Seeburg DS 100 pulse amp problem

I have a Seeburg DS 100 juke with a pulse amp problem. The box has the TSU7 selector unit with the tpa1 code A pulse amp. Mech will not trip. when scanning if i remove the 12AX7 mech will trip. if i put a small screwdriver into the rca socket while mech is scanning it should trip and it does not. both the tsu7 and the pulse amp have been recaped .Does anybody have any ideas. Also will a pulse amp from a LPC1 seeburg work with the tsu7? Thank you in advance for any help you can give. Norman

Hi Norman,
Other then color, and position of the RCA jack, ALL, TPA's are the same .
I'm sure I don't know what you are talking about when you say you insert a screwdriver in and cause it to trip ?? A positive going pulse, such as from a AA cell, in series with a #112 flashlight lamp, should cause a trip voltage to be generated, but to my knowledge, a "screwdriver" won't-- Do you have a service manual/trouble shooting guide ?? Ron Rich

Norman, let's get back to basics here.

-Do the battery test. Does the mech trip then?

-Is there approx 300vdc at the readout plungers when the detent switch is closed and a piece of paper is inserted between the plungers and the Tormat rivets. Service sw at 'operate'.

Rob-NYC

Ron,Rob thanks for fast reply. Ron: I do have the full shop manual including the troubleshoting guide. Rob. used a "D" cell tewsted and it showd 1.51 volts. FAILD the battery test. placed paper insulators between plungers and contacts with detent switch CLOSED tested for voltage at plungers with service switch in operate position. result: zero volts. Thank you for your help

Norman,
Sounds as if you have a TSU problem--it you do not have a short in the detent switch/read-out portion of the mechanism ??
Look or the read out voltage with the mechanism un-plugged-- Ron Rich
Ron Rich

Ron:checked voltage with both mech plugs unplugged. still ZERO volts on pins. BTW both TSU7 and pulse amp have been re- capped. also if when scanning and 12AX7 tube is removed--mech trips. thank you Norman

Norman, in case you don't already have this diagram:
http://s1192.photobucket.com/user/Rob-N ... ort=2&o=72 Note that the markings are not mine -but accurate.

I suggest removing the service switch plug as well. Make sure the test link is connected and both 0A2's in in their sockets and glowing (if original types -not the newer Zeners).

This is the same sheet I have used to troubleshoot these circuits for over 30 years.

Rob

Hi Norman,
Well, yes--of course you'll get zero volts f you check the pins with the mech un-plugged--you gotta check at the socket -----as Rob said--unplug the service switch too while checking--re-capping the TSU does not rebuild it !! Ron Rich

Still working on the problem going over ALL resistors in TSU including pulse amp. Trying to figure out why pulse amp wont cause the 2050 to "fire". Have to get to other jobs, so will take several days. BTW tried 3 known to be good 12AX7 tubes with no luck. I got this to pick up 30 or selections prior to it failing, so something had to be right for it to work a few times. Again thanks for your help. Norman

Norman,
Is the 2050 good ?? Is the bias voltage for it correct--is there a stepper involved on the TSU ?? Will the positive going pulse I described earlier trip the mech ?? Ron Rich

Sorry for late reply was out of town for a couple of weeks. Ron: Tried AA battery and bulb and that will trip mech during a scan. Also, as to a stepper, yes there is one with NO wallbox attached. 2050 is good Thank you all for your patience with me on this. Norman

Hi Norman,
OK--let's clear up some things in my foggy mind-- I suspect a mechanism problem here--
Which, 2050 is "good" --is the stepper 2050 installed, and if so, why (without a WOM, it's just burning power) ??
Have you checked the contiguity (SP ?--this is what my "spell checker" says ??) of the read out circuit from the reversing switch to each plunger ? Have you examined the Detent Switch for "pits/burns", and or, adjustment ? Is the 100 uh choke good on the detent switch--and not touching the chassis ?
Have you checked the RCA Tormat plug--are BOTH the shield and one small plastic coated wire firmly soldered to it's outside ? If so, have you checked for a resistance reading between the plugs tip and ring ? Ron Rich

I'll take a slightly different tactic from Ron and suggest going back to the diagram I linked and with mech and service sw unplugged, check for the 300vdc at the G-H link and finally at the female on the receiver.

A good practice is to replace the 36 ohm resistor. I typically use a 1 watt here.

Rob

Hello Ron, Checked choke on dentent switch has continuity. Detent switch removed cleaned and replaced adjusted acording to manual Not tuching chassis. Have continuinty between plungers and reversing switch. Ohmmeter test on tormat rca plug is 1.5 ohms.Stepper 2050 is NOT in socket It's in the cash bag so I dont loose it As a side note if when the mech is scanning with the tormat rca plug out and you try to plug it in during scanning isn't the mech supossed to trip as you plug the rca plug in? if so ,then I have a problem there as my mech will not trip. Rob; will check the items you sugessted and will get back later tonite.. Again thanks to both of you. Norman

Hi Norman,
No, the RCA plug removal/insertion is NOT a valid test--some will trip, others won't.
Ron Rich