I like to restore the FM reception to normal ops. So far I have
diagnosed that AM reception/tuning is in good condition. In the FM
mode no IF signal is getting to pin 1 of the IC LA1265 so I belief
that the little tuner block is at fault. I managed to remove the
shielding covers to get access to the tuner section which really
exposed a jungle of SMT devices.
To find my way around this multigang-ed tuner I hope that some one can
provide me with a copy of the DENON FM front end or any help to
troubleshoot the receiver

Thanks
Bram

Firstly, verify that there are proper supply voltages getting to the tuner
unit. If the receiver is digital controlled, check to see if the tuner unit
is being properly commanded by the uPC. Check to see that the local
oscillator and RF amp in the tuner is working.

If you replace any parts in the FM front end or do any kind of soldering,
you will need the instruments and skills to perform the front end
calibration if you want peak performance from your receiver.

You will need a good scope and the full service information to properly
troubleshoot the front end of your receiver. If you call the parts
department for Denon, I believe they will sell you ca copy of the service
manual and any parts you need.

--

JANA
_____


"Brasto" wrote in message
ups.com...
I like to restore the FM reception to normal ops. So far I have
diagnosed that AM reception/tuning is in good condition. In the FM
mode no IF signal is getting to pin 1 of the IC LA1265 so I belief
that the little tuner block is at fault. I managed to remove the
shielding covers to get access to the tuner section which really
exposed a jungle of SMT devices.
To find my way around this multigang-ed tuner I hope that some one can
provide me with a copy of the DENON FM front end or any help to
troubleshoot the receiver

Thanks
Bram

I have sent a diagram of the tuner section to your gmail address. A quick
glance suggests that pin 5 is the voltage contolled tuning input;
transistors TR 505 and 504 appears to be the AM and FM switches.

Mark Z.

"Brasto" wrote in message
ups.com...
I like to restore the FM reception to normal ops. So far I have
diagnosed that AM reception/tuning is in good condition. In the FM
mode no IF signal is getting to pin 1 of the IC LA1265 so I belief
that the little tuner block is at fault. I managed to remove the
shielding covers to get access to the tuner section which really
exposed a jungle of SMT devices.
To find my way around this multigang-ed tuner I hope that some one can
provide me with a copy of the DENON FM front end or any help to
troubleshoot the receiver

Thanks
Bram

On 11 sep, 12:24, "Mark D. Zacharias" wrote:
I have sent a diagram of the tuner section to your gmail address. A quick
glance suggests that pin 5 is the voltage contolled tuning input;
transistors TR 505 and 504 appears to be the AM and FM switches.

Mark Z.

"Brasto" wrote in message

ups.com...



I like to restore the FM reception to normal ops. So far I have
diagnosed that AM reception/tuning is in good condition. In the FM
mode no IF signal is getting to pin 1 of the IC LA1265 so I belief
that the little tuner block is at fault. I managed to remove the
shielding covers to get access to the tuner section which really
exposed a jungle of SMT devices.
To find my way around this multigang-ed tuner I hope that some one can
provide me with a copy of the DENON FM front end or any help to
troubleshoot the receiver

Thanks
Bram- Tekst uit oorspronkelijk bericht niet weergeven -

- Tekst uit oorspronkelijk bericht weergeven -

Mark,
That is great info and probably will lead me to the desired
result......
In the mean time I took another DENON unit apart which is a working
straight forward AM/FM tuner. It's front end is from a different
manufacturer and has a different format/technology, but it also had 8
pins with the same pitch as in the AVR3300. I decided to swapp both
tuners and guess what....the suspect works as advertised and the known
to be good tuner did not function in the AVR3300. So I learned at
least one thing...my front end is OK. I also learned that the AVR3300
does NOT provide the B+ and the Tuning Voltage is stuck at B+ value. I
am still struggling to understand all the *# Note numbers in your
schematic telling that things are OPEN. Is your schematic covering
various versions of the AVR3300 ?.
E.g. top LH corner shows Front End with floating AGC line and
additional pins 9, 10 and 11 which do not exist in my unit and a bunch
of akward connected resiustors.R504...R571)
Am I correct assuming that IC 507 (LC72131 is generating the VCO
voltage to pin 5 of the front end ? and also switches via pin 10 the B
+ thru TR505 ? I am afraid I might end up with a Buss problem in the
PLL circuit ?

Thanks also to JANA who pointed out that the drive signals from the
Uprocessor might be wrong rather than the tuner itself.....

"Brasto" wrote in message
ps.com...
On 11 sep, 12:24, "Mark D. Zacharias" wrote:
I have sent a diagram of the tuner section to your gmail address. A quick
glance suggests that pin 5 is the voltage contolled tuning input;
transistors TR 505 and 504 appears to be the AM and FM switches.

Mark Z.

"Brasto" wrote in message

ups.com...



I like to restore the FM reception to normal ops. So far I have
diagnosed that AM reception/tuning is in good condition. In the FM
mode no IF signal is getting to pin 1 of the IC LA1265 so I belief
that the little tuner block is at fault. I managed to remove the
shielding covers to get access to the tuner section which really
exposed a jungle of SMT devices.
To find my way around this multigang-ed tuner I hope that some one can
provide me with a copy of the DENON FM front end or any help to
troubleshoot the receiver

Thanks
Bram- Tekst uit oorspronkelijk bericht niet weergeven -

- Tekst uit oorspronkelijk bericht weergeven -

Mark,
That is great info and probably will lead me to the desired
result......
In the mean time I took another DENON unit apart which is a working
straight forward AM/FM tuner. It's front end is from a different
manufacturer and has a different format/technology, but it also had 8
pins with the same pitch as in the AVR3300. I decided to swapp both
tuners and guess what....the suspect works as advertised and the known
to be good tuner did not function in the AVR3300. So I learned at
least one thing...my front end is OK. I also learned that the AVR3300
does NOT provide the B+ and the Tuning Voltage is stuck at B+ value. I
am still struggling to understand all the *# Note numbers in your
schematic telling that things are OPEN. Is your schematic covering
various versions of the AVR3300 ?.
E.g. top LH corner shows Front End with floating AGC line and
additional pins 9, 10 and 11 which do not exist in my unit and a bunch
of akward connected resiustors.R504...R571)
Am I correct assuming that IC 507 (LC72131 is generating the VCO
voltage to pin 5 of the front end ? and also switches via pin 10 the B
+ thru TR505 ? I am afraid I might end up with a Buss problem in the
PLL circuit ?

Thanks also to JANA who pointed out that the drive signals from the
Uprocessor might be wrong rather than the tuner itself.....


I don't know what the story is on those extra pins - Denon's service manuals
can be pretty crappy, especially these scans of their older ones.
I think the PLL IC is probably bad - this is a pretty common failure.

You can apply an external tuning voltage to the front endm vary it through
the range and see if the tuner tunes, and also that there is an oscillator
output, but of course there should be, since you've pretty well found the
front end to be OK...

Am I correct assuming that IC 507 (LC72131 is generating the VCO
voltage to pin 5 of the front end ? and also switches via pin 10 the B+
thru TR505 ?

I think so; also bear in mind that the AM/FM switch outputs on pins 10 and
12 of IC 507 would each be high and low at any given time - that is, they
should not both be at the same state at the same time. This is another type
of failure the PLL IC could have.

Mark Z.

On 12 sep, 13:46, "Mark D. Zacharias" wrote:
"Brasto" wrote in message

ps.com...





On 11 sep, 12:24, "Mark D. Zacharias" wrote:
I have sent a diagram of the tuner section to your gmail address. A quick
glance suggests that pin 5 is the voltage contolled tuning input;
transistors TR 505 and 504 appears to be the AM and FM switches.

Mark Z.

"Brasto" wrote in message

roups.com...

I like to restore the FM reception to normal ops. So far I have
diagnosed that AM reception/tuning is in good condition. In the FM
mode no IF signal is getting to pin 1 of the IC LA1265 so I belief
that the little tuner block is at fault. I managed to remove the
shielding covers to get access to the tuner section which really
exposed a jungle of SMT devices.
To find my way around this multigang-ed tuner I hope that some one can
provide me with a copy of the DENON FM front end or any help to
troubleshoot the receiver

Thanks
Bram- Tekst uit oorspronkelijk bericht niet weergeven -

- Tekst uit oorspronkelijk bericht weergeven -

Mark,
That is great info and probably will lead me to the desired
result......
In the mean time I took another DENON unit apart which is a working
straight forward AM/FM tuner. It's front end is from a different
manufacturer and has a different format/technology, but it also had 8
pins with the same pitch as in the AVR3300. I decided to swapp both
tuners and guess what....the suspect works as advertised and the known
to be good tuner did not function in the AVR3300. So I learned at
least one thing...my front end is OK. I also learned that the AVR3300
does NOT provide the B+ and the Tuning Voltage is stuck at B+ value. I
am still struggling to understand all the *# Note numbers in your
schematic telling that things are OPEN. Is your schematic covering
various versions of the AVR3300 ?.
E.g. top LH corner shows Front End with floating AGC line and
additional pins 9, 10 and 11 which do not exist in my unit and a bunch
of akward connected resiustors.R504...R571)
Am I correct assuming that IC 507 (LC72131 is generating the VCO
voltage to pin 5 of the front end ? and also switches via pin 10 the B
+ thru TR505 ? I am afraid I might end up with a Buss problem in the
PLL circuit ?

Thanks also to JANA who pointed out that the drive signals from the
Uprocessor might be wrong rather than the tuner itself.....

I don't know what the story is on those extra pins - Denon's service manuals
can be pretty crappy, especially these scans of their older ones.
I think the PLL IC is probably bad - this is a pretty common failure.

You can apply an external tuning voltage to the front endm vary it through
the range and see if the tuner tunes, and also that there is an oscillator
output, but of course there should be, since you've pretty well found the
front end to be OK...

Am I correct assuming that IC 507 (LC72131 is generating the VCO
voltage to pin 5 of the front end ? and also switches via pin 10 the B+
thru TR505 ?

I think so; also bear in mind that the AM/FM switch outputs on pins 10 and
12 of IC 507 would each be high and low at any given time - that is, they
should not both be at the same state at the same time. This is another type
of failure the PLL IC could have.

Mark Z.- Tekst uit oorspronkelijk bericht niet weergeven -

- Tekst uit oorspronkelijk bericht weergeven -

...Oeps..Got myself in deeper trouble..I had this suspect front-end
swapped into a known to be good tuner TU580RD, it performed OK that
day. A few days later I reapplied mains to the TU580RD and NO more FM
reception. I then reinstalled its original front end and gray
hairs...it did NOT work any longer. Measurements showed that B+ had
gone. Doing some PCB line tracing ended up to SMD TR23 failed to
switch +12 VDC when so commanded. Removed the bug from the board and
patchwired +12 VDC to B+, Life returned to the TU580RD. I now have a
need to know Type/PN of the SMD switch (No markings left) at PCB
location TR23. ?? Who can help ??

So I learned the hardway that my original frontend from the AVR3300
probably developped a short in the B+ over times. I put the suspect
frontend back into the AVR3300, disconnected its B+ PCB jumper wire
and applied an external 12 VDC. No smoke but a full short..Let me tell
you that probing around in the tiny little front end is a challenge of
its own. Some engineer must have thought that RF leakage shall be
minimized by soldering a tripple housing at all the fingerstocks.
Unfortunately the circuitdiagram Mark so kindly provided to me does
NOT cover the front end. DENON has classified this part probably as a
Black Box....Sealed Do Not Open....

I'll just wait for another FM unit to canibalize its front-end

On 16 sep, 12:26, Brasto wrote:
On 12 sep, 13:46, "Mark D. Zacharias" wrote:





"Brasto" wrote in message

ups.com...

On 11 sep, 12:24, "Mark D. Zacharias" wrote:
I have sent a diagram of the tuner section to your gmail address. A quick
glance suggests that pin 5 is the voltage contolled tuning input;
transistors TR 505 and 504 appears to be the AM and FM switches.

Mark Z.

"Brasto" wrote in message

roups.com...

I like to restore the FM reception to normal ops. So far I have
diagnosed that AM reception/tuning is in good condition. In the FM
mode no IF signal is getting to pin 1 of the IC LA1265 so I belief
that the little tuner block is at fault. I managed to remove the
shielding covers to get access to the tuner section which really
exposed a jungle of SMT devices.
To find my way around this multigang-ed tuner I hope that some one can
provide me with a copy of the DENON FM front end or any help to
troubleshoot the receiver

Thanks
Bram- Tekst uit oorspronkelijk bericht niet weergeven -

- Tekst uit oorspronkelijk bericht weergeven -

Mark,
That is great info and probably will lead me to the desired
result......
In the mean time I took another DENON unit apart which is a working
straight forward AM/FM tuner. It's front end is from a different
manufacturer and has a different format/technology, but it also had 8
pins with the same pitch as in the AVR3300. I decided to swapp both
tuners and guess what....the suspect works as advertised and the known
to be good tuner did not function in the AVR3300. So I learned at
least one thing...my front end is OK. I also learned that the AVR3300
does NOT provide the B+ and the Tuning Voltage is stuck at B+ value. I
am still struggling to understand all the *# Note numbers in your
schematic telling that things are OPEN. Is your schematic covering
various versions of the AVR3300 ?.
E.g. top LH corner shows Front End with floating AGC line and
additional pins 9, 10 and 11 which do not exist in my unit and a bunch
of akward connected resiustors.R504...R571)
Am I correct assuming that IC 507 (LC72131 is generating the VCO
voltage to pin 5 of the front end ? and also switches via pin 10 the B
+ thru TR505 ? I am afraid I might end up with a Buss problem in the
PLL circuit ?

Thanks also to JANA who pointed out that the drive signals from the
Uprocessor might be wrong rather than the tuner itself.....

I don't know what the story is on those extra pins - Denon's service manuals
can be pretty crappy, especially these scans of their older ones.
I think the PLL IC is probably bad - this is a pretty common failure.

You can apply an external tuning voltage to the front endm vary it through
the range and see if the tuner tunes, and also that there is an oscillator
output, but of course there should be, since you've pretty well found the
front end to be OK...

Am I correct assuming that IC 507 (LC72131 is generating the VCO
voltage to pin 5 of the front end ? and also switches via pin 10 the B+
thru TR505 ?

I think so; also bear in mind that the AM/FM switch outputs on pins 10 and
12 of IC 507 would each be high and low at any given time - that is, they
should not both be at the same state at the same time. This is another type
of failure the PLL IC could have.

Mark Z.- Tekst uit oorspronkelijk bericht niet weergeven -

- Tekst uit oorspronkelijk bericht weergeven -

..Oeps..Got myself in deeper trouble..I had this suspect front-end
swapped into a known to be good tuner TU580RD, it performed OK that
day. A few days later I reapplied mains to the TU580RD and NO more FM
reception. I then reinstalled its original front end and gray
hairs...it did NOT work any longer. Measurements showed that B+ had
gone. Doing some PCB line tracing ended up to SMD TR23 failed to
switch +12 VDC when so commanded. Removed the bug from the board and
patchwired +12 VDC to B+, Life returned to the TU580RD. I now have a
need to know Type/PN of the SMD switch (No markings left) at PCB
location TR23. ?? Who can help ??

So I learned the hardway that my original frontend from the AVR3300
probably developped a short in the B+ over times. I put the suspect
frontend back into the AVR3300, disconnected its B+ PCB jumper wire
and applied an external 12 VDC. No smoke but a full short..Let me tell
you that probing around in the tiny little front end is a challenge of
its own. Some engineer must have thought that RF leakage shall be
minimized by soldering a tripple housing at all the fingerstocks.
Unfortunately the circuitdiagram Mark so kindly provided to me does
NOT cover the front end. DENON has classified this part probably as a
Black Box....Sealed Do Not Open....

I'll just wait for another FM unit to canibalize its front-end- Tekst uit oorspronkelijk bericht niet weergeven -

- Tekst uit oorspronkelijk bericht weergeven -
Well, it's an A OK, ordered a new Front end (Mitsubishi) and replaced
the SMD T105 (RN1205) which failed to switch the 12 V B+ to the front-
end.
The old front-end had obviously developed an internal short on the B+
line with temperature/time. I still donot understand this because
according to some lay-outs there is always 100 ohms in the internal B+
circuit. Probably that a short develops underneath one of the SMD
components and a tiny PCB trace.

Anyway, again thanks for your help(s), It saved another fine product
from the trashcan...