UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

Bufo Bill · 27th Jul 2021, 8:10 pm

Hi thanks for the clarification guys.
Before I noticed David's reply I checked the rails. While the DC measures fine on all test points the +100V rail keeps fluttering with AC when measured (no AC on the other rails), i get momentary readings from 2V up to 20V AC.
I also noticed on the A1 board of the 1821A resistors r310, r312, r126 and r120 are getting very hot, there is slight discolouration of the board surrounding these resistors consistent with excess heat.

27th Jul 2021, 8:10 pm	#70
Bufo Bill Heptode Join Date: Jan 2016 Location: Wolverhampton, West Midlands, UK. Posts: 777	Re: HP 180A Oscilloscope. Hi thanks for the clarification guys. Before I noticed David's reply I checked the rails. While the DC measures fine on all test points the +100V rail keeps fluttering with AC when measured (no AC on the other rails), i get momentary readings from 2V up to 20V AC. I also noticed on the A1 board of the 1821A resistors r310, r312, r126 and r120 are getting very hot, there is slight discolouration of the board surrounding these resistors consistent with excess heat.