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Post by vaguy22 on Dec 30, 2016 22:06:01 GMT
ok guys got the mech to behave with the 2050 out of its socket. as soon as I plug in the 2050, the mech trips and the solenoid on the mech stays energised. one side of the soleniod goes to the plate of the 2050 so I'll be checking for grounds there will try unplugging the PA chassis and see if it is grounding the grid of the 2050.I am getting 28 volts on the low voltage rectifier on the tsu so I will figure it is ok. will report back tomorrow eve Again guys thanks for your patience and help. Also--Happy new year to you all. Norman
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Post by Ron Rich on Dec 30, 2016 22:37:00 GMT
Hi Norman,
OK--didja locate a shorted/grounded wire on the wire to the plate--still can't see any other way that could energize the coil, with the tube out --or did you "miss-spoke" ??
As it now stands--that's a somewhat common problem--check the following The tube itself--they tend to remain fired, at the end of their life--what tube is it--a "coke bottle" style or an A version, or a B version ? Can you scan the mech with the service sw. in operate position ?
When it has scanned to, and selected a space, does the coil remain energized bringing the record up/down/up/down---- One of the "reject switches" remaining closed ? HNY to you too !! Ron Rich
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Post by vaguy22 on Jan 1, 2017 3:59:14 GMT
quick update. the only time trip solenoid trips is when the 2050 tube is IN it's socket.also tried a brand new military issue 2050 with the same resuts. this also happens when the 6X4 tube is REMOVED from the socket. also the tsu has been TOTALLY recapped. ALL caps are rated at 630 volts. could a short in the stepper be travling down to the grid of the 2050? Thank you Norman
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Post by Ron Rich on Jan 1, 2017 5:40:58 GMT
Hi Norman,
Couple of questions--PLEASE answer these, AND the ones above --
1. Is the 2050 energizing ( are you looking at the tube and seeing a "purple glow" ?) when the phono is in "stand-by" position--have you removed the PA from the TSU ? Still energized at that point ?
2. Have you checked for a closed "end of record reject switch" ?
Ron Rich
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Post by robnyc on Jan 1, 2017 8:24:06 GMT
Norman, here is the trip ckt: s1192.photobucket.com/user/Rob-NYC/media/tripckt2_zpscf293e4a.jpg.html?sort=2&o=76 It is for the VL (TSR-3)but this section is the same. You should be reading at least minus 20 volts DC at pin 5 on the 2050. Output from the rect should somewhat higher, but since I replace all of them, I don't know what the original reading would be. With a silicon bridge it is minus 28-29 VDC. A prolonged dead short on the stepper signal line may pull down the bias to a point where a tube that is somewhat critical will ignite. I simply separate the two lines (stepper vs trip). All that is needed is another 470K resistor and a 25mfd 235-50vdc cap. Clean and use the spare terminal on the strip. For home use this may not be important. If you do service the stepper to use wallboxes remember to replace the 5 mfd non-polarized cap and replace the 2 watt 100 ohm resistor in the 2050 plate ckt with a 1/2 watt so as to act as a fuse. Rob |
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Post by vaguy22 on Jan 1, 2017 16:23:58 GMT
Hi all Ron: Purple glow seen in 2050 with both the PA in or out End of record switch tests out ok. With 2050 OUT coil does NOT energize. the 2050 is a RCA coke bottle style changed it to a military surplus 2050--- same results.Rob Thanks for the schematic will look into this tonight. Also I have a 6 amp 250 volt bridge rectifier i can put in place of the original is 6 amp ok? Again thanks guys for your help BTW i am thinking that I have a switch problem in the mech. Norman
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Post by Ron Rich on Jan 1, 2017 16:53:34 GMT
Norman--With the PA out-tube in --can you get the mech to scan, with the service switch in the operate position ?? If so, scan it and manually lift the detent lever--will the phono now go into play, or does it instantly re-lift the detent lever and move on ?? The rectifier, if measured with the pricing unit run-plugged must measure at least 17 vdc--anything over that to about 32, is OK Ron Rich
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Post by robnyc on Jan 1, 2017 19:29:51 GMT
"I have a 6 amp 250 volt bridge rectifier i can put in place of the original is 6 amp ok?"
That will be fine. Just remember; positive goes to ground here.
Rob
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Post by Ron Rich on Jan 1, 2017 22:54:18 GMT
Norman,
IF, you replace it, I strongly urge that you at least fuse 1/2 of the AC side, as "bridges" tend to intermittently,"flash over" (short out) and that old transformer WILL NOT take any of that ! Ron Rich
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Post by vaguy22 on Jan 2, 2017 1:13:10 GMT
Rob: voltage on pin 5 of the 2050 is zero both when mech is in standby or scanning. with juke turnd OFF restiance between 2050 pin 5 is infinate resistance. output of bridge rect is -41 volts. Ron: with the PA out and the 2050 in, service switch in play, mech just taks record out and puts it back in soleniod energized all the time. output from bridge rect is 41 volts thanks Norman
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Post by robnyc on Jan 2, 2017 5:20:24 GMT
Ok Norman, you've found the problem (no bias) -now to find the cause. With the tube out of the ckt follow the minus voltage from the rectifier toward the tube. I suspect an open 470k-ohm resistor or an open connection after that point. This is a straight-forward procedure from this point-on.
I suggest keeping the 2050 out of the socket till this is solved. thyratrons are high-dissipation tubes and the their cathodes can be "stripped" by being made to conduct before they are fully warmed-up.
Rob
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Post by vaguy22 on Jan 3, 2017 1:34:38 GMT
Rob: I checked the resistors all but one are good the other one the 470 K connected to pin 5 of the 2050 was off but not that off it was replaced. now with the chassis back in the juke i am getting only - 9 volts on pin 5 of the 2050. tried mech and it still trips after picking up record. Is -9 volts enough or do I need more. DC at rectifier is - 31 volts. Thanks Norman
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Post by vaguy22 on Jan 3, 2017 3:24:11 GMT
Rob: more info i forgot to mention The _9 volts on pin 5 of the 2050 is there when the mech plugs are either removed or plugged in.when mech trips it scans until i stop it with lever. Thanks Norman
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Post by Ron Rich on Jan 3, 2017 3:46:55 GMT
Norman, I iz lost-- What at this point in time, is happening ? What happens if you establish credit,and make a selection (with the service switch in "operate")  Let me know--- then try the following--scan the mech using the Service switch--while scanning lift the detent lever--what happens ? If the rcord plays, will it reject at the end ?? Let me know-- Ron Rich |
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Post by vaguy22 on Jan 3, 2017 4:32:20 GMT
Ron havent got as far as it picking up selections. while scanning using service switch i lift detent lever--record comes up then rejects without playing and scans Record will NOT play. Thanks Norman
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Let me know--- then try the following--scan the mech using the Service switch--while scanning lift the detent lever--what happens ? If the rcord plays, will it reject at the end ?? Let me know-- Ron Rich