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 Astron RS-20A problems
docs89gta  [Team Member]
2/25/2013 3:27:26 PM
I have an Astron RS-20A that has died on me. First thing i found was the 5A fuse blown, replaced it and powered it up.
The power switch lit up for about 1-2 seconds and went back back out. Checked the fuse again and it was blown.
Of course, tried with another fuse and same results. Any ideas of what may be causing this, or what i should check first?

Eric KI4RUV
SpanishInquisition  [Member]
2/25/2013 3:31:20 PM
Make sure vr1 (MOV for surge suppression) isn't shorted.

Schematic is here:.
radioshooter  [Team Member]
2/25/2013 4:29:01 PM
Could be a couple of things, starting with a shorted output transistor causing the crowbar (overvoltage) circuit to activate. My divide and conquer method is to remove the wires from the positive (plus) terminal of the capacitors that lead to the large transistor(s); being sure you remember where they go. Then put a fuse back in and power it up with nothing connected to the output terminals. If the fuse doesn't blow, you have a problem with the transistors or the voltage regulator. If the fuse blows, one of the rectifier diodes is probable shorted.

Schematics for these supplies are on the web.

RS
docs89gta  [Team Member]
2/25/2013 4:32:45 PM
Thanks for those responses. I will check these out and see how it goes.

KB7DX  [Team Member]
2/25/2013 7:25:44 PM
I just lost an RS20A a month or so ago to a voltage spike on the house current. Got the TV too.
docs89gta  [Team Member]
2/25/2013 8:09:40 PM
Originally Posted By KB7DX:
I just lost an RS20A a month or so ago to a voltage spike on the house current. Got the TV too.




I think a power spike got mine too. I work close by to home and power dropped for about 2 seconds, when i got home, it was dead.
KB7DX  [Team Member]
2/25/2013 10:18:13 PM
Originally Posted By docs89gta:
Originally Posted By KB7DX:
I just lost an RS20A a month or so ago to a voltage spike on the house current. Got the TV too.




I think a power spike got mine too. I work close by to home and power dropped for about 2 seconds, when i got home, it was dead.

Mine went off while I was at work. Came home to find it off. It had been on continously for about 5 years save for power outages/shack remodels. I have been using Astron supplies for over 20 years and only one failure because of product. This is only the second failure, but clearly it wasn't Astron's fault. I'll be buying another....sometime.

Ar-Bret  [Member]
2/26/2013 1:16:38 AM
Well,

I just fixed a 20 for my brother...

The mov was crispy!

Not much really goes wrong with them...

I run a fe 50m's in my shack...

Bret
Aardvark  [Member]
2/28/2013 10:14:13 AM

Originally Posted By Ar-Bret:
Well,

I just fixed a 20 for my brother...

The mov was crispy!

Not much really goes wrong with them...

I run a fe 50m's in my shack...

Bret

+1

The linear power supplies such as the RS-20A and RS-50A (I have both) are much easier to diagnose and repair. Plus the schematics are readily available. Not so good with an SS-25 switching supply if it needs repair work.

BigHam  [Member]
2/28/2013 9:27:26 PM
maybe we can get a chance to work on it tomorrow dude
docs89gta  [Team Member]
2/28/2013 10:10:34 PM
Originally Posted By BigHam:
maybe we can get a chance to work on it tomorrow dude


Yeah, been kind of busy.. Hopefully will be somewhat slack tomorrow.
edjo69  [Member]
3/1/2013 1:52:24 AM
Have you checked the power connector just inside the case? I had the same issue with my RS-12 and when I pulled it apart the power cord connector had become unsoldered just inside the main case. I re-soldered it and it has been fine for a few years now.
Ar-Bret  [Member]
3/1/2013 2:53:57 AM
Originally Posted By Aardvark:

Originally Posted By Ar-Bret:
Well,

I just fixed a 20 for my brother...

The mov was crispy!

Not much really goes wrong with them...

I run a fe 50m's in my shack...

Bret

+1

The linear power supplies such as the RS-20A and RS-50A (I have both) are much easier to diagnose and repair. Plus the schematics are readily available. Not so good with an SS-25 switching supply if it needs repair work.



Yes, I'm not a fan of the switchers...I consider them a throw away device...

I did use some on some jobs years ago for backup...well sorta backup...

It was a floated battery array off a rs20 then if the rs20 puked it ran off batteries and the charge controller was run through a automatic home built electrical latched relay that would drop and pickup the 20 switcher...

We just didn't have room for everything we wanted in that space...it was a mobile emcom...

Anyhow, a few years back I got to see it again for a retrofit times 2...

So, those old custom days are gone, and now it's running a rig runner over a single float array with dual inbound rs-50's...

And yes radios did get a bit smaller since...ouch 1992...

I must have built it right to run that long...:)

It will be another 20 before the power supplies and such will need rework...

Also installed tons of 800mhz crap...I hate that stuff...but, also all new computers and gigabit network, some 5 ghz back haul links, and even a pile of easily deploy wifi for laptops and smart phones...cool!

Some of the old Vietnam era boys that are still in doing work still know that comm is number one!

Now, the new ones, they will have thier smart phone and no cell coverage...or trying to use talk around on the 800mhz units...good luck!

Bret
Bret
docs89gta  [Team Member]
3/6/2013 3:18:05 PM
Well, finally got a chance to dig into it.

Removed the VR1 and it's an open circuit, not showing signs of being bad.

What else would there be to check from here?
radioshooter  [Team Member]
3/6/2013 3:31:42 PM
Power it up, check across the capacitors. You should have ~ 22 volts or so there.

RS
docs89gta  [Team Member]
3/6/2013 4:25:57 PM
Well, when you power it up, within about 2 seconds it pops the 5A fuse. So, can't really check it.
KB7DX  [Team Member]
3/6/2013 4:41:50 PM
At this point you will need to disconnect the secondary windings of the transformer from the rest of the circuit and see if the fuse still blows. If so, the transformer is kaput. If it doesn't blow the fuse, then start checking the rectifiers, then the pass transistors. I'm going to place my bet now and say the transformer is kaput.
Oldford  [Team Member]
3/7/2013 7:45:36 AM
I can't see in the thread where you may have checked the pass transistor(s) Pretty common failure-I think they are all 2N3055.

GL de W1EL
Aardvark  [Member]
3/7/2013 10:53:41 AM

Originally Posted By docs89gta:
Well, when you power it up, within about 2 seconds it pops the 5A fuse. So, can't really check it.

Do yourself a favor and get a 5A circuit breaker from an electronics supply store and some jumper cables. Anytime I have had to work on a circuit that blows fuses, I have found it is much better to temporarily hook in a circuit breaker rather than go through fuses wholesale. Once the circuit is fixed, go back to the fuse.
docs89gta  [Team Member]
3/15/2013 6:05:37 PM
Ok, been busy lately but finally worked on it earlier today.

We disconnected the output of the transformer from the rectifier and powered it up, no blown fuse.

Reconnected the transformer to the rectifier without the red lead connected off the rectifier and no blown fuse, have approx 16 volts dc on the rectifier.

Time ran out and also ideas ran out. Any ideas on what else to check at this point?