Galaxy Pluto goes into TX when turned on

[Unit 75]

I picked up a Galaxy Pluto for free due to it not working. It was DOA. I replaced the regulator (TR51) with a 2SB817 and replaced TR50 with a TIP42C. The radio then came to life when I turned it on...but was in TX mode without keying the mic. Now, I have read that a faulty 4558D (dual op amp IC) will cause this. So, I replaced it with a new one and the radio is still doing the same thing. Has anyone encountered such a problem? If so, can you share what you did to rectify the issue? Thanks in advance.
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[Shadetree Mechanic]

Maybe it has the wrong mic? I think a Midland mic would cause this.

 

[Unit 75]

Not a mic issue

 

[Shadetree Mechanic]

Not a mic issue

Maybe a shorted capacitor?

 

[loosecannon]

use this block diagram and check the voltages on TR36, 37, and 38.
my guess is that TR38 is shorted.

http://www.cbtricks.com/radios/galaxy/dx88hl/graphics/88hl_block.gif
LC

 

[Unit 75]

I will check the voltages out on those 3 transistors and check that zener out as well in the morning and let you know what I find. Thanks for the reply, LC
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[Unit 75]

Hey, LC. You were right on the money bud. TR38 was shorted and R252 was cooked. I replaced TR36,37,38 and R252. The Pluto now keys up as it should. Thank you sir!
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[Unit 75]

So I start to do an alignment. Everything adjusted ok until I got to the receive alignment and find SSB receive to have very poor sensitivity. AM and FM are good. I can transmit from a close by radio and can barely hear myself with no signal measuring on the Pluto S-meter.......back on the bench it goes

 

[loosecannon]

glad to help.

isn't that always the way though, when you claim a victory on a radio another problem crops right up and challenges you to another match.

First thing i would do is find out if L13 and L14 (the SSB IF tuning cans) showed a peak or if either of them seemed to make no difference when turned.
if one of them makes no difference, check its surrounding components.

if they both show a peak but one of them shows a peak right at the position where the ferrite slug sits flush with the top of the can, then that can is bad and needs to be replaced.

transistors to check are TR19 through TR22. they are all SSB IF amps and if any one of them are blown it can tank your receive sensitivity.
you can use that same block diagram to check the voltages.
LC

 

[Unit 75]

L13 and 14 didn't seem to do anything when I turned them. The slugs, as found, are about middle and not at the top so I believe them to be ok for the moment. I will start out at FL3 crystal filter and go on through those SSB IF amps and see what I can find. Your right about something else coming up...lol. I will get this thing going. Have to be positive
Thanks, LC

 

[nomadradio]

L13 and L14 didn't make a difference when you turned them?

Definitely wrong. Each one should have a fairly sharp peak when tuned.

73

 

[Unit 75]

I injected a -67dB signal, no mod, into the antenna jack. L13 had nadda when the slug was moved the full travel up and down. L14 was found to be defective. Once L14 was replaced, both cans were adjustable. I now have signal reaching the S-meter. Thanks.
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[loosecannon]

awesome!

one more old radio saved from the heap!

are you going to re-cap and restore it?
LC

 

[Unit 75]

I just finished re-capping it and re-aligning it now. I have been working on it all morning. Looks very stable frequency wise. I let it warm up for an hour on the bench after the re-cap and before I started the alignment. All I need to get is a small style Ranger frequency counter module to install and it will be finished. Thank you for your input LC...much appreciated
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