Ethan

I finally have this "Stewter" B67 semi-working.  When I started practically nothing worked (hopefully I haven't made any problems bigger :oops:).  Now the thing is constantly in PLAY.  I checked the switch contacts and they seemed to be fine, but even tried installing a replacement just to make sure.  No luck.  It's a momentary switch so there's no actual connection made for play to initiate, just a momentary signal.  Now, should I be looking towards the Repro amp or this large mysterious IC marked "SC 10429"

Could you brilliant people take a look at this portion of the schematic and donate a clue :grin: .
SCHEMATIC HERE
I am just the Web Geek here.


PRR

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #1 on: June 02, 2005, 11:25:42 PM »
> should I be looking towards the Repro amp or this rather large mysterious IC marked "SC 10429"

No.

The repro amp does not keep the deck in Play.

The IC is possible but far less likely than something else.

The IC turns on transistors. Transistors fry. You cut off the interesting parts, but I suspect that these transistors turn on relays. Relays stick.

What do you mean "stuck in Play"? Play-light always on, or motors always running? Could the STOP switch have failed? C12 or C15 shorted-out?

Scenaria

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #2 on: June 02, 2005, 11:34:53 PM »
do you actually have tape loaded on the machine or are both hubs simply moving? if so are they going in opposite directions?

Ethan

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #3 on: June 02, 2005, 11:36:00 PM »
Sorry about that.  I've updated the link.  It now shows the whole schematic, but it's quite large!

Quote
What do you mean "stuck in Play"? Play-light always on, or motors always running?

Always running.

Does the whole schematic give any more ideas?
I am just the Web Geek here.

Butterylicious

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #4 on: June 03, 2005, 12:25:27 AM »
Q5 should change states when you press play.  Ifin it does look towards the realy it's driving.  Ifin it don't, start right there and look the other direction.  That whole little row of transistors (Q4,5,9,10,11) should react to their corresponding switches.  I think IC1 is just a bunch of latches to keep the corresponding lamps on.

jollyted

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #5 on: June 03, 2005, 12:32:37 AM »
Do you have a tape loaded?

Many of the older machines I work on must have a tape loaded providing opposing tension and triggering a tape direction sensor...otherwise the reel hubs being unloaded and without the opposing tension just spin!

And many of these machines (don't know specifically about your model) may not (initially on power-up) go into STOP mode (or any other transport mode) unless the tape is loaded and the tape breaks the 'tape' loaded sensor and resets the logic circutry.

Regards,

Ted
GRS PRO AUDIO SYSTEMS
DIV. GRS SYSTEMS, LLC

ANALOG CONSOLE, PSU's, MODULES & OTHER PRO AUDIO GEAR SERVICE & REPAIRS

NEW & USED POWER SUPPLIES FOR CONSOLES

http://www.grssystems.com

Ethan

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #6 on: June 03, 2005, 12:38:18 AM »
Thanks guys, I'll give it a go...
Quote from: "Butterylicious"
Ifin

???
What's "Ifin"?
I am just the Web Geek here.

Ethan

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #7 on: June 03, 2005, 12:40:27 AM »
Thanks Ted.

Yes tape is loaded.
I am just the Web Geek here.

jollyted

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #8 on: June 03, 2005, 12:43:02 AM »
Ethan...can you post or PM a copy of the rest of the transport shematic?

Regards,

Ted
GRS PRO AUDIO SYSTEMS
DIV. GRS SYSTEMS, LLC

ANALOG CONSOLE, PSU's, MODULES & OTHER PRO AUDIO GEAR SERVICE & REPAIRS

NEW & USED POWER SUPPLIES FOR CONSOLES

http://www.grssystems.com

Butterylicious

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #9 on: June 03, 2005, 12:49:15 AM »
Quote from: "Ethan"
Thanks guys, I'll give it a go...
Quote from: "Butterylicious"
Ifin

???
What's "Ifin"?


It's proof positive (musical taste aside) that I'm a red-neck.


Ethan

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #10 on: June 03, 2005, 12:49:17 AM »
Hi Ted,
The one posted up there now is the whole transport schematic.
The only other schematics I have are of the repro/rec amps and sensors, etc...
I am just the Web Geek here.

jollyted

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #11 on: June 03, 2005, 01:04:19 AM »
Hi Ethan,

Just curious about the sensors schemo. and about this machine in whole. Thanks

Regards

Ted
GRS PRO AUDIO SYSTEMS
DIV. GRS SYSTEMS, LLC

ANALOG CONSOLE, PSU's, MODULES & OTHER PRO AUDIO GEAR SERVICE & REPAIRS

NEW & USED POWER SUPPLIES FOR CONSOLES

http://www.grssystems.com

Butterylicious

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #12 on: June 03, 2005, 08:06:54 PM »
Wow, my first PM.   :grin:

I wanted to post this here too because if I'm right, others might learn something too.  Ifin I'm wrong, hopefully someone will be nice enough to correct me and I can learn something.

I'm not 100% certain, but I believe that row of transistors is switching relays via the jack connector marked J2.  All their emitters are tied to +24v and their collectors are all connected to the corresponding switches.  When you press one of the momentary switches, the base of the corresponding transistor should go hot (close to +24V).

Make sure that connector J2 does in fact hook up to the transport relays.  Press the various transport buttons and measure the voltage change at the base of their respective transistors (Q4, 5, 9, 10, 11).  Q4 should react to the rec button, Q5 to play, Q9 to stop, Q10 to FF, & Q11 to Rew.

Please remeber I am a hack at best.  I often make things worse B4 they get better.

Good Luck!
-Richard

Ethan

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #13 on: June 03, 2005, 08:41:37 PM »
Thanks Richard,
I couldn't find a sheet with relays.  The only other reference to J2-12 (the connection from the base resistor of Q5--transport schematic above) is here in the power supply:

The circled portion reads:
1st line: J2-11, 12, 13
2nd line: J3-11, 12, J6-2, 3
More confused... :oops:
I am just the Web Geek here.

Butterylicious

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #14 on: June 03, 2005, 11:41:50 PM »
Well that just can't be right.  That shows that point to be -12V but if it's connected to Q5 via D17...... that diode is pointed the wrong way........ and I'm officially lost w/o putting my paws on it.  I'll him-n-haw on it some more.  Something just isn't right.

Butterylicious

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #15 on: June 04, 2005, 12:30:03 AM »
Would it be to big of a PITA to link me to all the schematics?  In particular the page that shows the motards.

Butterylicious

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #16 on: June 04, 2005, 01:47:08 AM »
OK, I'm a dumb ass.  That connector goes to the remote control.  Forget everything I said B4.  A change of state APPLIED to the base of Q5 should cause the collector to go hot.  Hello, wake up Richard.

So that mysterious IC SC 10429 is probably a set of 8 latches.  For play, momentary voltage is applied to pin 19.  Pin 18 is latched hot until reset.  This is driving the lamps.  Now the tricky part, pins 7, 9, 10, 11, & 13 eventually get to ICs 3 & 4, which in combination with the sensor board tell the 2 motors what to do, along with the pinch roller solonoid tossed in there somewhere.  I'm quite rusty with my TTL.  I'd check xistors Q 27, 28, & 30.  Also make sure the edit button (S10) isn't depressed.

Ethan

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #17 on: June 04, 2005, 02:05:01 AM »
Thanks for all your Help Butter.  Otherwise, I would be going around in circles just blindly checking parts and replacing.  Another man I'm indebted to has offered to send me some extensive documentation via snail mail.  I really really appreciate all the help!

I'll let ya'll (let butter translate "ya'll" for you :wink: ) know how things turn out.
I am just the Web Geek here.

Ethan

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #18 on: June 04, 2005, 01:32:51 PM »
Good to know thanks.
Hopefully I'll get to the bottom of this when I have some time next week.  If anyone has any more ideas please let me know, I need all the help I can get.
I am just the Web Geek here.

NewYorkDave

Troubleshooting a Tape Transport-always in PLAY (Part Deux)
« Reply #19 on: June 04, 2005, 02:29:25 PM »
If the circuit includes logic, make sure the +5 is not only present (and really +5V), but also clean. Break out the scope.


 

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