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What's the anode voltage on the 577 CRT? If it's more than about 12 kV (I doubt it), it could be that there's some or more lead (Pb) in the CRT faceplate glass for X-ray protection, causing more UV

I decided to rescan the later W manual I found. The BAMA scan is from 2003 of an older manual I had and the later manual has updated Circuit Descriptions and Parts Lists. It should be completely

wrote: It was annoying enough that I was willing to risk repairing the oscilloscope and even undoing the modifications to support a 155-0022-00. I have the two 155-0022-00 channel switches which I got

Hi Tom, None of us have the proper 2220 service manual, nor do we know where to find it or buy it. By several accounts, the 2220 is just a crippled 2230 (much like the 2224 was just a crippled 2232).

Thanks Tom. I don't even have the proper manual for the 2220 and was just looking at the 2232 schematics. Also, the earlier messages are gone and I was just following the last two days by email. We

Hi Tom, I believe that Tan has said that he replaced Q9070 (although he called it something else), and that he had put Q9070 on its own heat sink. He thought this ruled out the "thermal shut down

Well, assuming that R907 is correct, the current is not excessive. I would guess the inverter is working correctly. Does the overtemp sense measure the heat from Q9070? If so, that would be my first

Oh, also you should check R909, CR908, Q908, and R908 as any of these could cause the duty cycle switch (Q9070) to overheat. It may be worth a look (with proper isolation) at the gate waveform on

Hi Tom, Thank you for your highly valued opinion on this matter! The voltage drop Tan is seeing across his R907 is very normal (even though this involves the dangerous assumption I'm making that his

Hi Tom, I don't think I would disable the thermal shutdown circuit if the transistors are really getting as hot as Tan has stated. It would be like taking a pain killer to mask a broken arm. But I do

Just looked at the schematic , I had incorrectly identified the diff pair as Q860 and Q869. The correct identification is Q860 and Q863 for the differential voltage error amplifier pair . Mike

You need to use your email client to send a message or reply to a message to send an attachment. I think I have that right. I have never sent an attachment using the yahoo web client. Regards, Tom

Hi Tan, I see that JC has reported that his properly working 2230 has 0.23 volts across R907. I remembered that I had a 2230 so I found it and a note on it said that I had worked on it in 2009 and

I don't think there is an attachments button when you're posting as message. Maybe just go to the Files section, create a new folder, and upload your image into that new folder. A PDF or TIFF would be

Is there room behind to pot for a dual concentric pot, one being a vernier for fine adjustment? Arden

I did not realize the noise was that bad on the 234-0408-20. Do you have a 155-0022-00? Where can I find the mods you are speaking of? If not, I would consider your 234-0408-20, as I would rather have

An update on the 577/D1 storage curve tracer: Nothing I have tried causes the phosphor of the 577 to glow. I covered the spectrum from 385nM (UV/purple), blue, aqua blue, green, yellow, orange, red,

Buy my what? The 234-0408-20 with popcorn noise? It makes channel 2 all but unusable in my opinion. I think you would be better off getting one of the common 155-0022-00 chips and making the minor

Fellow Tekkies, I got my PG508 in and, with a bit of cleaning of the controls, found it to be nearly pristine and very functional indeed. There is one issue: I'm finding the variable control on pulse

David, Can I buy yours? David