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Post by radiohead314 on Mar 18, 2016 5:50:15 GMT -5
Damage report: One dead 2SC3998 and one dead TDA4601 (likely). Three new bought TDA4601 where broken but I bought them cheap. Lesson buy these from trusted companies. And one DOA cap. And a number of fuses.
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Post by radiohead314 on Mar 18, 2016 5:42:37 GMT -5
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Post by radiohead314 on Mar 18, 2016 4:47:47 GMT -5
I think that if Q101 is shorted max voltage will be on primary and secondary side of the trafo. PWM can only switch it lower.
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Post by radiohead314 on Mar 17, 2016 15:28:22 GMT -5
One thing I learned is that the hthd overvoltage protection only works when both the q101 and the i101 are ok. When q101 is shorted the ov signal does nothing to lower the voltage and only the fuse can stop it. Also when the tda does not work this ov signal is useless.
So I think I have had very high hthd all through the system untill the fuse blew and unfortunately that was to late.
Might be over and under voltage are there to protect when the potmeter is used for the horizontal width of the image.
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Post by radiohead314 on Mar 17, 2016 14:39:18 GMT -5
Ok good point. With the hthd normal I think there is little risk for SMPS2 but I have to securely fix the cooling on the SMPS tighten the screws checking for enough pasta etc. WhenI go on with testing. I will do that tomorrow I will make mistakes if I do it now. Thanks!
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Post by radiohead314 on Mar 17, 2016 14:01:24 GMT -5
18.5V with video vertical and eht. No more squealing
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Post by radiohead314 on Mar 17, 2016 13:55:15 GMT -5
Yes I just measured 1.5V exactly hthd. I think the def on signal needs to come from the horizontal?
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Post by radiohead314 on Mar 17, 2016 10:34:31 GMT -5
Yes it seems so. And still squeeling but no other boards present.
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Post by radiohead314 on Mar 17, 2016 10:20:43 GMT -5
Man I bought 3 broken tdas and the one in was broken too. I am so lucky.
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Post by radiohead314 on Mar 17, 2016 10:19:59 GMT -5
Never mind stupid question He new tda new changes I turned it on and yes!!! The 17V is there no hthd led.
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Post by radiohead314 on Mar 17, 2016 9:37:36 GMT -5
Is it possible that q101 that measures good as a npn is still broken under high voltage?
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Post by radiohead314 on Mar 17, 2016 9:34:02 GMT -5
Wel it was not a good sign that you had different readings measuring them, the one before seemed to work HTHD was present ,stand by was not possible if I remember good but I don't see that can be the fault of the tda (I101). So perhaps replacing brings us back to the old problem? I am comparing a good tda (from cine 8) to the one I took out and indeed they measure the same. So I bought 2 broken tdas at least and one might be good just like the very first one. I will put it in as this one is clearly broken.
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Post by radiohead314 on Mar 17, 2016 8:56:50 GMT -5
0V on c25 now Replaced c125 with old one still 0V on c25
I do have a spare tda from a cine 8 supply. Perhaps the tda's I bought new are all bad.
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Post by radiohead314 on Mar 17, 2016 8:35:41 GMT -5
Sorry dubbel post . Good after start up of the+17vm z50 becomes zero to disable TH1. So now check if supply powers of and on with removing and replacing j30, when thats ok reconnect d114 and see what happens. Ok j30 removed gives standby and replace give 24 V on 17V d114 back and some low voltage on 24V and no more squealing. should I put the old c125 back too? Perha s the new panasonic caps are bad.
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Post by radiohead314 on Mar 17, 2016 8:11:31 GMT -5
Perhaps the c25 was a bad cap? I replaced only that one...
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