Lafayette 1200FM Purchase (and fault find)

[53buick]

Good Afternoon.
Not been on for a while as I sold everything up last year but then realised I missed it..
So, I was offered a Lafayette 1200FM for a reasonable price on the understanding that it needed work.
On initial receipt I can see it has been radically modified internally from a company called "Lucy and Charlie Electronics" in 2005.
Modification includes a change to the channel changer to a 5 position switch.
I can turn it to a "hi-hi" position which gives me the UK40 (27.60125->)
Once my frq counter turns up I can check it better. as I notice it doesn't RX/TX over Channel 20 on the UK40 band.
The "lo-lo" position, I can hear but not sure what frq it is yet, assuming it is lower than the original AM 40.
The modification has been done with a Toshiba UV erasable Eeprom (not seen one of those for years).

Something else I noticed is the RF meter is not functioning on receive, upon inspection I can see RV6 doesn't have a wiper on it so guess some heavy handed tweaker has been in here.
I have just ordered another 10K pot so will fit that when it arrives and hopefully that will fix that issue.

the "High" light on the front lights up when the NB switch is flipped, not sure what it does yet so looking forward to tracing that back.

If anyone has a handbook for one of these a copy would be gratefully received.

We do like a challenge don't we...
I will update soon but if anyone recognises this rig in the UK, please get in touch.
Spence

[Otter]

Is that a PTBM121 boarded radio? I think I remember Bigpimp saying there are two variants, PTBM121 and 059. If it's 121 Hygain V, Concorde 2, Tristar 747 manuals will cover it. If it's 059, Multimode 2 will be a good guide.

[53buick]

Hi, its an 059 board.
Hopefully a few bits will turn up this week which will determine which way the rig goes...
Either a tweak by me or sending off for a rebuild.

[MrWeetabix]

Feel free to post some pictures of the inside of the radio in its current state and then you can show us the finished product at a later date :-)

[The Collector]

Can it have one of those PIC mod's that Nick, Black Spirit does I wonder? It'd be handy to have the UK40 working

[53buick]

Hi, Nick has offered one of those mods to me for a bargain price.
At present I am waiting for my frq counter to arrive then I can see how bad it is.
First thing I want to do is get everything functioning and I can then make a list of what is required.
Someone has been at it with a big screwdriver as RV6 has lost its top therefore the signal meter is not reading anything at all on receive even from my fm rig right next to it.
I am sure the NB button is a 10kc shift as its wired into the output stage and fed back to the vco I think.
I am a fully qualified engineer but not been in design for over 20yrs so very rusty. Lol...
I will post pics tomorrow of the mods already done just for a laugh. Not to my standards at all, leads not cropped short etc.

[Otter]

Someone has been at it with a big screwdriver as RV6 has lost its top

That's not necessarily the case, I've had the top of one of those horseshoe potentiometers just fall off. There was no evidence of anyone tampering with anything in the radio. It just fell apart.

If it's going to Nick for a UK conversion you could do worse than to just send it to him and he'll be able to fix it.

If you want to look at it yourself, look for any green corrosion on the legs of the electrolytic capacitors and replace the capacitor that have it. Also look at the traces on the component side of the PCB, and see if there are any patches where they have darkened in colour. Capacitors leak, and the contents corrode the top layer traces. You should repair the trace if they have corroded.

[53buick]

So good news. I bought a frq counter from ebay and set it up on the output.
Checked all 5 bands and whats been done is the following:-
L-L - on frequency for 26.065 - 26.505
L - on frequency for 26.515 - 26.955
M - on frequency for 26.965 - 27.405
H - on frequency for 27.415 - 27.855
H-H on frequency for 27.601 - 27.991

The NB switch has been modified to get the alpha channels.

I am now about to replace the broken pot RV6.

One thing that isn't right is the rig is pulsing at the higher channels as of there isn't enough drive to the output stage?

I will check a few voltages around the pcb.
Cheers,
Spencer