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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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Tektronix 2335, no trace, no beam
Hi all,
I just bought a Tektronix 2335 oscilloscope, one minute working, the next minute the trace is gone. The beam finder does not work. nothing works. However I do see a flash of a blurry beam when I first turn it on, but that's it. When opened I see small resistor is burned open just to the left of q114 off the emitter on the vert out/HV power pcb. I can't tell what the value is and I don't have any schematics. The big question is this: What else is gone and why? I don't suppose anybody has the schematic for this board?? (same as 2336 scope) Please help if you have ANY ideas!! Bob email: To email remove NOSPAM |
#2
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Tektronix 2335, no trace, no beam
Bob Kelly wrote in
: Hi all, I just bought a Tektronix 2335 oscilloscope, one minute working, the next minute the trace is gone. The beam finder does not work. nothing works. However I do see a flash of a blurry beam when I first turn it on, but that's it. When opened I see small resistor is burned open just to the left of q114 off the emitter on the vert out/HV power pcb. I can't tell what the value is and I don't have any schematics. The big question is this: What else is gone and why? I don't suppose anybody has the schematic for this board?? (same as 2336 scope) Please help if you have ANY ideas!! Bob email: To email remove NOSPAM Bob, I believe the resistor you are referring to is R113, 1.6k. If you still need the print, reply to the group and I will email you a scan. Len Johnson |
#3
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Tektronix 2335, no trace, no beam - Tek2335-HV.pdf (0/1)
Yes that is the correct resistor, however replacing it doesn't seem to
help. It just burns up again. I pulled Q114 and Q115 and they check out ok. Even during the burn-up I get no trace. Everything else seems to look good. I do have the schematic thanks to a good samaritan, although I don't have the part list, so I can't tell what the transistors are exactly. (can tell pnp npn no trouble) Does anybody have any ideas?? see attached pdf. (I hope attachments are ok) Thanks Len!! I'll take a scan of the part list if you have it. Bob On Sun, 17 Aug 2003 17:26:42 -0000, Len wrote: Bob Kelly wrote in : Hi all, I just bought a Tektronix 2335 oscilloscope, one minute working, the next minute the trace is gone. The beam finder does not work. nothing works. However I do see a flash of a blurry beam when I first turn it on, but that's it. When opened I see small resistor is burned open just to the left of q114 off the emitter on the vert out/HV power pcb. I can't tell what the value is and I don't have any schematics. The big question is this: What else is gone and why? I don't suppose anybody has the schematic for this board?? (same as 2336 scope) Please help if you have ANY ideas!! Bob email: To email remove NOSPAM Bob, I believe the resistor you are referring to is R113, 1.6k. If you still need the print, reply to the group and I will email you a scan. Len Johnson |
#4
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Tektronix 2335, no trace, no beam
Yes that is the correct resistor, however replacing it doesn't seem to
help. It just burns up again. I pulled Q114 and Q115 and they check out ok. Even during the burn-up I get no trace. Everything else seems to look good. I do have the schematic thanks to a good samaritan, although I don't have the part list, so I can't tell what the transistors are exactly. (can tell pnp npn no trouble) Does anybody have any ideas?? see attached pdf. (I hope attachments are ok) Thanks Len!! I'll take a scan of the part list if you have it. Bob On Sun, 17 Aug 2003 17:26:42 -0000, Len wrote: Hi all, I just bought a Tektronix 2335 oscilloscope, one minute working, the next minute the trace is gone. The beam finder does not work. nothing works. However I do see a flash of a blurry beam when I first turn it on, but that's it. When opened I see small resistor is burned open just to the left of q114 off the emitter on the vert out/HV power pcb. I can't tell what the value is and I don't have any schematics. The big question is this: What else is gone and why? I don't suppose anybody has the schematic for this board?? (same as 2336 scope) Please help if you have ANY ideas!! Bob email: To email remove NOSPAM Bob, I believe the resistor you are referring to is R113, 1.6k. If you still need the print, reply to the group and I will email you a scan. Len Johnson |
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