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Breaking down epoxies at room temperature has often come up here and in the hpagilent group. My standard answer is Dimethylformamide, but other solvents can do it too. It's a messy process and some

It is also extremely smelly. Work outdoors or with fume exraction, or at least seriously good ventilation. EJP

Folks, a surprising number of you have asked to be included in a group purchase of the sets of four boards for this tester that Jared Cabot developed. I'm keeping a list of those who committed to the

So I've measured everything EXCEPT the high voltage levels (waiting on an HV probe). R1396 and R1399 feed the second grid on pin #8, the schematic says they should see +50 V, and I measured +50 V

You can try MEK, methyl ethyl keytone. It will dissolve a lot of epoxies. Be careful to not dissolve other things. 73 Glenn WB4UIV

A heat gun is often the method for removing the potting, but care must be taken since some of the potting compounds get very toxic with heat. Is there a model number on the dead supply? Vince.

I am also interested in a set of boards. Ed Pavlovic KC9MMM

I need to dissolve the black HV potting compound of a 12VDC powered Helium-Neon laser inverter power supply I have that stopped working. I would appreciate any suggestions on what works to do this.

If he does that with the same account the money was sent, paypal will likely turn around and charge him fees for each F&F transaction. It's happened to me. Vince. -- K8ZW

So, you're not using paypal/shipnow interfaced to pitney bowes?

I am trying to maintain my father's 475 and I might be interested in buying them. I am in Montgomery County, Maryland (ZIP 20901), where are you located? How much are you asking? -- Jeff Dutky

Out of about 30 TM 500 power frames I have had 7 that had misphased AC windings in at least one slot, no sign of any post-factory work in them. Failed pass transistors are pretty common. I have not

Hi, I have two 475 scopes. One is almost working as of a few years ago, but the trace brightness knob broke off some years ago. I haven't been using it. A friend of mine bought a 475 for parts, its a

It isn't necessary. Several of the existing tests exercise the pass transistors in various ways. EJP

Nice. It completely matches (except for the limitation to transistors or (other) active networks) the grid bias term as used in a 'scope: the most negative level of the (first) grid, causing blanking

No. It just caused a large hum at low output levels. I fixed it. I'm sure it was done at the factory. Hard to believe it could have been done during a repair: why? The FG504 manual mentions all this

Although English is not my mother tongue (Dutch is), I fail to see why using the term "Grid Bias Adjustment" for 'scope CRT's is wrong. If I'm correct, two reasons are given to disparage the term: 1.

Jargon is always contextual, to the application, and the particular [engineering] culture. (Interpreting the parlance in the vernacular, can result in misunderstandings.) Bias: In an electron tube, a

David Campbell wrote: In my defense, I was just following the diagnostic procedure in the service manual, and my circuit analysis skills are subpar. five of the transistors and two diodes in the

I think this is the right datasheet for the original: https://www.onsemi.com/pub/Collateral/D44H-D.PDF The bipolar transistors optimized for switching power applications tend to have low gain and