Teac 4010SU R2R

SCompRacer · July 24

A friend gave me a Teac 4310SU R2R. He had It stored at his dad’s house and dad moved it in into non-temperature-controlled storage shed. His dad sadly passed away and he was going through things and found it.

Yeah, it’s pretty rough. It’s got some dust, rust and corrosion issues. Thanks to Ken @SeleniumFalcon for some tips and info about the deck. He inadvertently convinced me to investigate it further. I’ve got time to waste so figured why not. If beyond reasonable repair, it could at least maybe become a source for parts.

I think the U in SU denotes US as it is fixed instead of variable voltage. The 4310 has a separate RA40-SU amp section connected with umbilical cords. I disconnected that and started with the top section. One positive thing is the amp section didn't get the same exposure as the upper section under the case cooling vent.

I tested the caps with the Cap Wizard and none tested bad. I learned this deck has around a dozen or so oil filled .1uf caps that earned the name ‘Suzuki bombs’ due to the nature of their spectacular failure.

I cleaned some of the dust and dead insects off board/capacitors that could be conductive and did the variac/dim bulb start up. The decks power bulb lit up and the function testing began. The drive and capstan motors worked with both speeds/both directions, and the capstan solenoid engaged.

I downloaded the service manual and there are many threads about troubleshooting and repair of this deck. With a little effort, we'll see where it leads. It needs a capstan belt as it turned to goo, on order. The counter was squeaky but a little plastic safe grease on the drive gear fixed that. The felt brake pads need to be reattached to backing bands. Lots of cleaning and lube ahead.

A long nearly case wide cooling vent above the top section contributed to dirt, moisture and insects getting in the top section. The adjustable resistors at right are for motor torque for tape tensioning.

SeleniumFalcon · July 24

My first serious tape deck was the 4010. I bought it at the base PX on Okinawa, I can remember how amazed I was at how precise all the transport functions were and what great sounding tapes it made. Good luck on the project!
It could be a worthwhile transport for an external playback preamp experiment?

SCompRacer · July 24

Thank you Ken!

SeleniumFalcon wrote: »

It could be a worthwhile transport for an external playback preamp experiment?

This sounds above my abilities and expensive.

In other words, replace the RA40-SU?

SeleniumFalcon · July 24

Actually there is an extremely good sounding, inexpensive, approach. Rod Elliott, of Elliott Sound Products, has taken his excellent sounding phono preamp, ESP P06, and figured out what would need to be changed to make it an NAB/IEC playback preamp. I just finished building one, from his PCBs, and it sounds truly amazing. I've been doing some measurements and trying different opamps and I like it.

SCompRacer · July 24

Duh, I can leave the RA-40SU in place and connect the Elliot Phono pre to the Playback Out, correct? No, I see EQ is applied before playback out.

msg · July 24

Man you retired guys just don't know how to stop working, do ya? It's like you can't help yourselves.

SCompRacer · July 24

If you don't use the body and mind, they deteriorate really fast...

pitdogg2 · July 24

Mind lubrication @msg, and not the liquid or THC type.

SeleniumFalcon · July 24

You would connect the playback head directly to the ESP preamp, just like connecting a turntable to a phono preamp. Here is the link:

https://sound-au.com/project247.htm

SCompRacer · July 24

A little progress.

I run outa rubbing alcohol but a bit cleaner.

You run into foam deterioration. Some manufacturers used felt. The foam/felt is to catch any oil running out of bearing so it doesn't make its way from the flywheel to the belt or capstan.

I cut some thin felt and glued it to the flywheel hub and had some foam that didn't deteriorate in oil from previous cassette deck repairs. The capstan cleaned up pretty good.

Pinch roller polished, cleaned and lubed.

I removed everything possible off the face plate and hit it with some Mother's aluminum mag polish. The counter bezel and power indicator lens are melted on.

Before removing the tape tension arm to clean/polish, I measured to backside of the tape contact pin from edge. Was around 4.0930". The arm is attached to a spring-loaded bracket that limits movement. I didn't see that spec in the manual.

Tape heads before. I'm concerned about the screw into side of reverse play head shield but don't want to move anything. An alignment tape would be needed if I change head locations and they are where they should be.

After some cleaning. Tape guides were removed to clean/polish. I may have to get some Brasso for a once more polish. You might notice how the ferrite cores in the heads are not aligned the same. They are two track heads with alignment for 4 track tape.

Now waiting for capstan and counter belts. While I didn't take pictures of it, the brake hubs had to be removed to get at C clip that held motor shafts in. I measured the distance from hub to back plate. One hub was rubbing faceplate despite several shims installed. I reglued the felt brake pads on backing straps upon assembly as brakes are applied when off, so the hubs hold pressure on them while glue dries.

I don't see a spec in the manual, so I adjusted hub distance from backing plate to match one that wasn't rubbing. Once face plate is on, I can use long Allen wrench through top and side access holes to get at the two set screws per brake hub to adjust.

SCompRacer · July 25

Someone was in this thing before. Screws missing along with bottom cover of drive section and top of amp. Not a huge deal but good for RFI rejection. If all goes well, I'll make covers out of 18 gauge.

I cleaned up the amp face and knobs. The controls and mic, phone jacks got a dose of DeoxIT. If all goes well, I'll remove and disassemble/clean the pots as you can do a better job of restoring and lubing them to a factory fresh feel.

The cabinet got some love too. It will need some minor repairs.

If you want a straight no smear caulk line in the tub or a knob indicator line, use tape.

And a power up and bulb test.

xschop · July 25

Really neat project. Do you replace the caps with better quality or are they not in the signal path?

SCompRacer · July 25

Once I get the belt and checks out well, I'll definitely replace the .1uf Suzuki bombs used as bypass. The can caps should be next. I'd use Adapt a cap for the multiple capacitor cans and a terminal strip for the singles. If the heads are not aligned properly, I'll need a calibration tape. I've done a little research, and they can run from $100 to $300.

Once you get into the amp section, or the EQ circuit, I'd definitely use at least, like kind and quality. OEM are Nippon Chemi Con (even on amp board) which are very good. Some guys will replace transistors too.
I used United Chemi Con in a Krell KSL total recap and it sounded great. I think a forum member still has it in use. Ken would be a good one to put on the spot for the answer to would real pricey caps in signal path be worth it in this amp.

I'm not sure the 4010 is worth a total recap of amp and EQ board. I already have a nice Pioneer RT-71 I went through that I don't use much. I have a couple party album drop tapes and one prerecorded. Tape is a little too pricey for me to get into heavily.

Found on internet...

Adapt a cap.

SCompRacer · July 25

I cut out a cover that was missing for the amp from the side of an old computer.

I cleaned the old faded flaky paint off the controls. Dab with a paint pen, scrape excess with razor blade, let dry and a quick wipe with rubbing alcohol, barely damp, on a tight weave linen to wipe off excess paint film.

And clean corrosion and repaint head cover.

Before.

msg · July 26

Rich, where/on what did you use the fader grease? I picked up somma that stuff after seeing you mention it on another thread.

I really enjoy these teardown and rebuilds you and Ken do. Even the ones @ALL212 does.

SCompRacer · July 26

It was just the right thickness to prop the heads up for a good viewing angle.

After disassembly and cleaning potentiometers I use a super thin layer on resistive element after cleaning it. It's also good for the shafts in housings and the rear shaft end stop. It makes for a nice, quiet smooth feel on the old parts. Some elements in the old gear have noticeable or deep wear marks from the wipers.

Thanks for the kind words. I'd enjoy this more if Ken or Aaron were doing it for me.

msg · July 26

I used my reaction vote for the Insightful.
Here I add my LOL 😂 too.

Frickin' Aaron. Almost as bad as a Frickin' Kevin.

SCompRacer · July 28

What I thought was tape residue turned out to be deep rust pitting on one spot on the capstan. I check ebay and find one for $15. Local pickup, 15 minutes away! Lucky me.

He is a retired tech, 78 years old, parting out tape deck parts. He gave me some screws I was missing, a couple of blank tapes, a pinch roller, two homemade reel stoppers and offered to let me use a demagnetizing tool. I asked what he wanted for it, $20, sold. He has calibration tapes and offered to calibrate the deck if needed. He also has a complete head assembly if I need it for $100.

https://www.ebay.com/itm/196456041372

EndersShadow · July 28

Awesome score! Can’t beat local help and experts!

SCompRacer · July 29

Capstan and counter belt showed up today. I did a partial assemble and it works. I played a tape recorded on another deck and it sounds pretty good with headphones. I'm going to get a small dial scale (like 5 or 8 pounds) and test motor torque and brake tension. I get a little over run when stopping fast rewind.

The playback volume pot was still scratchy despite DeOxit sprayed in it, so I removed, disassembled and cleaned it. Not many pics as the phone died so without picture backup, I quickly reassembled it.

Those two tension clips keep front and back pot turning the same rate. If you want R and L at different volume, you have to hold one and turn the other.

Cleaning volume pot well worth the effort, no more scratchy sound. One thing I check with pot apart is the tiny rivets that hold solder tabs to resistive element are tight. I've encountered loose ones and a gentle little tap on a solid backing surface snugs them up. I still have to test record and playing in reverse.

Those two spring tension clips keep front and rear pot turning at same rate.

SeleniumFalcon · July 29

Looking great, Rich!

Clipdat · July 30

There's certainly an astounding number of small intricate parts that go into these machines, isn't there? Makes me really appreciate the engineering prowess involved in designing and manufacturing them. Also with how complex (machining, tolerances, etc) some of the parts are, it makes me wonder how they turned a profit on these things.

Great work so far on the restore, looking forward to following along for the rest of it.

mhardy6647 · August 5

... at least in reel to reel decks, they tend to stay put during, uhh, scheduled disassembly. Cassette decks, on the other hand* -- small (often tiny), mission-critical bits go sproinging off into the surroundings with near-relativistic velocity whenever I work on 'em.

That said, I actually managed to find an errant, flyaway earring back for Mrs. H this morning. This is more along the lines of a monkeys/typewriters/Shakespeare sort of gambit as opposed to any searching prowess on my part.

Probably should have looked for some cassette drive parts while I was at it, perhaps.

______________
* I.e., on my other hand.

EndersShadow · August 5

We need to have the History channel pickup “Rich’s Restorations”….. I’d be down for a few seasons of that!

bcwsrt · August 5

Definitely an entertaining thread!

SCompRacer · August 7

Thanks for the kind words of support. I've been there with cassette decks! My fingers are too big for that small stuff.

First scale I received was boxed incorrectly. Need to read in ounces or grams, not pounds. 28.3 grams = 1 ounce. Then the dishwasher required repair. LED's on control panel gave out. Then I misplaced my ambition...

Teac says use reel with 4" hub, wrap 30" of string around it and check tension of brakes with deck off, and powered on motor torque for tape tensioning with spring scale. Pinch roller engaged, to pull away from capstan should be 4 pounds.

Forward/reverse play tape tension should measure 1.96 to 2.24 ounces. There is also a 1/2 mil tape tension button when using thinner tape. You adjust variable resistors for motors to achieve that. That's next on the list. There are Tentelometer's for measuring tape tension as well but no mention of specs using one in the Teac manual. They can be from mild to wild in price.

Brakes 5.5 to 7 ounces.

220 grams is ~ 7 ounces.

Pinch roller engaged, pull away from capstan should be 4 pounds.

Examples of two Tentelometer's snagged from web.
$160 on ebay.

$167 on reverb.

SCompRacer · August 7

All eight .1uf Suzuki bombs swapped out. Four in drive area, one was on a board, the other three on back of controls.

I did the find the foil side with my little scope and marked the new caps. I installed foil side like they had it.

I tested a few value wise, the worst was 11% off.

The capacitor lead that is connected to the 'scope common or coax shield braid (black alligator clip) with the lowest trace amplitude is the capacitor lead connected to the outer foil.

Leakage at 200v and rated value of 400v. You don't want to touch the leads with a high voltage test.

SCompRacer · August 8

Another issue fixed. The Fast Forward/Rewind button wasn't holding when pressed. A small solenoid wire the white lines point to was broken off terminal strip behind the switch. Had to remove control assembly to find and fix that.

I slapped the front cover on it. Deciding whether to replace the can electrolytics and AC motor run capacitors.

Looking pretty good now considering what I started with.

SeleniumFalcon · August 9

Wow, what a transformation! Nice job!

SeleniumFalcon · August 10

This model should make trying an external playback preamp very easy, RCA connections already provided. Most of the time shielded cables have to be routed to access the playback head directly. Teac has done it for you.

SCompRacer · August 10

Thanks for the kind words!

IIRC didn't that external amp you suggested indicate input direct from tape head with a capacitor in series? The 4010S has the EQ and preamp board in the top section between head and playback out.

I did a quick Paint mod to the schematic. Wouldn't I have to add two (R and L) RCA out with two ON/ON DPDT switches to choose between direct from head or to EQ/preamp board? Ground circuit not drawn in schematic. I'd just have to scare up some coax.

Proposed for direct out from tape head in Blue, no EQ.

Teac 4010SU R2R

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