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 Post subject: Cap Change Crutch For Newbies and Oldbies
PostPosted: Jul Tue 21, 2020 10:05 pm 
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Location: Greenville, TX
Now that we need to change all paper caps, electrolytics and some resistors, I have added a routine which has prevented me from making wiring errors.
For example, unknown paper cap.
1. Cut it out close to the body and note the value.

2. If it is between two tubes, draw two circles representing the tubes and add the appropriate pin number on each tube and draw the cap between the two circles and add its value.

3. Now, carefully remove the remainder of each lead from the tube pins.

4. Install the capacitor and cross out the sketch. This only takes seconds but can save hours.

If the next component is connected to a coil or a terminal strip, draw another sketch where all terminals are shown and draw in the cap to the correct terminal. There is a volume control in my sketch.

Attached photo shows progress on a recent radio. I have not made an error as long as I have followed this process.


Attachments:
Cap Change.jpg
Cap Change.jpg [ 128.47 KiB | Viewed 5528 times ]

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 Post subject: Re: Cap Change Crutch For Newbies and Oldbies
PostPosted: Jul Thu 23, 2020 1:39 am 
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Joined: Jun Sat 09, 2007 8:14 am
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Location: Melbourne, Florida
Another was is to work one lead off at a time and immediately connect one end of the new part. If you want to do both at once then put an alligator clip on each terminal as you clean it up.

RRM


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 Post subject: Re: Cap Change Crutch For Newbies and Oldbies
PostPosted: Jul Thu 23, 2020 2:21 pm 
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We all have our own twerky way of doing things. Mine is like this.
.01 V3~5 to V1~6. I do all the paper caps and then check off each one as it is replaced. I verify each one with the schematic as I'm replacing it. I may try Dale's idea because I'm better at pictures then the written word and it will take the same amount of time going through the chassis. I take a lot of Hi-Res pictures of the chassis also and it has saved me a few times.

Freeman


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 Post subject: Re: Cap Change Crutch For Newbies and Oldbies
PostPosted: Aug Sun 02, 2020 12:56 am 
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I hope not too off topic but... do the obvious ones first (main B+ filter and coupling caps) then power up the radio (on a variac!) to prove correct. Then do the rest one at a time, testing the radio between each replacement.
Cheap insurance against "finger (brain?) trouble"!
Cheers
Roger
PS. Take photos too!

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 Post subject: Re: Cap Change Crutch For Newbies and Oldbies
PostPosted: Aug Sun 02, 2020 1:54 pm 
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Joined: Jul Fri 10, 2020 11:10 pm
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This makes sense to me. I like it.

Thank you for this great tip!

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 Post subject: Re: Cap Change Crutch For Newbies and Oldbies
PostPosted: Aug Sun 02, 2020 2:01 pm 
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Location: 13 Critchley Avenue, PO Box 36, Monteith Ont, P0K 1P0
engineer wrote:
I hope not too off topic but... do the obvious ones first (main B+ filter and coupling caps) then power up the radio (on a variac!) to prove correct. Then do the rest one at a time, testing the radio between each replacement.
Cheap insurance against "finger (brain?) trouble"!
Cheers
Roger
PS. Take photos too!


Yup, logical, safe, easy and each step verified. This is the KISS rule exemplified.


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 Post subject: Re: Cap Change Crutch For Newbies and Oldbies
PostPosted: Aug Sun 02, 2020 2:20 pm 
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Location: Columbus Ohio
I do one cap at a time and if polarity is needed I use two wire clamps, one red one black to mark the connections, or if soldering to a post or terminal strip, take a red and black sharpie and mark which is which. The old cap lays there until replaced and then goes into the trash or resell box. And then onto the next one. Old caps bring decent money, $25 for a medium flat rate box is my normal price.

edit.
I like the spots marked in the unit under repair because my shop has a curse, no sooner do I get busy, I get interrupted, and it's nice to
come back and know exactly which wires were cut, where the new cap goes and the removed cap laying there leaves no room for doubt.
I can spend hours doing nothing around the house without bother, but let me sit at the bench and try to do something and the interruptions begin, this really pisses me off. Normally its a text from someone who will not carry on a conversion they start, you reply quickly but yet have to wait 1-15 minutes for another reply, always right when you have the soldering iron warming up a connection, never fails.

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 Post subject: Re: Cap Change Crutch For Newbies and Oldbies
PostPosted: Aug Thu 06, 2020 1:29 am 
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I make a printout of the schematic, and circle each component as it is replaced.

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 Post subject: Re: Cap Change Crutch For Newbies and Oldbies
PostPosted: Aug Fri 14, 2020 8:01 pm 
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I make a sketch of the whole chassis underneath, tube pins numbered and all resistors and capacitors (not mica) sketched in. Resistor values as found are written. Now I can follow what needs to be replaced and where. It also allows me to double- and triple-check my work.


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 Post subject: Re: Cap Change Crutch For Newbies and Oldbies
PostPosted: Aug Fri 14, 2020 8:23 pm 
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Location: 13 Critchley Avenue, PO Box 36, Monteith Ont, P0K 1P0
Tim Tress wrote:
I make a printout of the schematic, and circle each component as it is replaced.


This I have also done, with a checkmark after the change and test play.


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 Post subject: Re: Cap Change Crutch For Newbies and Oldbies
PostPosted: Sep Mon 07, 2020 1:36 pm 
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In addition to closeup photos I do the sketch thing all the time. Also use the loose gator clips especially if I am being disturbed (wife calling me) during the procedure.


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 Post subject: Re: Cap Change Crutch For Newbies and Oldbies
PostPosted: Sep Mon 07, 2020 5:53 pm 
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Location: Sanford Fla 32771 (USA)
Tim Tress wrote:
I make a printout of the schematic, and circle each component as it is replaced.

I do this also but tape an enlarged schematic to a cardboard backing so it can stand up where I can look at it while my hands are busy in the chassis, and it also makes it easy to write on (lots of different color felt tips )
Of course lots of high res photos, digital camera are a miracle for restoring and documenting radios..

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Last edited by pauls.ironhorse on Sep Tue 08, 2020 3:55 am, edited 1 time in total.

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 Post subject: Re: Cap Change Crutch For Newbies and Oldbies
PostPosted: Sep Mon 07, 2020 6:01 pm 
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Tim Tress wrote:
I make a printout of the schematic, and circle each component as it is replaced.

+10

Another fine point of procedure:
For any part that will be "replaced on sight", i first check all the resistors connected to the same terminal. For a given terminal, if 2 or more components are going to be replaced, then everything gets removed so I can "start clean". Otherwise, the part gets installed with J-hooks.

Variation:
If 20-30% of the resistors test bad, I stop testing and replace ALL resistors.

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"Voltage is fun to watch, but it's the CURRENT that does the work."


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 Post subject: Re: Cap Change Crutch For Newbies and Oldbies
PostPosted: Sep Mon 07, 2020 6:40 pm 
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Joined: Jul Fri 10, 2020 11:10 pm
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For me this is the best corner of the website!

Great stuff always.

Thank you!

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 Post subject: Re: Cap Change Crutch For Newbies and Oldbies
PostPosted: Sep Sat 12, 2020 6:08 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: 253 Blanche St. Plymouth, MI USA
Most caps go to chassis on one side. So, just note the "high" side. The other (chassis) lug can be picked up closer than the old one was, usually on the same socket and thats why having a stock of RADIAL lead caps is good to have.
I use 70% radials. Smaller and cheaper, and makes for a neater job. Especially in cramped quarters like portables or AA5's.

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 Post subject: Re: Cap Change Crutch For Newbies and Oldbies
PostPosted: Dec Wed 09, 2020 7:23 pm 
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Joined: Mar Tue 10, 2020 3:52 pm
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All good guidance.

My best crutch is my cellphone camera. High resolution and I can build a file folder on my computer so I can refer to before and after pictures as I go along whatever the project.

I'm a Mint Linux (now Kubuntu) user. I use KDEConnect to transfer pictures and other files back and forth between the Android phone and Linux computer wirelessly. All free software.


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 Post subject: Re: Cap Change Crutch For Newbies and Oldbies
PostPosted: Dec Thu 10, 2020 3:08 am 
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Location: Thornhill, Ontario, Canada
pixellany wrote:
... For a given terminal, if 2 or more components are going to be replaced, then everything gets removed so I can "start clean". Otherwise, the part gets installed with J-hooks...
I've said it before, I am a big fan of J-hooks! They reduce the risk of wrecking lugs, terminals and tube bases.
Cheers,
Roger

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 Post subject: Re: Cap Change Crutch For Newbies and Oldbies
PostPosted: Jan Fri 01, 2021 4:58 pm 
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Joined: Aug Sat 29, 2009 12:06 pm
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Location: Milford, CT
Last year I re-capped and changed all the resistors in a NC-173. I simply used my IPhone to take photos of the section I was working on. Changed a few tubes that were suspect. Turned it on and it worked beautifully. For me photos are the way to go.


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 Post subject: Re: Cap Change Crutch For Newbies and Oldbies
PostPosted: Jan Fri 01, 2021 5:34 pm 
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engineer wrote:
I hope not too off topic but... do the obvious ones first (main B+ filter and coupling caps) then power up the radio (on a variac!) to prove correct. Then do the rest one at a time, testing the radio between each replacement. Cheap insurance against "finger (brain?) trouble"! Cheers Roger PS. Take photos too!
Not off at all. A method I pioneered for myself in the 60's when it was clear to me that re-capping the entire device was the solution to repeat problems. Back then re-capping meant choosing which new PAPER cap to install, my go to was Aerovox, epoxy ends and cycolac tube. The hard pea green plastic C-D's often leaked right off the distributors counter! Works for me, the The old Hammarlund SB-110-X is still working...

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