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IZ3LSV

[San Dona' di P. JN]

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G8MNY  > TECH     04.05.23 10:15l 64 Lines 2843 Bytes #999 (0) @ WW
BID : 46588_GB7CIP
Read: GUEST
Subj: IC 735 Lamps Mod
Path: IZ3LSV<DB0ERF<OK0NAG<OK0NBR<SR1BSZ<IW0QNL<ON0AR<GB7CIP
Sent: 230504/0908Z @:GB7CIP.#32.GBR.EURO #:46588 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To  : TECH@WW

By G8MNY                            (New Mar 223)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
 ________________________________________________________
³         ÚÄÄÄÄÄÄÄÄ¿ ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿  ==  ==  == ³
³ ßßßß == ³  \     ³ ³ Rx 14.273.5 vfo A 12³    _    _   ³
³ /~\     ÀÄÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ   (_)  (_)  ³
³ \_/                          ____  IC-735              ³
³      ßßß ~~~~~~""""""~~~   /'    `\    ßßß   /"~"\  [] ³
³  0   ÜÜÜ                  |(~)     |   ÜÜÜ  |     |    ³
³           Þ Þ Þ Þ Þ Þ    ³  ~       ³        \._./  [] ³
³ /~~\ ßßß  Þ Þ Þ Þ Þ Þ     |        |   ßßß  ==  ==  == ³
³ \__/ ÜÜÜ  # # # # # #  []  \.____./    ÜÜÜ  [___] [___]³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
I now have 3 of these old triple convertion HF PLL rigs, a heavily used one for
/P use, club events, & training courses etc. a spare one, and a cleaner one in
the shack.

SYMPTOMS
There are 4 of these lamps illuminating the meter & the LCD panel. So the odd
blown lamp it is not to bad to use the rig. The lamps are grain of wheat 12V
wire ended & run on about 10V. They have a green cover over each bulb. Unlike
LEDs the light goes 360deg around to illuminate large areas.

PREPING REPLACEMENTS  
Having a box of tiny screw 6V SMD white lamps, I set about using them as 
replacements....
        oÄÄ¿
      :~ ~:6         They needed a series 68R so they did not blow up,
      :   :8         which is soldered from the tip & lead wired towards 
  ____:   :R  +10V   the bulb & then bent sideways. The earth wire is
Gnd   øÄÄÄ´ÀÄÄÄ      soldered to the case solder point.
     ³³   ³³Green
Glass³³   ³³Cover
 Bulb \\_// 
       ~~~
FIXING IT
Access is fairly straight forward, but a few screws!
 1/ Remove power lead, remove top and bottom covers, including the 4 anti
    rattle screws around the LS.
 2/ Unscrew the 2 front panel Locking screws, and tilt the panel down to access
    the wire ended lamps (in PCB holes) and unsolder the blown ones.
 3/ If needed for more access, unscrew the 4 screws for PA unit, remove
    external Phono Rx patch lead, release the LS lead, RF drive lead from
    underside PCB & 2 other connectors to the upper PA unit.
 4/ Carefully remove the dud lamps green covers, and put them on the new bulbs.
 5/ Cut the new lamp wires to length & tin them. Solder in with the lamps case
    on the earth side if possible. 
 6/ Now put everything on its side, and make power safe, power up the rig and
    check for correct lamp function.
 7/ Power down and reassemble.


Also see tech buls "IC 735 No RF Output Fault", "IC 735 No PA Bias Fault",
"PA instability in ICOM IC735", "Autocaller with old Maplin kit" & "CW/SSB Rig
Frequency".


Why don't U send an interesting bul?

73 de John G8MNY @ GB7CIP


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