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RESULT: -75V drifts badly as the machine is turned on and heats up (High @ -73.5V when turned on and drifting slowly to -75.05V when warmed up.). | RESULT: -75V drifts badly as the machine is turned on and heats up (High @ -73.5V when turned on and drifting slowly to -75.05V when warmed up.). | ||
Found shorted D83 - 1N4152 not aware of symptoms related to this defect. | Found shorted D83 - 1N4152 not aware of symptoms related to this defect. This would have affected the DAC Function. See Page 3-9 for Circuit Description. | ||
Replaced D708 with proper 9V TC ZENER, -75V Supply is now rock solid @-75.015V, no "drift" as the machine is turned on and as it heats up. | Replaced D708 with proper 9V TC ZENER, -75V Supply is now rock solid @-75.015V, no "drift" as the machine is turned on and as it heats up. | ||
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Replaced K101 K102 and K103 relays. | Replaced K101 K102 and K103 relays. | ||
No symptoms or malfunctions noted. | No symptoms or malfunctions noted. | ||
==Symptom: Complete Unit shut down #2== | |||
Bad HV transformer. Unit #2 quit working after a short time of operation. Very low S/N B010169 unit is very old and very early production model. Had brown epoxy potted HV XFMR. No luck with finding a functional new or used part. Found a manufacturer who was willing to make a small batch of these transformers, contracted for a batch to be made. Replaced old part with new one, unit works again. There is copious discussion on the TEKScopes Group regarding this repair. 250+ hours of operation proves this part is durable. I have very few of these transformers remaining available for sale. (Contact Me OFF-LIST for details.) | |||
[[Category:Instrument repair reports]] | |||