Jaws Mark 2 LC7120

[3pinplug]

In the picture where I read 13.8V onthe head of the screw , there is a white insulating washer fitted there which is preventing the screw thread from touching the wall of the radio, but at the component end where the IC Tab is the screw is bolted straight to this tab. Shouldn't this insulating washer be fitted to the hole on the components tab then I wouldn't end up with 13.8v on the screw itself? Hope you know what I mean by this as its always diffculy typing an explantion.

thanks claude - yes that radio is the same layout, I dread to think how big the "Claude archives are", you seem to have everything ever made to hand! Even whilst I am typing the magician is at work - Claude you are a gentleman thankyou ever so much!!

[14CS06]

Hello

Jaws Mark 2 LC 7130











@+
Claude

[ChubbyChops]

Shouldn't this insulating washer be fitted to the hole on the components tab then I wouldn't end up with 13.8v on the screw itself?

Yes, that is the correct way.

[14CS06]

Hello

@+
Claude

[3pinplug]

Brilliant Claude! so looks like it is fitted on the wrong side, will switch it round and see what happens. Means though that someone has been at the chip will look closely around there.
Merci beacoup!!

[3pinplug]

Good news!!
I have moved the white insulator to the IC tab side and bingo - no more 13.8v on the mounting screw to allow any shorts with the case. Also now when i put the lid on i don't loose power on ch20, so looks like it was the wrong position insulator / power shorting to case causing this Found the mic has a dodgy wire causing intermittent transmit so redoing mic connections tomorrow, then fingers crossed i can fire it up fully for a call out. Will be back with results!

[The Collector]

Jaws 2...the return.


Sounds like a good name for a film....

[3pinplug]

I have returned but jaws is still at sea!
I have the mic working, have the squelch pop, PA function working with nice loud audio but only a very quiet hiss coming out the speaker, which does not change when i move the volume control . The radio does not appear to be receiving either so will run through the receive alignment tomorrow.
Anything else i should check if this is a common fault thats come up before?

[ChubbyChops]

Get the receiver aligned first and if that doesn't improve things, start looking at caps that feed the audio amp.
It's probably been twiddled to death and judging by the way the driver trans was fitted, not by someone who knows what they are doing !

[The Collector]

Could the 13.8v going through the chassis have blown something RX-wise that's also attached to it?

My knowledge of radio internals ends here..good luck...

[Otter]

It could even be a dodgy mike connection. I think those radios have the audio ground go through the mike cable.

[3pinplug]

Sorry for the delay, ordered a new audio chip and it took a while to get here, good old “Royal Snail”!!
I have sound again, but still no vco voltage, however two coils had broken ferrite coils, so i desoldered them and managed to get them out the underneath of the core and then put the good end back in. Suspect the inner of the coils may be damaged as they are jammed and broken again, not going to be easy to get them out this time!will see what i can do and see how i get on and come back. But at least i have sound now so going in the right direction. Thanks all so far.

[14CS06]

Hello

One here



https://www.ebay.co.uk/itm/304055068697 ... SwIchg4YTO

@+
Claude

[Otter]

Hello
One here

Holes in the top cover, non-original bracket and label missing from the microphone. You would have to be stupid to pay £40 + £9.95 p&p for that.

[The Collector]

Sorry for the delay, ordered a new audio chip and it took a while to get here, good old “Royal Snail”!!
I have sound again, but still no vco voltage, however two coils had broken ferrite coils, so i desoldered them and managed to get them out the underneath of the core and then put the good end back in. Suspect the inner of the coils may be damaged as they are jammed and broken again, not going to be easy to get them out this time!will see what i can do and see how i get on and come back. But at least i have sound now so going in the right direction. Thanks all so far.

Can you buy new coil things for your radio, or will you need a scrapper to pilage some from?