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Teac A-4010s Help

G

GR3GRS

Member
Hey everyone! I recently acquired a Teac A-4010. Got home to fire it up only to find out the pinch roller won’t engage on the capstan. The assembly is not seized. I referred to the service manual for troubleshooting and it referenced several check points on the unit. The first was the F3 fuse on the rectifier board. Opened the unit up, sure enough the fuse was blown. Went to the hardware store got a new fuse soldered it in, turned the unit back on and the fuse blew again. I removed the D1 diode. The diode removed from the unit had a symbol with two arrows pointing at each other with two lines in the center which looks like the current could go into the diode from both directions, but not come out? Does this seem correct? I am wondering if I should start at the C202 capacitor before I mess with anything else. Could anyone please offer some insight? Any help would be great. Thanks.

-Greg S.
 
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Hey Greg,
I have an A-4010 also, it worked for a while after I aquired it, but developed an engagement issue-I can't remember exactly what right now.
Anyway, when I get time I am going to replace all of the grey Suzuki capacitors (also known as "time bombs" because when they fail they can explode or buldge)
because a failure can cause electro/mechanical engagement issues.

See this:
https://audiokarma.org/forums/index.php?threads/oil-capacitors-in-teac-4010.862627/page-11

Also, this:
https://audiokarma.org/forums/index...help-on-teac-a-4010s-rtr-pinch-roller.883643/
 
Last edited:
Greetings from RojoLand!

D1 is an FR-1K diode and can be replaced with a run-of-the-mill 1N4007 diode (or, better, use a UF4007). Banded end of the replacement diode should go away from the fuse and toward C202 (you want about +130 V across C202). The diode is bridged by C201 (0.1 µF 400 V), one of the Suzuki-bombs (which I urge you to replace yesterday along with all the rest of them in the set). I suspect C202 (100 µF 150 V) is shorted — replace it too. With C202 disconnected (and the set unplugged), check resistance between C202's connections on the Power board (not the component itself). If you find a very low resistance, you've got a shorted component downstream and you'll need to trace through the schematic to find it. (Use the C202 negative-side connection as "ground" for such tracing, NOT the chassis!) That +130 V supply runs all the solenoids and most of the relays in the set.

Be advised that there are differing schematics for this model depending on its age. Please state your rig's serial number.

Take care,
—
J. E. Knox "The Victor Freak" (current caretaker of A-4010S S/N 48104)
 
rojoknox said:
Greetings from RojoLand!

D1 is an FR-1K diode and can be replaced with a run-of-the-mill 1N4007 diode (or, better, use a UF4007). Banded end of the replacement diode should go away from the fuse and toward C202 (you want about +130 V across C202). The diode is bridged by C201 (0.1 µF 400 V), one of the Suzuki-bombs (which I urge you to replace yesterday along with all the rest of them in the set). I suspect C202 (100 µF 150 V) is shorted — replace it too. With C202 disconnected (and the set unplugged), check resistance between C202's connections on the Power board (not the component itself). If you find a very low resistance, you've got a shorted component downstream and you'll need to trace through the schematic to find it. (Use the C202 negative-side connection as "ground" for such tracing, NOT the chassis!) That +130 V supply runs all the solenoids and most of the relays in the set.

Be advised that there are differing schematics for this model depending on its age. Please state your rig's serial number.

Take care,
—
J. E. Knox "The Victor Freak" (current caretaker of A-4010S S/N 48104)
Click to expand...
I appreciate the input. So I have the IN4007 diode in and a new fuse. Good news is the fuse didn’t blow, bad news is the pinch roller and brake solenoids still don’t seem strong enough to fully engage the mechanisms. I’m getting around 20v at both solenoids. I’m not sure what the problem could be. Do you happen to have a link for a replacement for the C202 capacitor?
 
Greetings from RojoLand!

Twenty volts is WAY too low. (You ARE measuring against C202's negative lead, right? NOT THE CHASSIS.) If you measure AC volts and see a significant number, that would definitely point to C202 being bad. You might also check the DC voltage across C202 in Stop mode — no solenoids are operating in that case, so C202 should have plenty of volts on it. If you were checking in Play mode, the solenoid load would be pulling voltage down severely if C202 is bad.

You can search any electronic supplier for "100 µF 150 V axial electrolytic capacitor" — they aren't hard to find. One example, at Antique Electronic Supply: https://www.tubesandmore.com/products/capacitor-160v-axial-lead-electrolytic
(The 160 V increased rating is of no consequence.)

If replacing C202 doesn't bring your solenoid voltage back up, go after those Suzuki-bombs. Again, they tend to fail short (and go Pop-BANG! in the process), and must be replaced. There are a bunch of them in the set, across solenoids and switches under the front cover, behind the control button assembly, a stack of them near the capstan motor (that stack may instead be a rectangular white block with several wires coming from it, and that block may be OKeh), and even one on the power-supply board.

I still need your unit's serial number so I'm looking at the correct schematic. There were a number of changes in later models, both in the record amplifier and on the mechanical deck.

Take care,
—
J. E. Knox "The Victor Freak"
 
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