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"




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