Transmission1

Hey all

Now you all know by now that I know pretty much bugger all about the insides of radios, so here's my latest...and probably an easy issue to solve...but not for the likes of me.

I'm about to sell a really nice little Lucas 27/81 radio that I've had for a few years, but on testing it and taking a few pictures etc, I've noticed it TX's and RX's on only half the channels, and on the one (channel 21 I think it was), there's a 1 second pause before it decides to TX, so I'm thinking it's not locking on properly.

Now if I recall on some radios like Amstrad's, there's a tiny little red component that you can adjust to help lock-on, but I can't see anything like that on this thing. These particular radios are like the Icom 1050, York 867, Signal 40 etc etc chassis/board-wise.

Could anyone kindly point to, or circle, the bit that I need to twiddle please, or if it's not that easy, to tell me to leave well alone?

P.S. I have no testing equipment other than a multimeter and I only really know how to test for DC voltage or continuity on it!

Thanks TM1.

More close-ups:

Seems to me like VCO problem.
I suggest to measure VCO voltage on ch1 and ch40 tx/rx and post here.
Posting schematic could help better, than photos

ch25 wrote: 17 Jun 2020, 14:14 Posting schematic could help better, than photos

Indeed . I was going to say that it's usually the coil with the wax in it near the pll , but it looks as if there's wax in them all ....

Hello

Schematic

@+
Claude

Thank you Claude

Unfortunately, I haven't got the manual/schematic for my other, brand new Lucas as typically it was missing from the box.

Hopefully someone can make sense of all the squiggly wires and stuff and let me know which coil or "can" to attack then. I'd sooner sell it working on all channels if possible for obvious monitary reasons, plus I don't like having to list stuff for spares when I'm 99.9% sure a little twist somewhere will sort it.
It also sounded a bit scratchy on RX on the high channels it could hear on, so that'll hopefully help matters.

Thanks all so far.

Make measurements I described on pin 7 PLL - IC-201

PLL out of lock and raspy signals are symptom of ageing electronics.

Cheers Chris...and thanks for telling me exactly which component too as you could paint all I know about electronics on my little fingernails

I'll try and get some time on it tomorrow, childminding duties aside.

Raspy bits are also signs of an aging user

Thanks again Chris, that helps even more mate.

I can Google it, but I assume that pin 7 is counted along from one particular end...maybe with that little indent on it, or does it criss-cross across pin number-wise? (told you I know nothing ).

The Collector wrote: 18 Jun 2020, 08:34 Thanks again Chris, that helps even more mate.

I can Google it, but I assume that pin 7 is counted along from one particular end...maybe with that little indent on it, or does it criss-cross across pin number-wise? (told you I know nothing ).

Hello

@+
Claude

Thank you Claude. I'm just in the loft now so will try and measure the voltages.

Hello

Service manual
Icom ICB 1050
JWR M2

@+
Claude

Just typed war & piece to find I'd timed out on my log in time and lost the whole damn lot!

Anyway, short version -


Couldn't get voltages, all over the shop. Analogue meter needed???

No TX on any channel when tested this time !!!

Got a bit miffed, so dug out wax on pot thing closest to chip thing, got ch1 locked on, but not 40!

Adjusted it again, locked on ch40, not ch1!

Dug out next pot thing in anger, adjusted and got TX on all 40ch's. Yeah!

Dug out next pot, this affected RX, adjusted until central of sound cut-off points. Still tinny sound but reckon it's possibly just the small speaker.



Thanks to all, especially Chris and Claude

Will still sell it as needing a tweak just in case, as needle doesn't go up as far as it should. It's at the same level as on low power, but I'm not going to mess with even more wax