Hi all,
Worked into a part time gig fixing items for the local ham radio store.
Mostly it was big "Astron" linear PSU that were too heavy to ship.
Got a new assignment this weekend.
Got this Alinco unit to repair. Some heads up on it for you should one get dumped on your desk.
Started on the PSU.
The hope was for something fun and easy.
It was neither.
Just for the record this PSU is a turkey.
You can't imagine how poorly it's made.
Lots of weak soldering, klugey connections.
When circuit boards are made, this one looks to be 'hand stuffed'.
Not something we see often in this day and age.
On the bottom things are soldered, then the excess wire lengths are cut off.
In this case that excess wire length is just a bit longer than I like to see.
As those wire stubs get handled they can bend over and cause shorts with nearby circuits.
Here is what I found.
Pre repair condition.
The unit was intact.
The front panel voltage control did nothing.
Had a steady 15.2 volts output.
The rear panel has a switch that chooses between the preset value of the rear panel pot, and the adjustment of the front panel knob.
That worked just fine, the rear panel preset pot circuit was perfect.
When the switch is set for the front panel control, the PSU did not adjust.
Repair effort.
The lack of service data on this product was a major issue.
Found a 'free' schematic in Europe but the scan was poor, numbers hard to read.
Another issue is ROHS solder.
Under the best of conditions that stuff works 'kinda half ass'ed'.
It don't mix well with real solder I use here.
Inside this box is not the best of conditions.
I touched up worst solder joints as I found them.
Items soldered to the bottom of the board, the solder did not migrate through the vias to the top.
At first when selected the front panel voltage control works but the change is so slight that it makes no difference.
The long string dmm would show a couple of mV change in 15 volts.
Clearly not right.
Something was disconnected but where?
Had to go through this thing circuit by circuit to see what was connected and what was not.
The problem ended up in two places.
Looks like the client cracked the circuit board traces under the front panel adjustment.
They cracked because the copper was so thin, any flexing from the parts on top caused them to break.
After a few dis assemblies and re assemblies I found this joyous problem out.
Thin copper on consumer circuit boards is a misery waiting to happen to the next guy. Or hundred.
The second problem was a zener diode failed during the repair, so after I got the front panel adjustments fixed, the voltages were all wrong.
Went to Radio Shack this morning and got a zener that works but it's not exactly the right one.
Voltages are slightly off.
So rather than a front panel range of 5 to 15 volts I get 5 to 13.7 volts.
Good enough for government work but not good enough to leave with a client.
Human nature being what it is, they want their 13.8 and we can't tell them different.
Surprisingly enough the output current is very good.
A little bit of ripple at the high draw above 25 amps.
Good looking product, too bad it was made so poorly.
As of right now.
It's working with the above mentioned voltage issue.
I am going to hang on to it until I can order in a proper zener.
When the part comes in, 're center the voltage' and call it done.
Share a thought.
Jack Crow
Worked into a part time gig fixing items for the local ham radio store.
Mostly it was big "Astron" linear PSU that were too heavy to ship.
Got a new assignment this weekend.
Got this Alinco unit to repair. Some heads up on it for you should one get dumped on your desk.
Started on the PSU.
The hope was for something fun and easy.
It was neither.
Just for the record this PSU is a turkey.
You can't imagine how poorly it's made.
Lots of weak soldering, klugey connections.
When circuit boards are made, this one looks to be 'hand stuffed'.
Not something we see often in this day and age.
On the bottom things are soldered, then the excess wire lengths are cut off.
In this case that excess wire length is just a bit longer than I like to see.
As those wire stubs get handled they can bend over and cause shorts with nearby circuits.
Here is what I found.
Pre repair condition.
The unit was intact.
The front panel voltage control did nothing.
Had a steady 15.2 volts output.
The rear panel has a switch that chooses between the preset value of the rear panel pot, and the adjustment of the front panel knob.
That worked just fine, the rear panel preset pot circuit was perfect.
When the switch is set for the front panel control, the PSU did not adjust.
Repair effort.
The lack of service data on this product was a major issue.
Found a 'free' schematic in Europe but the scan was poor, numbers hard to read.
Another issue is ROHS solder.
Under the best of conditions that stuff works 'kinda half ass'ed'.
It don't mix well with real solder I use here.
Inside this box is not the best of conditions.
I touched up worst solder joints as I found them.
Items soldered to the bottom of the board, the solder did not migrate through the vias to the top.
At first when selected the front panel voltage control works but the change is so slight that it makes no difference.
The long string dmm would show a couple of mV change in 15 volts.
Clearly not right.
Something was disconnected but where?
Had to go through this thing circuit by circuit to see what was connected and what was not.
The problem ended up in two places.
Looks like the client cracked the circuit board traces under the front panel adjustment.
They cracked because the copper was so thin, any flexing from the parts on top caused them to break.
After a few dis assemblies and re assemblies I found this joyous problem out.
Thin copper on consumer circuit boards is a misery waiting to happen to the next guy. Or hundred.
The second problem was a zener diode failed during the repair, so after I got the front panel adjustments fixed, the voltages were all wrong.
Went to Radio Shack this morning and got a zener that works but it's not exactly the right one.
Voltages are slightly off.
So rather than a front panel range of 5 to 15 volts I get 5 to 13.7 volts.
Good enough for government work but not good enough to leave with a client.
Human nature being what it is, they want their 13.8 and we can't tell them different.
Surprisingly enough the output current is very good.
A little bit of ripple at the high draw above 25 amps.
Good looking product, too bad it was made so poorly.
As of right now.
It's working with the above mentioned voltage issue.
I am going to hang on to it until I can order in a proper zener.
When the part comes in, 're center the voltage' and call it done.
Share a thought.
Jack Crow
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