Restoration of Collins S-Line

Dave, W3ST

When you mention the word, “restoration” to a classic car owner, typically, he would explain that it involves completely rebuilding the car from the ground up, replacing what is worn with new parts and fresh paint applied to make the car appear that it just rolled off the assembly line. In a similar vein, restoring a Collins radio is very similar but a great deal less complicated and costly. Here the radio restorer is attempting to sweep years away. He wants to make the radio appear in like new condition by performing such tasks as

  1. thoroughly cleaning the set to remove years of dirt, grime, and tobacco nicotine
  2. relubricating all mechanical parts
  3. touching up paint scratches or repainting the cabinet, if warranted
  4. replacing weak tubes and damaged parts
  5. realigning the tuned circuits to factory specifications
  6. removing any modifications that were done by a previous owner, in general, restoring the radio back to its original circuitry.

Please keep in mind that it would be impossible to cover such a broad subject as this one. I claim that there are more skilled and competent folks out there who have “better” tricks or techniques than I do. I would welcome their contributions to add to this material.

Some “pre-owned” Collins, fortunately, need just a realignment and some high pressure air or a whisk of a soft bristled brush to sweep out the “cobwebs,” so to speak. While others  and I have seen many  need a major restoration because the radio had been subjected to a “hostile environment” where the former owner(s) did not cover the radio when not in use, or, in many instances, coated the radio with tobacco nicotine. Suffice to say, then, the following restoration procedures become a matter of personal choice based on the condition of the Collins or any other radio set.

Much as you may despair over the dismantling of your Collins, there is only way to do the job right. That is, to strip the unit down, much the same way the car restorer cleans, inspects, replaces parts, and, then, reassembles the car, finishing the job with a complete tune-up. Of course, restoring a car takes considerable time and expense but the outcome is well worth it, driving up the value appreciably. A restored Collins radio, likewise, if properly done, demands a higher price as well, as long as it has been done carefully and correctly.

You begin by getting organized. Find several small boxes for larger parts and those little plastic baggies for screws, nuts, etc. Keep everything together and it’s a good idea to mark the containers so you know where the parts came from, such as screws and other fasteners. I like to keep the knobs separate from everything else, so they do not get scratched. Likewise the plastic dial mechanism and the fiduciary window are placed in separate plastic bags. Remove all the HF crystals and the 100 Khz marker and place in a small box or plastic bag.

Do take your time and don’t rush. It normally takes me at least two hours or more to remove the parts that you do not want to expose to the wash bath to be described later.

Also, cover the Collins ID tag  sometimes they peeled off  with a piece of masking tape to protect it during the cleaning of the radio. A tell-tale sign that a Collins has been subjected to a bath is the condition of the metallic looking labels that look wrinkled and faded from being exposed to a thorough cleaning bath.

Removal of all the knobs: (The main tuning knob and the little fiduciary index knob to the right of the dial opening will be removed later) Generally, the knobs sometimes bind on their shafts so you may have to carefully use a screwdriver that has been covered with a tape so as not to scratch the front panel to pry off the knobs. I prefer not to remove the small inner pointers on the exciter and load controls since they can be difficult to remove. It is easy, especially, when they are tight to snap these plastic index pieces.

Before using a screwdriver to pry up on the knob, try gripping the base of the knob with your fingernail, if possible. When reinstalling the knobs, coat the shafts with a little white grease so the knob slides on the shaft more easily.


Once the knobs are safely stored in a container, the next task is to remove the tubes, the crystals, and the meter. The HF crystals should not be pulled out of their socket using a pair of pliers, since the pressure of pliers generally deforms the thin aluminum crystal case. I prefer to use a small screwdriver to very gently pry one end of crystal until you can wiggle it free. Remember if you are restoring he 75S-3A or C, there is a set of crystals under the chassis as well as on the top side of the chassis. You can refer to the manual when remounting the crystals in their respective holder or make a set of notes if you wish.

Cleaning the crystals with Brasso polish or a similar metal polish makes the aluminum bright and shiny. I take an old washcloth with a little polish soaked into the rag. I lay the rag flat on a table and slide the crystal back and forth until the crystal has been cleaned, with all that black oxide on the cloth. Lay aside the crystals until the polish is slightly dry and then polish. Be careful that you do not jar or drop the crystals  they are rather delicate and do not stand much abuse.

When cleaning the glass tubes, try a somewhat moist rag dampened with water. It is easy to remove the tube’s markings, particularly, the tube type. At this point, you may want to check the emission of the tubes in a good quality tube tester, unless it was determined beforehand that the radio met alignment specifications.

The meter is removed by removing the four nuts that hold the meter to the front panel. Also remove the dial light socket and the two meter leads from their studs. The two bottom nuts holding the meter can be difficult to remove using an ordinary nut driver. I use a X inch socket with a long screwdriver blade wedged in the socket. You can use a piece of cardboard or paper to buildup the socket opening so it does not drop off the screwdriver. This can be a real tedious procedure but take your time and with a little luck, you can remove these two bottom nuts. I like to spin the nuts back on the meter rather than lay them aside.

Now comes the fun part – removal of the dial and front bezel (escutcheon). Up this point, you did not require any special tools, just those found in most tool kits. However, it is indispensable to have the two tools listed below

Bristol Wrenches can be obtained from many sources but I prefer Jensen Tool Company, 99PS Bristol Spline Blade Set, 11 piece, Product number 3-110, Price – $42.75



Snap ring pliers can be obtained from Sears, Roebuck and Company, Product number 45489. Price – $11.99

Now, remove the main tuning knob that has two bristol type set screws. Note: the earlier S/Line and KWM-2’s had main tuning knobs that slid on a slotted shaft. Next, remove the small round black knob that positions the clear plastic index or fiduciary. Be careful that your bristol wrench does not slip to either lacerate your finger or mar the front panel. You may find that the bandswitch knob has a set screw as well  some do and some don’t. However, most of the control knobs have a flat spring insert to bind the knob to the shaft.

Removing the PTO: (Refer to the Collins Radio Association’s website at and click on to the “Collins Album section.” Click on February, 2000 before proceeding further to get some background on removing the PTO as well as going one step further to follow the procedure as described on relubing and replacing components in the PTO

Now, remove the two black oval head screws from the top of the escutcheon (the black dial face plate located in the center of the front panel). Be careful that you do not lose the two aluminum spacers. In the KWM-2, an additional self-tapping screw must be removed from the light bracket at the extreme left, viewing the radio from the front.

Pull the light bracket straight back (only applies to the KWM-2/2A) until it is free of the screws and adjacent components, and place the PTO to one side of the chassis. Tie it down so it stays put and does not bounce around as you proceed ahead. It is not necessary to remove any electrical connections to the PTO from underneath the chassis.

Loosen the two setscrews on the dial hub, using a No. 6 Bristol wrench from your Xcelite 99PS set. Remove the two self-tapping screws which hold the PTO assembly to the chassis.

You need to use your Bristol (spline) wrench to loosen the two set screws on the hub of the circular tuning dial. Sometimes, these two set-screws are stubborn to break free. This is caused by the application of a thread compound used to lock in the setscrew. You can use the tip of a soldering iron to heat the screw which will soften the compound. Ordinarily, the screws can be broken free. Leave the screws in the hub.

Remove the plastic idler wheel that meshes with the circular dial. Watch you don’t lose the inner bushing. Also remove the PTO mounting screws holding the PTO to the top of the chassis. Pressing gently against the back of the dial, the PTO shaft should slip out of the dial bushing. If it does not, a flat blade screwdriver inserted between the dial bushing and the brass bushing on the PTO shaft should be very gently worked to loosen and slide the dial off the shaft. Take care not to handle the plastic dial too roughly to avoid scratching the surface. The PTO should be moved back into position and refastened with the two screws to the chassis. Take your time here!

Keeping the dial pressed toward the front of the radio with one hand, carefully pull the oscillator assembly back by tilting the PTO so as to disengage the drive assembly from the black nylatron drive ring on the dial assembly until the PTO shaft clears the dial hub. Set the PTO back out of the way so the dial clears the front panel and slide the dial off the PTO shaft.

Remove the flathead screw next to the tuning knob shaft, and remove the escutcheon by pulling it straight out from the front panel. DO NOT loosen the large nut or remove the panel bushing as the concentric bushing has been set to turn the dial assembly without binding or slipping.

Remove the snap ring from the front panel tuning shaft at the front of the escutcheon, and pull the drive washer assembly through the panel bushing from behind the escutcheon so as to disengage the dial assembly from the drive ring.


Place the dial in a safe place out of the way. (this is the time to take apart the dial assembly and clean with mild dish detergent, after taking the sections apart.



Reinstalling the PTO After Cleaning

Now the PTO must be reinstalled in the radio. It’s a little tricky here too. Retrieve the plastic dial assembly. Hold the PTO up and slide the plastic dial back onto the tuning shaft, but leave the set screws loose for now. Be careful not to scratch it.

Position the PTO so that the dial clears the dial cords etc. and becomes visible in the window.

When remounting the nylatron drive ring that is part of the tuning shaft, you have to carefully mesh the raised inner diameter of the black nylatron drive ring with the two drive washers or the pinch drive..

This operation can be viewed through the inspection hole in the hub assembly looking from the rear bottom position of the dial assembly. Use care and make sure the ring surface seats in the space between the copper drive washers. Holding the dial in position, insert the PTO shaft through the hub and into the nylon bushing in the front panel. Turn the dial by rotating the tuning knob shaft to make sure that the dial is being driven. Tighten the two setscrews onto the PTO shaft. To finish completing the dial reinstallation, refer back to the excellent article mentioned on the CRA website at the beginning of this section above.

You can remove the clear plastic fiduciary dial window with the red line index mark by removing the two small screws from the upper aluminum plate. It pops out when you move the PTO tuning shaft out of the plastic bushing. For you first time restorers, you can leave it in place and use a cue tip moistened with window cleaner to clean the plastic, both inside and outside. I like to remove it for a thorough cleaning but it takes some patience to get it back in position. Your call here!

While doing this, ensure that the teeth on the plastic dial mesh properly with the idler gear on the rear of the front panel. The screw holding the idler gear can be loosened as needed to adjust. Also work with it to ensure that the pinch roller on the main tuning shaft mates properly with the inside groove of the tuning dial. Hold the PTO steady and reinstall the PTO mounting screws to the top of the chassis but do not tighten completely.

Working with the PTO box in one hand and the tuning knob in the other, you should be able to move the box slightly horizontally and vertically until the knob turns the dial in a relatively consistent manner. When it feels good, tighten the rear mounting screws and the chassis top screws. These can be loosened and played with some more if necessary to tweak the pinch roller alignment.

By now you have probably noted that the alignment of the two plastic dials may be off. Some of the numbers on the rear dial may not appear properly between the white masked areas on the front dial. Not to worry, this can be adjusted. There is a black reference dot at the top edge of the dial that you can see if you look up at an angle into the front of dial opening. This dot should align with the 50 or 150 numbers. Turn the knob until you see this dot at the top of the dial window. If it doesn’t line up with 150, loosen (but do not remove) the screw holding the idler gear. Move the idler gear away from the teeth of the dial and then gently rotate the rear dial while holding the front dial stationary, until you see 150 centered in the window. Then tighten the screw holding the idler gear. (This procedure is a little tricky – you may have to remove the idler gear as a last resort if you can not remesh the gear to the teeth. I prefer the “0” point on the dial since it easier to see if both halves of the dial are aligned correctly.)

Next you will need a known signal such as a low level tune carrier at a known frequency such as precisely 3900 Khz. Using the calibrator could cause you to align to the “wrong” 100 khz signal, so a single known carrier is preferred. With a low level test signal from a signal generator, etc. set at 3900 khz. fed into the antenna connector, tune the dial to 100.Note: if you know that you are at the correct 100 Khz division, then, using a frequency generator is rather superfluous – unless you unknowingly loosened the end stop mechanism on the PTO shaft.

Then remove the tuning knob if you had remounted it. While holding the plastic dial by hand (its set screws must still be loosened), use a small screw driver to turn the PTO slotted shaft through the opening hole in front of the escutcheon. Hold the plastic dial and turn the shaft until you hear the reference carrier and zero beat it. Be sure the “100” aligns with the tuning hair (vertically) and tighten the dial set screws. Note: using the “0” point on the dial seems to be a better reference against the 1 Khz line on the outer dial face.

You should then verify tracking of the PTO from end to end. By loosening the brass collar on the PTO shaft, you can adjust the end point stop excursion about 6.5 khz below zero and 6.5 khz above 200. The calibration should be very close at zero and 200 without having to change the hairline much. If not, you will probably need to repeat the end point spread adjustment (with L302) as described in the Collins owner’s manual.

Cleaning Process

Everyone has his favorite cleaning solution.    I prefer “Simple Green” that you can buy from WalMart, etc. For years, I used plain old ammonia but the fumes were too much when cleaning a Collins indoors in a laundry tube. I use Simple Green full strength without noticing any adverse effects. You can cut it with 25 percent water, if you prefer.

Fill a discarded spray bottle if you buy Simple Green in a two quart container and go to work spraying the Collins liberally and then scrub gently both top and under the chassis with a soft hair paint brush. The solution “attacks” nicotine and dirt without using a brush but I like to scrub in the corners and hard to get to places. Do the same for the cabinets as well.

This process takes no more than 5 minutes or so. Do not let the Collins sit but immediately apply ordinary tap water from a garden hose to rinse the radio thoroughly. You will be amazed at the nicotine stained water and dirt deposits slide down the chassis and front panel. Why hams exposed their radio to cigarette smoke is beyond me since it leaves that slightly brown gold appearance that is readily noticeable everywhere. Ugh!

Shake the water off the radio and then use a hair dryer in the first phase of drying out the radio. You can use a towel to dry off the cabinet and radio, like the front panel, etc. Then place the Collins in the hot sun – not on a cool, cloudy day. Some restorers use their kitchen oven but I prefer Mother Nature’s way best!

Oh, the frightful sighs I hear from those who would never “bathe” their Collins but I have never “lost” a Collins, even when the audio and power transformers were left in the radios such as my recent restoration of my 75S-3B receiver. My way may not be your way!

While the radio is drying out in the hot sun, polish the knobs using a product named “Magnolia – Glayzit Telephone Refinisher”. Call 1-800-527-2101 for availability. Polish such as Pledge or Son of a Gun (STP product) work as well to restore the glaze of the knobs and front panel. Buff with a soft rag. If you need to fill in the pointer grooves and the Collins model number (75S-3B) engraving on the front bezel, you can rub the engraving with a white lacquer stick. These sticks can be obtained from an art supply house.


“The Line-up of Chemicals”

Glazit, Brasso, Pledge, Simple Green, Son of a Gun, Windex

Finally, lubricate all moving parts. Dab a little ball of white lithium grease to each of the switch detents, the slug tuned rack bearings, or any movable metal surfaces.. Apply a small amount of light oil to the inner shafts on the front panel controls before putting on the knobs and on the PTO shaft concentric bushing. In other words, any moving mechanical surface deserves a little dab of grease or light machine oil with the exception of any of the plastic gears associated with the dial assembly and idler wheel.

If you have taken your time and were in no rush, your Collins should be glistening with a new-look appearance. I have taken Collins radios from a 75A-4 to a KWM-2A that were rather dirty and grimy and have transformed them into radios that look good, work well, and, yes, even smell good!

This feature on such a comprehensive, wide-ranging subject as Collins restoration, undoubtedly, has only scratched the surface � not on our Collins! There are many opinions on ways do to a better job than some of the approaches that are presented here. I do hope that the material is welcomed and appreciated by the Collins community. Of course, I welcome your suggestions and comments. My newly acquired S/Line, together with complete set, the 312B-4 and 516F-2, is now occupying my shack ready for service or to be admired by some Collins aficionado.