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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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Commodore Amiga A1080 Monitor
I'm looking for a schematic for the above named monitor. My vertical
has compressed down to a thin line across the center of the screen. Replacing the electrolytic capacitors has not helped. Searches of the web have been fruitless. One monitor schematic for the Commodore A2002 was alleged to be similar but when I get down to the component level they are very different. -- Rick Jones Remove the Extra Dot to e-mail me |
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"Rick Jones" wrote in message ... I'm looking for a schematic for the above named monitor. My vertical has compressed down to a thin line across the center of the screen. Replacing the electrolytic capacitors has not helped. Searches of the web have been fruitless. One monitor schematic for the Commodore A2002 was alleged to be similar but when I get down to the component level they are very different. -- What use would a schematic be? It should be easy to find the vertical output IC or transistors on the board, check to see if they're shorted, if they are then look for an open fusible resistor nearby. Could also be as simple as a cold solder joint in that area. |
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James Sweet wrote:
"Rick Jones" wrote in message ... I'm looking for a schematic for the above named monitor. My vertical has compressed down to a thin line across the center of the screen. Replacing the electrolytic capacitors has not helped. Searches of the web have been fruitless. One monitor schematic for the Commodore A2002 was alleged to be similar but when I get down to the component level they are very different. What use would a schematic be? It should be easy to find the vertical output IC or transistors on the board, check to see if they're shorted, if they are then look for an open fusible resistor nearby. Could also be as simple as a cold solder joint in that area. I need the schematic to determine exactly which components those are on the PCBs. -- Rick Jones Remove the Extra Dot to e-mail me |
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On Mon, 15 Nov 2004 21:22:40 -0600, Rick Jones
put finger to keyboard and composed: I'm looking for a schematic for the above named monitor. My vertical has compressed down to a thin line across the center of the screen. Replacing the electrolytic capacitors has not helped. Searches of the web have been fruitless. One monitor schematic for the Commodore A2002 was alleged to be similar but when I get down to the component level they are very different. Have you tried these URLs? http://project64.c64.org/hw/peri.html http://amiga.serveftp.net/schematics.html I suggest you identify the vertical output IC or transistor pair. It should be fairly obvious which IC is the right one by following the yoke connector to the main PCB. These ICs are usually mounted on a heatsink and are packaged in SIPs. Their supply is most often derived from a winding on the flyback transformer. There will be a series rectifier diode and probably a low ohm fusible resistor. If you still can't find the vertical IC, post some part numbers and someone will be able to recognise it. You will most probably find that the datasheet for the IC will contain an application circuit that will closely match the layout in your monitor. - Franc Zabkar -- Please remove one 's' from my address when replying by email. |
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Even a "Digital Camera" photo may assist others in helping, please make sure
it is clearly produced. "Franc Zabkar" wrote in message ... On Mon, 15 Nov 2004 21:22:40 -0600, Rick Jones put finger to keyboard and composed: I'm looking for a schematic for the above named monitor. My vertical has compressed down to a thin line across the center of the screen. Replacing the electrolytic capacitors has not helped. Searches of the web have been fruitless. One monitor schematic for the Commodore A2002 was alleged to be similar but when I get down to the component level they are very different. Have you tried these URLs? http://project64.c64.org/hw/peri.html http://amiga.serveftp.net/schematics.html I suggest you identify the vertical output IC or transistor pair. It should be fairly obvious which IC is the right one by following the yoke connector to the main PCB. These ICs are usually mounted on a heatsink and are packaged in SIPs. Their supply is most often derived from a winding on the flyback transformer. There will be a series rectifier diode and probably a low ohm fusible resistor. If you still can't find the vertical IC, post some part numbers and someone will be able to recognise it. You will most probably find that the datasheet for the IC will contain an application circuit that will closely match the layout in your monitor. - Franc Zabkar -- Please remove one 's' from my address when replying by email. |
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"Rick Jones" wrote in message ... James Sweet wrote: "Rick Jones" wrote in message ... I'm looking for a schematic for the above named monitor. My vertical has compressed down to a thin line across the center of the screen. Replacing the electrolytic capacitors has not helped. Searches of the web have been fruitless. One monitor schematic for the Commodore A2002 was alleged to be similar but when I get down to the component level they are very different. What use would a schematic be? It should be easy to find the vertical output IC or transistors on the board, check to see if they're shorted, if they are then look for an open fusible resistor nearby. Could also be as simple as a cold solder joint in that area. I need the schematic to determine exactly which components those are on the PCBs. This is not meant to be an insult, but if you can't identify the vertical output IC or transistors by glancing at the board then you probably should do some research on CRT display repair before you dig into this one. Very worst case you could simply follow the traces back from where the vertical yoke plugs in. |
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Franc Zabkar wrote:
I suggest you identify the vertical output IC or transistor pair. It should be fairly obvious which IC is the right one by following the yoke connector to the main PCB. These ICs are usually mounted on a heatsink and are packaged in SIPs. Their supply is most often derived from a winding on the flyback transformer. There will be a series rectifier diode and probably a low ohm fusible resistor. If you still can't find the vertical IC, post some part numbers and someone will be able to recognise it. You will most probably find that the datasheet for the IC will contain an application circuit that will closely match the layout in your monitor. OK, here's some info: The monitor was manufactured by Toshiba; the name is etched into all of the PCBs. The main board that lays flat across the bottom has what appears to be P/N PW5253. This has one IC on it - a 42-pin DIP P/N TA7644. I have tried to find a datasheet for this IC but no luck. A second small PCB stands at the back of this and has P/N PWPW5252-3. This board has all of the connectors for RGB, composite video, split video and mono audio input for the built-in speaker. There is one IC on this board, P/N TC4053. The third board is mounted vertically on the right side (facing the front of the tube). This PCB is P/N PW5252-1. There are 3 ICs on this board - P/N HD7407, P/N TC4053 and P/N AN5352. The 4th board in the system is the yoke board, which I guess we're all pretty sure is no concern with this particular problem. Also, the 3 digital chips - 7407 and 4053 - would not seem to be of concern. Research on the AN5352 IC showed it to be a character generator, which seems odd for a monitor. This unit has no capabilities to function as a terminal AFAIK. That leaves the TA7644, which I can find no detailed information on, just general data that it's a monitor controller IC. Either the vertical circuit is a part of this 42-pin chip or it's all generated discretely. -- Rick Jones Remove the Extra Dot to e-mail me |
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On Wed, 17 Nov 2004 19:12:23 -0600, Rick Jones
put finger to keyboard and composed: Franc Zabkar wrote: I suggest you identify the vertical output IC or transistor pair. It should be fairly obvious which IC is the right one by following the yoke connector to the main PCB. These ICs are usually mounted on a heatsink and are packaged in SIPs. Their supply is most often derived from a winding on the flyback transformer. There will be a series rectifier diode and probably a low ohm fusible resistor. If you still can't find the vertical IC, post some part numbers and someone will be able to recognise it. You will most probably find that the datasheet for the IC will contain an application circuit that will closely match the layout in your monitor. OK, here's some info: The monitor was manufactured by Toshiba; the name is etched into all of the PCBs. The main board that lays flat across the bottom has what appears to be P/N PW5253. This has one IC on it - a 42-pin DIP P/N TA7644. I have tried to find a datasheet for this IC but no luck. A second small PCB stands at the back of this and has P/N PWPW5252-3. This board has all of the connectors for RGB, composite video, split video and mono audio input for the built-in speaker. There is one IC on this board, P/N TC4053. The third board is mounted vertically on the right side (facing the front of the tube). This PCB is P/N PW5252-1. There are 3 ICs on this board - P/N HD7407, P/N TC4053 and P/N AN5352. The 4th board in the system is the yoke board, which I guess we're all pretty sure is no concern with this particular problem. Also, the 3 digital chips - 7407 and 4053 - would not seem to be of concern. Research on the AN5352 IC showed it to be a character generator, which seems odd for a monitor. This unit has no capabilities to function as a terminal AFAIK. AN5352 = NTE1835 http://www.nteinc.com/specs/1800to1899/NTE1835.html http://www.nteinc.com/specs/1800to1899/pdf/nte1835.pdf That leaves the TA7644, which I can find no detailed information on, just general data that it's a monitor controller IC. Either the vertical circuit is a part of this 42-pin chip or it's all generated discretely. TA7644 = NTE1547 http://www.nteinc.com/specs/1500to1599/NTE1547.html http://www.nteinc.com/specs/1500to1599/pdf/nte1547.pdf This is the "jungle IC". Follow pin 26 (vertical drive output) to either a vertical output IC, or to a heatsinked transistor pair. FYI, you can search for datasheets of equivalent devices at this URL: http://nte01.nteinc.com/nte/NTExRefSemiProd.nsf/$$Search?OpenForm - Franc Zabkar -- Please remove one 's' from my address when replying by email. |
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"Rick Jones" wrote in message ... Franc Zabkar wrote: I suggest you identify the vertical output IC or transistor pair. It should be fairly obvious which IC is the right one by following the yoke connector to the main PCB. These ICs are usually mounted on a heatsink and are packaged in SIPs. Their supply is most often derived from a winding on the flyback transformer. There will be a series rectifier diode and probably a low ohm fusible resistor. If you still can't find the vertical IC, post some part numbers and someone will be able to recognise it. You will most probably find that the datasheet for the IC will contain an application circuit that will closely match the layout in your monitor. OK, here's some info: The monitor was manufactured by Toshiba; the name is etched into all of the PCBs. The main board that lays flat across the bottom has what appears to be P/N PW5253. This has one IC on it - a 42-pin DIP P/N TA7644. I have tried to find a datasheet for this IC but no luck. A second small PCB stands at the back of this and has P/N PWPW5252-3. This board has all of the connectors for RGB, composite video, split video and mono audio input for the built-in speaker. There is one IC on this board, P/N TC4053. The third board is mounted vertically on the right side (facing the front of the tube). This PCB is P/N PW5252-1. There are 3 ICs on this board - P/N HD7407, P/N TC4053 and P/N AN5352. The 4th board in the system is the yoke board, which I guess we're all pretty sure is no concern with this particular problem. Also, the 3 digital chips - 7407 and 4053 - would not seem to be of concern. Research on the AN5352 IC showed it to be a character generator, which seems odd for a monitor. This unit has no capabilities to function as a terminal AFAIK. That leaves the TA7644, which I can find no detailed information on, just general data that it's a monitor controller IC. Either the vertical circuit is a part of this 42-pin chip or it's all generated discretely. - It's unlikely any of this stuff is the vertical output, it'll be either a 6-12 pin IC standing vertically screwed to a heatsink, or a pair of TO-220 or similar cased power transistors on heatsinks. |
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I'm looking for a schematic for the above named monitor. My vertical
has compressed down to a thin line across the center of the screen. Replacing the electrolytic capacitors has not helped. Searches of the web have been fruitless. One monitor schematic for the Commodore A2002 was alleged to be similar but when I get down to the component level they are very different. Rick, Let me know if you ever find a schematic. You likely came across my site looking for that diagram and I've never found one either. The 1080 was the same as the 1902 (non-A version) or so I was told. Anyway, take a look at the different 1084 schematics. One of them may be similar enough in the vertical circuit at least to get you going. If you can find a the same IC used, you're close. It's likely to be the 300 series board location (ie the vertical output IC will be marked I301). If so, all the components will have a 3xx number: R301, C301, etc. If you can't find a print, that may help find your way around. Once you find the vertical IC (resolder it, of course) check for B+. If it has none, check backwards for a missing source from the flyback (shorted diode, open fuse/resistor, etc.). Don't overlook a bad yoke connection. Commodore monitors are infamous for bad solder connections. When I get one on the bench, no matter what the symptoms are, I first resolder all the connections to the flyback and H driver transformer, all diodes and power transistors and all resistors of 1 Watt and higher, and any other connections that look "flaky". Then I go for other problems if there are any. Ray -- My return addy is spamblocked. To reply, remove the zeroes. |
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Rick Jones wrote:
I'm looking for a schematic for the above named monitor. My vertical has compressed down to a thin line across the center of the screen. Replacing the electrolytic capacitors has not helped. Searches of the web have been fruitless. One monitor schematic for the Commodore A2002 was alleged to be similar but when I get down to the component level they are very different. Rick, You're quite correct about the A2002 schematic. I have both monitors but no schematic for the 1080, unfortunately. However, I did some digging inside my 1080 and the following info may help. This is now on my site with a correction regarding the (dis)similiarity between models. Sorry for the confusion. It was made by Toshiba and is unlike any other CBM monitor and my other schematics will not substitute. Note that it is nearly identical in outward appearance and features to Commodore monitor models 1902 (non-A model) and 1084. However, the internal construction, components and board numbers are completely different. I own a 1080, and I have collected some information about it to assist those who might have to repair one. The chassis number of my monitor is TAK8520. Although the construction of this monitor makes troubleshooting difficult because of crowded boards, all boards are silkscreened on both sides with component identifier numbers. All internal controls are marked as well. Note that each section of the monitor is numbered, and that can be used to locate components in each circuit. The following is viewed facing the rear of the monitor with the back cover removed. The bottom main PC board contains the Horizontal Sweep, HV, Vertical and low voltage power supply circuits. The PC board designation for the H sweep section is 400 (example: H output transistor is Q404). The vertical sweep section is designated 300. The power supply is 800. The left upright mounted PC board is analog video and digital signal processing (100) and an audio amplifier (600). That board swings away to the left (remove two screws) for better access to it and the bottom board. The rear upright PC board is an A/V and RGB connector interface and has both 100 (signal) and 600 (audio) components on it. Lastly, the CRT board (500) mounted on the back of the picture tube contains the driver and output transistors for the CRT. The Low Voltage Power Supply (LVPS): main switcher transistor is Q801, a 2SD1432. The line fuse is a 3 Amp F801, and the B+ fuse is a 1.2 Amp F802. Both fuses are on the bottom PC board in fuse clips. HV & Horiz Sweep: the Horizontal Output (Line Output) transistor is a 2SD1427 Q404 and the flyback (line output transformer) T461 is part number TFB5017AD (which looks like a Panasonic number). Vertical circuit: this monitor uses descrete components (no ICs). The output transistors are Q304 2SC2073 and Q305 2SA940. Note that this monitor has a service switch in the center of the bottom board towards the left side. That switch should be in the NORMAL position. If in SERVICE, the vertical sweep will collapse to a single horizontal line (used for CRT setup adjustments). Ray |
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Ray Carlsen wrote:
It was made by Toshiba and is unlike any other CBM monitor and my other schematics will not substitute. Note that it is nearly identical in outward appearance and features to Commodore monitor models 1902 (non-A model) and 1084. However, the internal construction, components and board numbers are completely different. I own a 1080, and I have collected some information about it to assist those who might have to repair one. The chassis number of my monitor is TAK8520. Although the construction of this monitor makes troubleshooting difficult because of crowded boards, all boards are silkscreened on both sides with component identifier numbers. All internal controls are marked as well. Note that each section of the monitor is numbered, and that can be used to locate components in each circuit. The following is viewed facing the rear of the monitor with the back cover removed. The bottom main PC board contains the Horizontal Sweep, HV, Vertical and low voltage power supply circuits. The PC board designation for the H sweep section is 400 (example: H output transistor is Q404). The vertical sweep section is designated 300. The power supply is 800. The left upright mounted PC board is analog video and digital signal processing (100) and an audio amplifier (600). That board swings away to the left (remove two screws) for better access to it and the bottom board. The rear upright PC board is an A/V and RGB connector interface and has both 100 (signal) and 600 (audio) components on it. Lastly, the CRT board (500) mounted on the back of the picture tube contains the driver and output transistors for the CRT. The Low Voltage Power Supply (LVPS): main switcher transistor is Q801, a 2SD1432. The line fuse is a 3 Amp F801, and the B+ fuse is a 1.2 Amp F802. Both fuses are on the bottom PC board in fuse clips. HV & Horiz Sweep: the Horizontal Output (Line Output) transistor is a 2SD1427 Q404 and the flyback (line output transformer) T461 is part number TFB5017AD (which looks like a Panasonic number). Vertical circuit: this monitor uses descrete components (no ICs). The output transistors are Q304 2SC2073 and Q305 2SA940. Note that this monitor has a service switch in the center of the bottom board towards the left side. That switch should be in the NORMAL position. If in SERVICE, the vertical sweep will collapse to a single horizontal line (used for CRT setup adjustments). Thanks Ray. The monitor is underneath my bench at work and I'm off until the Monday after Thanksgiving so I won't get to delve into it again until then. Maybe with this info and the datasheet for the NTE equivalent of the big TA7644 IC I can troubleshoot the problem. -- Rick Jones Remove the Extra Dot to e-mail me How come we choose from just two people for President and fifty for Miss America? |
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