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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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Sharp HT-M700 DVD player - need help with pickup not driven...
Inserting disks you obtain "READING" message for a long time. Then "NO
DISK". Inside inspection (as per FAQ): the spindle motor correctly runs. Sled doesn't move unless you manually move it to a different location; it correctly comes back to the original position. It is correctly driven. Neither attempt to focus nor laser light up are performed (dead pickup). Removed/cleaned/remounted the pickup flat cable: no change. The lens servo works if manually powered (lens goes up and down) The laser lights up if manually powered. Power supply voltages are as per onboard indications. Seems a problem with the pickup driver circuitry. I published a snapshot of the main board @ http://www.qsl.net/iw1dhi/pickup-driver.JPG. Any idea about what to check further? Any information about test points? Any picofuse around?? Thanks in advance. Emanuele. |
#2
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Sharp HT-M700 DVD player - need help with pickup not driven...
On 1 Ott, 23:46, Emanuele Girlando
wrote: Inserting disks you obtain "READING" message for a long time. Then "NO DISK". Inside inspection (as per FAQ): the spindle motor correctly runs. Sled doesn't move unless you manually move it to a different location; it correctly comes back to the original position. It is correctly driven. Neither attempt to focus nor laser light up are performed (dead pickup). Removed/cleaned/remounted the pickup flat cable: no change. The lens servo works if manually powered (lens goes up and down) The laser lights up if manually powered. Power supply voltages are as per onboard indications. Seems a problem with the pickup driver circuitry. I published a snapshot of the main board @http://www.qsl.net/iw1dhi/pickup-driver.JPG. Any idea about what to check further? Any information about test points? Any picofuse around?? Thanks in advance. Emanuele. nobody out there ?? |
#3
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Sharp HT-M700 DVD player - need help with pickup not driven...
On Mon, 01 Oct 2007 14:46:54 -0700, Emanuele Girlando
put finger to keyboard and composed: Inserting disks you obtain "READING" message for a long time. Then "NO DISK". Inside inspection (as per FAQ): the spindle motor correctly runs. Sled doesn't move unless you manually move it to a different location; it correctly comes back to the original position. It is correctly driven. Neither attempt to focus nor laser light up are performed (dead pickup). Removed/cleaned/remounted the pickup flat cable: no change. The lens servo works if manually powered (lens goes up and down) The laser lights up if manually powered. Power supply voltages are as per onboard indications. Seems a problem with the pickup driver circuitry. I published a snapshot of the main board @ http://www.qsl.net/iw1dhi/pickup-driver.JPG. Any idea about what to check further? Any information about test points? Any picofuse around?? Thanks in advance. Emanuele. I don't know anything about your model, but I'd check the AM5868S driver IC. There is an application circuit in this datasheet: http://www.amtek-semi.com/files/AM5868.pdf Verify the inputs coming from the uP and check Vcc1 and Vcc2. I'd also look for a tray-in/tray-out switch at one of the connectors. - Franc Zabkar -- Please remove one 'i' from my address when replying by email. |
#4
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Sharp HT-M700 DVD player - need help with pickup not driven...
On 5 Ott, 23:15, Franc Zabkar wrote:
On Mon, 01 Oct 2007 14:46:54 -0700, Emanuele Girlando put finger to keyboard and composed: Inserting disks you obtain "READING" message for a long time. Then "NO DISK". Inside inspection (as per FAQ): the spindle motor correctly runs. Sled doesn't move unless you manually move it to a different location; it correctly comes back to the original position. It is correctly driven. Neither attempt to focus nor laser light up are performed (dead pickup). Removed/cleaned/remounted the pickup flat cable: no change. The lens servo works if manually powered (lens goes up and down) The laser lights up if manually powered. Power supply voltages are as per onboard indications. Seems a problem with the pickup driver circuitry. I published a snapshot of the main board @http://www.qsl.net/iw1dhi/pickup-driver.JPG. Any idea about what to check further? Any information about test points? Any picofuse around?? Thanks in advance. Emanuele. I don't know anything about your model, but I'd check the AM5868S driver IC. There is an application circuit in this datasheet: http://www.amtek-semi.com/files/AM5868.pdf Verify the inputs coming from the uP and check Vcc1 and Vcc2. I'd also look for a tray-in/tray-out switch at one of the connectors. - Franc Zabkar -- Please remove one 'i' from my address when replying by email. Franc, Vcc1 and Vcc2 are both at 5V. Specs call for +12V at pin8 (Vcc1) ... but it is connected to power supply +5V .. so I assume it is correct. Mute (pin28) is down to 0.37V in normal conditions. It rises at +2.2V during attempts to read disks. Sounds good. I'll further investigate tomorrow. Thank you very much for your support. |
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