Oil capacitors in Teac 4010

[ivo]

A friend of mine just rid off his old Teac, so I take it off course. It's power on, both vu meters jump to the red and stuck there the capstan motor never move at all. So, I opened the unit and what I found is a small board with 4 capacitors related to the main motor two of them exploded. All around foil and plastic film. This is oil capacitor 0.1mF 400 working volts ( attached photos) I have few polypropylene yellow capacitors 0.1mF 400vdc.
Can i replace this bad old oil caps with the new yellow poly?
I suspect that the F1 fuse on the power supply board is blown too...

 

[rojoknox]

Greetings from RojoLand!

The pictured yellow film cap will work, but I would recommend using 630-volt parts rather than the original-spec 400 V ones. There are over a dozen Suzuki-bombs in the A-4010S; some are mounted across solenoids and switches underneath the face plate, some behind the transport-control cluster, some on one or more tagboards (as your photo shows) and there's one on the power-supply board too. All must be replaced!

I haven't opened my RA-40S record amp up yet, but there may be more Suzuki-bombs in there too. Recapping is needed in any event.

Fuse F1 (2 A) is the rear-panel fuse (not on the PS board), and could be blown indeed, but it's more likely given the Suzuki-bomb explosion that F3 (1 A) is the one that popped. It *is* on the PS board, as is F2 (also 1 A). F3 is the one farthest away from the bridge rectifier, and it's right next to a Suzuki-bomb.

What's the serial number on your machine? Mine is #48104.

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

 

[ivo]

Hi J.E. ! Thank you for the respond and help! I replaced the two bad Suzuki "bombs"(!) with two yellow film caps and also replace the bad F3 fuse. Unfortunately, the fuse blows immediately after the unit was turned on. I tried again with a new fuse but the story was the same... Probably something is not good with the power supply board? Im going to take out the transport from the wood case and take a look at the power supply board, there are another two "bombs" laid in this board. Any idea?
P.S. The serial # on this unit is 11023, obviously much older than yours...
Ivo.

 

[ivo]

Obviously, the power supply on my Teac is different (oldest model) then your. It is with only one 200mF cap, the new models have two of them. Im wondering if the 0.1mF Suzuki cap on this board make the F3 fuse blow out...

 

[rojoknox]

Greetings from RojoLand!

Yes indeed, you have an older unit than mine! (So is yours a non-S A-4010?) It's old enough to have the earlier power-supply card, mounted inside the box underneath the takeup motor. F3 fuse blown means there is likely another shorted Suzuki-bomb or other short circuit present. I reiterate — it's IMPERATIVE to replace ALL of those Suzuki-bombs, and they're all over the place. Let me have a look at the older schematic…(yes, there are several schematics out there for the A-4000/A-4010 series)

Looking now at "A-4000 Transport Mechanism Wiring Diagram" ("This circuit diagram can be used for machines after Serial No. 6799"). Have you checked/replaced C202 (100 µF 150 V; one of the two can caps atop the right chassis box) yet? That is the power-supply filter cap for the relay-and-solenoid supply. If shorted, that would be a prime candidate (and at over 50 years of age should be replaced anyway). I don't recall where I found this (wasn't at HiFi Engine) but a Google search should turn it up online. It's the A-4000/A-4010 service manual; PDF has 64 pages, and first page is marked "ORIGINAL." Text is typewritten, and page 2 mentions the change of head positions beginning at S/N 8354. (Originally, head order was Erase, Record, Reverse Play and Forward Play; after #8354, it is Erase, Rev Play, Record and Fwd Play.) Any-hoo, I'd suggest measuring resistance (power off, caps discharged) from D1 cathode (or C202's positive terminal) to C202's negative terminal [NOT chassis ground!] — would expect to find a short — and then lift the + connection from C202 and recheck. If you still find a short from D1 cathode (or the wire disconnected from C202 positive) to C202 negative, then the short is farther down the circuit (and likely a shorted Suzuki-bomb). But C202 should replaced in any event. Might be good to test D1 as well (if shorted, replace it with a 1N5408 or UF5408.)

When you turned the deck on and blew the fuse, was a tape threaded up? (that is, was the shut-off arm lifted to its operating position?) If it was NOT threaded up and still blew a fuse, I'm pretty sure C202 is the culprit as the safety switch blocks DC power from the rest of the transport control circuit. (That is, unless C222, a Suzuki-bomb which bridges the safety switch, is shorted…!)

Do note that the motor control circuitry runs on the *primary* side of the power transformer and is thus connected to the line (and isolated from the chassis). Measure all voltages and resistances relative to the "ground" at C202 negative terminal, or the WHT wire from the power transformer connected to the Power switch (you'll see this on the schematic).

As you might know, the tape deck chassis can run independently from the RA-40 record amplifier — as such it is an A-4000 playback-only deck.

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

 

[ivo]

Hi, J.K. I have the schematic you mentioned from HIFI Engine. Ok, I measured the resistance between D1 cathode and negative on C202 its giving me 3.85 mOhm. Obviously, not shorted. I was so surprised. But ill replace this electrolytic anyway. Think the D1 is not shorted too? Probably the Suzuki 0.1 mF capacitor related to the left side of the F3 fuse is shorted? Ill oreder the parts tonight and will start the recapping process
Thanks!!

 

[rojoknox]

Greetings from RojoLand!

3.85 milliohm? That sure sounds shorted to me! Or did you mean to say MΩ or megohm? (capital M) Either way, good plan to replace C202.

Use your DVM's diode test (assuming it has one) or high ohms scale to test D1. Lift one end of C202 first (if not already done), since C202 will affect the reading you get.

As for that Suzuki-bomb, it doesn't matter where it is. Replace ALL of 'em on sight. (I couldn't readily identify it on the schemo.)

Glad you found the schematic.

Take care,
—
J. E. Knox "The Victor Freak" (or, "Pobre Pepe" — "Poor Old Joe")

 

[ivo]

Im sorry! Its shorted or its open - show zero on my meter. I don't know why the meter was giving me these digits before. Maybe i didn't discharge the capacitor successful... Now I measured it with two different meters and always is 0. The measurement of the diode is 635. Unfortunately, the measurement of the resistance with the positive end of the c202 disconnected is 0 too... So the problem is not only in the power supply...

 

[ivo]

I couldn't find online this electrolytic capacitor 100uf 150v. All capacitors for sale with these parameters are small circuit board capacitor and they will not work with this application. How do I need to phrase this research? Thanks for any help.
Ivo.

 

[rojoknox]

Greetings from RojoLand!

Measuring resistance across C202: With the + lead disconnected, and the capacitor fully discharged (if indeed it can hold a charge!; use a clip lead with a 1k resistor in series to bring it down), set meter to read Ohms (a high ohms scale on non-auto-ranging meter) and hold meter test probes to the cap terminals. A good 'lytic should show an initlal low reading, then slowly go upwards and upwards, eventually reading "open" or infinite (this is the capacitor charging from the meter voltage). If you see a steady low resistance or "zero" as you state, yep-purrz, it's shorted!

If you're getting "zero" ohms from the + wire (disconnected from C202) to C202 (-), then yeah, you quite likely have another blown Suzuki-bomb (it may not have literally blown but they do fail shorted). Now is the time to get those buggers outta there! It's not hard, just tedious. Remember that there are some underneath the face plate (two on the brake assembly, one on the pinch-roller solenoid, one on the safety shutoff switch); three behind the transport-control cluster, the stack of them that you found, and one on the power-supply board. You may also find green Mylar caps on some solenoids and boards; these are fine.

Back to C202: The original is, as you see, a clamp-mounted can cap of 25 mm diameter (1"), and they are rather hard-to-find. I was looking for 1-inch can 'lytics a while ago and found precious few of them, none in the value I needed. You do have some options. Just Radios has a 100-µF 500 V 'lytic in a clamp-mount can (https://www.justradios.com/SINGLEsection.html) that will work fine. You can go higher in voltage; just not lower. Alternatively, Hayseed Hamfest (https://hayseedhamfest.com/pages/quote) can make a custom one for you. (I'd recommend going to a little higher voltage, say 200 or 250 WVDC.) The important thing to note is that the can must be *isolated*, not the ground connection. The part from Just Radios has a plastic sheathing around the can (but I would add an additional insulator between the can and clamp anyway). You're correct that the small PC-mount cap isn't particularly suitable. Those won't have the ripple-current rating needed, and won't last long. Bigger is better here.

The other big clamp-mount 'lytic, 1000-µF 50 V (C201) is another hard-to-find one. I think this one will work:
https://www.mouser.com/ProductDetai...=sGAEpiMZZMvwFf0viD3Y3btn7qQ7T4niDh8uWTI4TZo=

It's a 35-mm-diameter part like the original, but with a 100-volt rating. Uses screw terminals rather than solder connections (should be no big deal).

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

 

[rojoknox]

Greetings from RojoLand!

Follow-up — after studying the early schematic and drawings some more, I see there are two tagboards full of Suzuki-bombs in there: the one you found with two blown parts (that's the one underneath and to left of the capstan motor as viewed from the back), and another with more caps on it underneath the supply reel motor (in the background of your photo). You are in for some fun, and you have my sympathies. I had a similar issue when I redid my Concertone S510-R (Teac-made). It too was full of those blasted things, and one of them went off in my presence. Pop-BANG!! Looked much like this pic (this is of an A-4010S, but not my unit):



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

 

[rojoknox]

Greetings from RojoLand!

Another suggestion to replace C202, the 100-µF 150 V electrolytic:

https://www.mouser.com/ProductDetai...n0r9vR22V%2B1m3UQX3qDPrdgR8zBVYrNqo9zDBDvcA==

This is a 100-µF 500 V, 105°C two-lead part with plastic sheathing, high ripple-current and long life (5000H at rated temp). 25 mm diameter. All that for US$5.08.

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

 

[ivo]

Hi J.E.!! Thank you so much for the wide subject post! I really appreciate that! I already ordered 15 yellow film caps and one 100uf 385v electrolytic capacitor from Mouser site part# 594-2222-052-58101. It is a little bit smaller but ill put some piece of carton around...
I have a question: When I measured a few of the Suzuki caps with my meter with continuity signal on I got a signal. Is that mean they are shorted or because these caps are still on board the signal means nothing?
And yes there is another tagboard with six(!) Suzuki bombs in this unit. This deck is full of military supplies
Thanks again for your answers, I hope I didn't bother you so much! I really appreciated your time, so
Ivo.

 

[rojoknox]

Greetings from RojoLand!

No bother at all.

Because some of the Suzuki-bombs are mounted across solenoids and relay coils, those will always show short (or nearly so) when still in-circuit. The caps mounted across switches can be tested in-circuit with the switch open, of course.

Good luck with the search-and-destroy mission!

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

 

[ivo]

Hi J.E.! Reacaped the transport and all commands are working perfectly now. I believe the four caps tag board and the big electrolytic can capacitor were the reason of the malfunction. Still not have the capstan belt and don't know how the deck sounds.
The amplifier: After i plugged the amplifier the VU meters slowly went to the red and stuck there. Followed the schema with the open unit in front of me and in the relay board found two small 0.01mf oil caps. I suspect these two bombs are shorted and making the meters jump to the red. Will replace them anyway.
The search/destroy mission continues!
Ivo.

 

[ivo]

0.01uF 400V 10% Polycarbonate Film Audio Capacitors K77-1 / Jensen type KA
Is these are good for this job? Or they are good just for the speakers propose...
Thanks!

 

[rojoknox]

Greetings from RojoLand!

You need not go for fancy "audio" capacitors to replace Suzuki-bombs. Basic axial yellow film caps will do, and they'll be cheaper too. But go for 630 V parts. They're bigger (i.e., have more internal surface area) and can handle higher voltage spikes. "How good they sound" means nothing in this application. (Indeed, it means nothing in *any* case!)



Glad to hear you got your rig running! Be sure to hunt down ALL those Suzuki-bombs. The service manual will tell you how to remove the face plate. If you haven't done it yet, you will probably need to replace the capstan and counter belts, and oil the motors.

I still need to study the RA-40 manual and see what might be causing the meter pegging. Very likely a leaky cap though. It means that DC is being applied to the meters. (Do the meters peg and stay there, or peg and then settle back down?)

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

 

[rojoknox]

Greetings from RojoLand!

You found Suzuki-bombs on the relay board? Uff-dah! First time I've seen that; all the relay boards I've encountered have all green Mylar caps on 'em. Definitely change those out. But I don't think they have anything to do with the meter pegging. Everything that runs the meters is in the RA-40 unit.

The VU meters connect to the Line Out jacks through 3.6k resistors R160 and R170, and have 0.005-µF capacitors C107 and C117 across them. If there is DC getting to the meters and pegging them, you can measure this by putting a DC voltmeter across the Line Out jacks. Normally, there is NO DC here, just the audio (AC) signal. That signal comes from the collectors of Tr22 (left) and Tr24 (right) via C105 and C115 respectively (the schematic is not helpful here as it does not show values of C105 and C115!). If those two 'lytics are leaky, there will be a negative DC voltage on the Line Outs and a lesser amount on the VU meters. The RA-40 should have all its electrolytic capacitors replaced anyway, since they are now 50 years old if not older.

Incidentally, the Line Outs on this rig are of high impedance (100kΩ!) and will get "bogged down" if connected to an amp's low-impedance line input. (A buffer circuit could be built to handle that.) They'd be great with a tube amp though. The mic inputs are high-impedance as well.

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

 

[ivo]

Well, I didn't mention that the two small oil Suzuki 0.01uF 400v capacitors-bombs are in the relay board belong to the RA-40! Sorry about that! I believe this relay board operating the record function from the two round buttons for record and receive a signal from play switch. These two record switches are working normally and the red lights are on when they are pressed together with the Play button, which is actually normal function. All cables between A-4000 and RA-40 are disconnected except the main big socket which provides the power to RA-40 and the signal from the Play buttons, I believe?

 

[ivo]

Ok there is no VU jump when the RA-40 is on Tape mode. There is no jump either when the unit is on Record mode with two red lights On. The VU meters jump only on Source position when the transport is on idle.
No DC on the Output RCA jacks.