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Re: How to clean Helitrim potentiometers?
My FG503 has one Bourns pot (Frequency adjust) that is riveted closed, and two AB brand 'ModPot' pots that are held together with small flathead screws. I've had good success in opening those up and
By Jared Cabot · #175832 ·
Re: Tek 577 D1 Repair (B07xxxx)
6. B072023 2020-Nov-15~30: Broken Trace The last trace's broken into two traces:1st half of last trace and 2nd half of base trace. </g/TekScopes/photo/255563/24?p=Created,,,100,1,0,0>
By Jack2015 · #175831 ·
Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Just a quick note, I have updated the files yet again for those who have downloaded them in the past. I added cutouts to the card edge connector to ensure full compatibility with mainframes that may
By Jared Cabot · #175830 ·
Re: Slightly OT: How can I dissolve Potting Compound?
Gasoline is worse, but... MEK is listed as a precursor... but a lot of industrial chemicals are precursors... and despite being listed... it produced, and used in vast quantities, in the U.S. Model
By Roy Thistle · #175828 ·
Re: Slightly OT: How can I dissolve Potting Compound?
My first experience with MEK was in early 1966 in the Navy,I spilled some on my belly, It burned like fire, buy the time I got my pants down to wash it off it was gone, just a patch of very white skin
By Leon Robinson · #175827 ·
Re: Slightly OT: How can I dissolve Potting Compound?
Hi Dennis: If it is some kind of epoxy, then acetone dissolves it better then MEK. Cured epoxy resins, like moulded parts, can be exposed to MEK... and show "fair" resistance. (MEK will eventually
By Roy Thistle · #175826 ·
Re: Slightly OT: How can I dissolve Potting Compound?
MEK is really nasty stuff and a precursor to methamphetamine, from what I understand.? A funny but horrifying story about MEK came from a coworker.? Seems a coworker of his years ago wanted some of
By Jim Ford · #175825 ·
Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
Please include me in the list as "JF" since I meet the above qualification as, not identified by full name and some limitation. I'll send you and email now so you know who I am. Thank you sir.
By nonIonizing EMF · #175824 ·
Re: Slightly OT: How can I dissolve Potting Compound?
If the heat gun can melt epoxy resins, it may be hot enough to melt other plastics - like the insulation on wires (unless it's Teflon or silicone - which it may be in an HV supply). There are quite a
By stevenhorii · #175823 ·
Re: Slightly OT: How can I dissolve Potting Compound?
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
By Ed Breya · #175822 ·
Re: Slightly OT: How can I dissolve Potting Compound?
It is also extremely smelly. Work outdoors or with fume exraction, or at least seriously good ventilation. EJP
By EJP · #175821 ·
Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
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
By Larry McDavid · #175820 ·
Re: Grid Bias Adjustment on 475A
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
By Jeff Dutky · #175819 ·
Re: Slightly OT: How can I dissolve Potting Compound?
You can try MEK, methyl ethyl keytone. It will dissolve a lot of epoxies. Be careful to not dissolve other things. 73 Glenn WB4UIV
By Glenn Little · #175818 ·
Re: Slightly OT: How can I dissolve Potting Compound?
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.
By Vince Vielhaber · #175817 ·
Re: I built a TM500 mainframe tester, and updated the design. Someone might find this useful?
I am also interested in a set of boards. Ed Pavlovic KC9MMM
By Ed Pavlovic · #175816 ·
Slightly OT: How can I dissolve Potting Compound?
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.
By Dennis Tillman W7pF · #175815 ·
Re: Peter Keller's Book Mailing Status
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
By Vince Vielhaber · #175814 ·
Re: Peter Keller's Book Mailing Status
So, you're not using paypal/shipnow interfaced to pitney bowes?
By John Griessen <john@...> · #175813 ·
Re: Tek 475 scopes.
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
By Jeff Dutky · #175812 ·