TEAC 80-8 Reel Motor Grinding and Pinch Roller Problem

Sounds good, I'll start there and also check the volts going in. One thing I'm confused about: does there not need to be a wire attached to the middle pin (which carries the bias signal) on that J211 connector, where I have my scope probe in the pictures I posted a few posts back? If not, how does the bias signal reach the channel cards?
 
I may have gotten very lucky. After cleaning, unplugging, replugging, desoldering and resoldering, I noticed the VU meter on one of the channels I thought was dead was flickering. So I rechecked the record and erase capabilities of the machine- and they worked. Kind of.

Some channels don't erase fully, so the newly recorded material just stacks onto the previously recorded material. So I'm praying this will just be a matter of simply adjusting the channel card pots!
 
I have nailed down a few problems. I can see the bias signal present on the scope for all channels but 7 and 8, and these are the ones which will not erase or record. I can hear the distinctive click of the relays when channel 7 is armed for recording, but not on channel 8. This led me to think the relays on Channel 8 are bad so I swapped in Channel 1's card into the Channel 8 slot, and after a test, I found the card from Channel 1 I just inserted had bad relays. But they were working fine before the card was inserted into Channel 8..... so could there be some voltage going into whatever card is inserted in Channel 8 that is frying the relays?

FYI, 7 & 8 playback fine, and the input monitoring works fine.
 
Ok, disregard my previous post. ALL the relays are fine, sometimes they just need to be tapped. I suppose I will need to clean the contacts.

Here are my current issues, any help is always appreciated. I did in fact measure the bias signal at J3 on the boards which work, and it is right about 50v.

1. I have two channel cards which will not output bias signal at the J3 connector (they originally came out of Channel 7 and 8). When other cards are inserted into the 7 and 8 slots, bias is output. So, that leads me to believe bias is making it to all the boards ok, it's just not making it through the two faulty boards for some reason.

2. The card which was originally in Channel 5 will put out bias IF it a different brown RCA connector is plugged in at J3. In other words, there must be something wrong with the Channel 5 brown RCA connector.

Any ideas?
 
I number the cards as they are in the machines as the bias traps have to be adjusted to the heads. Also there is a erase depth pot that some play with and then I have to put them back to correct just like taking off the solenoid.
It is also a possibility that the pinch Roller has shrunk so it might need to go to Terry for new rubber and the correct size. No amount of adjustment will make up for an undersized Pinch Roller- they do not have that kind of range.

The tension arm switches should be wired the same way as the last one to normally open contacts. With the arm down the normally closed contacts are being used and the plunger activation will confuse things more as then will be disconnecting where they should be connecting.

The lack of bias from some cards is due to a failed or not working bias amp on that card- it can also be connection and bad solder or even shorted Tantalum caps.
Decks like this are not the kind to work on for your first one plus these are known for relay problems for many years. If a brown connector is suspect get the ohm meter out and check it. That is not likely the problem but always a lot of guessing going on in here and that is not how these are worked on. I have worked on many of these as well as the 40-4 which is the same kind of machine.
The tension arm plastic piece is called a stop.
I tell people all the time to not even mess with the Pinch roller solenoid just take the fork off the solenoid. Too late now.
 
Yeah next time I certainly won't be touching the pinch roller solenoid.

I investigated into the brown connector problem. The connector in question does indeed have continuity all the way up into the head, so I suppose the wire itself is ok. With a different channel's brown connector plugged into the board, I measure bias at J3. With no connector plugged into the board, I measure bias going to the connection point. But with the connector in question plugged in, there is no bias on the tip of the connector which protrudes through the pcb and thus no bias being sent to the head. It's very strange considering the wire seems to have continuity.
 
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