Teac 4010SU R2R

schwarcw

Wow! The deck looks fabulous! Great work as always Richee!

SeleniumFalcon

I thought the service manual showed an RCA connection from the playback head to the lower circuits:



If you want to try this out I bought two sets of PCB for the ESP, power supply and preamp, I'd be happy to send a set to you, gratis. I probably even have some of the parts I over ordered.

SCompRacer

Hey Carl! Thanks!

Ken, my transport is similar to image but less the variable voltage switch. That is a very kind offer! I may take you up on that once I get the sewer line fixed... I think it is a better option than totally recapping and replacing transistors in the amp section. I don't think this deck is worth that much effort and expense.



The amp section is slightly different.



The heads connect to PCB, then from PCB to Playback Out.



Poking around wiring there and pull these out, find this. I don't recall doing anything to mess these wires up.

heiney9

As always, cool and entertaining. I have very little ability to go this far into a piece of electronic equipment. Love these kind of detailed threads.

Keep up the great work

H9

xschop

Some alloy reels in the works? Fantastic build here. Really enjoying your work.

pitdogg2

Mice

SCompRacer

Kind of busy around here and little ambition, but I did get a few minutes to start looking into what might be an issue.

Deck powered on, set to 3.75 ips, tape not playing, let's call it idle. (The 4010 does not have a pause function. Only play, reverse play, FF and stop). The capstan motor is partially powered, can feel it vibrate. Set speed to 7.5 ips, capstan motor silent. It does play fine at 3.75 ips with no excess motor heat.

Teac has .1 uf caps between field wires of capstan motor, C209-C212. I've read a report when they fail, the motor can run hot and at incorrect speed, or not at all. In this model they use a capacitor block. Ken mentioned how he likes his Struder because the manuals are so good. Wires are color indicated, don't change in a circuit. Teac 4010 manual is lacking in that department. And my deck does not have a 50/60Hz selector.

Number 1,2,3,4, 11 and 12 on the multiple .1uf capacitor block are capstan motor wires. They were nice enough to put schematic on side of block if I wish to try it with new external caps. Some of the schematic wire colors are correct. I'm partially color blind (dear wife usually helps me there) so if number 1 is Blue where is the violet? No indication of what C209-C212 are on the block though. The issue could even be further upstream.

skipshot12

Dang nice job, wonderful to see it wasn’t tossed.

Would like to have 1/10 of your concentration & patience.

Skip

SCompRacer

Thanks for the kind words!

More progress. Parts from Mouser arrived. Still waiting for the 2.8uf 5% capstan motor run capacitor from China. Closest Mouser had was a 2.7uf. A wise man told me to keep the values correct and with tight tolerance on the AC motors.

The scraped insulation....



The wires were good so desoldered and slipped shrink tubing over the bald spots.



While doing that repair, I found a wire on the speed control switch that wasn't soldered at the factory.



Replaced electrolytics for the power supply. Used snap ins for the can caps. I wrapped them with some thick double-sided tape and did some bending on the other clamp to secure them.





Replaced electrolytic caps in amp section. I also cleaned the contacts in all the relays with Kim wipes damp with contact cleaner.





They ranged from 32% to 60% out of tolerance.

SCompRacer

There isn't sufficient depth to fabricate a capacitor bank with the new larger.1uf 400VAC film caps so it will be split into two separate boards. 1,2,3,4, 11 and 12 are for the capstan motor windings. I did point to point with small gauge hook up wire following the schematic on potted caps.

SeleniumFalcon

Excellent job! Nice tip on the "Kim-Wipes", didn't know about that one. I like the color matched shrink tubing on the exposed wires, nice touch! From what I gather capacitors when they are old tend to increase the capacitance value, I suppose the electrolyte chemically changes? Becomes more "electrolytic"? You can see by the slight scorching of the insulation on the connecting wires that when this deck was assembled the workers used soldering guns and plenty of flux paste. I remember having a phone conversation with Tom Tutay and he felt that older audio gear that was assembled with a solder gun would have solder junctions that were contaminated by the iron from the gun's tip and that the operating temperature was much higher than is used today.

SCompRacer

Thank you Ken! I keep a box of multi color shrink handy.

The Kim wipes have a short fold at one end. I cut that end to as little as 1/8" wide for tight spots. A single layer tears easily while doubled up holds up better when moist with contact cleaner. The way this was stored I figured it best to clean all contacts. The motor control relays have no covers while the signal relays do. I had to clean the output relay contacts on the Krell amp a while back too.

The use of a solder gun explains the large blobs of solder and melted insulation. I had to use some liquid tape on some wires on the speed switch. One site suggested to redo every solder joint on the older Teac's!




Finished the second 1uf capacitor bank terminals 5 to 9, 13 to19.

SCompRacer

Some bad news, Richee screwed up, but I managed to fix it. Part of it was my eyesight, which I caught prior to installing the second snubber cap board. I tied 14 and 15 into the 5,6, 13 circuit. Some of the small rings on the capacitor block broke when desoldering the wires. There isn't much slack in some wires, so I didn't want to cut them. Therefore, I was unable to test all the pinouts.

On my potted capacitor block, the schematic on side shows terminals 14 and 15 are not part of circuit. They are just connection points for wires. Terminal 16 looks like it is part of the 5, 6, 13 circuit so that's what I did. Oh, the pot schematic is not listed in the manual. They just show the snubber caps in circuit with numbers that do not match the numbers on the block.



Powered it up, bench lights got dim and I heard a sizzling noise and oh, that smell. I quickly powered off and since power supply capacitors store energy the sizzling continued for several seconds. I torched the windings in the capstan motor.



I called the local retired tech near me that I got the capstan (tape drive) from weeks ago. He had a used potted capacitor block with the wires cut so I could test and see if the schematic matched the actual circuits. That block clearly shows terminal 16 is not part of the 5,6, 13 circuit. Oh well, things happen....



He gave me a used capstan drive motor for free, so I was able to get back to where I was before, a functioning transport. The new snubber caps did help. The capstan motor doesn't vibrate like it did before powered on, not playing, but if you turn the cooling fan, you can feel it seems powered. I have no prior experience with the 4010 so I guess that is normal.



He has a Dual 1019 that needs some work, so I'll help him with that next week, no charge.

SeleniumFalcon

Nice recovery, Rich! I noticed in your signature that you use a Bottlehead Eros in your system. That preamp can be adapted so it will function as a tape playback preamp. Some simple changes to the feedback network I would imagine. A selector switch would make it do both.

SCompRacer

Thanks! Scary moments....

Speaking of the Eros, love mine. It punches way past its price point. I have two NOS Telefunken EF86 and an Amperex '60's white label 7308 in place of 6DJ8.

I was aware the Eros could be used as a tape pre-amp as once upon a time he had sold it as one. It is archived now. I'm still considering the one you built but do not have 100% confidence in this transport yet. The capstan motor still gets some power at idle. You can feel it if you try and turn the fan. It's like in a holding or brake mode. I'll look into the relays next to see if they are sticking.

https://archives.bottlehead.com/product/eros-tape-head-preamplifier-kit/index.html

Got the two snubber boards secured. One in original position, the other to left. Still waiting for the 2.8uf capstan motor capacitor from China. A 2.7uf is temporarily in place. I gutted the original 2.8uf can capacitor and cut a slot in it to hold the new square cap.

SCompRacer

More progress. Getting close to checking head alignment time, though it sounds pretty good. It both records and plays. I think Ken was encouraging me to get a calibration tape and experience the joy of doing it myself. So far, $105 in parts invested in it.



Got two 3uf motor run caps for the reel motors. Still waiting for the 2.8uf capstan motor cap to arrive. Currently running a 2.7uf. The way I understand it, using a slightly different value won't change the motor speed but it will affect the torque. It sounds good at both speeds, so maybe I'll leave the larger physical size 2.7uf in there. A smaller physical sized 2.8uf ceiling fan cap is making its way from China.

I gutted the old can capacitors and cut slots to mount them in.



This falls into the you get what you accept category. If the tape is contacting the head in fast forward or fast rewind, you'll get that annoying fast play gibberish. While not mentioned in the manual, I found you can adjust the travel of the tape lifters to compensate for slightly worn linkage.



This adjustment will favor one lifter or the other to get that 'clear both forward and reverse play head' balance.

SCompRacer

The cabinet got some TLC. I filled the worst veneer damage on the corners, right side face. I left some dings in for character. I also went a bit darker with stain to hide some stains on the top. The last coat of clear satin poly on the top.



I hung it from basement ceiling to finish bottom, front, sides. Once dry the feet cleaned and side trim polished, installed.

SCompRacer

It sees daylight again. I have to decide if I will recap the EQ/preamp board and replace the Germanium transistors with silicone. It sounds pretty good with no buzzing or rushing noise so maybe just recap and test the Ge transistors for leakage. I'm told Germanium are more analog sounding and distort in a more pleasing manner than silicone. Also it could use head alignment, recalibration.

I messed up with color of the veneer hard fill here and there on the edges, should have got the wife involved.

EndersShadow

Looks like it just came off the factory floor! Great job Rich!

SCompRacer

The heads on the 4010SU were not aligned properly. All the height and azimuth screws had been turned. Heads not parallel to tape, etc. Record and playback had some issues. One head shield was touching the azimuth screw. Fixed that and coarse aligned heads per manual. A clear leader tape helped me. A lighted magnifier was needed for my old eyes. A calibration tape is needed for fine tuning.





I have calibration tapes on the way from Germany, seller ural91. They make replica tapes like the Teac YTT-1002 (3.75ips) and YTT-1003 (7,5ips). Recording level, azimuth, frequency response and they added speech announcement of frequencies. Folks that have them speak highly of the quality. They are a less expensive alternative to MRL calibration tapes with only four frequencies. Having the replica Teac tape will make it easier to follow the procedure in the manual. This is all new to me.

1. Playback level / output level (measured e.g. with a millivoltmeter), Level meter 0VU setting
2. PB-Head gap - azimuth adjustment
3. PB-EQ setting
4. Frequency response according to the corresponding standard level and equalization. A series of –10dB recorded sine wave signals is displayed on the VU meter.
5. DBX - Level setting
6. Sweep - Stepless sliding tone part 31.5 to 12500Hz, -10dB
7.Multi-frequency signal consists of 17 frequencies recorded simultaneously with -20dB 31.5, 40, 63, 125, 250, 315, 500, 1K, 2K, 4K, 6.3K, 8K, 10K, 12.5K, 14K, 16K, 18K for fast frequency response control with appropriate measuring devices or software

They were supplied at the old magnetic flux standard of 185nWb/m. Tapes have improved so I inquired about getting the tapes done at 250nWb/m and they complied. Basically, you can record at higher levels with newer tape. One can always dial down to 185 or higher than 250 if desired during calibration.

Got a nice Leader Lag 126 audio signal generator for $90. Sad about the dial but compared to some offerings in rough shape for big money, this one is a beauty. It has much less distortion than my signal generator and much easier to dial in the small voltages required for calibration. I checked calibration and it was very tight. An AC millivolt/dB meter is expected Thursday. I already have a scope so should be good to calibrate when tapes arrive.

A big shout out to Ken who has helped me understand the alignment process and why Teac requires a DIY bias trap to aid in calibration.

SCompRacer

Caps for the EQ/pre amp and amplifier board expected tomorrow. Small values, a whole $22 with some extras ordered, including shipping. What else to do?

The RG Keen PNP Germanium transistor tester. The guitar crowd loves Ge transistors for their fuzz face clones. I guess you could call it a tube type PNP. It measures leakage, flip the switch and you get gain. Ge PNP are touchy. Heat from your fingers changes value so you have to leave them stabilize for a couple minutes. I used a switch for gain instead of push button.



Next Mouser/Digi order I'll get some exact value resistors, maybe even a zif socket. For now, I got 2.2M and 2.47k values with my add-a-resistor-in-series-to-get-value setup.




A Toshiba 2SA49. My amp board has two of each. Toshiba 2SA49, 2SB94, 2SB440. One 2SB415. Two TEN brand 2SB39. Two Sanyo 2SB405.



Some folks say these $20 TC1 testers net results as good but IMO, the Keen method provides more accurate real-time results. The neat thing about this tester is just stick any leg in a different number on zif socket and it sorts out E/B/C.