Dealing with 3 scopes all having the Test4 Failures
2465A S/N B011512 Test4 Fail 3 (Fixed)
2465B S/N B010817 Test4 Fail 13 ( This Post)
2465A DM S/N B010824 Test 4 Fail 2 (Haven’t started)
Thank to all for the info in this post. This has been long journey but glad to see an underlying condition could be existing.
I’m looking at completing the repair of the 2465B instrument pre 50,000 S/N. Got started on it about 6 months ago troubleshooting with help from members. Did the repair by replacing the U2460 (original part # NEC D4364C-15LL, replaced with part # NEC D4364C-20L) and replaced the Dallas Keeper battery purchased from Mouser.
That was June 2019. Other things took my interest so just now getting back to calibration. After doing the required calibration I kept getting diagnostic
of test 04 fail 13, Test 04 fail 11, Test 06 fail 01, then back to test 04 fail 01. Couldn’t seem to get ahead of it. So did what I should have done before attempting the calibration and checked the battery voltage. Yea I found it at .6VDC. No wonder I’m dealing with these faults.
So now onto why would the battery be drained in 6 months. The old battery I removed that was from the 1988 vintage was in the same condition so I just thought changing it 6 months ago would allow for another 10 yrs. But that wasn’t the case. So tracing thru the circuit there isn’t anything that I see that would allow for a quick drain of this battery. Feeding two IC, an amplifier, and two caps. Not sure how long it took to drain the battery.