Re-capping a Pioneer CT-F1000

Time to take on a "major" re-capping project: a super sweet Pioneer CT-F1000 KCU (US/Canada model) cassette deck (a 3-headed beauty), built in March of 1978. I have already restored the transport to full speed, replacing "all" rubber drive parts (belts, idler tires, pinch rollers), lubricated and aligned mechanically, and DeOxited all sensor microswitches. The motors (of which there are 2) required no restoration, which is typical for this model , unlike her sisters: CT-F900, CT-F950, CT-F1250, which usually all need the reel motors to be rebuilt.

I will do separate DIY threads covering the rebuilding of Pioneer reel motors (not for the faint of heart), and the restoration of a TOTL Pioneer cassette deck transport. This thread is to chronical the massive re-capping project that this unit presents.

The problem with most vintage gear (in excess of 25 years old), is the fact that electrolytic caps tend to dry out, since the electrolyte is moist, and must stay that way for proper function. Some caps drift severely, in the lower capacitance direction. Some caps fail open, and simply cease to perform whatever function they were designed in to do. Others that fail, do so by failing short, generally causing catastrophic damage to the unit. You may be enjoying a ticking time-bomb . Some will swell and leak, causing all kinds of corrosion damage to the circuit boards in the area, while others will literally blow up. Some caps measure OK on a capacitance bridge, but, in the circuit, leak DC, causing noise, bias shifting, instability, etc. I truly recommend re-capping gear you intend to keep and enjoy, or sell to someone you care about.

Re-capping requires a complete service manual, with all published supplements, addendums, errata, and modification sheets. Each board is gone through, electrolytic caps are each measured to get their physical dimensions (replacements must fit in the space provided. Not to fear nrmally, since modern caps tend to be 1/3 the size of the originals (causing other problems)). Then the caps are checked to see which Pioneer series they are in (indicated by Pioneer part number). Now you must attempt to determine what characteristics were inportant to the designers that established a specific Pioneer part number series. Hints come from what cap manufacturer series was used (usually, and hopefully, more than one), "if" you can find the very old data sheets you need (so far all the series I've encountered have been long obsolete), or mfg-to-mfg cross-reference lists. You must also track what kind of circuits the particular Pioneer part number series is used in (coupling, de-coupling, filtering, feedback, etc.). Without the original Pioneer part drawings, you must engage in significant guesswork, supplemented by informed/experienced reverse-engineering.

The next step is to attempt to find modern manufacturers for parts that conform to the design criteria determined in the previous step, followed by locating distributors that handle the replacement parts (in the onesy-twosy quantities you will need), and determine the per unit cost. (Note: I prefer to keep things original. I don't try to second think the original designers, unless the future owner pays significantly for an upgrade or modification. I do tend to use a bit better part than the original, but not to point of using the very expensive, esoteric, sometimes snake-oil parts). It gets to be a lot of fun when the part you need is not made by anybody in the size and/or voltage you need (like finding low voltage electrolytics in the sub-1uf values). Then you need to substitute a different kind of part altogether. I have had to do that with a couple of caps in this project and, if I remember, I will let you into my head as to how I decided how to proceed.

I then created an overall Pioneer database for electrolytic caps, which I can then draw on for other models down the line, and from which, I create a model-specific database, which shows each cap, on a per-circuit-board basis, with all the associated info (original part number, dimensions, value, working voltage, new mfg part number, distributor part number, price, etc. etc. etc.). The database also contains a table of consolidated data, where all like parts are grouped, used as a purchasing list for the model.

Here is where I am at the moment. Now for the bottom line so far: There are 16 circuit boards in a CT-F1000, and 166 electrolytic caps to replace. Let's just say that I'm quite intimidated by the task, since these bad boys are not designed to be disassembled to the degree that I will have to (daughter boards are soldered to the mother board, inter-board connctions are made via wire-wrap and soldered, individual wires).

I will chronical this thread with abundant photos as I go. If you intend to follow in the path I blaze, you will need a cache of fresh pace-maker batteries.

Next step: ordering enough parts to do all 4 of the CT-F1000s currently in my stable. While I wait for them to come in, I'll finish sweetening my last 4 PL-630 turntables (BTW, they have 21 electrolytics in them )...

Rich P

The Parts Are In

The new caps are in, except for the low leakage caps. So I thought I would show ya'll a couple of nice nudies before I begin surgery. Here are the replacement caps I have selected:






As I said, there are 16 PCBs, with 166 'lytics to replace. There are no super large valued caps to try to ignore, so ALL are going to go. The total per deck cost turned out to be only $35 in parts. The labor will be another thing all together. Except for the low-leakage Xicons, all the parts came from Digikey. So far Digikey has been perfect (not one component extra or shy, all parts filled correctly), and I have made some truly complicated orders (like this one).

As I stated previously, I picked up enough to do all 4 CT-F1000s in my stable, with a couple of extras in each value, for good measure. I find that it works better to do gear in batches, when possible. Each unit gets easier and faster and the quality of the work improves with each unit that way. Two CT-F1250s are next .

The pics are nice 'before' pics. If all goes well, you will not be able to tell the difference from the 'after' shots, unless you look real close...





Rich P

Recapping the Power Supply Board

OK...I decided to do one of the harder PCBs to access, 1st. Nothing like facing your fears, head-on. I haven't got the guts to do the control board, yet, but I may do that one next. As it turned out, the power supply board is easy to look at, but hard to get to to change out parts. I had to remove the back panel, then move the transformer, fuse board mount, and accessory A/C outlet.

Then I covered the control board (under the transport) with a few stiff layers of cardboard, and moved the transformer up on that, then folded the back panel (power cord still attached) over the front top of the unit to get it out of the way and to have better access to all sides of the power supply board.

The power supply board had 13 caps to change, and most of them were big enough to see the effects of modern technology. As long as the can is bigger than the minimum can size, the difference in size is quite dramatic. Several of the new ones were less than 1/3 the size of the originals, physically.

While I was at it, I decided to freshen up the solder joints, since flow-solder has a more limited life span than manually applied joints, especially since I saw a couple of questionable joints. (I have to remember to get me one of those old soldering heat sink clips before I do any of the audio related PCBs, since they have several styrol (polystyrene) caps, which despise heat, and could easily rebel at their ripe old age )

Chicken that I am, I put the back panel back on, measured the power supply outputs, and played some tape for a while, to ensure all was well. It was.

Here is a pic of the unit without her backside



Rich P

Recapping the Control Board

I just finished the control board. I really thought it would be harder to get at that it was. Actually, Pioneer and a bit of spacial relationships sensitivity made it a piece of cake.

As it turns out, 2 small caps were not the same value as the schematic and parts list. I always buy a couple of extras of each value, so I had an extra of the variant value of one cap. Then, the other cap actually used the original value of the first variant cap, as its variant value, so, I only have to buy more of the 1st cap's variant.

There were a total of 19 caps on the control board.

Before I move on to the audio-related boards, I decided to do a more thorough functional test, and found that the 400Hz test tone (used for user-calibration of the Dolby record level on a per tape basis) is not being produced. Everything else works fine. Needless to say, the test tone generator board is next.

The pics show the controller board in its fully assembled state (now you know why I was initially intimidated by it), the controller board made accessible, the controller board before recap, and the controller board after the recap. If you compare the last two, you can begin to see the difference in old and new cap sizes...









Rich P

Recapping the Test Tone Board

Well...the test tone generator board was next. Here is where the recap is a direct correction of a failure. The board was not generating the 400Hz Dolby Cal tone. As it turns out, one of the 3 'lytic caps on this board, a 2.2uF, 50V, output coupling cap was kaput.

Apparently, another, so called, tech had been into this one because there were probe pokes all over it. If I had just proceeded to recap the board, without the functional test, I would have never known that it had a problem with the cal tone (which someone else had given up on ). The 2 2SC711-E transistors both checked to be OK with a meter (its a simple 2 transistor oscillator circuit).

I replaced the 'lytics, then retouched all the solder joints (a couple looked OK but questionable). Then, I used the legendary jumper cables and powered up the board outside of its mother board installation. 400Hz was there, right on the money

I didn't really take pics during this process, because, I was in troubleshooting mode, but I have taken a pic after re-installation (so you can at least see what it looks like, after recap and repair. Note that there are several nice mylar caps on this board.

The pots and switches are real scratchy, and look to be hard to get to for recapping the volume assembly. So, in keeping with my tendency to do the hard stuff 1st, the volume assembly is next for recapping.



Yee haa! This is fun! (so far)...

Rich P

Recapping the Volume Assembly

Well...I finally found the "Pain in the Neck" factor

The volume assembly required the removal of the entire face section of the chassis, in order to get at the bottom of the board for recapping. That was just the beginning. Once I recapped the volume assembly, I decided to DeOxit all the user controls (front panel pots and switches) because I do it on all the gear I do, plus, several of them were manifesting problems.

The real pain began when the output fixing section of the test tone switch (fixes the output level, bypassing the output level pot) was not cleaned up completely by a simple spray and actuate operation. I had to take it out for some up close and personal work (disassembly and manual contact cleanup ). That required accessing the bottom of the main board (mother board), lifting it up and sliding it forward a couple of inches. Easier said than done (by a long shot). The back panel had to removed again, and de-soldering that switch was something I don't want to repeat for a very long time. I didn't lift any pads in the operation, and that's a good thing (actually no pads lifted at all so far with this unit).

In and out, up and down, panels shifting all around, a real pile of metal spaghetti. When it was all reassembled (no extra hardware left over ), I found that I had broken a wire off the pause switch board ('cause it wouldn't pause). I was actually surprised that was all that got broken. Now a full functional test again, to make sure everything works and the intermittent controls were successfully cleaned up, they were . Now the smile slowly creeps back onto my face, sheepishly, at first. The hard parts are now complete. I can relax and enjoy the rest of the recapping.

Whew! I think I'll do another PL-630 before I do the next CT-F1000

The attached pics show the disassembly level necessary to recap the volume assembly, as well as an after pic of the volume assembly (fully installed). The frustration factor was so high during the main-board bottom access and switch repair operation, I'm sorry to say, I didn't think of you guys, so no pics of that level of disassembly (I also didn't want to scare you off, and I would have, believe me). I hope you will understand.





The next step will be recapping the 4 Dolby boards (left REC, right REC, left PB, right PB)...

Rich P

Recapping the Dolby Boards

After a bit of distraction, doing some commission work for fellow AKrs, and some necessary work to checkout my new CT-F1250 (transport rebuild, and removal of swollen pinch rollers to have Terry Witt make some new ones), I'm now officially back on the job.

Folks, the hard parts are over. Access should be easy from here on.

The Dolby boards can easily be desoldered from the main board, and worked on separately, on the bench. What a relief. Access is provided to the underside of the main board, via an access panel on the bottom of the unit (1st pic).

There are 4 identical Dolby boards: left and right record, and left and right playback. To minimize the impact of the operation on pre-alignment performance, number each board and put them back in the same positions as they came out of. Also, do not mess with the position of the pots at this time.

Due to the inablility to find .33uF, 10v, low-leakage, 'lytics (audio coupling caps), I chose to replace those (lower left corner in the pics) with a .33uF 50v polyester film. Significantly bigger, physically, but causes no problem in this case.

As usual, don't forget to re-touch all solder joints on the Dolby boards. 30 years is too long for wave/flow soldered connections.

The pics show the bottom of the main board, visible through the access panel on the bottom, the Dolby boards installed in the main board, the Dolby boards before and after recap.









Next, the Playback Flat Amp board...

Rich P

Recapping the Playback Flat Amp

This one was pretty straight forward. The board came out for work, like the Dolby Boards. The only caveat was an internal conflict in the service manual. The part list showed a 0.47uF, 50v cap, while the actual cap and the board assy dwg showed a 35v cap. Since the caps I'm using for std cap replacement do not provide a 0.47uF cap in 35v, I went with the part list, 50v value (single voltage step up, so no risk with modern caps).

As usual, a retouch of every solder joint.

The pics show the Playback Flat Amp, installed next to the Dolby boards, as well as "before" and "after" pics. Note: some significant reduction in physical size...






Next, the Playback Equalizer Amp...

Rich P

Recapping the Playback Equalizer Assy

The Playback Equalizer Assy, is the 1st amp the the PB heads see. You can bet there will be some low noise, high stability parts on it. You would win that bet.

This board recapped in a straightforward manner, similar to the Dolby boards, except that the head leads remain connected throughout the process. You need to find a way to position the board and route the leads, so that flipping the board, front to back (done frequently), is done by a 180 twist of the leads. This is to minimize stress on the connection points.

The first non-standard caps to consider are the orange ones near the top, center of the board. They are a 4.7uF, 25v, low-leakage 'lytic. Fortunately, I found a direct replacement, in a Xicon LLRL series, from Mouser. It is even nearly the same color (for what that is worth).

Don't move the pots at this time to minimize impact on the pre-alignment performance.

As usual, re-touch all the solder joints, with one MAJOR exception, having to do with the other special caps on the board. Notice the unusual looking caps at top center. These are styrol (polystyrene) caps (one of the closest to the ideal cap that there is). Stay completely off of the printed nodes to which these caps are directly connected, or you will likely damage them. Their drawback is their sensitivity to heat. They just cannot take more than 85 degC. Soldering temps are normally far in excess of that. You need to connct a soldering heatsink clip between the solder pad and the body of the cap if you must solder them. Styrols of this type and form are very rare and expensive today. If you open up your gear, any kind, and find an abundance of these, you have a truly high quality piece of equipment. They were quite expensive even back in the day.

The pics are of the PB Equalizer "before" and "after"




Next, the Meter Amp Assy...

Rich P

Recapping the Meter Amp Assy

The Meter Amp Assy recapped in a similar manner to the PB Equalizer, desoldering it from the main board, but keeping the leads connected at the top. Orient leads and board so as to minimize stress on the lead connections to the board, as you flip the board back and forth, during the process.

Remember to re-touch all solder joints, and to leave the pots untouched.

The pics are "before" and "after". (Note: You can really see the size differential between the originals and the modern replacements on this board :yes: )




Next, the REC Equalizer Assy...

Rich P

Recapping the Integrated Circuit Amp

I know I said I would do the record equalizer next, but I changed my mind. I decided to do the left and right integrated circuit amps next. These boards provide the mike, record, headphone and flat amp stages. Before somebody asks, the amp IC is a PA4001 (quad-amp).

I got my 2nd demerit, on this project, on the 1st of the 2 IC amp boards. I broke a wire connected to the top of the amp, and had to solder it back on To make sure I didn't do that again, I took the wires connected to the other board and secured them to the board via tywrap and a hole that seemed to be put there just for the purpose. In that way, no stress was placed on the wire connections and the wires had to bend in the middle.

These boards had another sub-1uF, low voltage, low leakage lytic (0.68 uF 10v). As before, I sub'd it with a 0.68uF, 50v polyester (Panasonic V series). The holes were layed out in the board perfect for it. You can see it in the middle of the bottom of the board. Also, this one had another low leakage part, for which I was able to find an actual modern replacement (10uF, 16v, replaced with a Xicon LLRL series part, from Mouser) -- visible near to where the wires connect to the board at the top (orange).

As usual, all solder joints were touched up.

The pics show the IC Amp assys installed, and out for recap (before and after).





OK. Time to do the record equalizer board for sure...

Rich P

Recapping the Record Equalizer Assy

I just noticed...we're coming up the back stretch. Anyway, The Record Equalizer Assy was nothing special (only 2 caps on it). However, I did find a fractured solder joint near the top, on one of the coil leads

As usual, all solder joints were touched up.

The pics show the board installed, as well as a "before" and "after" pic.





Next, the Peak Amp Assy...

Rich P

Recapping the Peak Amp Assembly

The Peak Amp Assy is next. It only had 2 caps on it, but it had the complication of having 3 wires to leave connected. No broken wires this time

This board provides the Peak detection function and drives the "Peak" indicator, when the input signal gets to +5db, or more, while recording.

All solder joints were retouched as usual.

The pics show the board, buried under that cable bundle in the center of the pic, as well as "before" and "after" pics.





Next, the last board we will need to recap: the main/mother board. It has 18 caps distributed around, including a few that are attached to the bottom of the board...

Recapping the Main/Motherboard Assembly

Here we are, at the last board. 18 caps spread around in tough to get at places.

During this project I got pretty good at rocking the caps out a little at a time, then cleaning the solder off the pads, after the caps were gone (primarily using a solder sucker). I could not get to most of the caps on this board with my fingers. So, I used solder wick, and removed the solder with the caps installed, and freed the caps, picking them out with a pair of hemostats (installed the new ones the same way).

This board has 6 of those nice styrol (polystyrene) caps. Heat, above 85degC, is deadly for these. So, when it came time to re-touch all the solder joints on this board, I took a red sharpie and colored every joint that was in direct contact with one of the styrol caps (meaning: don't solder here). The red color came off when I cleaned the flux off. This was one scummy board, so it took alot of ISA to clean it up.

The pics show the main board "before," "after" (hard to "see" the difference), and the bottom of the board "after."





Rich P

Recap of the Recap

Stats:

* 16 Circuit boards to recap
* 166 caps, total, to swap out
* Total parts mismatch between manual and actual part: 2
* Total mis-ordered parts (incorrect value, or missing from original order): 1
* Broke 2 wires, and had to solder them back on
* "Partially" lifted 3 pads (Only the corners of C-type pads, so no problem)
* Total part cost: approx $40
* Total labor: approx 26 hours

Results:

* Test tone inop, corrected: bad 'lytic coupling cap, found/cleared by re-cap
* Intermittent record equalization problem (attenuated highs), corrected: fractured solder joint on REC EQ board, found/cleared by solder joint retouch
* Various areas of need for electrical alignment almost cleared. Only a minimal need to align/calibrate this unit now.
* This unit records on std bias tape so that you can almost not tell which is tape and which is source (Dolby on or off). My wife could not tell. Only the disappearance of hiss indicated that Dolby is in. Remember, with 3 heads, I can monitor the tape as I make it. I could not tell the difference between the various settings: Dolby in/out, etc.

This will be a real nice machine for somebody (probably me ). I will be replacing all 3 transport sensor micro-switches (just because), performing a complete alignment/calibration (REC/PB/Dolby), and polish her up real nice.

These last pics show the baggie of old parts I took out of this unit (maybe I should sell these "vintage' caps on the bay ). And, oh, I thought you might like to see what she looks like with her clothes on. Just know that I have not polished her up yet (that's last).




I've 3 more of these to to recap (2 with rack mount ears), before my vacation is over. But, first...I think I'll re- foam my new AR9s...

Rich P

Great advise as always, Rich. Yes, a service manual is a must. When I do a recap, I replace only with the parts that were in the unit. Not by the SM. There may have been a "running change" at some point. Also, as a matter of safety after desoldering, I use IPA on the solder pad and surrounding area. That removes flux that remains on the PCB during the manufacturing process. As a side benefit, it also allows you to see the traces to the associated components. This reduces the possibility of creating a "bridge." As a greater safety, I set my DMM to the continuity setting and check near by components against the new solder. Just a safety proceedure that takes a second or two per solder. Saves headaches later.

26 hours! No service center would accept that job. That's why AK is so great. I was in a repair shop about 10 years ago that's now closed, when an elderly couple walked in with a Sony STR 7065A with a power switch problem. The repair guy wouldn't accept the receiver! He said it was too old. I felt bad for that couple. I really doubt that a shop today would get involved with a total recap.
Ron

jblmar said:

Great advise as always, Rich. Yes, a service manual is a must. When I do a recap, I replace only with the parts that were in the unit. Not by the SM. There may have been a "running change" at some point. Also, as a matter of safety after desoldering, I use IPA on the solder pad and surrounding area. That removes flux that remains on the PCB during the manufacturing process. As a side benefit, it also allows you to see the traces to the associated components. This reduces the possibility of creating a "bridge." As a greater safety, I set my DMM to the continuity setting and check near by components against the new solder. Just a safety proceedure that takes a second or two per solder. Saves headaches later.

26 hours! No service center would accept that job. That's why AK is so great. I was in a repair shop about 10 years ago that's now closed, when an elderly couple walked in with a Sony STR 7065A with a power switch problem. The repair guy wouldn't accept the receiver! He said it was too old. I felt bad for that couple. I really doubt that a shop today would get involved with a total recap.
Ron

Click to expand...

While I am in there, I retouch "all" solder connections on the PCBs. I find that 30 year old wave-soldered connections are at greater risk for failure than the old 'lytic caps are. I have tested many caps after recap jobs and found all but a couple to be almost functional (at or just below the spec for the part), but I have seen more than my share of fractured solder joints, due to oxidation of the solder. Also, I do not believe in leaving flux behind, either. I use a special blend of denatured alcohol and isopropanol (Flux-Off NR, by Chemtronics). My goal is to get in and out, leaving it very difficult to detect that I had been in there in the 1st place That's a nice trick, when you have been "in there" like I have been in there for units like this.

As to repair time, it included time to research the needed parts and sources, to generate the recap database, and to chronicle the process with photo and thread posts. I am always very slow and meticulous with the first unit of a particular model, double and triple checking everything as I go. Subsequent units of that model are significantly faster, but still take longer than most folks would want to pay for at normal service rates ($50-$75 per hour). We folks 'round here do what we do for love, mostly. I know that the others that do this kind of work on AK (EW, Vintage_TX, PunkerX, yourself, etc.) don't do what they do for free, but they also don't charge ANYWHERE NEAR what their work is truly worth. As I said, it's a labor of love.

Rich P

That's the name of the game. Don't forget that a service center needs to get units in and out fast to turn a profit. Like you, time isn't the issue. It's making it look the way it should.
What I've seen in 25+ year old equiptment is as you say. Broken solder joints. Mostly due to heat. I had that problem in my Marantz 300DC. It made a very loud popping sound through both speakers after being on for around 20 minutes. Broken solder. You could see the solder joint "move" when you wiggled the component.
The IPA makes the board look nicer. Marantz used alot of flux! The boards were shiny! Not anymore.
Ron

Rich,
That is a fantastic tutorial, thank you. Now to start on my CTF-1000 that I just found the other day. Wouldn't play so I got to looking around at the switches. Sure enough the one that is on top right when looking at it was dirty, 13V in-5V out when closed. A quick clean up of the contacts and Viola!...motion. Now to figure out the pesky FF/REW idler wheel setup. I don't know if someone else was in here but the idler wheel itself turns very hard. If you compress the springs so that the outer edges do not ride on the end of the shaft it spins easy. Maybe I have a broken part?
If you have a pic of that idler wheel would you post it when you get a minute?

Thanks and again...Nice Work! Bob

You probably have a split nylon shaft in the idler/clutch assembly. This is very common, since the nylon shrinks with age. The split shaft allows the clutch spring pressure to be transferred to the overall assembly, resulting in binding. You might contact Bob at Vintage-Electronics. He has an ePay ad, stating that he rebuilts those assemblies. Tell him about the split and ask if he has a fix.

Rich P