Teac 80 8 Channel Card RCA Wiring

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thereelman77

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I need to know the proper wiring for the channel card amplifiers on the Teac 80 8 deck. They were incorrectly plugged in after a calibration and sat for sometime. The current way they're plugged in is (from top to bottom, looking at card from outside of deck) RED, ORANGE, BROWN. I am having a problem calibrating the deck and do not want to blow anything by guessing what the correct configuration is.

Thanks.
 
Maybe a fellow 80-8 owner will know better what you are talking about, but your thread title and first post don't make sense. Can you post a pic of what you are talking about?

Brown typically relates to 1 in the electronics world, red 2, and orange 3.
 
And furthermore I have hard evidence Teac used that convention for internal wiring harnesses...
 
The correct way is (from top to bottom): orange, red, brown.
I own a 80-8 myself, so I know ;)
DSC_0228.webp

Good Luck!
Alfredo
 
Thank you Alfredo! My cables were plugged in incorrectly. Unfortunately my recording issue is still occurring.....It was working alright with the cables reversed, but now the slapback issue is back again, now occurring in NORM mode while recording.
 
Oh wow...never knew the 80-8 amp cards actually had RCA connections on them...crazy, man...crazy. :)
 
The "slapback"issue sounds like some of the channels are not switching to the sync,(normal) head-stuck playing from the playback,(monitor), head.An easy way to tell is slip a piece of paper between either head and play back.The paper will mute the respective head's playback.OR you have the sync and playback head wiring swapped on some channel cards.
 
I put my money on relay issues not switching the playback source.

Do what wkrbee says. ;)
 
That certainly sounds like a relay issue.
I have the same problem with one of the cards.
I've tried to clean the relay contacts, but that didn't help.

While in playback, the "norm" mode sounds fine though.
It seems both heads are being fed thru the amplifiers in record mode when the relays are stuck.
One thing I haven't tried yet, is to unplug the monitor head.

You only need the monitor head for calibrating, so after that I guess you could simply unplug it (the orange one) and get rid off the 50's style echo.
Some users even completely remove the monitor head to use it as a spare in case the sync/rec/norm head is worn out.
But in that case recalibrating will be a pain in the ...

I know this is quite of a work-around, but as long as you don't replace the relays/cards, this will do fine.

Good Luck!
Here's a frequency response plot from all channels in monitor mode, with the blue(ish) line being the defective channel.
There are phase issues while calibrating, but it's still doable...
80-8_response_SM911.webp
 
You may have the original non-sealed relays. Clear plastic are the old non sealed ones,translucent orange are the newer sealed type.The old ones were upgraded to hermetically sealed by Tascam at one point and were available through them- but I don't know now-there may be another source.The 'normal' and 'monitor' heads have two different part numbers.The playback response of the 'normal' head is inferior to the 'monitor' head.The 80-8 was designed to multi-track record from the 'normal' head and mix-down from the 'monitor' head.
 
Yep...Teac didn't start using same parts for sync and repro heads on the 1/2" 8-track format until the 38 and 58 models.

Can somebody put up a pic of what the relay footprint looks like?

It looks like from the schematic the relays are SPST, but the footprint on the PCB layout looks like SPDT?

This is a link to a 1 form C SPDT part at Mouser: http://www.mouser.com/ProductDetail/Fujitsu/LZ-24H/?qs=%2fha2pyFadug5LdXyMUX99eyUqwrcs533WRduxPy8czA%3d

They aren't hermetically sealed and Mouser is out of stock, but they are $2.33 apiece and, more importantly, the LZ series look to be a readily available footprint still which is not the case for those of us with vintage MCI mixing desks with obsolete relays. :)

Anyway, before you can really track down replacements there needs to be some confirmation on the form and type of the relays besides the fact that they are LZ-2 type...they come in flavors.
 
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Wow! Thanks for the responses. I have been having this issue for sometime now but I honestly haven't made time to work on it....I like the idea of the relays. I had been getting some electronic advice from someone else and he was recommending possibly the power supply??

That is exactly the problem I have been having Alfredo, I was unable to calibrate...NORM mode worked fine. BUT a few things; Since I posted I have discovered that the channel card functions were not working properly. When I had the cards wired backwards, the slapback issue had stopped HOWEVER the calibration pots are not working properly. MONT. level and EQ pots are modifying the NORM level and EQ settings. (So when I would try to calibrate NORM playback, I could only use MONT. pots to adjust it...Does this sound like a relay issue? It seems so to me? This problem still occurs with the cards plugged in normally.

Also I tried the paper test and the slapback issue stopped with the paper underneath the NORM head....And the relays are clear plastic (2 of them per card).
 
Yup...this sounds like failed relays.

Can you take a good picture of the relay itself or post any identifying information screened on the relay, and then also post a pic of the solder side of the amp card?
 
I thought I found a source for a compatible relay type. Alliedexpress has this type: lzn2 24vdc.
But indeed, which flavor?

About the heads:

I've examined the 80-8 service manual and found that both monitor & normal head share the same part number.
The manual however states that there is a difference in emphasis, with the normal head giving the best response.
emphasis80heads.webp

heads80.webp
 
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Here is a pic of the upper side, while I was replacing the opamps.

However, I have no backside pics yet...
card.webp
 
I need pic of the PCB. You posted the same PCB layout i referred to earlier that looks like its SPDT but the schematic presents that its SPST.
 
OK,
We got 'em.
Not the best quality picture, but in the middle you can find K1 and K2.

This looks like DPDT I guess?
2014-05-05 21.04.29.webp
 
Alright, so you are saying to replace all the opamps on all 8 of the cards?
 
Replacing the opamps make it sound tighter and punchier and lowers the noise floor (a bit).
NE5532's are reasonable cheap. Getting the old (4558) ones out, was a pain the ... however, due to the strange solder type Teac used.

But regarding the slapback issue, you "only" have to replace the relays.

If buying these from allied express, this will be quite expensive.

So, Reelman77, could you tell by the pictures if these are DPDT?
I see (from left to right on the PCB) 2x1 input, 1 coil input and 2x2 alternating outputs.

There must be cheaper ones available I hope...
 
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