Recently I acquired an Icom A6 in the "Sports pack" version, i.e.
including an adapter for the car lighter plug. This adapter is called a
CP20. Through a slight mistake in my car cabling, I managed to connect
it to the battery the wrong way around, plus and minus were inversed.
Yes yes it's stupid don't tell me. The lighter plug contains a fuse (8
Amp!) I replaced that but still the radio won't work, I suppose
something in the CP20 blew quicker than the fuse.
NB the radio itself is fine, works like a charm on 6xAA batteries.

Two questions now:
-) how to open the CP20? There seem to be four small covers over screw
heads, but they won't move for any effort I applied. Drill through them?
-) any suggestions as to the CP-20's insides? Schematics, perhaps? What
are the most obvious candidate victims?

TIA,
KA

jan olieslagers wrote:
> Recently I acquired an Icom A6 in the "Sports pack" version, i.e.
> including an adapter for the car lighter plug. This adapter is called a
> CP20. Through a slight mistake in my car cabling, I managed to connect
> it to the battery the wrong way around, plus and minus were inversed.
> Yes yes it's stupid don't tell me. The lighter plug contains a fuse (8
> Amp!) I replaced that but still the radio won't work, I suppose
> something in the CP20 blew quicker than the fuse.
> NB the radio itself is fine, works like a charm on 6xAA batteries.
>
> Two questions now:
> -) how to open the CP20? There seem to be four small covers over screw
> heads, but they won't move for any effort I applied. Drill through them?
> -) any suggestions as to the CP-20's insides? Schematics, perhaps? What
> are the most obvious candidate victims?
>
> TIA,
> KA

You probably blew the protection diode---look for a little black
thingie, close to the input jack-that has burned up.

jan olieslagers wrote:
> Recently I acquired an Icom A6 in the "Sports pack" version, i.e.
> including an adapter for the car lighter plug. This adapter is called a
> CP20. Through a slight mistake in my car cabling, I managed to connect
> it to the battery the wrong way around, plus and minus were inversed.
> Yes yes it's stupid don't tell me. The lighter plug contains a fuse (8
> Amp!) I replaced that but still the radio won't work, I suppose
> something in the CP20 blew quicker than the fuse.
> NB the radio itself is fine, works like a charm on 6xAA batteries.
>
> Two questions now:
> -) how to open the CP20? There seem to be four small covers over screw
> heads, but they won't move for any effort I applied. Drill through them?
> -) any suggestions as to the CP-20's insides? Schematics, perhaps? What
> are the most obvious candidate victims?
>
> TIA,
> KA

If you're not into miniature electronics,you probably don't have tools
or parts to repair it anyhow--get friendly w/an avionics tech.

Jerry Wass schreef:
> jan olieslagers wrote:
>> Recently I acquired an Icom A6 in the "Sports pack" version, i.e.
>> including an adapter for the car lighter plug. This adapter is called
>> a CP20. Through a slight mistake in my car cabling, I managed to
>> connect it to the battery the wrong way around, plus and minus were
>> inversed. Yes yes it's stupid don't tell me. The lighter plug contains
>> a fuse (8 Amp!) I replaced that but still the radio won't work, I
>> suppose something in the CP20 blew quicker than the fuse.
>> NB the radio itself is fine, works like a charm on 6xAA batteries.
>>
>> Two questions now:
>> -) how to open the CP20? There seem to be four small covers over screw
>> heads, but they won't move for any effort I applied. Drill through them?
>> -) any suggestions as to the CP-20's insides? Schematics, perhaps?
>> What are the most obvious candidate victims?
>>
>> TIA,
>> KA
>
> If you're not into miniature electronics,you probably don't have tools
> or parts to repair it anyhow--get friendly w/an avionics tech.

Thanks for thinking along! I do have a temperature controlled soldering
iron with a fine tip, otherwise I'd not even think of opening the damned
thing. And I do know how to use it, yes. Actually I hope to become
established as some kind of aviation electrician - though not an
avionics guru, HF is like black art to me!

As for your other suggestion: yes I hope it is a protection diode blown.
But is that likely? If it is anti-parallel to the input, it should
either be shorted and keep on blowing fuses, which it doesn't, or
completely dead in which case it shouldn't disturb normal operation. If
it is in series, it could also be shorted, still no problem, or have
infinite resistance - but that seems unlikely to me, though I'm not
complaining if it turns out to be that. Will keep you posted?

Jerry, do you agree about (carefully) drilling out the plastic screw
covers? Any other idea?

Jerry ...

I don't think that is going to be it. If the Grover diode is in parallel
with the input, yes, it will have blown the fuse and probably trashed itself
in the process. However, if that diode failed open, then the adapter will
work albeit without any protection. If it failed shorted then it will blow
the next fuse and according to the OP that didn't happen.

If that diode were in series with the hot lead, then all that would have
happened is that the diode would have been back-biased and not passed any
current. That didn't happen either as it did blow the primary fuse.

Most of those little adapters have switching power supplies inside of them
these days to buck the aircraft battery voltage down to whatever the radio
battery supply is plus a volt or so to back-bias the summing diodes in the
radio power supply line. Most likely it got zapped. Cheapest way to fix it
is buy a new one from Icom and learn from the experience.

Jim



> You probably blew the protection diode---look for a little black thingie,
> close to the input jack-that has burned up.

I was waiting for your input Jim, but was hoping for something more
hopeful... Yes it must be a switcher, to stabilise 3 amps in a box
roughly 4*2*1 inches! I'll still wrestle it open to see what looks
fried, then find some replacement.

Failing that, I might consider brewing my own non-switching regulator.
The original does 3 amps at 11V output, 12-24 input. But I'll only use
it at 12 volts (24V planes are beyond my means anyway, and I don't drive
trucks either) so at worst it'll dissipate 9 watts for short periods of
transmission (reckoning a max. batt. voltage of 14 volts), much less
during reception.

Will keep you posted.

KA


RST Engineering schreef:
> Jerry ...
>
> I don't think that is going to be it. If the Grover diode is in parallel
> with the input, yes, it will have blown the fuse and probably trashed itself
> in the process. However, if that diode failed open, then the adapter will
> work albeit without any protection. If it failed shorted then it will blow
> the next fuse and according to the OP that didn't happen.
>
> If that diode were in series with the hot lead, then all that would have
> happened is that the diode would have been back-biased and not passed any
> current. That didn't happen either as it did blow the primary fuse.
>
> Most of those little adapters have switching power supplies inside of them
> these days to buck the aircraft battery voltage down to whatever the radio
> battery supply is plus a volt or so to back-bias the summing diodes in the
> radio power supply line. Most likely it got zapped. Cheapest way to fix it
> is buy a new one from Icom and learn from the experience.
>
> Jim

"jan olieslagers" > wrote in message
...
>I was waiting for your input Jim, but was hoping for something more hopeful...
>Yes it must be a switcher, to stabilise 3 amps in a box roughly 4*2*1 inches!
>I'll still wrestle it open to see what looks fried, then find some replacement.
>
> Failing that, I might consider brewing my own non-switching regulator.
> The original does 3 amps at 11V output, 12-24 input. But I'll only use it at
> 12 volts (24V planes are beyond my means anyway, and I don't drive trucks
> either) so at worst it'll dissipate 9 watts for short periods of transmission
> (reckoning a max. batt. voltage of 14 volts), much less during reception.
>
> Will keep you posted.


Read the owner's manual, because my transceiver prohibits transmitting with a
power adapter in use. Yours might also.
--
Jim in NC

jan olieslagers schreef:
> Recently I acquired an Icom A6 in the "Sports pack" version, i.e.
> including an adapter for the car lighter plug. This adapter is called a
> CP20. Through a slight mistake in my car cabling, I managed to connect
> it to the battery the wrong way around, plus and minus were inversed.
> Yes yes it's stupid don't tell me. The lighter plug contains a fuse (8
> Amp!) I replaced that but still the radio won't work, I suppose
> something in the CP20 blew quicker than the fuse.
> NB the radio itself is fine, works like a charm on 6xAA batteries.
>
> Two questions now:
> -) how to open the CP20? There seem to be four small covers over screw
> heads, but they won't move for any effort I applied. Drill through them?
> -) any suggestions as to the CP-20's insides? Schematics, perhaps? What
> are the most obvious candidate victims?

OK guys, after a fruitless and frustrating night, here's the answers:
-) open it by main force - the shell halves are glued (or molten?) together.
-) insides is exactly as Jim described, and exactly as unrepairable.

Facit: into the dustbin except for the mechanical components.
Jim, you were right, damn you! };-)
KA

jan olieslagers schreef:

PS there was indeed a protection diode, a 1N5400 antiparallel to the
input. It was still alive, though not kicking.
KA