Help with Teac A-4010s

saabracer23

AK Subscriber
Subscriber
Hey all, I have a Teac 4010s that I wanted to freshen up as it didn’t work. I did a full recap along with completely cleaning and lubing all of the mechanical parts. I took it for a test run and as soon as I hit the what I’m guessing is the reverse button I heard a pop and magic smoke came out.

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There are the buttons I’m talking about. I opened up the back to see what had actually happened. I found a capacitor with a blown top.

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There was a two gang capacitor can there before and one side was 2.8uf at 250vac. I placed in a 3.3uf at 400vdc. The other side of the cab was 1uf at 250vac and I placed a 1uf at 400vdc. That capacitor is fine.

I have no idea what caused this. Is it possible that side of the cab saw more voltage and it exceeded the 400vdc? The original cab was measuring fine, though had a high esr.

Any help on where to go with this would be much appreciated!!! I need help lol.

Dan
 
Greetings from RojoLand!

The two-gang capacitor you replaced was a motor-run capacitor. However, you used a regular electrolytic cap to replace it; a BIG NO-NO as you found out! Regular electrolytics are polarized and operate only in DC circuits. You must use an AC-rated motor-run capacitor, which nowadays are film-type caps, for this. You need only replace the 2.8-µF capacitor (250 VAC minimum rating). The 1 µF part of the old can was for 50-Hz power, which we here in the US don't use. (I see you're in Salem OR — I'm up in Gresham!)

There are three motors in a Teac A-4010S (oddly enough, I'm working on my A-4010S too), and thus three sets of motor-run capacitors. The two-gang unit is the one for your capstan motor, and there is a four-gang unit that handles the two reel motors.

You say your deck "didn't work." Can you be more specific? Won't roll tape? No audio? Please elaborate.

By the way, keep an eye out for little gray Suzuki 0.1-µF 400 V "oil capacitors" connected across switches. They are little firecrackers just waiting to go Pop-BANG! like that electrolytic did. Replace them with 0.1-µF 630 V axial film capacitors. There is a capacitor tower just below and to the left (as seen from the back of chassis) of the capstan motor; it will either be a potted unit (good!) or a stack of Suzuki-bombs (bad!!). If you've got the Suzuki-bombs, keep an eye on the Dock-o'-the-'Bay for the potted tower as they show up fairly often and aren't expensive. Rebuilding the stack of Suzuki-bombs is possible but a fair bit of work. I had to do that on my Concertone S510-R (which is Teac-built).

Take care,

J. E. Knox "The Victor Freak"
 
Greetings from RojoLand!

The two-gang capacitor you replaced was a motor-run capacitor. However, you used a regular electrolytic cap to replace it; a BIG NO-NO as you found out! Regular electrolytics are polarized and operate only in DC circuits. You must use an AC-rated motor-run capacitor, which nowadays are film-type caps, for this. You need only replace the 2.8-µF capacitor (250 VAC minimum rating). The 1 µF part of the old can was for 50-Hz power, which we here in the US don't use. (I see you're in Salem OR — I'm up in Gresham!)

There are three motors in a Teac A-4010S (oddly enough, I'm working on my A-4010S too), and thus three sets of motor-run capacitors. The two-gang unit is the one for your capstan motor, and there is a four-gang unit that handles the two reel motors.

You say your deck "didn't work." Can you be more specific? Won't roll tape? No audio? Please elaborate.

By the way, keep an eye out for little gray Suzuki 0.1-µF 400 V "oil capacitors" connected across switches. They are little firecrackers just waiting to go Pop-BANG! like that electrolytic did. Replace them with 0.1-µF 630 V axial film capacitors. There is a capacitor tower just below and to the left (as seen from the back of chassis) of the capstan motor; it will either be a potted unit (good!) or a stack of Suzuki-bombs (bad!!). If you've got the Suzuki-bombs, keep an eye on the Dock-o'-the-'Bay for the potted tower as they show up fairly often and aren't expensive. Rebuilding the stack of Suzuki-bombs is possible but a fair bit of work. I had to do that on my Concertone S510-R (which is Teac-built).

Take care,

J. E. Knox "The Victor Freak"

Oh awesome, my brother lives in Gresham! Great to have someone knowledgeable so close! Thank you so much for the info.

Alright, so I need to purchase a new cap for the 2.8uf section, film 250v ac. Got it. So the 1uf part for the 50hz, are you saying it’s okay as an electrolytic or I need to replace that as well? Do I need to buy films for the 4 gang as well? The cans were polarized so I though polarized electrolytics would be okay. I replaced all of the .1 uf caps on the switch. Hard to see in the photo below.
A3DCDB81-949A-456B-B24F-3596C8438F5D.jpeg

Is this the stack you’re talking about? I put Wima films in there, that okay?

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Thank you again!

Dan
 
Greetings from RojoLand!

You should replace the 1 µF 'lytic you installed with a proper motor-run cap. The reason it hasn't blown yet is that your deck is set to 60-Hz mode (as it should be). If switched to 50-Hz operation, that 'lytic will blow just like the other one did. The original motor-run cap cans are NOT polarized — unlike the power-supply 'lytics which ARE regular polarized DC-rated caps (and should also have been replaced after 50 years). A capacitor used in an AC circuit (such as the motors in this deck) cannot be polarized.

The WIMA film caps you used will be fine. They have the same ratings as the Suzuki-bombs did. (I tend to prefer 630-volt film caps but that's just me.) Glad you've done those, and I see you have the older stack (used to be Suzuki-bombs) instead of the potted unit. You also have the older-type capstan-motor fan like mine has.

What is the serial number on your deck? Mine is #48104, and it has the potted unit. The record amplifier is an RA-40S. Later units have a slightly modified record amplifier, and Teac altered its model number to AR-40S. Teac made over 200,000 units of this model!

Speaking of Suzuki-bombs, did you also replace the ones under the front cover? There are four of them in there; two on the brake assembly, one on the capstan solenoid and another on the right tension-arm switch. There are three others on the transport control assembly too, easiest to replace by unscrewing the control assembly from the chassis and pulling it away. A fourth gray cap on that assembly is marked as an "MP" capacitor and can stay put. And finally, there's one lurking on the power-supply PC board.

Take care,

J. E. Knox "The Victor Freak"
 
Greetings from RojoLand!

You should replace the 1 µF 'lytic you installed with a proper motor-run cap. The reason it hasn't blown yet is that your deck is set to 60-Hz mode (as it should be). If switched to 50-Hz operation, that 'lytic will blow just like the other one did. The original motor-run cap cans are NOT polarized — unlike the power-supply 'lytics which ARE regular polarized DC-rated caps (and should also have been replaced after 50 years). A capacitor used in an AC circuit (such as the motors in this deck) cannot be polarized.

The WIMA film caps you used will be fine. They have the same ratings as the Suzuki-bombs did. (I tend to prefer 630-volt film caps but that's just me.) Glad you've done those, and I see you have the older stack (used to be Suzuki-bombs) instead of the potted unit. You also have the older-type capstan-motor fan like mine has.

What is the serial number on your deck? Mine is #48104, and it has the potted unit. The record amplifier is an RA-40S. Later units have a slightly modified record amplifier, and Teac altered its model number to AR-40S. Teac made over 200,000 units of this model!

Speaking of Suzuki-bombs, did you also replace the ones under the front cover? There are four of them in there; two on the brake assembly, one on the capstan solenoid and another on the right tension-arm switch. There are three others on the transport control assembly too, easiest to replace by unscrewing the control assembly from the chassis and pulling it away. A fourth gray cap on that assembly is marked as an "MP" capacitor and can stay put. And finally, there's one lurking on the power-supply PC board.

Take care,

J. E. Knox "The Victor Freak"


Awesome info, so I just looked at the can and I guess the one lead labeled “C” is not a negative lead, but a common? So I’ll order new caps for both cans that I replaced, can I easily source those from Mouser? I did replace the caps under the front cover, I had this fully disassembled and replaced every cap in it. Every nook and cranny.

Mine is serial number 96382. Mine also has the AR-40s amplifier.

I apologize, I did not answer your original question on it not working.

BFD19D60-F030-4827-914C-8DED5D793CCD.jpeg

Not sure if I’m doing it right lol, but I couldn’t get the black rubber wheel to “engage” and it still wouldn’t after the rebuild. I would push the forward button next to the fast and the uptake reel would would spin fast and as soon as I let go it would stop and be other reel would let some tape come out creating loose slack. Hard to explain. This was all after the rebuild, could this all be caused by my wrong caps?

Dan
 
Greetings from RojoLand!

I see yours is newer than mine. Yours also has the inch speeds shown as well as the metric ones on the Tape Speed switch. Mine shows only the metric speeds, as "19" and "9.5".

The pinch roller issue: It's VERY common on Teacs for the pinch roller mechanism to bind due to old grease that has become like glue. If you can't move the pinch roller up to the capstan by hand, or you can but only with a lot of force (and it doesn't come right back down), you'll need to remove, clean and lubricate, then reinstall the pinch roller mechanism. Here's a step-by-step YouTube service guide for A-4010s (which also shows how to replace the capstan belt):

All of my Teacs (A-6300, A-3440 and A-4010S) needed this. So did my Tandberg 10X. (That was a pill to loosen up!)

Take care,

J. E. Knox "The Victor Freak"
(who used to take Sony U-Matic VTRs apart and put them back together)
 
Greetings from RojoLand!

I see yours is newer than mine. Yours also has the inch speeds shown as well as the metric ones on the Tape Speed switch. Mine shows only the metric speeds, as "19" and "9.5".

The pinch roller issue: It's VERY common on Teacs for the pinch roller mechanism to bind due to old grease that has become like glue. If you can't move the pinch roller up to the capstan by hand, or you can but only with a lot of force (and it doesn't come right back down), you'll need to remove, clean and lubricate, then reinstall the pinch roller mechanism. Here's a step-by-step YouTube service guide for A-4010s (which also shows how to replace the capstan belt):

All of my Teacs (A-6300, A-3440 and A-4010S) needed this. So did my Tandberg 10X. (That was a pill to loosen up!)

Take care,

J. E. Knox "The Victor Freak"
(who used to take Sony U-Matic VTRs apart and put them back together)


The pinch roller on mine moves quite easily and then returns. I lubed all moving parts and removed the old lube. Doesn’t mean I did it well enough. I took a video and I wanted to post it, but cant. Wanted to show how easily it moves, with one finger. Not sure I’m operating it correctly, though I think so. I’m going to read the users manual. Any other thoughts on the pinch roller?

Dan
 
Greetings from RojoLand!

If the pinch roller can be pushed easily up to the capstan and will fall down by itself just as easily, yet it won't engage when either of the Play buttons are pushed, then it can only be (a) the solenoid itself is burned out, (b) there's a shorted Suzuki-bomb cap across the solenoid, (c) the Remote dummy plug is missing, or (d) Fast Wind relay contacts K4d are dirty or burnt. Are you testing with a tape threaded up? I'm assuming other functions are working — do you have Fast Wind in either direction? If *nothing* appears to function, then the solenoid power supply may be borked. That's D1 and the 100 µF 150 V 'lytic on the power-supply board. (There's a Suzuki-bomb across D1, another worry if you haven't replaced it.) The shut-off switch S3 operates with the right tension arm, so nothing works if a tape isn't threaded up.

Apologies if you've already know all this — just trying to check possibilities. You've got the schemo at hand, no doubt, if you've done a recap.

Note that the solenoid supply is around 130 VDC!—as opposed to the 30 VDC or so the rest of the deck electronics use.

Hope this helps,

J. E. Knox "The Victor Freak"
 
Greetings from RojoLand!

If the pinch roller can be pushed easily up to the capstan and will fall down by itself just as easily, yet it won't engage when either of the Play buttons are pushed, then it can only be (a) the solenoid itself is burned out, (b) there's a shorted Suzuki-bomb cap across the solenoid, (c) the Remote dummy plug is missing, or (d) Fast Wind relay contacts K4d are dirty or burnt. Are you testing with a tape threaded up? I'm assuming other functions are working — do you have Fast Wind in either direction? If *nothing* appears to function, then the solenoid power supply may be borked. That's D1 and the 100 µF 150 V 'lytic on the power-supply board. (There's a Suzuki-bomb across D1, another worry if you haven't replaced it.) The shut-off switch S3 operates with the right tension arm, so nothing works if a tape isn't threaded up.

Apologies if you've already know all this — just trying to check possibilities. You've got the schemo at hand, no doubt, if you've done a recap.

Note that the solenoid supply is around 130 VDC!—as opposed to the 30 VDC or so the rest of the deck electronics use.

Hope this helps,

J. E. Knox "The Victor Freak"


I really appreciate you assisting me with this. I received the new motor caps and got them in.

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Does it matter which side of the foil is positive?

Here is underneath the front hood. You can see the Suzuki bombs have been replaced with the Wima films.

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I’m assuming this is the solenoid that isn’t engaging.

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If I put my meter across the two terminals on the solenoid and measure 130v (ac?) then that would mean that it’s burnt out?

Here is a photo of the back dummy plug that I assume is what you’re talking about. There is a screw cap on it and under the screw cap this is what I find.

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So should my first step be to measure for voltage at the solenoid? At the moment I’m not exactly sure how functional the deck is as I only had it powered up for a moment before the one cap blew. I was trying to get it to function with a tape threaded up. So if I wanted to measure for voltage than I would need to make sure that the right tension arm is engaged manually with my finger in order to be able to get voltage to the solenoid?

Thank you,
Dan
 
The service manual for this unit is available from HiFi Engine (https://www.hifiengine.com/manual_library/teac/a-4010s.shtml). According to the tape transport mechanism schematic that is on page 36, the remote jumper plug has a single connection between pins 1 and 2. The photo you provided shows wire jumpers between pins 4 and 5 and also between pins 1 and 6 and no connection between pins 1 and 2. I’m not sure why this is the case. This difference may be related to the problems you are having.
 
Greetings from RojoLand!

Actually, the OP's rig is newer, and the dummy plug he has *is* correct. I made the same assumption you did at first.

Looking at the correct schematic, which is in back of the owner's manual for later models with the AR-40S record amplifier (also available on HiFi Engine), we see a more complex system that uses a delay relay. I need to study it some more.

Take care,

J. E. Knox "The Victor Freak"
 
Greetings from RojoLand!

At my other computer now, which is newer and doesn't choke on the Internet like my 16-year old machine downstairs…

To answer above questions, referring to the correct schematic (!):

(1) "Does it matter which side of the foil is positive?" No. The motor-run capacitor is non-polar.

(2) Your assumption about the solenoid is correct. "If I put my meter across the two terminals on the solenoid and measure 130v (ac?) then that would mean that it’s burnt out?" No. You can put your DC voltmeter across the two solenoid terminals. Do this carefully, as the solenoid power supply is not transformer-isolated and will be connected directly to the line. Do NOT measure between any point of this circuit and chassis ground. When the solenoid is activated, between 100 and 150 VDC (not AC) will appear across it. (Earlier, I was downstairs playing my A-4010S while reading your post; I measured the solenoid supply on my rig and found 109 VDC.) For that voltage to be present, of course, the shut-off arm must be up. Either thread-up a tape, or use some means to prop the shut-off arm up for testing.

The capstan solenoid (or pinch-roller solenoid) gets power via pins 1 & 6 on the dummy plug, the Stop switch (which is normally closed) and a rather complex network of "logic" relays (have a look at the schemo and you'll see what I mean). Any one of those relay or switch contacts, if defective, could cause the solenoid to not fire. Voltage present at the solenoid, but no firing, would mean the solenoid is open.

"At the moment I’m not exactly sure how functional the deck is as I only had it powered up for a moment before the one cap blew." Now that you have proper motor-run caps in place, the rig might be ready to run!

Take care,

J. E. Knox "The Victor Freak"
 
in your very first pic, it looks like the tape is threaded wrong. Didn't read ALL replies - trying to watch Bruins loose to Calgary...
 
Greetings from RojoLand!

'eddisc' spotted it correctly! (Good eyes!) The tape seems to be coming off the right side of the supply reel. This is wrong — it should unspool off the left side, go around the bottom of the tension-arm post, over the top of the reverse-foil sensor and then through the headblock. In the wrong way, the supply reel will begin spinning clockwise (trying to provide back-tension) and spew tape all over the place, at least until the shut-off arm happens to drop and stop the deck. (With no back-tension, the loose tape will likely ride off the capstan and pinch roller, letting the shut-off arm drop.)

Take care,

J. E. Knox "The Victor Freak"
 
in your very first pic, it looks like the tape is threaded wrong. Didn't read ALL replies - trying to watch Bruins loose to Calgary...

Greetings from RojoLand!

'eddisc' spotted it correctly! (Good eyes!) The tape seems to be coming off the right side of the supply reel. This is wrong — it should unspool off the left side, go around the bottom of the tension-arm post, over the top of the reverse-foil sensor and then through the headblock. In the wrong way, the supply reel will begin spinning clockwise (trying to provide back-tension) and spew tape all over the place, at least until the shut-off arm happens to drop and stop the deck. (With no back-tension, the loose tape will likely ride off the capstan and pinch roller, letting the shut-off arm drop.)

Take care,

J. E. Knox "The Victor Freak"

Thank you for the good eyes haha, you can tell I’m not super familiar with RTRs lol. So I believe I have it spooked up correctly now.

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Now, when I push the forward button the pinch roller will engage but then as soon as I let it go the roller will disengage. I’m assuming it’s supposed to stay engaged so that it keeps playing? Thoughts?

Dan
 
Greetings from RojoLand!

It should stay engaged; yes. There's a circuitous route through several switches and relay contacts. One relay contact should make when the FWD button is pressed and basically short the button out, keeping FWD mode going until another function is selected or end-of-tape is reached. I've got the schematic open right now and am going cross-eyed (!). Solenoid (+) power comes to the normally-closed Stop switch via pin 6 of the Remote plug (tied to pin 1 in the plug, which then comes from the solenoid power supply D2 and C4). From the Stop switch, power continues through the normally-closed relay contacts of K3d (one of two reverse relays) to pin 7 of the Remote plug, and to the normally-open contacts of the FWD button. Pressing the FWD button applies power to the coil of Operation Relay K1, and also through a further circuitous route: Pin 5 of the Remote plug, tied to pin 4 in the plug, and from pin 4 to the normally-closed contacts of the FWD button. K1's contacts KC close, which effectively short-circuit the FWD switch's normally-open contacts and keep the unit in FWD mode. So far, it would appear the K1 contacts may be dirty or damaged (or K1 isn't firing).

Take care,

J. E. Knox "The Victor Freak"
 
Greetings from RojoLand!

The two-gang capacitor you replaced was a motor-run capacitor. However, you used a regular electrolytic cap to replace it; a BIG NO-NO as you found out! Regular electrolytics are polarized and operate only in DC circuits. You must use an AC-rated motor-run capacitor, which nowadays are film-type caps, for this. You need only replace the 2.8-µF capacitor (250 VAC minimum rating). The 1 µF part of the old can was for 50-Hz power, which we here in the US don't use. (I see you're in Salem OR — I'm up in Gresham!)

There are three motors in a Teac A-4010S (oddly enough, I'm working on my A-4010S too), and thus three sets of motor-run capacitors. The two-gang unit is the one for your capstan motor, and there is a four-gang unit that handles the two reel motors.


J. E. Knox "The Victor Freak"

My A-4010s is slowing down in speed after playing for a little while.
I assume I should replace the motor run capacitor that is 2.8uF 250VAC.
However, you also mention that there are three sets of motor-run capacitors.
You say there is a two-gang unit for the capstan motor (which is, I believe, the 2.8uF 250VAC) and the two reel motors should have a four-gang unit on each.
Pardon my ignorance, but what do you mean by "two gang" and "four gang"?
Also, are the 2 reel motor capacitors the same uF and VAC rating as the capstan motor capacitor?

Thanks
 
Greetings from RojoLand!

Sorry for delay in responding — I am limited in on-line time since wife needs bandwidth to work at home.

"Two-gang" and "four-gang" mean that the capstan motor's motor-run capacitor has two sections and that the reel motors' cap has four sections (two for each reel motor). The capstan motor's run cap is indeed 2.8 µF 250 VAC (higher voltage rating is fine, and a 3.0 µF part should be fine as well if you can't get a 2.8). The second section is 1.0 µF, used only when the deck is switched for 50-Hz operation (unneeded in the US). The reel motors need the same, according to the schematic for S/N 14459-and-up. Be advised there are three or four different schematics for this model, as I have noted earlier in this thread. Check your unit's serial number.

The two reel motors share one four-gang (or four-section) motor-run capacitor. There is not a separate four-gang cap for each motor.

Take care,

J. E. Knox "The Victor Freak"
 
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