Concertone ZX75 car audio system

[Mark Carver]

A friend of mine has just bought himself, and imported here to the UK an
American RV. It is fitted with a Concertone ZX75 car audio system.

There's one problem with the FM radio tuner, it only tunes in 200kHz
steps, 88.1, 88.3, 88.5 etc.

In the UK we have stations every 100 kHz, for instance one station in
our local area is on 98.2 MHz.

Is there any modification (grounding a pin on one of the chips for
instance) that will make the tuner tune in 100 kHz steps ?

He has contacted Concertone's service dept, but they refuse to help,
saying that it is for the US market only.

TIA

 

[N_Cook]

Mark Carver <mark.carver@invalid.invalid> wrote in message
news:7on4jrF3p7h7oU1@mid.individual.net...

A friend of mine has just bought himself, and imported here to the UK an
American RV. It is fitted with a Concertone ZX75 car audio system.

There's one problem with the FM radio tuner, it only tunes in 200kHz
steps, 88.1, 88.3, 88.5 etc.

In the UK we have stations every 100 kHz, for instance one station in
our local area is on 98.2 MHz.

Is there any modification (grounding a pin on one of the chips for
instance) that will make the tuner tune in 100 kHz steps ?

He has contacted Concertone's service dept, but they refuse to help,
saying that it is for the US market only.

TIA

Without inside knowledge this is the only fudge I'm aware of, from my repair
briefs

Sony MDX C150 car CD+tuner conversion from Japan to UK (+New Zealand)
Made for Japan use and FM band set to 76MHz to 90MHz, UK is
about 88 to 108 MHz
Monitoring the VT line to the tuner varies from 1.52V to 4.2V from end to
end of this band. 2 banks of 6 channels programmable in this 76 to 90 M
range plus 3 more that come up annunciated as 1ch with a VT of 5.66V, 2ch
of 6.83V and 3ch of 8.04 V which coincides with a local station on 107.8MHz,
B+(for FM ) on the tuner is 8.3V.
I changed the 7.2M crystal associated with the LC7216 PLL to a double PAL
frequency crystal of 8.867238M
and this brought the range up to almost ideal, a slightly lower frequency
would be better.
LCD reading of 80.0 gives a tuned in station on 96.1M and 89.5 on LCD gives
a station at 107.8MHz.
7.2M is used on LC7218 FM circuits so probably fairly generally applicable.
For anyone wanting to put an analogue tuning knob on a pot
using regulated voltage of 8.3V at pin 8 of absent IC02
then VT of 8.04V gives 107.8MHz
and 4.21V gives 89M
Tuning voltage from LC7216 is pin 18 via FET ? Q2 marked G19



--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[Adrian C]

Mark Carver wrote:

A friend of mine has just bought himself, and imported here to the UK an
American RV. It is fitted with a Concertone ZX75 car audio system.

There's one problem with the FM radio tuner, it only tunes in 200kHz
steps, 88.1, 88.3, 88.5 etc.

In the UK we have stations every 100 kHz, for instance one station in
our local area is on 98.2 MHz.

Any chance of popping off the lid and giving us a few chip numbers?
internal photographs?

The large do everything chip is bound to have been used in other radio
designs, and step options for those may be more forthcoming. Maybe even
the PCB is used elsewhere.

--
Adrian C

 

[RV Guy]

On Dec 14, 7:00 pm, Adrian C <em...@here.invalid> wrote:

Any chance of popping off the lid and giving us a few chip numbers?
internal photographs?

Adrian C

Here you go

http://picasaweb.google.co.uk/ian.westwood/ZX75?authkey=Gv1sRgCKar9YSSwYaviQE&feat=directlink

 

[RV Guy]

On Dec 14, 7:00 pm, Adrian C <em...@here.invalid> wrote:

Mark Carver wrote:
A friend of mine has just bought himself, and imported here to the UK an
American RV. It is fitted with a Concertone ZX75 car audio system.

There's one problem with the FM radio tuner, it only tunes in 200kHz
steps, 88.1, 88.3, 88.5 etc.

In the UK we have stations every 100 kHz, for instance one station in
our local area is on 98.2 MHz.

Any chance of popping off the lid and giving us a few chip numbers?
internal photographs?

The large do everything chip is bound to have been used in other radio
designs, and step options for those may be more forthcoming. Maybe even
the PCB is used elsewhere.

--
Adrian C

Here you go ..

http://picasaweb.google.co.uk/ian.westwood/ZX75?authkey=Gv1sRgCKar9YSSwYaviQE&feat=directlink

 

[Adrian C]

RV Guy wrote:

Here you go ..

http://picasaweb.google.co.uk/ian.westwood/ZX75?authkey=Gv1sRgCKar9YSSwYaviQE&feat=directlink

Thanks.

http://www.datasheetcatalog.org/datasheet/sanyo/ds_pdf_e/LC72130.pdf

Ah, should have seen it coming. These are the days of microcontroller
programmed everything and there is a CPU hidden somewhere (other side of
the PCB?) that sets up registers in the PLL. It's not bridging pins that
does the magic anymore. If there isn't a hidden method to make the step
switch changes(like some car radio models common between US/Euro have)
then it's kind of outa luck me fears.

:-(

--
Adrian C

 

[hr(bob) hofmann@att.net]

On Dec 14, 9:38 am, Mark Carver <mark.car...@invalid.invalid> wrote:

A friend of mine has just bought himself, and imported here to the UK an
American RV. It is fitted with a Concertone ZX75 car audio system.

There's one problem with the FM radio tuner, it only tunes in 200kHz
steps, 88.1, 88.3, 88.5 etc.

In the UK we have stations every 100 kHz, for instance one station in
our local area is on 98.2 MHz.

Is there any modification (grounding a pin on one of the chips for
instance) that will make the tuner tune in 100 kHz steps ?

He has contacted Concertone's service dept, but they refuse to help,
saying that it is for the US market only.

TIA

I think the easiest thing to do is buy a European model that does the
correct tuning.

 

[Colin Horsley]

"Mark Carver" <mark.carver@invalid.invalid> wrote in message
news:7on4jrF3p7h7oU1@mid.individual.net...
|A friend of mine has just bought himself, and imported here to the UK an
| American RV. It is fitted with a Concertone ZX75 car audio system.
|
| There's one problem with the FM radio tuner, it only tunes in 200kHz
| steps, 88.1, 88.3, 88.5 etc.
|
| In the UK we have stations every 100 kHz, for instance one station in
| our local area is on 98.2 MHz.
|
| Is there any modification (grounding a pin on one of the chips for
| instance) that will make the tuner tune in 100 kHz steps ?
|
| He has contacted Concertone's service dept, but they refuse to help,
| saying that it is for the US market only.
|
| TIA

Look here:-
http://www.edl.co.nz/faq.php

and ask them about the PB1500 Band Expander.

"23. Can the PB1500 Band Expander receive both even and uneven Radio
Station ?
No you will only receive the Even Radio Band. the Band Expander shifts the
whole radio band 0.01Mhz so that it can tune the radio stations that it
could not previously receive. . . ..(top)

24. Does the PB1500 alter the AM Radio Stations ?
No unfortunately the AM is bypassed without change, it is to difficult to
shift the 10Khz steppings into the 9Khz steppings. . . ..(top)"



Colin

 

[RV Guy]

On Dec 15, 1:01 am, Adrian C <em...@here.invalid> wrote:

RV Guy wrote:
Here you go ..

http://picasaweb.google.co.uk/ian.westwood/ZX75?authkey=Gv1sRgCKar9YS....

Thanks.

http://www.datasheetcatalog.org/datasheet/sanyo/ds_pdf_e/LC72130.pdf

  Ah, should have seen it coming. These are the days of microcontroller
programmed everything and there is a CPU hidden somewhere (other side of
the PCB?) that sets up registers in the PLL. It's not bridging pins that
does the magic anymore. If there isn't a hidden method to make the step
switch changes(like some car radio models common between US/Euro have)
then it's kind of outa luck me fears.

:-(

--
Adrian C

Good Job Adrian. Thanks for figuring that out. Much appreciated.

 

[RV Guy]

Look here:-http://www.edl.co.nz/faq.php

and ask them about the PB1500 Band Expander.


      Colin

THANK YOU COLIN!

I spent hours googling for something like this but came up with
nothing.

I called them (the guy answered 2300 hrs local time!!) and the PB1500
seems to do exactly what I need. I have ordered 2 as a mate of mine
has the same problem!

Ł37 each with postage. Should save a bit buying 2 off.

I declare this problem solved!

Cheers all,

Ian.

 

[RV Guy]

Comedy email of the day from Concertone Support:
------------------------
Dear Ian,

We are of course interested in expending our business. The European
market could be an interesting business opportunity. Due to the size
of our corporation and the type of our business (OEM), in order to
move forward with your proposal you will have to provide US $20,000.00
as a development cost so that our factory can develop a tuner solution
according to the European frequency step standards. Regarding the
production, you will have to commit to buy at least 100.000 Concertone
units per year. If you feel confident with the above numbers please
let us know so that we can move to the next step.

Regards,
Concertone