开云体育

I picked up a working 2465B locally for a decent price, at least much more decent than eBay prices. It has a lot of miles on it and has certainly been used (40k+ hours) but obviously not abused. Physically and mechanically it's is really nice shape. I also did some quick tests (horizontal and vertical) with a PG506 and TG501 and calibration still seems to be just about spot on. The scope was removed from a working environment and was was part of an equipment auction for employees of the company.

The only thing noticeable and bother me is that the CRT is soft which is not surprising given the number of hours on the unit and the fan is a bit noisy. Its serial number is >55000 and appears to have been assembled in the early 90s perhaps even 1990 since that's the newest date code I saw on the few ICs I looked at. The electrolytics on the A5 board haven't leaked and the NVRAM (1990 date code) is still working. I'd have to assume the NVRAM is living on borrowed time and needs to be replaced. I'll also need to take a look at the condition of the caps on the power supply boards and figure out if any are in need of replacement. I'd think with all the hours on this scope, a lot of the electroytics are going to be a little tired.

Since I'd like to put a better CRT into the scope at some point, I'm assuming it wouldn't really matter if the calibration data is lost since it'd have to be recalibrated anyhow. I'm assuming the replacement NVRAM need to be programmed with some data before installation into the scope. Is the anyone out there willing to program one for me or any suggestions for a cheap programmer that would do the job?

I read through the calibration sections of the service manual and while it looks daunting It seems doable. The only piece of equipment that I don't have is the Tunnel Diode Pulser (Tek 067-0681-01.) or the 15pf input normalizer (the normalizer looks trivial to DIY). Is there anything else I can use as a substitute for the tunnel diode pulser? or is there anyone in the NJ area that has one?

I'm assuming it's be a good idea to replace the SMD electrolytic caps on the A5 pcb as well, even though they don't appear to be in bad shape.

Jay

Jay,

You know by now to recap the piece as PM. This way, you know it is up to date and better quality condensers are installed. There are some resistors that should be increased in wattage.. Condoraudio has a great kit. There are some resistors not in his kit that should be there, yet. You can get the parts list if you want then order. It is best to mount the new condensers with a gap from the condenser to the board to allow for air flow and get a good solder joint on each side.

As for the crt being weak/borderline, you can increase the heater voltage 20-30% higher for some minutes to see if that helps. This step is done without the scope being on, only a supply that is higher than 6.3V. If you have or access to a crt checker that is good to professional quality, you can check it. Crt checkers have different heater voltage selections so the previous step can be done with a checker. If weak, replace with a known good one.

There are resistors in the focus circuit and a few on the high voltage board that are known to go bad to being overstressed. They are the ones from B+ to C and C to B on the collectors. Use 1W 1% types, get ones that are physically correct for 1W such as 4x10mm or so, to replace the 1/4W types. These resistors will go high/open making it look like poor focus or a weak crt. The 100meg 1/4W carbon on the high voltage board, replace! That will be way out of tolerance. Ohmite has a blue body radial type that will directly fit that is larger in wattage or you can get 1% 1/2W axial from Mouser.

IF yours has a separate battery, use a Tadiran 2.4A/hr axial type. This is heavier in capacity than original and is cheaper. I had the old Dallas chip removed and a FRAM put in to eliminate the Dallas chip and battery. I had someone else do the work and programming since I am not set up to do programming. It was worth the cost in my case.

Yes, replace the SMD condensers on the A5 board! Tantalums work well. You can increase the capacitance if you want. Keep the voltage the same. Make sure the A5 board does not have condenser electrolyte leakage from the originals.

The noisy fan can likely be quieted by removing it then oiling it. Peel the label back to get to the rubber disc then remove the disc then oil well.

Mark

Thanks. The CRT's brightness is fine. It's the focus that is soft and is most noticeable in the corners. I'll have a look at the schematic and get my bearings on where the focus resistors are and replace them and see if there's any improvement.

Jay,

The resistors that are known to give problems are to Q1851, Q1852 and Q1890. Mouser part number for these are: 279-H4P150KFCA, 279-H4P180KFZA, 71-CCF60-332K-E3, 279-H4P430KFZA and (2 in series) 660-MF1/2CC2213F for R1853. For the 100meg: . See which radial leads fit in the original holes.

Mark