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weird AY160 problem



 
 
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  #1  
Old November 3rd 10, 02:51 PM posted to alt.collecting.juke-boxes
Gruggy
external usenet poster
 
Posts: 3
Default weird AY160 problem

Hey guys.

I'm working on an AY160 that's got a problem I've never seen before.
Whenever the box is in PLAY mode and the mech is scanning, it will
trip and play random records that were not selected. There is no
pattern to the random selections. The problem occurs even if the
memory is cleared (using the battery trick) and no selections are made
with the keypad. In fact, it occurs even if the big plugs for the
keypad and the main tormat connections are unplugged. This leads me to
believe that the problem is in read-out, and not write-in.

There is one thing that makes the problem go away: Unplugging the
sense loop connector from the pulse amplifier. With that unplugged,
the mech scans the full rack without tripping. This led me to suspect
the pulse amplifier.

So.

I've rebuilt the selection receiver, including the pulse amplifier. In
addition to all new caps, I replaced several resistors that had
drifted out of spec. The old 2050 and 6X4 had internal shorts, so I
got new ones. The transformer puts out all the voltages it should.

Could the OA2 tubes cause this problem? My understanding is that this
tube is essentially just like a zener diode. Each shows a voltage drop
of about 145 volts, so didn't think it necessary to replace them.

Could it be the Tormat itself? I've probably worked on 30 or 40
Seeburgs and haven't seen a bad Tormat yet, but there's a first time
for everything.

Could it be the little transformer inside the pulse amp? It doesn't
look broken or melted, and it has continuity through its coils -- but
I don't know any way to test it beyond that.

Demonic possession, perhaps?


--- gruggy ---
Ads
  #2  
Old November 4th 10, 03:16 AM posted to alt.collecting.juke-boxes
Rob in NYC[_2_]
external usenet poster
 
Posts: 103
Default weird AY160 problem

On Nov 3, 8:51*am, Gruggy wrote:
Hey guys.

I'm working on an AY160 that's got a problem I've never seen before.
Whenever the box is in PLAY mode and the mech is scanning, it will
trip and play random records that were not selected. There is no
pattern to the random selections. The problem occurs even if the
memory is cleared (using the battery trick) and no selections are made
with the keypad. In fact, it occurs even if the big plugs for the
keypad and the main tormat connections are unplugged. This leads me to
believe that the problem is in read-out, and not write-in.

There is one thing that makes the problem go away: Unplugging the
sense loop connector from the pulse amplifier. With that unplugged,
the mech scans the full rack without tripping. This led me to suspect
the pulse amplifier.

So.

I've rebuilt the selection receiver, including the pulse amplifier. In
addition to all new caps, I replaced several resistors that had
drifted out of spec. The old 2050 and 6X4 had internal shorts, so I
got new ones. The transformer puts out all the voltages it should.

Could the OA2 tubes cause this problem? My understanding is that this
tube is essentially just like a zener diode. Each shows a voltage drop
of about 145 volts, so didn't think it necessary to replace them.

Could it be the Tormat itself? I've probably worked on 30 or 40
Seeburgs and haven't seen a bad Tormat yet, but there's a first time
for everything.

Could it be the little transformer inside the pulse amp? It doesn't
look broken or melted, and it has continuity through its coils -- but
I don't know any way to test it beyond that.

Demonic possession, perhaps?

* *--- gruggy ---


Not really that unusual. If you look at the contact block on the mech
that rides under the Tormat, you'll likely see sparking as it scans.
This causes random pulses that trip the machine. Two causes: Corroded
center contact rail (long flat piece between the individual contacts)
Or worn grounding contacts that have lost intimate contact with that
plate.

If the plate is corroded you can attempt to clean it with some -mild-
abrasives (crocus cloth) and check that the contact plungers are
making solid contact.. With power off, pull down on the plunger block
and see if the plungers have enough over-travel to remain in contact
for at least 1/8 inch. If its just worn plungers you can raise the
block by loosening the two screws that attach it to the mech arm and
sliding it upwards slightly. Check also that the tormat has not been
bent due to some asshole using it as a handle.

You can eliminate the center contact plate by running a wire from it
to chassis ground. If you do this, you should also disconnect the two
plunger wires that touch it (middle of block) and insert a approx 3
amp fast blow fuse inline with the new grounding wire.

Rob
  #3  
Old November 4th 10, 12:06 PM
Alan Hood Alan Hood is offline
Senior Member
 
First recorded activity by CollectingBanter: Dec 2009
Location: Sheffield UK
Posts: 187
Default

Quote:
Originally Posted by Rob in NYC[_2_] View Post
On Nov 3, 8:51*am, Gruggy wrote:
Hey guys.

I'm working on an AY160 that's got a problem I've never seen before.
Whenever the box is in PLAY mode and the mech is scanning, it will
trip and play random records that were not selected. There is no
pattern to the random selections. The problem occurs even if the
memory is cleared (using the battery trick) and no selections are made
with the keypad. In fact, it occurs even if the big plugs for the
keypad and the main tormat connections are unplugged. This leads me to
believe that the problem is in read-out, and not write-in.

There is one thing that makes the problem go away: Unplugging the
sense loop connector from the pulse amplifier. With that unplugged,
the mech scans the full rack without tripping. This led me to suspect
the pulse amplifier.

So.

I've rebuilt the selection receiver, including the pulse amplifier. In
addition to all new caps, I replaced several resistors that had
drifted out of spec. The old 2050 and 6X4 had internal shorts, so I
got new ones. The transformer puts out all the voltages it should.

Could the OA2 tubes cause this problem? My understanding is that this
tube is essentially just like a zener diode. Each shows a voltage drop
of about 145 volts, so didn't think it necessary to replace them.

Could it be the Tormat itself? I've probably worked on 30 or 40
Seeburgs and haven't seen a bad Tormat yet, but there's a first time
for everything.

Could it be the little transformer inside the pulse amp? It doesn't
look broken or melted, and it has continuity through its coils -- but
I don't know any way to test it beyond that.

Demonic possession, perhaps?

* *--- gruggy ---


Not really that unusual. If you look at the contact block on the mech
that rides under the Tormat, you'll likely see sparking as it scans.
This causes random pulses that trip the machine. Two causes: Corroded
center contact rail (long flat piece between the individual contacts)
Or worn grounding contacts that have lost intimate contact with that
plate.

If the plate is corroded you can attempt to clean it with some -mild-
abrasives (crocus cloth) and check that the contact plungers are
making solid contact.. With power off, pull down on the plunger block
and see if the plungers have enough over-travel to remain in contact
for at least 1/8 inch. If its just worn plungers you can raise the
block by loosening the two screws that attach it to the mech arm and
sliding it upwards slightly. Check also that the tormat has not been
bent due to some asshole using it as a handle.

You can eliminate the center contact plate by running a wire from it
to chassis ground. If you do this, you should also disconnect the two
plunger wires that touch it (middle of block) and insert a approx 3
amp fast blow fuse inline with the new grounding wire.

Rob
Rob is correct with the above re the tormat and the connection pins etc. I have seen this on the older machines where the capacacitor that is across the detent swich causes problems.
I have also seen a worn clutch also give this fault.

Regards
Alan Hood
ami-man
UK
  #4  
Old November 4th 10, 01:40 PM posted to alt.collecting.juke-boxes
Gruggy
external usenet poster
 
Posts: 3
Default weird AY160 problem


Rob --

Thanks for the tips! I had already looked at the
contact block and tormat and they seemed okay,
but I will give them more attention. That ground-wire
trick seems like a good idea too; the center strip
did look a little discolored.

--- gruggy ---
  #5  
Old November 6th 10, 03:34 PM posted to alt.collecting.juke-boxes
Gruggy
external usenet poster
 
Posts: 3
Default weird AY160 problem


I went back to this thing yesterday and got it working.
On closer inspection the tormat contact plate
was pretty grungy with old grease. Cleaned it,
lightly polished it, and did the same for the
contact block pins. It works great now!

Thanks again to both of you for the advice.

--- gruggy ---
 




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