Re: Have a 2467B. Suggestions please on very poor focus


Mark Vincent
 

Ronan,

Check the power supply voltages for d-c and ripple. The electrolytics, some resistors and several tantalums are known to give problems. Mr. Yachad of Condor Audio has a parts kit for the 2465/7 series with instructions. He will be glad to help you if you have questions. He is on this group. He is excellent with these series of scopes.

You can check pin 2 of U4310 to see if you have the -2kv. The heater supply can be checked at pins 1 and 14 of U4310 using a battery operated meter or VOM, e.g. Simpson 260, across the two pins to see if you have the 6,3VAC for the heater. Do NOT measure the heater voltage from ground to either pin 1 or 14! Pin 3 of U4310 should be about -2100V, Check TP4302 for -1100V, If these voltages are low, the power supply is suspect as it is common to both oscillator circuits. Replacing the parts in the power supply and elsewhere can make things work right that look bad before replacing. Your focus and dim trace likely will be right with the new parts. U4310 can be bad. The focus adjust should be from 0 to 15V on one side of R4435. Check the zeners, diodes and transistors in the focus circuit to confirm if any are bad. R4333 I will say is way out of tolerance. Mouser has radial types in 100meg. The 1/2W or 1W will work fine. The original carbon one could be 50, 60, etc. percent high or even open. The carbon one in my 2465B was 170meg. It was replaced with a new one. Here is the link for 1W types in stock: https://www.mouser.com/Passive-Components/Resistors/Film-Resistors/Thick-Film-Resistors-Through-Hole/_/N-7gz43Z1yzvvqx?P=1z0vkovZ1z0wsz3Z1z0wljo&Keyword=100+meg+resistor&FS=True. The 1/2W part number is: 588-MOX-300001006FE. The 1/2W is more expensive than the 1W.

The 2 100mfd decoupling electrolytics for the two oscillator circuits should be replaced with something like Nichicon ULD or UHE type. The kit mentioned above likely has these two in it. Mr. Y. can confirm this.

The RIFA caps are to be pulled out and replaced! Those I know are in the kit. Anyone on this group will attest to replacing these automatically/on-sight.

I hope you get this nice scope working right. It is a great scope.

Mark

Join TekScopes@groups.io to automatically receive all group messages.