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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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PM5418 need prom dump
For this pattern generator I need the dump of the main prom (D313). It's a
27C256 with PLCC32 housing in a socket, located in the right corner on the back of the instrument. Can anybody help me? |
#2
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PM5418 need prom dump
On Wed, 13 Jul 2011 00:07:21 +0200 "H.den Boer" wrote in Message
id: l: For this pattern generator I need the dump of the main prom (D313). It's a 27C256 with PLCC32 housing in a socket, located in the right corner on the back of the instrument. Can anybody help me? What's wrong with the one currently in it? Have you tried reading the data from it with a lowered VCC? |
#3
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PM5418 need prom dump
For this pattern generator I need the dump of the main prom (D313). It's a 27C256 with PLCC32 housing in a socket, located in the right corner on the back of the instrument. Can anybody help me? What's wrong with the one currently in it? Have you tried reading the data from it with a lowered VCC? I can read it, but databit 6 is always '1' the pin is shorted to Vcc, |
#4
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PM5418 need prom dump
On Wed, 13 Jul 2011 11:41:19 +0200 "H.den Boer" wrote in Message
id: : For this pattern generator I need the dump of the main prom (D313). It's a 27C256 with PLCC32 housing in a socket, located in the right corner on the back of the instrument. Can anybody help me? What's wrong with the one currently in it? Have you tried reading the data from it with a lowered VCC? I can read it, but databit 6 is always '1' the pin is shorted to Vcc, Ouch. Well, reading an EPROM at a lower VCC will sometimes allow you to get all the data off a flaky device, but in your case, it probably won't help. Did you actually measure the short right at the pin with a DMM, or just assume it was shorted to VCC from the data pattern? |
#5
Posted to sci.electronics.repair
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PM5418 need prom dump
For this pattern generator I need the dump of the main prom (D313). It's a 27C256 with PLCC32 housing in a socket, located in the right corner on the back of the instrument. Can anybody help me? What's wrong with the one currently in it? Have you tried reading the data from it with a lowered VCC? I can read it, but databit 6 is always '1' the pin is shorted to Vcc, Ouch. Well, reading an EPROM at a lower VCC will sometimes allow you to get all the data off a flaky device, but in your case, it probably won't help. Did you actually measure the short right at the pin with a DMM, or just assume it was shorted to VCC from the data pattern? It measures under 25 ohms, so no luck there, the prom is fried anyway, it gets warm and consumes too much power. It's a wonder I can read it at all, but without bit 6 it is no good. |
#6
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PM5418 need prom dump
On Wed, 13 Jul 2011 12:34:27 +0200 "H.den Boer" wrote in Message
id: : For this pattern generator I need the dump of the main prom (D313). It's a 27C256 with PLCC32 housing in a socket, located in the right corner on the back of the instrument. Can anybody help me? What's wrong with the one currently in it? Have you tried reading the data from it with a lowered VCC? I can read it, but databit 6 is always '1' the pin is shorted to Vcc, Ouch. Well, reading an EPROM at a lower VCC will sometimes allow you to get all the data off a flaky device, but in your case, it probably won't help. Did you actually measure the short right at the pin with a DMM, or just assume it was shorted to VCC from the data pattern? It measures under 25 ohms, so no luck there, the prom is fried anyway, it gets warm and consumes too much power. It's a wonder I can read it at all, but without bit 6 it is no good. If I had one, I'd be willing to read the binary for you. You could try these groups, lots of very helpful folks the http://tech.groups.yahoo.com/group/TekScopes/ http://tech.groups.yahoo.com/group/h...ent_equipment/ http://tech.groups.yahoo.com/group/Fluke_DMM/ If anyone on those lists have a PM5418, I'm sure they be willing to get you a copy. You could also try Fluke, the last time I dealt with them they were pretty helpful. Good luck. |
#7
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PM5418 need prom dump
H.den Boer wrote:
For this pattern generator I need the dump of the main prom (D313). It's a 27C256 with PLCC32 housing in a socket, located in the right corner on the back of the instrument. Can anybody help me? What's wrong with the one currently in it? Have you tried reading the data from it with a lowered VCC? I can read it, but databit 6 is always '1' the pin is shorted to Vcc, Ouch. Well, reading an EPROM at a lower VCC will sometimes allow you to get all the data off a flaky device, but in your case, it probably won't help. Did you actually measure the short right at the pin with a DMM, or just assume it was shorted to VCC from the data pattern? It measures under 25 ohms, so no luck there, the prom is fried anyway, it gets warm and consumes too much power. It's a wonder I can read it at all, but without bit 6 it is no good. Does the supply current vary during read depending on the stored data? If so, you *MAY* be able to retrieve bit 6. It is a little difficult to be certain when you don't know what it should be, but if you stick a sense resistor in the VCC supply (maybe with two diodes across it to prevent excessive drop while switching) and scope that and the read signal while reading the chip, you may find you can tell the difference when the lower MOSFET in the D6 output stage switches on to attempt to output logic 0. If so, a PNP transistor, a few resistors and an inverter (possibly with a tristate output controlled by the read signal) may be enough to build a 'gimmick' jig to let your programmer read it. -- Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED) ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk [at]=@, [dash]=- & [dot]=. *Warning* HTML & 32K emails -- NUL: |
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