174 replies to this topic

[DAVIDG]

 One of the  Accu-track 2200 autoguider is on Ebay now.

 

              - Dave 

 

           https://www.ebay.com...:Bk9SR-KwncKzZQ

[GalaxyPiper]

 One of the  Accu-track 2200 autoguider is on Ebay now.

 

              - Dave 

 

           https://www.ebay.com...:Bk9SR-KwncKzZQ

That probably is a good price for that. It's really unusable without the base unit since they are meant to pair together...but, as Luck would have it, Oliveira already has that.

 

All he would have to do is create a "Y" pigtail with two mono RCA jacks, or whatever he needs, and he would be golden, and...it would keep it in its original condition. Easy Peasy.

 

And I meant to say, "Rodger Tuthill"....not Tillhill.

Edited by GalaxyPiper, 16 March 2025 - 09:41 AM.

[gnabgib]

While on the topic of drive correctors  I acquired an "oldie" last weekend.   This unit was built by Robert Johnson in 1966 and was used to power a 4-1/4" schiefspiegler he also built in 1966.  After some careful "checking out"   I finally powered it up and guess what, "IT WORKS"!  Enjoy the picts.  More on the schiefspiegler will be posted on classic telescopes later.  The schief is in good condition but in need of tlc!

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[DAVIDG]

 Is that a bell is see ? Even thou it works I recommend you replace any electrolytic capacitor since the odds are very good that they have dried out from being made in 1966.

 

                   - Dave  

[cavedweller]

While on the topic of drive correctors…

I chuckled at reading this, just this.

[GalaxyPiper]

 Is that a bell is see ? Even thou it works I recommend you replace any electrolytic capacitor since the odds are very good that they have dried out from being made in 1966.

 

                   - Dave  

I have to agree.

Most electrolytic capacitors only last about 30 to 35 years. When they start failing they can start "motor boating" signals as they charge and discharge rapidly, which can cause distortion and even components over heating, which can cause errors, to even fires.

They can overdrive transistors to failure that can have cascading results and more damage to other discreet components.

I would see to them sooner, rather than later, if you are going to use it.

Admiring it will cost you nothing as a conversation piece, or it will turn into a boat anchor, then the conversation will become quite different, along with a nice burnt ozone smell.

 

Bryan

Edited by GalaxyPiper, 21 March 2025 - 03:20 PM.

[gnabgib]

 Is that a bell is see ? Even thou it works I recommend you replace any electrolytic capacitor since the odds are very good that they have dried out from being made in 1966.

 

                   - Dave  

Good point about the capacitors!  As for the bell, I have no idea as to it's function.  Doing some circuit tracing on that one.

[DAVIDG]

 If the bell isn't ringing then the coils in it could be being used as inductors to help  filter a DC supply ?

 

                               - Dave 

[deSitter]

I have to agree.

Most electrolytic capacitors only last about 30 to 35 years. When they start failing they can start "motor boating" signals as they charge and discharge rapidly, which can cause distortion and even components over heating, which can cause errors, to even fires.

They can overdrive transistors to failure that can have cascading results and more damage to other discreet components.

I would see to them sooner, rather than later, if you are going to use it.

Admiring it will cost you nothing as a conversation piece, or it will turn into a boat anchor, then the conversation will become quite different, along with a nice burnt ozone smell.

 

Bryan

f you have to change out all one class of discreet passive device every thirty years, you'd get pretty tired of electronics.

 

Mr Carlson's Lab is a YT channel featuring repair and tuning of old radios, and there are many cases where the old can capacitors work fine. In fact it is sort of amazing how robust they are.

 

Likewise Ahh-Fix-It specializes in 70s hi-fi. He does recaps but not of everything. Fewer replaced than surviving.

 

-drl

Edited by deSitter, 21 March 2025 - 06:15 PM.

[DAVIDG]

 I like Mr Carlson Lab on YouTube as well, and on almost all of his restorations he replaces the electrolytic caps. It is the ceramic caps that usually hold up well but not the electrolytic one. 

     I also restore vintage electronics.  Attached is one of my radios I restored.  Changing electrolytic caps is good insurance that you won't damage any of parts of the rest of the  electronics if in this case a 59 year old cap electrolytic cap near the end of it's life dies and shorts out. Also for electrolytic caps this old the odds are very high that they have drifted off their original value. So in a drive corrector circuit of this vintage the odds are very good that it uses a resistor/capacitor circuit  as the time base to make the different drive rates ie Solar, Lunar and Sidereal so if the cap is drifted out of spec, the frequency the corrector it is making is no longer correct. So my advice is spend a few dollar, replace the old electrolytic caps so you  can continue enjoying your vintage electronics for years to come. 

 

              - Dave  

 

 

[GalaxyPiper]

Very nice restoration of that old tube radio. Well done!

Yeah the old electrolytic capacitors can make the old tubes work harder and hotter shorting their life.

They are light bulbs mostly, after all.

[gnabgib]

 Is that a bell is see ? Even thou it works I recommend you replace any electrolytic capacitor since the odds are very good that they have dried out from being made in 1966.

 

                   - Dave  

New replacement capacitors ordered.   Finally figured out the bell.   The 12vdc input has a diode protecting it against reverse voltage.  If you connect the 12vdc backwards the input fuses blow and this activates the bell!
 

[NinePlanets]

No one mentioned reforming electrolytics. Interesting.

[cavedweller]

No one mentioned reforming electrolytics. Interesting.

Never heard of it until now. Isn't the problem them drying out, bulging, and leaking?

 

How is all that fixed doing reforming?

[GalaxyPiper]

No one mentioned reforming electrolytics. Interesting.

Isnt that the process of making your own by hand using tinfoil, wax paper as a separator, and creating your own formula for the "gel" or electrolytic.

 

It's another way of "rolling your own" as a discreet component homemade capacitor. 

Nothing wrong with it, but like everything else, it is an art, a lost art these days.

 

Back in the early days of radio, the experimentor or "Wizard" made pretty much everything by hand, before it became an industry driven by demand.

Edited by GalaxyPiper, Yesterday, 10:50 AM.

[deSitter]

Isnt that the process of making your own by hand using tinfoil, wax paper as a separator, and creating your own formular for the "gel" or electrolytic.

 

It's another way of "rolling your own" as a discreet component homemade capacitor. 

Nothing wrong with it, but like everything else, it is an art, a lost art these days.

 

Back in the early days of radio, the experimentor or "Wizard" made pretty much everything by hand, before it became an industry driven by demand.

No, it is gradually allowing the capacitor to operate at - capacity by ramping up the voltage through a resistor and monitoring the voltage drop across the latter.

 

Something yada yada chemistry oxide layer mumble mumble magic happens.

 

-drl

[jcricket]

"Reforming capacitors"

 

I am not a physicist or engineer, but I do work on old vacuum tube stereo stuff A LOT. I have tried "reforming caps" over my many years of working on these old beasts. I BELIEVE that this is part of the fictional lore that is associated with this field. All fields have some of this "lore". My luck has been very limited in this matter, mostly failure. Also, the longevity of the life of the cap in question has only a small fraction of its original life left once reformed. They are never like new. 

 

The statement of them drying out and either opening or shorting is a very real one. For the cost of caps today, I wouldn't even consider reforming, not for any reason. 

 

Now making your own............. A very interesting proposition that I have considered. But, the math for that is waaayyyyyy over my head.

[jcricket]

 Got back to message #59 and the schematic at the bottom of the page.  How this circuit works it that it is using a resistor(s) and capacitor to make a RC  time base. Change the value of resistor(s) or the capacitor and that changes the frequency that the unit is making. The lower left section of the schematic is  the hand controller that allows the user to adjust the output frequency with a variable resistor and two push button to override the normal operating frequency and speed it up or slow it down by pushing the appropriate button. One button is normally closed (NC) and is wired across a resistor. When that button is pushed the resistor is now added to the circuit, increasing the resistance and the frequency is reduced. The other button is normal open (NO), when that button is pushed, the current now flows through  the switch, taking the resistor it is wired across out of  the circuit and the current flow through the switch which is low resistance and that make the frequency increase.

   So to modify an exiting DC/AC inverter you have to determine how the time base is working. On many it uses a resistance/capacitance circuit. Then you cut into the circuit and make a circuit similar to hand paddle circuit that adds or removes resistance to change the speed. Since all these DC/AC inverters circuits are not the same, you have to understand how it works to modify it to make the frequency variable.

 

                  - Dave   

Hey Folks,

I know a little bit about electronics, not much but a little. The statements of variable frequency to alter the speed of an AC motor is a correct one. That has been used in industry for years. 

 

I have been reading snippets about another method of controlling the speed of an ac motor. It is accomplished by controlling the amount of current to the motor. This is frequently referred to as pulse width modulation or PWM. Essentially the idea is to run the given motor at 60 cycles, but to vary the amount of time the actual cycle has power. This is often shown as a 60hz square wave rather than a sine wave.  I have been recently dabbling with this idea and researching it. I am working on three vintage drive systems. One from edmund, one from criterion, and anther from the celestron polaris mount from the 80/90's. 

Take all of what I have just said with a pond of salt.

[DAVIDG]

 I have over 40 years of experience in designs and building all type of electronic analytic equipment. Reforming caps works on an electrolytic capacitors that is only few years old. In the drive correctors we are discussing in this thread we are talking about ones that around 50 years old or older. It is either dead or very close to it and it has drifted from it original value. We are not talking about $100 part . A new capacitor of the values in these devices is around $1.00.  Just replace it 

   In antique electronics the purest restorer will take an old capacitor and cut it open and pull the guts out it, then put a modern day capacitor in the shell so it looks like  the original but they are not trying to reform these old caps. 

 

                   - Dave 

[GalaxyPiper]

No, it is gradually allowing the capacitor to operate at - capacity by ramping up the voltage through a resistor and monitoring the voltage drop across the latter.

 

Something yada yada chemistry oxide layer mumble mumble magic happens.

 

-drl

Like an explosion?! Ramping too much electricity through a capacitor will cause it to blow up like a firecracker.

Also, the formula for making capacitors was stolen, but they only got half the recipe. So capacitors now are failing early by swelling.

Just replace it with a new one. Time is money too. If you are spending $40.00 work on $2.00 a component, then you are wasting money.

Edited by GalaxyPiper, Yesterday, 10:58 AM.

[deSitter]

Like an explosion?! Ramping too much electricity through a capacitor will cause it to blow up like a firecracker.

Also, the formula for making capacitors was stolen, but they only got half the recipe. So capacitors now are failing early by swelling.

Just replace it with a new one. Time is money too. If you are spending $40.00 work on $2.00 a component, then you are wasting money.

No, you don't run them past spec voltage! You just monitor the voltage drop across the resistor as you gradually run them up to spec. Apparently the failure mode is the degradation of an aluminum oxide layer that is integral to the operation, when they remained discharged for long periods. Reforming them gradually rebuilds this layer. Sudden application of spec voltage to a malformed capacitor can cause it to explode or fail short. There are some spectacular YT videos of this

 

The "capacitor plague" of the late 90s/early 2000s was based on a electrolyte formula that failed to include a key ingredient necessary to prevent the electrolyte from chewing into this layer. If you are going to indulge in industrial espionage, better make sure to get it all.

 

-drl

[GalaxyPiper]

No, you don't run them past spec voltage! You just monitor the voltage drop across the resistor as you gradually run them up to spec. Apparently the failure mode is the degradation of an aluminum oxide layer that is integral to the operation, when they remained discharged for long periods. Reforming them gradually rebuilds this layer. Sudden application of spec voltage to a malformed capacitor can cause it to explode or fail short. There are some spectacular YT videos of this

 

The "capacitor plague" of the late 90s/early 2000s was based on a electrolyte formula that failed to include a key ingredient necessary to prevent the electrolyte from chewing into this layer. If you are going to indulge in industrial espionage, better make sure to get it all.

 

-drl

Ok. I'm not old enough yet to "know it all" and like to learn. I really had not heard of this being done. I know as a kid I used to take the RCA tubes out of the Television set and run down to Thrifty's on my bike and they had a Tube checker just as you walked in. I had learned that if you run the tubes "Hotter" for a few seconds it would "Rejuvenate" the tube (basically burning off the electrons off of the plate to make it more receptive. But you had to be careful, or you would burn out the filament and then had to buy a new tube anyway. it was a handy trick and at least it made the tubes last a little longer before you did have to buy a new tube. saved some dough too that I would usually buy an ice cream cone for my trouble while there.

I'm dating myself, but this was in the early 1970s before my dad finally broke down and bought a Color Zenith T.V. that was solid state.

Edited by GalaxyPiper, Yesterday, 01:14 PM.

[deSitter]

Ok. I'm not old enough yet to "know it all" and like to learn. I really had not heard of this being done. I know as a kid I used to take the RCA tubes out of the Television set and run down to Thrifty's on my bike and they had a Tube checker just as you walked in. I had learned that if you run the tubes "Hotter" for a few seconds it would "Rejuvenate" the tube (basically burning off the electrons off of the plate to make it more receptive. But you had to be careful, or you would burn out the filament and then had to buy a new tube anyway. it was a handy trick and at least it made the tubes last a little longer before you did have to buy a new tube. saved some dough too that I would usually buy an ice cream cone for my trouble while there.

I'm dating myself, but this was in the early 1970s before my dad finally broke down and bought a Color Zenith T.V. that was solid state.

Yes - the same process can add life to an old CRT. Sometimes is works really well.

 

-drl

[NinePlanets]

Ok. I'm not old enough yet to "know it all" and like to learn. I really had not heard of this being done. .

That's why I mentioned it.    I was curious to see if anyone else had done this.

It's interesting to watch the comments ooze into the thread.

 

Yes, I have a power supply I built specifically to zap shorted NICAD's (works on lead-acid sometimes too) and also reform electrolytics, way back in the day. I had an enormous stash of old new stock caps and I would reform them before using them in projects.

[cavedweller]

 ...

   In antique electronics the purest restorer will take an old capacitor and cut it open and pull the guts out it, then put a modern day capacitor in the shell so it looks like  the original but they are not trying to reform these old caps. 

 

                   - Dave 

 

I recapped a Marantz receiver, and the new filter caps were half the size of the originals, even though they were higher capacitance and higher voltage. I like looking through the vent screen and seeing the new ones I put in there.