STD4 mech - loud buzz at end of rack

[andylevine]

FINALLY found enough free time to get the mech reinstalled in the STD4 project!  Happy (ok, THRILLED) to see the whole selection system is working properly.  I'm working through the first set of niggling problems....Individual 'Selection playing' lamps periodically going in and out (dry solder joints maybe...), non-functioning credit switch on service switch (), and occasionally 'missing' a selection by one slot (yes, Ron Rich , I found this one in one of your guides, probably the MicroLog Troubleshooting one).

The problem that I'd like to get fixed first is a loud 'buzz' from the DCC when the mech hits the far right end of the carriage and is about to reverse.  I figured this was coming from the trip relay in the DCC so I popped it out, carefully removed the cover and cleaned the switches. I also cleaned the 2M1 switch (again).  That didn't seem to resolve it.  The buzz only occurs on one end, the other end is fine. Is it possible the mech is scanning just slightly too far??  


Also, how does anyone work on these mechs while they are still in the cabinet??  Its SO tight in there and that little door in the back is darn near useless.  For that matter, I could never figure out how to test this stuff OUT of the box, unless you have a complete other wiring harness to hook all the bits up.

Any suggestions welcome...Thanks
Andy

[Ron Rich]

Hi Andy,
There actually is no "TRIP" relay in any control center--If there is a relay in a control center it is more properly referred to as the "Detent" relay. The "trip (off) relay" is located in the amp. Th buzz you hear is probably generated by the scan control subtract coil, being held energized. The usual cause for this is "people". The scan subtract switch that rides under the TMU, is "bent"--see the service manual for proper adjustments, after you "un-bend" it This is a likely cause of your selection now playing lamp problem, in that the "shoe" is not properly adjusted on the mechanism carriage -- tone arm cradle, which allowed that scan control arm to bend, and the lamp "pick-ups" to bend also. (see photo in Mechanism Guide).
Your free play problem is most likely you have that switch dis-abled. That switch requires the coin switches be plugged in CORRECTLY ( just swap, plugs around--or connect a jumper as shown in the schematics for your phono).
How do I work on the mechs in the cabinet-- very carefully--with the DCC un-plugged ! Ron Rich

[andylevine]

Ron... I used the term 'Trip Relay' based on what was printed on my DCC ....see pic.... I'll get my Sharpie out and fix it :-)




Thanks for the tip on the Scan subtract switch, will adjust properly when I get back to it this afternoon.

The Credit switch issue??? I think I've narrowed it down further.  Looking at the schematics, it looks like that switch goes directly to the dime circuit in the DTP.  Not being able to put actual dimes in my coin gear (some previous evil owner stole the nickel/dime counterweight), I manually just hit the dime coin switch ... it didn't register!  The other 3 (5, 25, and 50) all registered properly).  So I'm guessing dirty contact on one side or other on the black box or cable.  Will clean with eraser and see.  If that doesn't work could be bad pricing card I bought off eBay or other Black Box issue?

[Ron Rich]

Hi Andy,
Yep--- I know there are references to that relay as a "trip relay"--even I did so in one of my guides, it's just simpler/less confusing, to define it as a "Detent" relay, which is why I rit that --- lol--
Well, if the dime switch "don't work--try changing the plugs as I said earlier--The "free play switch", on the service switch assembly, is only partly connected there, due to ITS, considerations. Yes--can be price programmer related-- Ron Rich

[andylevine]

Hi Ron,

Well, the Scan Subtract switch was just fine on this mech, the little ramp that triggers the switch was slightly out of adjustment, but not by much. You were correct (duh...) that the noise IS coming from the subtract solenoid. Its not staying energized long, I just think it's a really noisy coil. I may pull and try to clean it inside with a cue tip and alcohol. I did NOT change the little lozenge capacitors around those solenoids when I recapped the DCC. Not sure if that would help.

The dime switch I think is almost assuredly black box ... I dont think its the pricing card because the nickel and dime on this card aren't even wired. According to Tonys Black/Grey they did that knowing that the BONUS1 would trigger the credit when enough nickels and dimes were deposited. I tested the coin switch at the end of the cable heading to the black box (pin 22 if I remember) and definitely see it register at slightly over 6V when the switch closes. Seeing that the 'Insert more coins' lite ALSO doesn't come on, I came to the conclusion the dime path in the black box must be fault. I need to look at it from the other side as well I think. I don't think I really want to open the black box. If this bothers me enough, I'll look for one on ePay, though finding one that has been tested there is not easy. Tons for sale, none that anyone will guarantee work.

Andy

[Ron Rich]

Andy,
The ramp can not "un-adjust" itself !--the problem IS that the switch housing is bent ! Noisy coil is usually because it has been "cleaned" but not readjusted correctly upon re-assembly. That coil plunger MUST bottom on the core stop, with ZERO pressure on the nylon when bottomed. Also, if the plunger has been "sprayed" with any, type, of oil based cleaner, the rubber in the core stop is gone--If you have a copy of my "Seeburg Mechanism Guide", there is a mention of the replacement rubber I use there. Ron Rich

[andylevine]

+1 for Ron Rich !! No rubber at all on the core stop. Replaced using your recommended method and readjusted correctly. It had been positioned ALL the way down, so with no rubber and a long travel it just rattled galore. MUCH better now Muchas Gracias! I'll email you a beer!

[Ron Rich]

I'll drink it-- make it a German "Union Brau"--please ! Ron Rich