FT480R repair
 

I need to replace the T/R relay on an FT480R.
(Intermittent Rx, curable by a quick blip on TX)

I don't have an exact replacement, so I'll use a
Varley 12V relay, with suitable mods to the driving cct,
and dangle the relay in the space behind the front panel.

Is there a knack to removing the main board without first
unsoldering the numerous connections? (i.e., can it just
be a tedious job, or must it be downright finicky?)

There is a second pair of change-over contacts on the
relay, but with both outputs wired together...this would seem
to suggest some form of muting effect that deals only with
the T/R or R/T changeover period. Any ideas?

FT480R repair
 

The basey fundemold to effect replaceage of the relayle is the carefold
slidy PCB out of its cradley, snippet the blacklode and whiteley wirey, then
stufflo the relayme dowdy into the backly sidelode aspecters of the s-metery
and Bob's your unkerbold - o yes!

FT480R repair
 

"Anonymous" wrote in message ...
I need to replace the T/R relay on an FT480R.
(Intermittent Rx, curable by a quick blip on TX)

I don't have an exact replacement, so I'll use a
Varley 12V relay, with suitable mods to the driving cct,
and dangle the relay in the space behind the front panel.

Is there a knack to removing the main board without first
unsoldering the numerous connections? (i.e., can it just
be a tedious job, or must it be downright finicky?)

There is a second pair of change-over contacts on the
relay, but with both outputs wired together...this would seem
to suggest some form of muting effect that deals only with
the T/R or R/T changeover period. Any ideas?


From the circuit diagram:

The relay switches two things:

Antenna (Rx/Tx)

13.8V to the Tone unit.

One side of the relay coil is to the 13.8V internal rail, other side is to
the Main Unit and, unless it is very convoluted, isn't connected to either
set of relay contacts nor do the two sets of contacts seen to be connected
to each other.

I've done one of these before and, as I recall, "pin for pin" relays were
available- I think Farnell.

FT480R repair
 

"Theo" wrote in message
...
The basey fundemold to effect replaceage of the relayle is the carefold
slidy PCB out of its cradley, snippet the blacklode and whiteley wirey,
then
stufflo the relayme dowdy into the backly sidelode aspecters of the
s-metery
and Bob's your unkerbold - o yes!

:-)))))))


C'mon Theo, give the man a break...

tox

FT480R repair
 

"Brian Reay" wrote in message
...

From the circuit diagram:


Which I can scan the relevant section of and place on my website for
download.

FT480R repair
 

"Brian Reay" wrote in message
...
"Anonymous" wrote in message
...
I need to replace the T/R relay on an FT480R.
(Intermittent Rx, curable by a quick blip on TX)

I don't have an exact replacement, so I'll use a
Varley 12V relay, with suitable mods to the driving cct,
and dangle the relay in the space behind the front panel.

Is there a knack to removing the main board without first
unsoldering the numerous connections? (i.e., can it just
be a tedious job, or must it be downright finicky?)

There is a second pair of change-over contacts on the
relay, but with both outputs wired together...this would seem
to suggest some form of muting effect that deals only with
the T/R or R/T changeover period. Any ideas?

From the circuit diagram:
The relay switches two things:
Antenna (Rx/Tx)
13.8V to the Tone unit.
One side of the relay coil is to the 13.8V internal rail, other side is to
the Main Unit and, unless it is very convoluted, isn't connected to either
set of relay contacts nor do the two sets of contacts seen to be connected
to each other.
I've done one of these before and, as I recall, "pin for pin" relays were
available- I think Farnell.

You're looking at the wrong cct diagram. Read my lips, "Main Unit"

FT480R repair
 

"Anonymous" wrote in message ...
There is a second pair of change-over contacts on the
relay, but with both outputs wired together...this would seem
to suggest some form of muting effect that deals only with
the T/R or R/T changeover period. Any ideas?

The same cct is used for both RX AGC and TX ALC and
it looks as thought the change-over time between sets of contacts
is used to discharge the cct in preparation for the other mode.

Anyway, anybody done maintenance and know the answer to
lifting out the main board? (The Maintenance Service Manual
offers no help in this regard)

FT480R repair
 

Anonymous wrote:
"Anonymous" wrote in message ...

There is a second pair of change-over contacts on the
relay, but with both outputs wired together...this would seem
to suggest some form of muting effect that deals only with
the T/R or R/T changeover period. Any ideas?


The same cct is used for both RX AGC and TX ALC and
it looks as thought the change-over time between sets of contacts
is used to discharge the cct in preparation for the other mode.

Anyway, anybody done maintenance and know the answer to
lifting out the main board? (The Maintenance Service Manual
offers no help in this regard)

I had to replace a crystal on the PLL board in my FT480R, it wasn't all
that difficult to remove and that might get you access to what you need
on the Main board.

Have you tried getting a replacement relay from Yaesu? They had my
FT480 crystal and a crystal I needed for an FT290 and they weren't as
expensive as I thought they'd be... " For customer service, technical
support or parts, please call 714-827-7600."

FT480R repair
 

Anonymous wrote:
I need to replace the T/R relay on an FT480R.
(Intermittent Rx, curable by a quick blip on TX)

Are you sure the PLL locks when you go back to receive?

FT480R repair
 

How rude! He was only trying to help you.

What a strange way to maintain standards.

"Anonymous" wrote in message ...
You're looking at the wrong cct diagram. Read my lips, "Main Unit"




--
Posted via a free Usenet account from http://www.teranews.com

FT480R repair
 

"gwatts" wrote in message
...
I had to replace a crystal on the PLL board in my FT480R, it wasn't all
that difficult to remove and that might get you access to what you need on
the Main board.

An interesting suggestion, thanks....should certainly get me to the
underside
of the main board.

Have you tried getting a replacement relay from Yaesu? They had my FT480
crystal and a crystal I needed for an FT290 and they weren't as expensive
as I thought they'd be... " For customer service, technical support or
parts, please call 714-827-7600."

I've a junk box going back 40 years with some relays....."the most expensive
component already in the junk box is cheaper than the cheapest one you can
buy".....a much more interesting exercise to modify the cct to accomodate
what I have to hand....a 27-year-old rig has no resale value anyway.

FT480R repair
 

"Brian Reay" wrote in message
...

However, it seems he has the details he needs and was simply seeking to
draw attention to the fact he is working on a radio.

You're always so negative, OM,and quite wrong.

FT480R repair
 

"gwatts" wrote in message
...
Anonymous wrote:
I need to replace the T/R relay on an FT480R.
(Intermittent Rx, curable by a quick blip on TX)

Are you sure the PLL locks when you go back to receive?

No reason the PLL frequency should change between TX and RX
as I'm only using it on FM simplex.

Another symptom is that the RX comes back on but
the squelch gradually becomes ineffective until you're listening to a
low-level noise and the squelch control is inoperative to cut it out.

The AF amp appears to be permanently powered at 13.8V so
my presumption is that I'm listening to an amp with no input.

FT480R repair
 

something wrong with switch cleaner ???


"Anonymous" wrote in message ...
I need to replace the T/R relay on an FT480R.
(Intermittent Rx, curable by a quick blip on TX)

I don't have an exact replacement, so I'll use a
Varley 12V relay, with suitable mods to the driving cct,
and dangle the relay in the space behind the front panel.

Is there a knack to removing the main board without first
unsoldering the numerous connections? (i.e., can it just
be a tedious job, or must it be downright finicky?)

There is a second pair of change-over contacts on the
relay, but with both outputs wired together...this would seem
to suggest some form of muting effect that deals only with
the T/R or R/T changeover period. Any ideas?

FT480R repair
 

On 8 Aug, 16:50, "Anonymous" wrote:
I need to replace the T/R relay on an FT480R.
(Intermittent Rx, curable by a quick blip on TX)

I don't have an exact replacement, so I'll use a
Varley 12V relay, with suitable mods to the driving cct,
and dangle the relay in the space behind the front panel.

Is there a knack to removing the main board without first
unsoldering the numerous connections? (i.e., can it just
be a tedious job, or must it be downright finicky?)

There is a second pair of change-over contacts on the
relay, but with both outputs wired together...this would seem
to suggest some form of muting effect that deals only with
the T/R or R/T changeover period. Any ideas?

Get over it ,,chuck it in the bin ,old and outdated like many of the
cretins on here ,
Spend some money u tight git get a good radio.
Regards
Zakdingle

FT480R repair
 

In article , "Anonymous" wrote:

No reason the PLL frequency should change between TX and RX
as I'm only using it on FM simplex.

Just goes to show that YOU really don't understand the technology
that your dealing with...... Maybe a few courses in Modern
Radio Design, would help you understand how the PLL System
works in an FT480R.....

FT480R repair
 

"You" wrote in message
...
In article , "Anonymous" wrote:
No reason the PLL frequency should change between TX and RX
as I'm only using it on FM simplex.
Just goes to show that YOU really don't understand the technology
that your dealing with...... Maybe a few courses in Modern
Radio Design, would help you understand how the PLL System
works in an FT480R.....

Which bits of it do you say that I don't understand?

Loop stability in control systems, perhaps? Lead/Lag
compensation? Triple loop PLLs to give 10Hz steps but
without the final loop stepping in 10Hz?

What exactly?

FT480R repair
 

"J." wrote in message
...
On Wed, 08 Aug 2007 15:01:57 -0700, zakdingle
wrote:

On 8 Aug, 16:50, "Anonymous" wrote:
I need to replace the T/R relay on an FT480R.
(Intermittent Rx, curable by a quick blip on TX)

I don't have an exact replacement, so I'll use a
Varley 12V relay, with suitable mods to the driving cct,
and dangle the relay in the space behind the front panel.

Is there a knack to removing the main board without first
unsoldering the numerous connections? (i.e., can it just
be a tedious job, or must it be downright finicky?)

There is a second pair of change-over contacts on the
relay, but with both outputs wired together...this would seem
to suggest some form of muting effect that deals only with
the T/R or R/T changeover period. Any ideas?

Get over it ,,chuck it in the bin ,old and outdated like many of the
cretins on here ,
Spend some money u tight git get a good radio.
Regards
Zakdingle


I have to say that I had a 480 and a 470 in the '80s, and at the time they
were fine radios, if a bit deaf on ssb.

What's wrong with trying to fix old gear, for god's sake? And why do most
threads on here degenerate into some form of slanging match?

No wonder the average level of helpfulness and worthwhile threads is
pretty
poor. The obsessives are killing it.

J.

Repairing old gear can be fun - and lets face it - most "hams" or "Cber's"
for that matter don't have the "equipment" to repair the newer stuff with
SMD devices. Parts are still fairly easy to get - with the Internet. Usually
you can find it with some luck.
Though I do newer equipment repairs - my eyes prefer the older stuff - much
more. I have some older tube gear that I've had for projects for quite some
time now - been too busy to do them. Am awaiting the day I can start on them
and see the warm glow and listen to the audio coming forth.

L.

FT480R repair
 

"Anonymous" wrote in message ...
I need to replace the T/R relay on an FT480R.
(Intermittent Rx, curable by a quick blip on TX)

Does the Beanifits Office know about this little earner?

FT480R repair
 

In article , "Anonymous" wrote:

"You" wrote in message
...
In article , "Anonymous" wrote:
No reason the PLL frequency should change between TX and RX
as I'm only using it on FM simplex.
Just goes to show that YOU really don't understand the technology
that your dealing with...... Maybe a few courses in Modern
Radio Design, would help you understand how the PLL System
works in an FT480R.....

Which bits of it do you say that I don't understand?

Loop stability in control systems, perhaps? Lead/Lag
compensation? Triple loop PLLs to give 10Hz steps but
without the final loop stepping in 10Hz?

What exactly?



It is the part where the PLL Frequency doesn't change because you
at using FM Simplex. There are many reasons for the PLL to change
between Tx and Rx, even with the radio in FM Simplex mode.

1. The receiver may have an IF Frequency of 10.7 Mhz which would
require the PLL to be offset from the Receive Frequncy by the
IF Frequency,
2. The Transmitter exciter may use a different Offset Frequency
than the Receiver IF Frequency, and most Transmitters don't
modulate the Tx Output Frequency directly, but modulate an
IF Frequency that is, either "mixed" to the Tx Frequency, or
"multiplied" to the Tx Frequency.

Just to name a few. Now Sir please, expound your brilliance on why
you made such a Stupid Comment in the Original Post, as sited
above...........

FT480R repair
 

"You" wrote in message
...

It is the part where the PLL Frequency doesn't change because you
at using FM Simplex. There are many reasons for the PLL to change
between Tx and Rx, even with the radio in FM Simplex mode.

1. The receiver may have an IF Frequency of 10.7 Mhz which would
require the PLL to be offset from the Receive Frequncy by the
IF Frequency,

This is classic radio design, the vast majority of crystal controlled VHF
rigs from the seventies and eighties had a separete crystal for TX and RX
because of the IF stage in the receiver. Not true of all rigs though. The
FDK Multi 2000 as well as a PLL VFO has a number of crystal memories and has
a single crystal for each memory, but it's more the exception than the
rule - probably done to reduce cost of two crystals rather than one for each
channel.

FT480R repair
 

"Radiosrfun" wrote in message
...

Repairing old gear can be fun - and lets face it - most "hams" or "Cber's"
for that matter don't have the "equipment" to repair the newer stuff with
SMD devices. Parts are still fairly easy to get - with the Internet.
Usually
you can find it with some luck.
Though I do newer equipment repairs - my eyes prefer the older stuff - much
more. I have some older tube gear that I've had for projects for quite some
time now - been too busy to do them. Am awaiting the day I can start on
them
and see the warm glow and listen to the audio coming forth - along with the
sparks and smoke!