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rebuilt regulators

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billd View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Dec/23/2017 at 9:14pm
At least one replacement or third-party used the TO-220 style... haven't dug into others.
Motorola up into 1970 used TO-3
The third party TO-220 used a small heat-sink riveted to the transistor, it was free-standing.
Motorola didn't mount the TO-3 transistor to the case or housing. It was totally isolated electrically.
They used thermal-conducting potting materials. They conducted heat to the case but not current. 
I've demonstrated how quickly they respond to heat by warming the up with a hair dryer while watching the voltage drop on a running alternator on my test stand. I was curious as to how close to the Motorola specs. They have a "ramp" specifying the voltage change at various temperatures and I was experimenting on live regulators with heat. 

I may change transistor case styles as it's actually far more than needed - I can easily handle the power dissipation and amperage with a smaller transistor and the TO-220 style. 

My second version DOES use a darlington pair in a TO-220 case, am building a mock-up tonight - maybe.... my wife needs a quilt mounted on the machine tonight (she's already been paid for it, she was commissioned to make it special for a guy)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Dec/27/2017 at 11:24pm
A question came up in another post related to the regulator circuits I've been working on, hoping to be able to refurbish originals with new guts - 
Is being able to tweak or adjust voltage important at all for any reason, to anyone?

Our cars were never equipped with adjustable regulators so it just seemed that once things were set at the correct voltage, they'd be sealed, even if they originally had a trimmer on the board. 

With the holidays and health things I've not made a lot of progress the last few days but hope to get back at it shortly. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 6PakBee Quote  Post ReplyReply Direct Link To This Post Posted: Dec/28/2017 at 8:22am
Originally posted by george w george w wrote:

Never had a Motorola regulator apart. Did they use a TO-3 case device inside the housing ? And if so, how was it mounted in order to use the case as a heat sink ? I would think a TO-220 or 247 could work if you can find a suitable device.



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Post Options Post Options   Thanks (0) Thanks(0)   Quote CamJam Quote  Post ReplyReply Direct Link To This Post Posted: Dec/28/2017 at 10:04am
Impressive that you managed to get the potting material off without destroying the wiring. That stuff is TOUGH!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 6PakBee Quote  Post ReplyReply Direct Link To This Post Posted: Dec/28/2017 at 6:03pm
Originally posted by CamJam CamJam wrote:

Impressive that you managed to get the potting material off without destroying the wiring. That stuff is TOUGH!


I'm not that smart.  There seems to be at least two kinds of potting.  One is a black, tarry substance with what appears to be small beads mixed in it.  That's what this regulator had and I was able to remove it with a heat gun.  The other kind I've run into is a tan, hard substance that I haven't been able to soften up or easily remove with either heat or chemicals.  I could obviously remove it with brute force but I've found that typically brute force is hard on electronics. LOL
The difference between people and AMC's is that they will always be making more people; they won't be making more AMC's

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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Dec/28/2017 at 6:48pm
That's most likely not a genuine Motorola unless it's one made in the 1970s.
Motorola did use the larger TO-3 case transistor in their R2AM4 and earlier.
Motorola did change circuits and technology in the early 1970s so it's possible that replacements used the later technology, but the originals were the large TO-3 and look a whole lot different inside.

Many of the third party regulators use the TO-220 transistors and all it takes to soften the material is hot water. 
The one shown above is one exactly like I disassembled a while back - a sand-like substance (but larger, as said, more like beads)

Note how they modified the resistor by "grinding" some of it out. 
The problem with carbon resistors is they change with time and aren't as "accurate" - meaning the tolerance is greater. A 1K may be 980 or less depending on the tolerance of resistor used. 

I'm about done with version two and hope to test it this weekend.
I have the PC board designed and will contact a local company about manufacture if all goes well.
(version two doesn't use a Zener but uses a different "comparator" type design. (if that's a word...)

Version one was a great success so I'm really hopeful. It stood up to some heavy loads
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Dec/28/2017 at 7:06pm
Here's the third party regulator I had apart a while back. 
The Motorola is out in my shop and it's too cold to go back out there just for a photo now....

Also shown - the first version I made with the larger transistor - same case style Motorola used, and the breadboard I'm working on with the second version of my circuit.

(I hope to have a working prototype in a proper case released soon)

This is the version I already tested and have the board designed for........
it works fine.



This is the third-party or replacement regulator (upper left corner of pic) and the new circuit I'm working on that does not use a Zener diode for "sensing" or regulation.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Dec/31/2017 at 12:41am
PC board made, began assembly of a pilot version.
(Then Lucky became interested in what I was doing and wanted to carry some of the parts away, so I stopped.)

I'll have to replenish my PC board supplies because this is the last single layer copper one side board I had and my pens were pretty well dried up. I have enough solution for a few more, perhaps but will likely have someone else make the boards if I end up doing enough of these. 
It takes a lot of time to make the board, drill the holes, etc. 


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Post Options Post Options   Thanks (0) Thanks(0)   Quote DoughertyAMX Quote  Post ReplyReply Direct Link To This Post Posted: Dec/31/2017 at 8:27am
A true work of art Bill.  Your attention to detail and the quality of your work is amazing.

Doug
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Dec/31/2017 at 9:54am
Interesting, that's what my boss used to say at my annual reviews...........
Anyway, I had to shift some things around from my original board layout when I determined that it wasn't easy to get this transistor, or even one with the same specs, in a different case style.
So I shifted some things around on the board to open up a space and decided to do it similar to how Motorola did it - multi-levels. They mounted the switching transistor to a "shelf" in the housing and had the main board directly below that in the main body. That is why some ORIGINAL regulators have a housing that is not solid under the tag - that's where the transistor is, on one level, while the board is more "around back". They had to have an open face to screw the transistor to the "shelf" - which aided in heat transfer, but made it more complicated to assemble the regulator guts into the housing. Once the transistor was in place and secured, then they potted it and the material flowed around the "shelf" to encase the transistor and board, the transistor one one side a bit below the tag, the board in back, on the other side.
I will mount the transistor on stand-offs above the blank area of the board (at least for this design)
Depending on the original regulators I can get to salvage the housing and harness from I can also mount the transistor exactly like the originals - assuming I can get my hands on a few of that design.
The transistor case itself in the case of a TO-3 is the collector and is electrically "hot" so must be electrically insulated - otherwise the secret ingredient of any electric device, the smoke, will escape.
I note that they did like I'll do - test each circuit and tweak it as needed to get the regulated voltage desired by soldering resistors and other parts on the back side of the board to "adjust". The third party replacements ground out the carbon resistors where Motorola placed resistors on the back side of the board to "adjust" the voltage before it was potted.

My other design has a trimmer - I may end up doing something similar since even with modern parts of tighter tolerances, you get enough variation it will bug me.
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