as possible. On the scope I can see a 10 mV, 1.28 Mhz distorted sine wave on Pin 10, but no 5HZ +/- clock signal. So I will have to wait for the parts to come over from the Far East ( how long is a piece of string hi!).