Poorly 360FM

[astradyne]

I have a MK2 360FM here which isn't happy at all. It appears that power is only getting through to the signal meter bulb. There's no channel display, no TX/RX LED and no sound from the speaker.

After a quick preliminary look I've found two mods. One is for the bleep on the tone switch, the other looks to be the diode mod for a K40 speach processor mic. Coverage is standard. Both the squelch and RF gain are missing their stop positions.

I've noticed minor repair work on a blown track at the back of the radio, but other than that everything appears to be in good order. No obvious physical issues.

Any ideas guys? I've attached a few photo's for reference.

[cb4ever104]

Check TR41 2SA473 8V regulator . That's where I'd start to look .

Sammy

[astradyne]

Check TR41 2SA473 8V regulator . That's where I'd start to look .

Sammy

Cheers for that Sammy. Checked the 473 and found it had a little over 13V going in but nothing coming out. I've replaced that and there's now a channel display and working TX/RX LED. Still no audio from the speaker and no TX power. I'm guessing some numpty has wired it back to front and taken the A1012 and audio IC out too. I'll check those tomorrow and replace them if necessary (thankfully I have a few spares in my tool box). It's way too nice to consign to the scrap heap.

[dt307]

no stops on the controls is an easy fix did to on a 360 this morning...no need to dismantle anything and takes 2 secs

position the control away from the stop
the little indentation on the control find a small flat screw driver that fits snug
give the screw driver a few taps
check the stop starts to bite then give a few more taps till it does

[cb4ever104]

Still no audio from the speaker and no TX power

I presume you've tried both internal and external speakers Andy ? Sorry . Had to ask No TX could be lots of things . Start with the driver circuit , and move to the final .

Sammy

[astradyne]

Tried external speaker too Sammy. Dead as a Dodo.

The A1012 is firing out 13V on all pins even in RX, so something's clearly amiss there. I've got a bag of new 42C's here so I'll pop one in later. Thankfully I've also got a spare audio IC. It's used but I know it's working 100%. Plus I'm also certain I've got a few 2166's and 1969's knocking around.

[cb4ever104]

The A1012 is firing out 13V on all pins even in RX

Even on AM/FM ? Should be around 6V depending on how the AM/FM power has been set . 13V is fine for SSB . I picked up a really nice 360FM a few years back as well . No output also . Both of the little bias resistors on it turned out to be o/c . Transistors were fine . 10p fix . My favourite kind of fault

S.