Under Dash Cassette Deck Wiring

I picked up a really cool under dash cassette deck at Goodwill today. It's a Teac AC-9 from 1972.

I opened it up, replace the belt and it actually plays cassettes hooked up to a 12V desk top power supply via the red and black wires. The remaining wires are;
Yellow
Orange
Blue
White

It has a balance on it so it should be stereo. I would imagine the remaining 4 wires are positive and ground for 2 channels, however, I can't find a wiring diagram online that tells me what's what.

usually, there are power, [red] ground, [black] and speaker wires.
did you have speakers hooked up during your bench test ? if not, maybe the other wires are for the speakers ?

Go to the "support section on the TEAC USA website and see if they're any help.

There's one for sale on Ebay ($250), and a few service manuals priced around $20.
Looking at the unit on Ebay, balance seems R/L instead of a 4-way fader.
Whether the 4 wires (non-power/ground) are for 2 speakers (powered & grounded to tape deck) or 4 (speakers themselves grounded to chassis vs tape deck, I don't know.
TEAC at the time had some pretty high-end reel-to-reel stuff - I don't recall their tape decks.
We ran stuff like Craig, Pioneer, and Muntz back then, IIRC.

I sent them a message and they said it was too old for them to support.

Suggest U open the unit and double check where each wire goes...
1 wire is to 12V+
1 wire is ground & speaker ground
1 wire is left speaker +
1 wire is right speaker +

By following each wire internally will disclose its function, most crucial is the 12V+ and ground, the speaker +'s are easily reversed ..

Just my $0.02...

After you get the wiring figured out, you can get some really good sound from it. What I do is I got a cassette adapter that goes in with a wire and small stereo jack out. I use a Sony DFJ-401 walkman which has a line out input port, I play CDs through the cassette deck into a good amp in the trunk, with some really good 6x9 speakers and it sounds fantastic.

You never want to get the speaker wires "out of phase" or the + positive to the +positive on one speaker and the + positive to the - negative on the other speaker as you will have poor sound quality. When you do this one speaker will cancel out the other as one is "pushing" air and the other is "pulling" air (for lack of a better term). You will have little or less base. It's best to wire the speaker in phase or correct, positive to positive and negative to negative.

See if you can find instructions for another aftermarket cassette add on from around the same time or aftermarket radio from the same time, It's not always the case but a lot of the time the coloring is pretty standard.

Edit with better link:


https://www.ebay.com/b/TEAC-Vintage-Audio-Video-Electronics/175740/bn_57088095



$25 bucks plus $4.00 shipping yikes but may be worth it?

one for $17.49

https://www.ebay.com/itm/125308582463?hash=item1d2cf93a3f:g:mCwAAOSwY5Jie8il

search buy it now title:


TEAC AC-9 AC9 Service Manual **ORIGINAL**

True...
Whenever the amplifiers has separate ground leads for each channel speaker outputs...
However in a (4) wire system, the amplifier's negative speaker output leads are also chassis ground so its not possible to connect a speaker out of phase from the amplifier side only @ the speaker unit itself if its ground and positive leads are reversed.....

Just my $0.02...

Understand all of that but DUFFMAN is trying to identify if those four (orange, white, blue, yellow) wires are positive and negative speaker wires. If they are? then there's a chance DUFFMAN could get one speaker out of phase. Getting both out of phase would not be a really big issue but one speaker out of phase is.

With what you say that the - negatives are grounded to the deck's chassis, then it should be easy for DUFFMAN to determine the - negative (ground/earth) wires with an Ohm/multimeter by putting each wire to the deck's chassis.........is that correct???

Mike

https://www.ebay.com/itm/125308582463?

As I posted previously with only (4) output leads the connections are as listed below, and are easily identified with an ohm meter and taking off the bottom chassis cover..

1 wire is to 12V+
1 wire is ground & speaker ground
1 wire is left speaker +
1 wire is right speaker +

Since to get stereo audio output the speaker ground (12V-/speaker ground) has to be connected. Note the ground connection is common for the L/R speakers so the only other hookup options are L+ and R+ so the speakers will be in-phase. Later tape & head units and amplifiers that had a higher output power used what's called a BTL output scheme and here the L & R speaker negative connections are not grounded, so it is more possible to wire a speaker out-of-phase. Higher powered tape/head units are rated @ like 15Wx2 or 15Wx4, while the AC9 has a standard lower-powered amplifier rated @ like 5Wx2. Also note that if the tape/head unit having a 15Wx2 or 15Wx4 amplifier output capability, by grounding any of the speaker output leads the unit should shut down. Or in extreme cases output stage damage may occur, but later circuit designs typically have more sophisticated built-in protection. There are many subjects I know little about...
But car audio/component system design we do know something...
Having designed/built various show vehicles for SEMA and CES clients, plus doing product development/sourcing for many of the major audio and OE auto brands...

Just my $0.02...

Thanks Sinitro. DUFFMAN said there are six (6) wires and that he was able to hook up the red (+) and the black (-) and then he was left with four (4) wires the yellow, blue, white and orange which he thinks are speaker wires. So can he determine which of those four remaining wires are the ground/negative (-) with a multimeter by way of the deck chassis?

DUFFMAN wrote:

I don't think it's worthwhile it's only a cassette player, would rather have a Pioneer under dash super tuner with a better FM tuner/amp & cassette.

Very sorry I missed the point about the red and black power/ground leads, making a total of (6)....
Since the AC9 amplifier was rated @ 6Wx2 means that it uses standard amplifier circuits not the BTL higher powered type. To answer the question now with the remaining (4) wires should be Right Speaker +/- and Left Speaker +/-, by using a multi-meter check for continuity between chassis and each wire, the "-" should be ground so (2) wires should read continuity to each as well as to chassis ground. Leaving (2) wires which should be Left Speaker + and Right Speaker +, confirming each is easily done by powering up the unit, play a cassette, keep the volume level low and confirm the respective +/- speaker outputs by adjusting balance left to right...

Just my $0.02...