this is a great news. May I ask you about my problem? I have +2, and RGB works perfectly, but not the TV output. I am not a HW familiar. Being guided by my colleagues, I found out, that TR4 (hopefully, I remember it well, that it was TR4) was broken. So, I replaced it with a tranzistor BC639. But, after few seconds of running, this tranzistor exploded again. So, at the beginning, there had to be something else faulty, which had caused TR4 to break down.
Are you able to tell wether this is faulty TEA2000 problem? Will your replacement work with +2?
this is a great news. May I ask you about my problem? I have +2, and RGB works perfectly, but not the TV output. I am not a HW familiar. Being guided by my colleagues, I found out, that TR4 (hopefully, I remember it well, that it was TR4) was broken. So, I replaced it with a tranzistor BC639. But, after few seconds of running, this tranzistor exploded again. So, at the beginning, there had to be something else faulty, which had caused TR4 to break down.
Are you able to tell wether this is faulty TEA2000 problem? Will your replacement work with +2?
Thanks
Hood
...oh I am sorry, I have been misleading you. It is not TR4, but TR9 that exploded. It can be replaced either by BC639 or by KC639 (they have different pinouts, but should do).
I'm not sure I have the schematic of the model you have. Can you tell me what +2 model have you got? I assumed that it's the gray model, but I cannot find such transistor, or at least, not related to video circuitry. My guessing is that transistor belongs to the supply circuit, and it may be related in generating 12V from 9V supply, but that part of the schematic is missing...
I'm not sure I have the schematic of the model you have. Can you tell me what +2 model have you got? I assumed that it's the gray model, but I cannot find such transistor, or at least, not related to video circuitry. My guessing is that transistor belongs to the supply circuit, and it may be related in generating 12V from 9V supply, but that part of the schematic is missing...
I'm not sure I have the schematic of the model you have. Can you tell me what +2 model have you got? I assumed that it's the gray model, but I cannot find such transistor, or at least, not related to video circuitry. My guessing is that transistor belongs to the supply circuit, and it may be related in generating 12V from 9V supply, but that part of the schematic is missing...
....exactly, TR9 belongs to the supply circuit. The schematics are in the Velesoft's notion below. It really may have nothing in common with video circuitry. If you had any ideas how to fix it, I would be grateful to you.
....exactly, TR9 belongs to the supply circuit. The schematics are in the Velesoft's notion below. It really may have nothing in common with video circuitry. If you had any ideas how to fix it, I would be grateful to you.
Thanks
Hood
....and as I remember, TR9 is supplying power directly to TEA2000.
Thanks for the information. TR9 not only feeds the TEA2000, but also feeds the voltage level converters that make the RS232 and KEYPAD connections: 1488 and 1489. So the TEA might not be the defective component.It could be even a shorted D19, or C41. It's not the first time I find a dead capacitor introducing noise to the line, or worse.
By the way: my replacement works on a +2 grey, but you will surely have to do some modifications to the video amplifier stage next to the input to UM1233 if you want to use the RF modulator (you have to bypass TR2 and TR1 and connect directly from the cathode of D3 to VIN at the UM1233). A similar hack will be needed if using the composite signal through the DIN connector.
Comments
Hi,
this is a great news. May I ask you about my problem? I have +2, and RGB works perfectly, but not the TV output. I am not a HW familiar. Being guided by my colleagues, I found out, that TR4 (hopefully, I remember it well, that it was TR4) was broken. So, I replaced it with a tranzistor BC639. But, after few seconds of running, this tranzistor exploded again. So, at the beginning, there had to be something else faulty, which had caused TR4 to break down.
Are you able to tell wether this is faulty TEA2000 problem? Will your replacement work with +2?
Thanks
Hood
...oh I am sorry, I have been misleading you. It is not TR4, but TR9 that exploded. It can be replaced either by BC639 or by KC639 (they have different pinouts, but should do).
Hood
ZX Spectrum +2:
LAYOUT
http://zxm.speccy.cz/dok/sch/plus2layout.png
POWER CIRCUIT
http://zxm.speccy.cz/dok/sch/plus2pwr.png
SCHEMATIC
http://zxm.speccy.cz/dok/sch/plus2sch.png
....exactly, TR9 belongs to the supply circuit. The schematics are in the Velesoft's notion below. It really may have nothing in common with video circuitry. If you had any ideas how to fix it, I would be grateful to you.
Thanks
Hood
....and as I remember, TR9 is supplying power directly to TEA2000.
Hood
By the way: my replacement works on a +2 grey, but you will surely have to do some modifications to the video amplifier stage next to the input to UM1233 if you want to use the RF modulator (you have to bypass TR2 and TR1 and connect directly from the cathode of D3 to VIN at the UM1233). A similar hack will be needed if using the composite signal through the DIN connector.