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7D20 RAMS
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pe1fbo
Hi All,
Today I fixed my 7D20, it had come up with an error, (fail 531). A closer look in the manual pointed to U710, a dynamic RAM (4116) from the prehistoric ages. All RAMS on the memory board where from ITT, date code 8232 and 8237 and had also a white 'TEK' marking. I replaced the bad chip with one from a scrap TEK 9100 logic analyser, also an ITT chip, and made me wonder, because this chip gave me exactly the same error.... So was it perhaps something else ? However a 9100 has 16 4116 so I took an other one, this time an NEC one with a white TEK marking... And this seemed to be working fine. This made me curious and I started to test them all. I found three other ITT chips which were bad, non of the NEC or Mostek chips failed. Could it be that the ITT chips are of inferior quality, or is the chip OK and is this a timing problem in the design of th 7D20 ?. I must say, that the scrap 9100 was also failing due to a bad uP board, the cause is still unknown. Here are the error codes and their chips associated in case you have a similar issue with the RAMS. Dynamic RAMS 4114 521 U910 53 U810 531 U710 532 U610 5321 U510 54 U410 541 U310 542 U210 Static ones 321 U900 4 U800 41 EAROM - Fred de Vries ps look at for a similar case |
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Robert Morein
4116 RAMs did not have completely standard refresh requirements. The RAMs that fail probably need to work with a different refresh controller.
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----- Original Message -----
From: pe1fbo To: TekScopes@... Sent: Sunday, February 29, 2004 9:07 AM Subject: [TekScopes] 7D20 RAMS Hi All, Today I fixed my 7D20, it had come up with an error, (fail 531). A closer look in the manual pointed to U710, a dynamic RAM (4116) from the prehistoric ages. All RAMS on the memory board where from ITT, date code 8232 and 8237 and had also a white 'TEK' marking. I replaced the bad chip with one from a scrap TEK 9100 logic analyser, also an ITT chip, and made me wonder, because this chip gave me exactly the same error.... So was it perhaps something else ? However a 9100 has 16 4116 so I took an other one, this time an NEC one with a white TEK marking... And this seemed to be working fine. This made me curious and I started to test them all. I found three other ITT chips which were bad, non of the NEC or Mostek chips failed. Could it be that the ITT chips are of inferior quality, or is the chip OK and is this a timing problem in the design of th 7D20 ?. I must say, that the scrap 9100 was also failing due to a bad uP board, the cause is still unknown. Here are the error codes and their chips associated in case you have a similar issue with the RAMS. Dynamic RAMS 4114 521 U910 53 U810 531 U710 532 U610 5321 U510 54 U410 541 U310 542 U210 Static ones 321 U900 4 U800 41 EAROM - Fred de Vries ps look at for a similar case Yahoo! Groups Sponsor ADVERTISEMENT ------------------------------------------------------------------------------ Yahoo! Groups Links a.. To visit your group on the web, go to: b.. To unsubscribe from this group, send an email to: TekScopes-unsubscribe@... c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. |
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I had something similar with my 7D01, except that RAMs were from even lower
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layer of Pleistocene, they were 1 K capacity. Surprisingly, I was able to find RAMs at the local junker store and price was not too unreasonable. It is interesting that sequence of fixing resembled closely what Fred described: first replacement did not work, but second chip did. Then, I put back the original chip and that worked, so I concluded that problem was with those 'low bidder' sockets that Tektronix' accountants liked to buy for instruments that had lot of DIPs. The sockets looked like infamous TI products, but judging from age of the plug-in, I would say, it came after TI fixed flux wicking. Regards Miroslav Pokorni ----- Original Message -----
From: "pe1fbo" <sh331182@...> To: <TekScopes@...> Sent: Sunday, February 29, 2004 6:07 AM Subject: [TekScopes] 7D20 RAMS Hi All, |
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Brian Goldsmith
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----- Original Message -----
From: "Miroslav Pokorni" I would say, it came after TI fixed flux wicking. Gosh,after two tinnies of Foster's Lager,I certainly cant say that correctly!!!! :-) Brian Goldsmith |
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jeans
Yeah Brian, but would you care??
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Don Black. Brian Goldsmith wrote: ----- Original Message ----- |
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What did you mean, Don? Before or after Foster's?
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Regards Miroslav Pokorni ----- Original Message -----
From: "jeans" <jeans@...> To: "Brian Goldsmith" <brian.goldsmith@...> Cc: "Miroslav Pokorni" <mpokorni2000@...>; <TekScopes@...>; "pe1fbo" <sh331182@...> Sent: Monday, March 01, 2004 6:04 AM Subject: Re: [TekScopes] 7D20 RAMS Yeah Brian, but would you care?? |
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