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Only one company is associates with bad IC sockets - that is Texas Instruments. Their sockets are easy to find by removing the IC because the TI logo is stamped underneath the IC in the middle of the socket where it can be easily seen.
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TI saw an opportunity to make money selling sockets when IC sales were booming in the late 1960s and early 1970s. Unfortunately for them other companies already had all the patents locked up. Other manufacturers sockets used two flat spring contacts (one on each side of each pin of the IC) to grip the pin from both sides of the pin's very wide flat dimension. TI could not find a way around these ironclad patents. The only way left to grip an IC pin was by the very thin thickness of the metal the pins were stamped from once the IC was finished in manufacturing. A metal die stamps away all of the metal from this metal frame except for the pins themselves and the die leaves behind very rough edges where it stamps the metal frame. As a result the flat side of the IC pin is smooth and an excellent place for a socket to grab the pin and the edge of the pin is thin and very rough. The worst place to grab the pin is on the thin rough edges. These rough edges gouge into the contacts in the TI socket and the result is they will eventually develop intermittent problems. There is not much you can do except replace them which is a tedious job that can cause other problems without the proper equipment to do that with. Dennis Tillman W7pF -----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Colin Herbert via groups.io Sent: Friday, June 05, 2020 5:00 AM To: [email protected] Subject: Re: [TekScopes] DM502 with problems I've had a look at that possibility, Roger. I have cleaned the attenuator cam-switch contacts on a couple of 400-series scopes, but I can't see how to clean them on the DM502. I have taken the cover off the cam-switch assembly, but I simply can't see the gold-plated (?) contact fingers and pcb contacts. It seems more like the time-base switch contacts on 400-series scopes than the attenuators on the same scopes. Correction: I have taken another look after removing the cover and I can see the contacts underneath the cam-switch. I think I'll have a go with the IPA and paper, though whether IPA is as required as it is with attenuator contacts, I'm not sure. The pcb material looks as though it is fairly ordinary, rather than the polyphenylene oxide used in scope attenuators, which can be damaged by some solvents. Another fault is that sometimes one or more sections of the seven-segment led displays tend to flick on or off - maybe this will improve with switch-contact cleaning? Colin. -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Roger Evans via groups.io Sent: 05 June 2020 11:55 To: [email protected] Subject: Re: [TekScopes] DM502 with problems Correction, I don't think the cam switches improve with use, if they are dirty they need cleaning with IPA and strips of paper. Roger -- Dennis Tillman W7pF TekScopes Moderator |
