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Hi Tony Thank you very much for your guidance. I have been looking for an image of SERVICE ROM for about 5 years without success. It is unbelievable that nobody in the group has this file. After all,

Rogerio, The Xeltek 610P will also program these. I suspect any programmer that can program a 128K battery backed RAM chip, and can be set to start at 0E hex, should be able to program the chip. You

Heitor, POST 3000 indicates that the acquisition RAM has failures. The fact that the testing took place indicates the processor, address bus, data bus and ROM should be ok. The next step would be to

Hi Jared, To change the line voltage on the TM503B simply pop out the bright grey plastic piece that is part of the line selector/power switch/power connector assembly on the back. (The piece that

Did some poking around today. Deoxit didn't change anything. I noted, however, that the linearity issue is definitely temp related. It starts out in spec, then drifts out as the instrument warms up. I

Yep done similar repairs just from the top of the board when the need arose. -Ray

Roger, I agree, probably too much hassle. I looked at the Advin website but the earliest programmer I see that specifically supports these two chips is the SpeedPro 280A. It is USB connected but does

Model numbers with a letter following the model make life a lot easier when looking up an instrument on the Internet. Take 465 vs 465B, 2265 vs 2465A. Raymond

I find it interesting that the first version of a Tek model had no letter after it, while the first version of an HP model always had an "A", which would be the second version of a Tek scope or other

Roger, The PDF schematic is a bit hard to read but you are right they are S types which, based on a 74S112 datasheet, four Clock inputs could pull 4ma each worst case for 16ma total. I think the

Hi Jared, Congratulations on finding a TM503B. "B" versions of a product are uncommon for Tek to make. They are an indication that the product sold very well. Tek was also convinced it would continue

So there is a very easy albeit brutal sounding way of dealing with removing DIL type chips: Take same slim side cutters and snip through every single leg as close as you can to the body. Then you heat

John, Tony, My copy of the manual has U128 and U230 as 74S122 (not LS122), my memory says that most LS devices are rated to around 40MHz which is why I suggested HCT as a possible alternative. Anyway,

That may be a very useful hint, John! Simple to check and repair. I'll check the PSU and its startup behavior, although it seems that the problem with Ethernet connectivity is caused by the NVRAM

John, The oscillator can be replaced by most any other of the same design and frequency. The Motorola K1100A series would be the correct datasheet to look at. There are several other manufactures such

Raymond, I have seen several TDS30XXB scopes with flaky power supplies. The problem is in the optoisolator used for feedback, which looses gain with age and demands too much current from the TL431

... and supported by the TL866II plus, of course, because the main issue is that the DS1742W isn't... Raymond

This is turning into a monologue. I don't mind. The closest (and much closer than I expected) 3.3 V (DALLAS) NVRAM device that I have found so far is the DS1250W. It's a 512K x 8 device, RAM only, so

I have now removed the PSU/timer board from the chassis so can provide a bit more detail on the crystal. It is a Motorola K1100A 50.00MHz. The nearest datasheet I could find was this although its for

hi Siigi, Thank you for your reply. I had understood that the scope will not boot with "blank" NVRAM's. Is this correct? If not I can give the reading and copying a try, as Martin suggested, but that