#31
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Quote:
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Pioneer SX-1080, Pioneer PL-115D, Pioneer CT-F9191, Pioneer RG-1, Wollensak 8050A, Akai 4000DS MkII, Pioneer CS-05 & Polk 1.2TL Denon 5803A, Pioneer DVL-700, Pioneer CT-W603RS, Toshiba HD-A3, D-Link DSM-520, Dish VIP-722, Polk 1.2TL, CSi5, LS/fx, RT-800 and PSW-650 |
#32
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lug of terminal strips. A pencil with the hottest tip will work on the other lugs. We used the common weller station. Alternative is snip off one end to test then tack back on if OK. I always replace into the lug to keep it looking neat & save time but thats just me. BTW I dont know if its come up but the ground lugs on Zeniths break off sometimes & go int. Poke each one with a small screwdriver & resolder any that crack open. 73 Zeno |
#33
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ditto those ground connections on zenith term strips, esp happens after you have been tugging and flexing them a lot.
you can check that diode in circuit somewhat. both sides go to the power supply, but thru some rather high resistance so you should be able to get a front to back measurement to at least see some change when testing. |
#34
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CR 201 on the schematic
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#35
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I wish the Photfacts scans were clearer. If I'm counting correctly, I believe CR201 is across pins 11 and 12. I'm attaching a pic of what I think it is. I can also post a pic of the entire section of the underside if you like.
Does anyone else think it looks like it was either replaced before, or someone already cut one lead, tested it and then soldered it back together?
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Pioneer SX-1080, Pioneer PL-115D, Pioneer CT-F9191, Pioneer RG-1, Wollensak 8050A, Akai 4000DS MkII, Pioneer CS-05 & Polk 1.2TL Denon 5803A, Pioneer DVL-700, Pioneer CT-W603RS, Toshiba HD-A3, D-Link DSM-520, Dish VIP-722, Polk 1.2TL, CSi5, LS/fx, RT-800 and PSW-650 Last edited by TinCanAlley; 08-09-2013 at 08:16 PM. |
Audiokarma |
#36
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Looks like it was snipped but not changed.
73 Zeno |
#37
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I am looking at the zenith factory schematic, so the numbers could be different from the sams, but that looks right. you can check that diode, the 33k and if you look further back there should be a couple 100k 5% resistors. Interesting that its already been snipped and soldered back.
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#38
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the sams should show a 20v pp blanking pulse at the base AND emitter of the blanking amp transistor at the horz rate.
if bad this looks like the replacement http://www.nteinc.com/specs/500to599/pdf/nte506.pdf Last edited by DaveWM; 08-10-2013 at 08:24 AM. |
#39
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you could also check the bias voltages at the blanking transistor (if the blanking pulse is incorrect per the scope). If the diode is good and the fly pulse is getting to the base of the transistor BUT the bias is incorrect, that would effect the gain of the transistor and upset the output at the emitter. The sams shows the pulses at both the base and emitter (which look the same) I presume to check that the transistor is working properly (if not it would be a defective transistor OR incorrect bias).
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#40
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Forgive my ignorance, but the transistor (Q202) is clear on the other side of the chassis from the circuits we're looking at. Is that because the pulse is coming off the horizontal module, going through these circuits and then traveling cross to the other side of the chassis to the transistor? I'm getting better at reading schematics and wish they were to scale. LOL
Anyway, I've managed to locate just about all the pieces and will talk with my brother tomorrow about setting up a day for him to come by with his equipment so we can do some serious testing. Last question... Where are you seeing the pulse from that circuit? I'm looking at Photofacts and there isn't one for the emitter, but is one for the base which is shared with the collector of the vertical blanking. Strange thing is, there are two different patterns for the same test point. Both are 18V and then they differ with numbers I can't figure out. One graph is 30 and the other is 7875 (both numbers followed with a little curved line that looks like an oversized tilde). They both are different wave forms. No clue as to what those numbers are trying to tell me. Thanks
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Pioneer SX-1080, Pioneer PL-115D, Pioneer CT-F9191, Pioneer RG-1, Wollensak 8050A, Akai 4000DS MkII, Pioneer CS-05 & Polk 1.2TL Denon 5803A, Pioneer DVL-700, Pioneer CT-W603RS, Toshiba HD-A3, D-Link DSM-520, Dish VIP-722, Polk 1.2TL, CSi5, LS/fx, RT-800 and PSW-650 |
Audiokarma |
#41
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the two rates are the vert and horz (30 and 7865) these are for setting up the scope sweep speed.
I am looking at a factory manual, the scope readings do not match up, with the sams so can't really help. So you are back to checking for a pulse (should be two a vert rate pulse and a horz rate pulse both are for blanking. you can trace the pulse from the flyback (should be pretty big at the horz rate, like 200v pp) thru a cap (.0047) thru the resistor (33k) thru the diode all the way to the transistor, and then see it at the emitter. The best way to know for sure is to have a working set to compare to, but I realize that is not something that you have. I would check the diode (easy since its already been clipped), and the transistor (again easy since it's socketed). if they check use the scope and see if you get both horz and vert blanking. |
#42
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Quote:
__________________
Pioneer SX-1080, Pioneer PL-115D, Pioneer CT-F9191, Pioneer RG-1, Wollensak 8050A, Akai 4000DS MkII, Pioneer CS-05 & Polk 1.2TL Denon 5803A, Pioneer DVL-700, Pioneer CT-W603RS, Toshiba HD-A3, D-Link DSM-520, Dish VIP-722, Polk 1.2TL, CSi5, LS/fx, RT-800 and PSW-650 |
#43
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diode check base to collector check it like a diode
diode check base to emitter check it like a diode Ohm check emitter to collector should read open both ways (switch leads). if if doubt just do a you tube search on checking transistors with DVM there are plenty of demos. I use a analog meter that has a built in reversing switch in the resistance mode. |
#44
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I know I'll get it. I've made quite a bit of progress and gained quite a bit of knowledge in the past month. Thanks
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Pioneer SX-1080, Pioneer PL-115D, Pioneer CT-F9191, Pioneer RG-1, Wollensak 8050A, Akai 4000DS MkII, Pioneer CS-05 & Polk 1.2TL Denon 5803A, Pioneer DVL-700, Pioneer CT-W603RS, Toshiba HD-A3, D-Link DSM-520, Dish VIP-722, Polk 1.2TL, CSi5, LS/fx, RT-800 and PSW-650 |
#45
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BC open one way, low resistance when leads reversed. BE open one way, low resistance when leads reversed. you need to make sure you are doing this right. But I dont really understand why you are futzing around with the horz board. Check the diode in the blanking circuit. |
Audiokarma |
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