DIY Rebuilding the Transport for a Pioneer CT-F900 Cassette Deck

[pustelniakr]

There are so many requests for information on putting new belts on a CT-F900 that I have decided to chronicle one of my latest commissions: the restoration of a a nice little Pioneer CT-F900 Cassette deck.

Note: The actual transport (not the circuitry) for the CT-F950 cassette deck is VERY similar to the transport in the CT-F900. This guide should serve you will there also. Also, the CT-F1250 transport is quite similar, but has a direct-drive capstan motor. There are significant similarities with CT-F900, but also some significant differences.

Rebuilding the transport of this model is significantly more difficult than performing the same job on the older CT-F1000 or the CT-F9191, but, if patient and careful, the job can be done.

When I restore one of these beauties, I usually perform the following:

1. Perform a complete initial functional test. This is to determine what repairs may need to be made, and to provide a reference baseline to compare to, in case my repair actions break something (it happens), and so I can provide a comprehensive formal quote to the owner (in case of a commission job). In some cases, it is not possible to determine all of what may need work, until certain prerequisite work is done, such as, when a deck will not play tape, record and play electronics cannot be adequately tested. In such cases, the quote must go out in stages.

2. Rebuild the transport (covered, in detail, by this thread). Unless the owner is local to me, all work described in this thread is mandatory. This is to ensure that the job is complete, so the expense of shipping does not need to be repeated.

3. Rebuild the reel motor (covered in a separate thread: http://www.hifihaven.org/index.php?...eer-ct-f800-900-950-1250-cassette-decks.4292/). This task is also mandatory. After 30 years, small DC motors with brushes and centrifugal speed regulation switches all need work. It is quite common for these motors to have dead spots at their age.

4. Replace the pinch rollers. This is expensive, due to the fact that they are no longer available as spare parts. We do have a specialist available, Terry Witt (http://www.terrysrubberrollers.com/), who is the master of rubber rollers and idlers. After 30 years, all rubber dries, and hardens, and glazes, even if not used (the effect of ozone and other environmental components). If the pinch rollers for one of these dual-capstan, TOTL, decks are not resilient and supple, they will squirt tape right out one side or the other, and your favorite, irreplaceable tapes WILL get eaten. Pinch roller replacement is not mandatory, but HIGHLY recommended, unless the rollers are beyond restoration by cleaning and rejuvenation (cracked, eccentric, pitted, etc.).

5. DeOxit all user controls and internal switches (they do tend to corrode and get dirty over 30 years). This is part of a basic restoration.

6. Complete REC/PB/Dolby alignment/calibration. This is an optional service, but if desired, the basic restoration is a prerequisite operation, since you cannot get stable performance for calibration, if the transport is not up to snuff.

7. Complete recap (replacement of ALL electrolytic capacitors: http://www.hifihaven.org/index.php?threads/re-capping-a-pioneer-ct-f900-cassette-deck.4303/). This is an optional service, but if desired, the basic restoration and a complete REC/PB/Dolby alignment/calibration are required, since recapping is likely to significantly affect the calibration, and the calibration requires the transport to be fully up to snuff.

8. Once the machine is fully up to factory specifications, or as close as possible, the appearance is worked on to match, with a complete cleaning and polishing, inside and out, and connectors are DeOxited and Pro-Golded, and polished.

9. Finally, the unit is subjected to a full, comprehensive functional test, to ensure that all features are operational. Then the unit will get installed in one of my systems and enjoyed for several days, to ensure I have not missed anything. Then the shipping packaging is designed and built, to ensure that the unit will survive a drop off of the roof (shippers appear to do that).

Please note that this particular unit had been subjected to some ham-handed repair work in the past, just in case you notice its lack of clean wire routing, etc. The photos were taken as the unit was coming apart, not as it was going back together.

To give you an idea of just how nice looking these decks are, I have attached a pic of it, before I began the work.



Enjoy,
Rich P

 

[pustelniakr]

Vintage Restoration Boiler Plate

First a bit of boiler-plate DIY info:

1. If you are an impatient individual, tending to get frustrated, and force things, or get rough. DO NOT attempt this operation. You could very easily wind up with a pretty, brushed aluminum paperweight. Generally, if a unit is fresh, and unmolested, it is less expensive for a knowledgeable tech to restore/repair. If I have to clean up a ham-handed, fumbled job, it will definitely cost ya.

2. Make sure that your tools are in good condition. For example, if the tips of your screwdrivers are worn, you will damage the heads of your screws (some are in pretty tight), and you will play heck trying to get them out. New screwdrivers make all the difference in the world. All it takes is for your driver to slip one good time in a stubborn Phillips head screw, and you could make it next to impossible to remove, and you will damage your driver as well (take a look at your old Phillips screwdriver.

3. Do not get curious about additional details of the mechanism. There are an abundance of tiny little parts just waiting to jump out of your machine and into the nether world, if you are not careful or know what to expect. These little parts can be worth the entire cost of your machine, since, if you do not find them, or if you break them, you will have a non-functional unit.

4. Unless you have an eidetic memory (photographic), take pics, notes, etc., as you go. It is not a good thing to have extra parts left over at the end of a job. I have a large supply of tiny zip-lock bags which I use to put parts from various stages of work. In this way the number of screws, or a couple of screws and a spring or c-clip will key my memory to the stage or assembly they go back into.

5. There are no magic bullet chemicals. Use each chemical or lubricant, etc., only where it is appropriate. If not, you have a paperweight again. If you are not sure what to use where, seek wise counsel, from reputable sources.

6. Before you do any disassembly or work, put a baggie over your power plug, and hold it on with a rubber band. The very last thing you want to do, is get surprised by a spark, or G_d-forbid, a jolt. Guess what...paperweight time again.

7. NEVER force ANYTHING. If you have to force it, you are not doing it right and you will likely break something, or get a part on wrong...paperweight time again (Getting irritated at that phrase? Good.).

8. Mickey Mouse has no part in a vintage restoration shop. NO half-tail operations, no funky monkey rigging, no time bombs for someone else to clean up. I cannot tell you how many times I have seen serious, just enough to get by kind of repairs (blobs of glue to replace lost c-clips, weird wire twists holding on broken parts, etc.) If you break or lose something, buy a parts unit and replace it right. Chewing gum, bailing-wire rigs will ALWAYS come back to bite you.

9. There are innumerable tricks of the trade that are too detailed to discuss in a DIY thread (how to hold a tool, how to keep a c-clip from jumping across a room, etc.). Be prepared to learn some/many of them the hard way (by experience). Sorry folks, it comes with the territory.

10. Get a service manual. They are just too readily available to justify flying blind. If you are a cheap ________, buy one on CD. They are only around $10 on the bay. I prefer originals. The color coding in the drawings is a real help to an old man like me.

Last but not least...I accept no responsibility for how well or successful you may be at performing this operation. Results will vary from unit to unit, and from individual to individual. You know...some folks should simply not try this kind of work. Most folks can be successful however.

Enjoy,
Rich P

 

[pustelniakr]

Accessing the Interior

The first step is to gain access to the interior of your unit. Depending on which sub-model you may have, you may need to remove different screws.

If you have the basic model, you remove the 6 screws from the side of the bonnet (black metal cover), 3 on each side. The bonnet will then lift straight up and off.

If you have a model with a wood (or simulated wood) cabinette, the screws will either be the same ones as on the metal cased unit, or, the will be 4 screws on the under-side of the unit. If the screws are on the side, the cabinette will lift straight off the top. If the screws are on the bottom, the unit will slide out of the cabinette, to the front.

The attached pic shows the CT-F900, partially disrobed...



Enjoy,
Rich P

 

[pustelniakr]

Removing the Faceplate

To get the faceplate off, first, remove the six screws (labelled A on the 1st attached pic). They are just behind the front face, 3 on the top and 3 on the bottom.



You do not need to remove any knobs before removing the faceplate (just be careful not to scratch them), but, you do need to lift up gently on the cassette-half retainer (it holds the cassette in the tape well). It is located just behind the center of the tape well hood, behind the 'B' label in the attached pic. Most CT-F900s that have been worked on by folks without knowledge, have the cassette-half retainer broken. This is because they do not know that when removing and reinstalling the faceplate, it must be lifted to clear the opening in the faceplate (force her and she breaks). If you break it, you can see how to repair it here: http://www.hifihaven.org/index.php?threads/rebuilding-a-pioneer-ct-f900-transport.4299/#post-82710

The 2nd attached pic shows the unit with its faceplate removed. The cassette-half retainer is labelled 'C', and immediately above the 'C' is the part that will be broken if you force it (the rotation limiter). If broken, the retainer will fold down too far when the tape is removed, making it a real PITA to get a cassette into the well.



Please note that, if the transport control button label panel comes off in the faceplate, take it out of its well and install it on the transport button assy, as shown, securing it temporarily with tape on each side.

Enjoy,
Rich P

 

[pustelniakr]

Freeing the Transport Assembly

Yes. It IS NECESSARY to remove the transport assembly to get to the belts, etc. Again, do not try to do half-tail work. It WILL bite you.

Before you attempt to remove the transport, you must take note of the grounding springs and how they are installed and connected (unless you like excessive hum). The grounding springs are necessary, because of cost cutting near the end of the Big Silver period, where the metal transport frame, of earlier models, was replaced by a plastic one.

The 1st grounding spring can be seen in the 1st attached pic, labelled 'A', and it connects the head assembly to the metal transport mechanism by spring tension under the reel idler arm (immediately above the 'A').



The 2nd grounding spring can be seen in the 2nd attached pic (seen from the top of the transport), labelled 'D', and connects the metal transport mechanism (via the back of the reel idler arm shaft) to the transport back plate.



Then, before removing the transport assy, remove the cassette-half retainer so it does not get broken, by snapping it out of its hinge at the points labelled 'C' in the 1st pic, taking note of how the spring is oriented 1st.

To release the transport, as an assembly, remove the 6 screws that hold it in. There are 4 in the front, labelled 'B' in the 1st pic, and 2 on the bottom, also labelled 'B' in the 3rd pic.



Do not remove the transport yet. There are a couple of things to do yet...

Enjoy,
Rich P

 

[pustelniakr]

Removing and Accessing the Transport Assembly

In order to get the freedom to get the transport out of the unit, you will need to disconnect the transport control cables from the control board, labelled 'A' in the 1st pic.



Next, in order to work on the transport, without having to lay it on top of circuit board components, stand the unit on its side, transport down, then move the transport out on the bench, next to the unit, as shown in the 2nd pic. (Note, if you did not remove the cassette-half retainer, you just heard a snapping sound, as it broke.



Enjoy,
Rich P

 

[pustelniakr]

Removing the Plunger Chassis Assembly

Now its time to get down to the nitty-gritty...

To access the inner works of the transport, you need to remove the Plunger Chassis Assembly. This is the assembly that holds the 'Head Assy' solenoid, the transport terminal block, and the capstan thrust bearings.

This assembly is removed by removing the 5 screws that retain it, labelled 'A' in the 1st pic.



Next, the Plunger Chassis Assembly is rotated away from the rest of the transport, rotating it on its wiring, as shown in the 2nd pic. Put a pad under it, so it does not get damaged.



Enjoy,
Rich P

 

[pustelniakr]

Removing the Capstans

You now need to remove the capstans and their belts. But, before you do, note which capstan goes where, and how they and their belts are oriented, then reach around the front of the transport and remove the oil retaining washers on the front of the capstans (they will run away and hide, if you do not get them now. They can be seen, labelled 'A' in the 1st pic.



Next, remove the 2 capstan belts.

Time to remove the capstans. Take the smaller one out 1st, but lift it out of its bushings slowly. There are some small parts that are likely to fall out (a 3-pointed thrust spring and a lubricating polyethylene washer (note how these parts are oriented on the capstan shafts, its important). Then do the same thing, in removing the capstan with the flywheel.

Now, so you do not forget how the little parts are oriented on the capstan shafts, put them all on the capstans now, as shown in the 2nd pic (top down: oil retaining washer, lubricating washer, thrust spring (no spring on the smaller capstan)).



Put those capstans securely away. If they get bent, even slightly, your deck will produce nothing you will want to hear.

Enjoy,
Rich P

 

[pustelniakr]

Removing the Sub-Chassis Assembly

Now, we will access the front of the transport mechanism (Its getting scary eh?).

Fold the Plunger assembly back down on its wiring (careful man!), below the back of the sub-chassis screws, and remove the 6 screws retaining the sub-chassis (labelled 'A' in the 1st pic).



The 2nd pic shows what the front of the sub-chassis looks like.



The brake solenoid actuates the brake arm, 'G', which lifts the brakes and allows the reel idler. 'C' to contact its drive, 'B', which is driven by the belt from the reel motor.

The direction of rotation of the reel motor causes the reel idler, 'C', to rock to drive the supply reel/clutch, 'D', or the take-up reel/clutch, 'E'.

When the take-up reel ('E') rotates, it drives the optical motion sensor, 'F', via a belt. If this sensor stops seeing take-up reel motion, the unit will drop out of play or fast mode driving.

Enjoy,
Rich P

 

[pustelniakr]

Sub-Chassis Restoration Work

Here are the operations to be performed on the sub-chassis:

1. Note the orientation of the 2 belts and remove them.

2. Remove the 2 screws retaining the reel motor ('A'), then, remove the reel motor and rebuild it (discussed here: http://www.hifihaven.org/index.php?...eer-ct-f800-900-950-1250-cassette-decks.4292/). When complete, reinstall the reel motor.

3. Carefully remove the reel idler ('B'), watching for the retaining c-clip, and any lubricating washers and their orientations. Then, either replace the idler tire, or the whole idler, as may be needed. The idler may be cracked. Do not try to rejuvenate the tire rubber. It won't last, and you will be back in here in less than a month...

4. Remove the brake arm ('C'), noting its orientation and assoc. parts, and clean the old lube (now wax) from where its shaft was, and put in some fresh white lithium grease (not too much), then reinstall the brake arm.

5. Carefully note how the reel idler arm and its parts are oriented, remove it by its main shaft ('D'). Careful here, there are springs to go sproing. Clean out the old lube from where its shaft was (now become wax), and put in a bit of fresh lithium grease, then reinstall it.

6. Put a "single drop" of light sewing machine oil on the idler arm intermediate joint ('E').

7. With a q-tip dipped in isopropanol (67-63-0) scrub all drive surfaces and belt grooves clean.

8. Install 2 new drive belts.

Operation note: The take-up reel/clutch ('F') is a 2-stage clutch. The upper stage drives the reel with higher torque (less slip) for FF mode. The lower stage drives the reel with less torque (more slip) for PLAY mode. The front of the main shaft of the reel idler arm ('D') rides in a part of the mechanism that raises or lowers the whole idler arm, depending on drive mode. The supply reel ('G') is similar except that the idler always drives the upper stage for REW, and a brake always contacts the lower stage for a very light back torque (very high slip) during PLAY mode.

Note: Do NOT mess with the spring that pulls the idler arm (marked D-E-B) up so the idler contacts its drive. It does NOT need to be made stronger. If the idler slips, it is because the rubber is hard, or slick, or too thin.





Enjoy,
Rich P

 

[pustelniakr]

Transport Front Restoration Work

Here are the operations to be performed on the front of the transport:

1. Remove the brake plate ('A', 1st pic), by drawing down its spring (retains and applies brake pressure). The brake plate will then slide out from under the head base assy ('B', 1st pic).

2. Remove the 2 brake pads ('C', 2nd pic) and clean/rejuvenate them with a good rubber rejuvenator, like Rubber Renue by MG Chemicals or Rubber Magic by J. Selvey. Then reinstall them.

3. This next task is NOT for the faint of heart or clumsy. Clean the slide bearings for the head base assy. The lube has likely turned to wax, so it is fairly important. but dangerous! Carefully! Remove the bearing retainers ('D', pic 2). There is one tiny ball bearing under each one. There is a matching ball bearing directly under the base plate, under where the upper bearings were. Capture each bearing and put them in a small container where they will not roll away and hide. Then clean out the old lube from where they were, and add fresh white lithium grease. Then carefully (PLEASE) put each bearing back, and reinstall the bearing retainers ('D', pic 2).

4. Apply some fresh lithium grease to the edges of the brake plate, where it slides under the head base plate, and reinstall the brake plate and retain it with its spring.





WHEW! Now THAT was down-right frightening!

Enjoy,
Rich P

 

[pustelniakr]

Transport Rear Restoration Work

Here are the operations to be performed on the rear of the transport. This is essentially the PLAY actuator of the transport. it serves to lift the heads and push the reel idler back to the lower torque drive position:

1. Note the orientation of the 2 springs ('A') tied to the mechanism. Then remove them.

2. Remove the retaining c-clip ('B') and remove the actuator arm ('E').

3. Remove the idler drive ramp ('D'), clean out the old lube, and replace it with fresh white lithium grease.

4. Remove the rocker arm ('C'), clean off the old lube, and re-lube with fresh lithium grease and reinstall.

5. Clean the old lube off of the actuator arm ('E'), re-lube with fresh lithium grease, and reinstall.

6. Reinstall the actuator arm springs, and secure them with a good quality contact cement.



Not so bad...

Enjoy,
Rich P

 

[pustelniakr]

Reinstall the sub-Chassis

Now reinstall the sub-chassis, being careful to get the brake lifter arm so that it is able to lift the brake plate.

Also, make sure that the head base is able to move up and down without binding (this action brings the pinch rollers and heads up in play mode).

Also, make sure that the grounding spring from the head assy, is properly positioned under the reel idler arm.

Enjoy,
Rich P

 

[pustelniakr]

Reinstall the Capstans

Now put a single drop of light sewing machine oil in each of the 2 front capstan bushings, and a single drop in each of the 2 rear capstan bushings. Then slide each capstan in its bushing assembly, and install the oil retaining washer back on the front of each capstan shaft.

Install 2 new capstan drive belts.

Rich P

 

[pustelniakr]

Reinstall the Plunger Chassis

Clean out the old lube from the capstan thrust bearings ('A'), and replace with fresh white lithium grease.

Reinstall the plunger chassis, ensuring that the solenoid properly engages the Play Actuator.

Also, ensure that the grounding spring from the terminal block plate is correctly located behind the c-clip holding the reel idler arm shaft.



Enjoy,
Rich P

 

[pustelniakr]

Transport Re-installation

Perform the following operations:

1. Slide the completed transport assembly into the unit and secure with its screws.

2. Reconnect the 2 transport control cables to the control board.

3. Reinstall the cassette-half retainer in the top of the front of the transport.

4. When you reinstall the faceplate, be sure to lift up the cassette-half retainer, so it clears the opening in the faceplate, or it will break.

Enjoy,
Rich P

 

[pustelniakr]

Recommended Operations

In addition to the above listed operations, I strongly recommend the following:

1. Replace the pinch rollers (accessible from the front). You will need to adjust the height of the supply side roller, and that can only be done, by cutting the plastic off of a new cassette, so that you can see the tape-to-head contact, while the tape is playing. Then you adjust the roller/guide height (by the roller mounting nut tension, so that the tape does not touch either tape guide edge on the guide attached to the REC/PLAY head. Take your time and use a flashlight and a jeweler's loupe to see it. It will take a bit of skill development, but it can be done. You will also need to adjust the pinch roller pressure for each roller.

Note: The plastic retaining/adjustment nut, holding the left pinch roller assembly, WILL strip, if you try to simply unscrew it. Notice that the pinch roller assembly is spring pressured, so, as you unscrew the plastic nut, the assembly will move outward. IN its original position, you will notice that you can push the assembly in against the spring somewhat. Do this, and screw the adjustment nut in a bit. This will move the plastic nut off of the locking varnish used to hold it in its adjusted place. Then you can carefully remove all of the locking varnish from the threads of the shaft. Once the varnish has been removed, you can safely unscrew the plastic adjusting nut, and remove the pinch roller assembly. It is this varnish that causes the plastic nut to strip, if you do not remove it in this way.

2. Replace all 3 of the micro-switches that can be seen at the top of the transport. These are most likely corroded and not making good contact. Since there is no wiping action for the contacts, DeOxit is not a good solution here.

• 1 of these: http://www.digikey.com/products/en?keywords=sw1467-nd
• 2 of these: http://www.digikey.com/products/en?keywords=ss-01gl13-e-nd

Finally, thoroughly clean and demagnetize the tape path, and enjoy your newly restored CT-F900...

Enjoy,
Rich P

 

[pustelniakr]

Supplemental Info:

Repairing a broken Cassette-Half Retainer

If you have a broken cassette-half retainer, fear not. If you are careful, and skillful, all is not lost. It can be repaired.

What will most likely be broken is the rotation limiter (the small appendage, extending down in the 1st pic). The main caveat is that you will need to have the part and the piece that broke off, or a whole one. This because you will need to make a mold. If you only have the broken pieces, temporarily glue them together with superglue (not a good repair, but it will hold till a mold is made.



You will need to form a small box out of tin foil, large enough to hold the whole part, laying flat. Then fill the foil box with low melting point wax. When the wax has been poured, fit the whole part, broken side down.

When the wax has solidified, pair down the wax until the wax is flush with the top surface to be replaced.

The attached pics show the original part, top and bottom, as well as the original part in the new mold.





Enjoy,
Rich P

 

[pustelniakr]

Supplemental Info:

Repairing Cassette-Half Retainer (cont.)

Now that the mold has been made, prepare the broken part, by filing/grinding the remaining part of the broken appendage, giving enough space to be occupied by the new molded material, and to form barbs like on a fish hook, so the new molded portion will be able to stick and not pull off.

Of course, if you super-glued the broken appendage on, to make the mold, you will need to snap it back off (see how easy it snapped off?)

Place the broken part in the new mold, and fill the remaining space in the mold (the appendage part) with well-mixed JB-Weld. After 24 hours (not sooner), remove the part from the mold and snip the excess flash off and sand off the new molded portion.

Voila! A repaired cassette-half retainer.

The attached pics show the repaired part in the mold, out of the mold, and compared to an original, whole part.







Enjoy,
Rich P

 

[pustelniakr]

Supplemental Note:

To verify that all is well with your take-up reel drive, do the following:

1. Take a sharpie (marker), and put some marks on the edges of the take-up clutch drive surfaces, so you can see how they rotate relative to each other.
2. Once the deck is back together enough to load and play a tape, fake the deck into thinking there is a tape in it: push in the tape presence sensor button (to the right of the right capstan), and press play.
3. The heads should come up. Release the tape presence sensor button. the button should be held in by the risen head plate, and the transport should continue driving. If not, you will have to adjust the tape presence switch linkage (rotate the switch slightly, etc.).
4. Now observe the take-up reel turning, and the tape counter counting.
5. With your fingers, momentarily stop the take-up reel from turning (taking it by the hub).
6. If you rebuilt your transport correctly, and all your parts are good (tires, belts, etc), the reel motor should continue turning, the reel idler should continue turning, and the take-up reel clutch drive surface should continue turning (the take-up reel clutch slipping correctly).
7. If you hold it this way too long, the unit will drop out of play, because the counter stops counting while the reel is stopped.
8. If what I described, while stopping the take-up reel, does not happen, find out why. Reel motor stopping (weak)? Reel idler not turning (slipping)? Everything stops turning (clutch bound)? Etc. This will require a repair action of some kind. This is because, when actually playing a tape, the take-up clutch drive surface will rotate at a different rate than the actual take-up reel (clutch slips, to provide correct, smooth take-up torque). This is verified by looking though the cassette window during play and watching those marks I told you to make with a sharpie.

Note: If the idler is slipping, do NOT mess with the spring that pulls the idler arm up so the idler contacts its drive. It does NOT need to be made stronger. If the idler slips, it is because the rubber is hard, or slick, or too thin.

Enjoy,
Rich P