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Post by mauro on Mar 20, 2018 0:29:13 GMT
Have a KD jukebox and following the troubleshooting guide gets me as far as - J test (write in) -
Problem is I don't have the test lamp so I attached my meter to see if there was any voltage but it didn't show any.
What voltage are we looking for here?
Without a test lamp I'm not sure if this should show voltage on a DMM.
I plan on building a test lamp but was wondering what components I should suspect until I'm able to build it.
All capacitors are new and resistors check out. Tubes have been tested and even swapped to make sure.
I've tried everything that seems reasonable to me but I'm hoping someone can help steer me properly.
Thanks again, Mauro
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Post by Ron Rich on Mar 20, 2018 0:59:08 GMT
Mauro,
Have you tryed the "battery test" ? If not do so--you need to determine if it's a read-out, or write-in problem--Ron Rich
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Post by mauro on Mar 20, 2018 1:22:44 GMT
Mauro, Have you tryed the "battery test" ? If not do so--you need to determine if it's a read-out, or write-in problem--Ron Rich Yes, battery test produced some selections but not all selections. |
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Post by Ron Rich on Mar 20, 2018 1:30:03 GMT
OK--If you used a known good D cell for that test, your problem is in the read-out---check for proper/clean Detent switch settings, and that the plungers that ride the TMU are flat, and have silver left on top-check TMU grounding plate for lost plating---Check TMU/record rack/plunger aliments--Ron Rich
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Post by mauro on Mar 20, 2018 1:51:29 GMT
OK--If you used a known good D cell for that test, your problem is in the read-out---check for proper/clean Detent switch settings, and that the plungers that ride the TMU are flat, and have silver left on top-check TMU grounding plate for lost plating---Check TMU/record rack/plunger aliments--Ron Rich Thanks Ron, I'll go through all the readout checks and adjustment in the next couple days and probably have more questions. It's off to bed now. Enjoy your evening. |
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Post by mauro on Mar 21, 2018 1:00:43 GMT
Ok, so I went through the tests again using an analogue meter instead of a test light (which I don't have yet) and I get to L test (write in) and it tells me to replace 25PCU-1.
Somehow I have trouble believing that and I feel it's user error, That's me.
Let me recap, battery test selects some but not all selections, I would think that shows the readout and trip are somewhat functional and the problem is in the write in portion.
Please correct me if my thinking is flawed. And if not what should I be focusing on?
Hope I can get it up and running for the weekend!
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Post by mauro on Mar 21, 2018 1:16:21 GMT
Just tried the battery trick and it's selecting all selections now.
I adjusted the trip coil position.
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Post by Ron Rich on Mar 21, 2018 2:47:27 GMT
Maur,
If the read-out/sense is OK, which you have proven-it's in the write in. On that model, that "stepper" is prone to causing that problem--be 2000% sure the two wipers are homed AND making good contact (clean the board, and wipers with a pencil eraser then a safety solvent, then a light coat of Doxit-5. Also do the same to the two "connectors" going to it, and the insulated portion of the write-in contact(s) in the pricing unit. Ron Rich
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Post by mauro on Mar 21, 2018 3:16:26 GMT
Hi Ron,
I've done all the stepoer cleaning and verified home continuity prior to starting troubleshooting.
I am also using a "good" free play adapter to eliminate the pricing unit from the equation.
Looks like I got another tough one!
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Post by Ron Rich on Mar 21, 2018 3:22:44 GMT
Mauro,
If you are sure The wipers are making contact with enough force to carry current, Yup, You got another "one of those--did you change the diode on the electronics board ? Did you meter the ES (Analog meter !!) ? Ron Rich
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Post by mauro on Mar 21, 2018 15:04:28 GMT
Ron,
I am going to retension the home contacts to make absolutely sure. I didn't consider they may have good contact but not good enough to pass current?
Also you mentioned replacing the diode, I see CR551 on the TEU board is a 1N368 Germanium Diode. I'm not sure if this is readily available, is there a cross to a silicon diode I could use to replace it?
Thanks for the insights.
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Post by robnyc on Mar 21, 2018 15:19:42 GMT
Have a KD jukebox and following the troubleshooting guide gets me as far as - J test (write in) - Problem is I don't have the test lamp so I attached my meter to see if there was any voltage but it didn't show any. What voltage are we looking for here? Without a test lamp I'm not sure if this should show voltage on a DMM. I plan on building a test lamp but was wondering what components I should suspect until I'm able to build it. All capacitors are new and resistors check out. Tubes have been tested and even swapped to make sure. I've tried everything that seems reasonable to me but I'm hoping someone can help steer me properly. Thanks again, Mauro Mauro, I have only a few of the test steps in an ancient xerox of the original manual - as you've seen it is of limited use anyway. Here is the simplified of the W-I for the TSR-3 and essentially all the tube tormat series: www.flickr.com/photos/90641375@N06/36140664003/ At the W-I capacitor you should see around minus 300VDC. At limiter diode/capacitor approx 145 +- a few. Use only a high impedance meter DVM-VTVM. This is a high voltage-low current ckt and low impedance meters such a cheaper VOM loading will distort readings. Check for these voltages with --all-- externals removed: kbd, mech, C.U.-that includes your free-play device. If the voltages are there, begin adding back the removed components to check for leakage within each. I've owned three L's and a K. There is a significant likelihood that leakage within the tormat ckt board itself exists. In ALL of the above machines I found some degree of leakage in tormat board and in two cases, amp boards. If you remove all externals and still see defective readings the board will probably be the culprit. I drew on experiences in TV repair I got as a kid working p/t in a shop, I shine a light through the board look for blackening around high voltage points. Here, these can be edge connectors and tube sockets -but anywhere a constant high-potential exists while the machine is powered. Newly made boards are available now, years ago the solution was to remove the connections within the board and run point-to-point wires. This involved removing tube sockets, drilling out the holes with H-V connections so that when the socket was reinstalled those pins didn't touch the board and then run wires along the surface. This is tedious and sometimes when a number of connections are involved at one area a terminal strip must be used to isolate all connections from the board. If testing reveals leakage I suggest getting new unpopulated boards from one of the vendors. As for the test light, my only use for it is to check the timing of the detent switch.. I just use this: www.flickr.com/photos/90641375@N06/40897811082/ & clip leads. I don't why the direct links are not working. Just copy-paste www.flickr.com/photos/90641375@N06/36140664003/www.flickr.com/photos/90641375@N06/40897811082/RobNYC |
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Post by robnyc on Mar 21, 2018 15:22:29 GMT
Ron, I am going to retension the home contacts to make absolutely sure. I didn't consider they may have good contact but not good enough to pass current? Also you mentioned replacing the diode, I see CR551 on the TEU board is a 1N368 Germanium Diode. I'm not sure if this is readily available, is there a cross to a silicon diode I could use to replace it? Thanks for the insights. Mauro, any diode of at least 800V rating is Ok. 1N4006 (800v)- 4007 (1KV). RobNYC |
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Post by mauro on Mar 21, 2018 17:17:24 GMT
Hey Rob,
Great to hear from you!
With Ron and yourself supplying great advise like this I should have this thing selecting in no time.
Nice methodology and diagrams, they will help tremendously.
I'll report back after I try all these suggestions and change that diode.
Thank you,
Mauro
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Post by mauro on Mar 21, 2018 22:07:35 GMT
Ok, I've checked the voltages at the WI .068 cap and there is -300vdc across it. I also checked the voltage at the 10uf cap at the diode (which I replaced) and there is about -149vdc there.
So not sure where to go next?
I checked the selector switches and there is continuity across the banks as well. Not sure about the end switches, if you think it will help I pull the selector and check them all.
Is a broken wire the last possibility or is there another test/check I should do?
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