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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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Identify this components please.
Hi,
Strapped directly across the b-e junction of a TIPL755A bipolar in a SMPS out of a HP54502A scope is the following - Body - cylindrical, black plastic, 5/8" long by 1/4" dia. Body markings - MCS MTS 90A. Leads - two, axial. PCB marking - S1. Polarity markings - nil. Condition - s/c. Naturally I don't have a schematic but my guess is that it's some sort of over-voltage clamp. A great deal of googling hasn't helped me so any info would be much appreciated. Happy Holidays - Joe |
#2
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Identify this components please.
Joe McElvenney wrote in message
... Hi, Strapped directly across the b-e junction of a TIPL755A bipolar in a SMPS out of a HP54502A scope is the following - Body - cylindrical, black plastic, 5/8" long by 1/4" dia. Body markings - MCS MTS 90A. Leads - two, axial. PCB marking - S1. Polarity markings - nil. Condition - s/c. Naturally I don't have a schematic but my guess is that it's some sort of over-voltage clamp. A great deal of googling hasn't helped me so any info would be much appreciated. Happy Holidays - Joe inductor ? |
#3
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Identify this components please.
Joe McElvenney wrote: Hi, Strapped directly across the b-e junction of a TIPL755A bipolar in a SMPS out of a HP54502A scope is the following - Body - cylindrical, black plastic, 5/8" long by 1/4" dia. Body markings - MCS MTS 90A. Leads - two, axial. PCB marking - S1. Polarity markings - nil. Condition - s/c. Naturally I don't have a schematic but my guess is that it's some sort of over-voltage clamp. A great deal of googling hasn't helped me so any info would be much appreciated. Happy Holidays - Joe It doesn't appear to have the schematic but the 'service' manual is available for free at the manufacturer's website: http://www.home.agilent.com/agilent/techSupport.jspx?pid=54502A%3Aepsg%3Apro&pageMode= MN&cc=US&lc=eng -- http://improve-usenet.org/index.html aioe.org, Goggle Groups, and Web TV users must request to be white listed, or I will not see your messages. If you have broadband, your ISP may have a NNTP news server included in your account: http://www.usenettools.net/ISP.htm There are two kinds of people on this earth: The crazy, and the insane. The first sign of insanity is denying that you're crazy. |
#4
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Identify this components please.
On Mon, 22 Dec 2008 13:35:11 +0000, Joe McElvenney
put finger to keyboard and composed: Hi, Strapped directly across the b-e junction of a TIPL755A bipolar in a SMPS out of a HP54502A scope is the following - Body - cylindrical, black plastic, 5/8" long by 1/4" dia. Body markings - MCS MTS 90A. Leads - two, axial. PCB marking - S1. Polarity markings - nil. Condition - s/c. Naturally I don't have a schematic but my guess is that it's some sort of over-voltage clamp. A great deal of googling hasn't helped me so any info would be much appreciated. Happy Holidays - Joe Is there an S2? I don't know what a coil would be doing across a B-E junction, but can you measure any inductance? I can't imagine that S1 is an OV clamp, unless it is a reverse biased diode for protection against excessive negative voltages. But then a diode would have a polarity marking. Does the body of the device have sharp ends (like a 1N4007 diode) or are the ends rounded like a resistor? - Franc Zabkar -- Please remove one 'i' from my address when replying by email. |
#5
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Identify this components please.
Hi everybody,
It appears that the components is a thermal switch that shunts base current away from the switching transistor when the ambient board temperature reaches a certain figure due to a fault condition such as an overload or a fan failure. I have the HP service manual but it doesn't have a parts list or schematic for the SMPS, so I'm reduced to guessing my way round the circuit. The unit works without the temperature switch but I can use a locally available substitute while looking for the real thing. I am currently investigating a source of C122F1 SCR's so I may fix the +5.2V regulator. BTW, I gave the marking incorrectly - twice; they are MCI MTS 90A. Thanks for your help - Joe |
#6
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Identify this components please.
On Wed, 24 Dec 2008 19:58:37 +0000, Joe McElvenney
put finger to keyboard and composed: Hi everybody, It appears that the components is a thermal switch that shunts base current away from the switching transistor when the ambient board temperature reaches a certain figure due to a fault condition such as an overload or a fan failure. I have the HP service manual but it doesn't have a parts list or schematic for the SMPS, so I'm reduced to guessing my way round the circuit. The unit works without the temperature switch but I can use a locally available substitute while looking for the real thing. I am currently investigating a source of C122F1 SCR's so I may fix the +5.2V regulator. BTW, I gave the marking incorrectly - twice; they are MCI MTS 90A. Thanks for your help - Joe US patent number 5,512,732 ... http://www.google.com/patents/pdf/Sw...0K xc1wO6MuFw .... refers to a "ferrite reed switch" obtained from Therm-O-Disc, Inc of Mansfield, Ohio, model MTS-90B with a Curie temperature of 90 degC. US patent number 4,509,029 ... http://www.google.com/patents/pdf/Th...sZS7rwyBfNBD3Q .... assigned to Midwest Components, Inc, (MCI?) describes a thermal switch consisting of "a reed switch surrounded by an annular collar made of ferrite material and a pair of annular permanent magnets". The latter patent refers to a brochure entitled "Thermal Reed Switches" by Tohoku Metal Industries. I suspect that "MTS" may stand for "Magnetic Temperature Switch". There are plenty of Google hits for this term. AFAICT, Midwest Components, Inc is a division of Therm-O-Disc, Inc: http://www.thermodisc.com/index.asp This site lists an MTS90B part made by MCI: http://www.mwcomponents.com/~midwest...ser_part=mts90 - Franc Zabkar -- Please remove one 'i' from my address when replying by email. |
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