TSA7 Code A reject loop

[paradisecs]

I have an LS2 that I finally have selecting records.  The Service switches work fine, selections are made, and reject works but only when the mech is not plugged to the amp.  When the mech is plugged in to the amp and I make a selection it selects the record and then immediately rejects it. 

I know it's not mechanical because it works without the amp plugged in.  

Does this sound like something with the mute relay?  I've never opened one of the can style relays #306914 before.  If it was an issue in the mech switches it wouldn't work with the amp unplugged, correct?

I'm going to go go peruse my Console-Era guide to see what I can find but thought I'd post here in case I'm following the wrong idea.

Stephen

[Ron Rich]

Hi Stephen,
Look at the service manual-- the reject circuit on the LS-2 is exactly the same as all other 160 select models starting with the LPC-1, and 100 select models starting with the S-100.

The coil that is fired is a "Detent" coil when the contacts on the mech are connected to the selection system but when they are connecting it to the cancel or end of record TRIP off, it is the trip coil. When you un plug the amp, the mechanism is not "working", it is just failing to trip ! Hint: Unplug the main mech cable from the SCC (mech in play position !). Un plug the mech/mute from the amp-- plug the amp plug in - out a few times-- if you can hear it "clicking", one or more of the "reject switches" is shorted closed. Ron Rich

EDIT: You can also check this operation another way-- un-plug the mute/mech plug from the amp-- play a record--plug the mute plug back into the amp while playing. If the record trips off  at that point, one of the "reject switches" is closed. If it does not-- adjustment of the 3M11-12 contacts is wrong . RR

[armandh]

as i recall there is also a mute contact on the mech that holds the mute relay during scan
any short to ground in this circuit would also cause the solenoid to reject when it's control
is shifted from the "selection" relay back to the mute relay.

[paradisecs]

Thanks Ron for reminding me how the circuit worked. The problem was in the 3M switches. One of the screws was loose. Once that was tightened down the 3m12 aligned properly and started working. I went ahead and adjusted them all again anyways. Your tip on plugging/unplugging the mute plug from the amp led me to it. As a rule I try to avoid plugging things in when hot. I can finally get this thing out of the way.

Stephen

[Ron Rich]

Hi Stephen,
I thought of that after I wrote the above, and was gonna add it-- but got distracted and forgot -- anyway-- you can not "hurt" anything with that mute/mech plug as it only serves to supply a ground to the relay in the amp. Other plugs can cause BIG problems if plugged/un-plugged when "hot" !!! Good idea not to play with them, when power is on.-- Glad you found it-- Ron Rich

[Mark]

I was thinking about that too... I don't plug anything into or remove a plug (from the amp, control center, etc) while the machine is on for fear of shorting something or toasting a fuse. The info Ron provided on the LS2 is a real "Gem"...

[paradisecs]

Ron,

In all of the units I've worked on so far, granted less than 20, I never realized that 3m11 and 12 could be out of adjustment if the mech is working without the amp. I guess I've gotten lucky and haven't had to adjust the switches until now. This LS2 has put me through the works but I think it's ready to move out of my shop.

Stephen

[Ron Rich]

Hi Stephen,
Well what an I say-- IF, you had READ, the FAQ's on contacts here--you woodov seen that checking the screws was one of the first things to do-- Ron Rich

[paradisecs]

Good morning Ron,

Reading and retention are two different things.

Stephen

[Ron Rich]

Hi Stephen,
Yes--LOL-- that's why I keep repeating myself--READ, ReREAD, again and again ! It will sink in--no one has a harder head then I do ! Ron Rich

[armandh]

generally removing the mute plug hot is not a problem EXCEPT...,.

The first of the 6000? home console 12" LP key pad style came from the factory without the relay mute [more DS like]
there was a factory mod to relay mute. [also a mod to the FM discriminator circuit]
any way if you unplugged the mute it lifted the ground between the control and amp.
these were powered by non polarized 2 prong plugs and had the usual hiZ resister and low value cap gnd to line.
if the 2 plugs were in the socket opposed the chassies were line voltage apart at very low current
all of the difference would appear on the base of the transistor driving the opto isolator and triac [on off circuit]
problems ensued. a ground wire between the sections + new driver returned it to robust operation