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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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Battery monitor IC
I repaired a guitat tuner today - blown 78L05 as
no supply reversal protection. I was intrigued by another 3 pin TO92 device marked 8054 HN 3C31 Presumably working order - just wondered what it did. Probably 8054HN not 8054 datecode , by Seiko, activation voltage 3.8V to 4.2V, battery monitor. One line is connected to INVERSE READ of the 80C51 micro , I didn't trace any other lines. But what would it do presumably when 5V drops to 4V or so. Just kill the LED drives or shut down completely via some other undiscovered trace. Seems odd having this sophistication but no diode protection against battery or ext ps reversal, especially in a product destined for musos. electronic hints and repair briefs , schematics/manuals list on http://homepages.tcp.co.uk/~diverse |
#2
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On Wed, 2 Mar 2005 13:30:22 -0000, "N Cook"
put finger to keyboard and composed: I repaired a guitat tuner today - blown 78L05 as no supply reversal protection. I was intrigued by another 3 pin TO92 device marked 8054 HN 3C31 Presumably working order - just wondered what it did. Probably 8054HN not 8054 datecode , by Seiko, activation voltage 3.8V to 4.2V, battery monitor. One line is connected to INVERSE READ of the 80C51 micro Are you sure it isn't connected to the uC's reset pin? , I didn't trace any other lines. But what would it do presumably when 5V drops to 4V or so. Just kill the LED drives or shut down completely via some other undiscovered trace. Seems odd having this sophistication but no diode protection against battery or ext ps reversal, especially in a product destined for musos. I think it's a PSU supervisor IC used to hold uPs in reset mode in the event of low Vcc. I believe the output pin should be high if Vcc is OK. IIRC, I've seen an S8053ALR used in an Akai VCR for this purpose. - Franc Zabkar -- Please remove one 's' from my address when replying by email. |
#3
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"Franc Zabkar" wrote in message
... On Wed, 2 Mar 2005 13:30:22 -0000, "N Cook" put finger to keyboard and composed: I repaired a guitat tuner today - blown 78L05 as no supply reversal protection. I was intrigued by another 3 pin TO92 device marked 8054 HN 3C31 Presumably working order - just wondered what it did. Probably 8054HN not 8054 datecode , by Seiko, activation voltage 3.8V to 4.2V, battery monitor. One line is connected to INVERSE READ of the 80C51 micro Are you sure it isn't connected to the uC's reset pin? , I didn't trace any other lines. But what would it do presumably when 5V drops to 4V or so. Just kill the LED drives or shut down completely via some other undiscovered trace. Seems odd having this sophistication but no diode protection against battery or ext ps reversal, especially in a product destined for musos. I think it's a PSU supervisor IC used to hold uPs in reset mode in the event of low Vcc. I believe the output pin should be high if Vcc is OK. IIRC, I've seen an S8053ALR used in an Akai VCR for this purpose. - Franc Zabkar -- Please remove one 's' from my address when replying by email. So what would happen to a microcontroller without such an IC and low Vcc state. It wouldn't corrupt the internal ROM. I originally suspected it might be a negative rail inverter or negative v. reg. |
#4
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On Wed, 2 Mar 2005 22:34:13 -0000, "N Cook"
put finger to keyboard and composed: "Franc Zabkar" wrote in message .. . On Wed, 2 Mar 2005 13:30:22 -0000, "N Cook" put finger to keyboard and composed: I repaired a guitat tuner today - blown 78L05 as no supply reversal protection. I was intrigued by another 3 pin TO92 device marked 8054 HN 3C31 Presumably working order - just wondered what it did. Probably 8054HN not 8054 datecode , by Seiko, activation voltage 3.8V to 4.2V, battery monitor. One line is connected to INVERSE READ of the 80C51 micro Are you sure it isn't connected to the uC's reset pin? , I didn't trace any other lines. But what would it do presumably when 5V drops to 4V or so. Just kill the LED drives or shut down completely via some other undiscovered trace. Seems odd having this sophistication but no diode protection against battery or ext ps reversal, especially in a product destined for musos. I think it's a PSU supervisor IC used to hold uPs in reset mode in the event of low Vcc. I believe the output pin should be high if Vcc is OK. IIRC, I've seen an S8053ALR used in an Akai VCR for this purpose. - Franc Zabkar -- Please remove one 's' from my address when replying by email. So what would happen to a microcontroller without such an IC and low Vcc state. It wouldn't corrupt the internal ROM. I originally suspected it might be a negative rail inverter or negative v. reg. I think these supervisor ICs are used where loss of sanity in the uC can have serious consequences, ie a mechanism jam in a VCR. I wouldn't think a guitar tuner would have this kind of requirement, though. Have you confirmed whether the 8053 is connected to the uC's RD* or reset pin? - Franc Zabkar -- Please remove one 's' from my address when replying by email. |
#5
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"Franc Zabkar" wrote in message ... On Wed, 2 Mar 2005 22:34:13 -0000, "N Cook" put finger to keyboard and composed: "Franc Zabkar" wrote in message .. . On Wed, 2 Mar 2005 13:30:22 -0000, "N Cook" put finger to keyboard and composed: I repaired a guitat tuner today - blown 78L05 as no supply reversal protection. I was intrigued by another 3 pin TO92 device marked 8054 HN 3C31 Presumably working order - just wondered what it did. Probably 8054HN not 8054 datecode , by Seiko, activation voltage 3.8V to 4.2V, battery monitor. One line is connected to INVERSE READ of the 80C51 micro Are you sure it isn't connected to the uC's reset pin? , I didn't trace any other lines. But what would it do presumably when 5V drops to 4V or so. Just kill the LED drives or shut down completely via some other undiscovered trace. Seems odd having this sophistication but no diode protection against battery or ext ps reversal, especially in a product destined for musos. I think it's a PSU supervisor IC used to hold uPs in reset mode in the event of low Vcc. I believe the output pin should be high if Vcc is OK. IIRC, I've seen an S8053ALR used in an Akai VCR for this purpose. - Franc Zabkar -- Please remove one 's' from my address when replying by email. So what would happen to a microcontroller without such an IC and low Vcc state. It wouldn't corrupt the internal ROM. I originally suspected it might be a negative rail inverter or negative v. reg. I think these supervisor ICs are used where loss of sanity in the uC can have serious consequences, ie a mechanism jam in a VCR. I wouldn't think a guitar tuner would have this kind of requirement, though. Have you confirmed whether the 8053 is connected to the uC's RD* or reset pin? - Franc Zabkar -- Please remove one 's' from my address when replying by email. Guitar tuner back with owner, so nothing else known. I agree that by the time 9V had dropped to 4.2V , LEDs would be decidedly feint and whole unit will not operate much longer and no consequential damage anyway if it did, compared to lack of power reversal protection. |
#6
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On Wed, 2 Mar 2005 13:30:22 -0000, "N Cook"
put finger to keyboard and composed: I repaired a guitat tuner today - blown 78L05 as no supply reversal protection. I was intrigued by another 3 pin TO92 device marked 8054 HN 3C31 Presumably working order - just wondered what it did. Probably 8054HN not 8054 datecode , by Seiko, activation voltage 3.8V to 4.2V, battery monitor. Just by accident I found these devices by KEC. They may be similar. http://databook.kec.co.kr/Data/PDF/K...45AP_AF_AT.pdf - Franc Zabkar -- Please remove one 's' from my address when replying by email. |
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