Re: Panasonic TX-65x700 start problem
Hello
Resoldering did not change the problem.
I've made a vidoe of the starup process with the 3 phases.
[url]https://youtu.be/WmgrGgEntKc[/url]
Heating the main board did not changed anything.
What i can tell also, is that if I leave the tv off for 15 min, it will go to the 3 restart phase needed to have it working.
If then I just switch it off and restart, then it works immedialtly.
After some minutes off it goes back to the toubled startup.
...
perette
Senior Member
Last Activity: 03-15-2022, 11:54 AM
Joined: 03-04-2013
Location: clamart
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Re: Panasonic TX-65x700 start problem
hello everybody
I've been able to open the beast.
Here are some pictures.
Rapid inspection did not show any big issue, but, on the back of the power board some soldering are clearly damaged.
especially on components on heatsink.
As the problem seems to be heat related, i guess that this can explain symptoms.
I'll renew all "suspect" soldering and let you know the outcome.
Best regards
JM...Leave a comment:
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Re: Panasonic TX-65x700 start problem
Hi Davi
I'll do it this week. The TV is located at my daughter's house.
Agree that caps are less and less a concern. Having a look does not cost a lot.
Pictures will be taken and I have a way to (cautiously) cool down a component with compressed gas duster.
If it's temperature sensitive, then I may be able to locate the bad guy.
Many thanks
Jean MarcLeave a comment:
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Re: Panasonic TX-65x700 start problem
hello dskall
Thanks for the advice, I was planning anyway to make a deep inspection.
I can't fond any doc on the net on this TV set, so I don't know if there is a T-Con or any info on the intenrla design.
It's only a 2 years old TV and I guess that rhere is not a lot of fiedback on weaknesses.
Let(s move this way.
I'l do it this week.
Best regards
JMLeave a comment:
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Panasonic TX-65x700 start problem
Hello everyone.
A friend of mine has a Panasonic TX-65x700.
Since yesterday it shows the Following symptoms.
Cold start, black screen, backlight works
Restart, blue and black vertical bands ( always the same scheme), sound OK, no osd (see picture)
Next restart, ok image and sound, stable.
It looks like somethingnneeds to be a bit more heated to run properly.
I was thinking to open the back, and heat with an hair drier one board after another to find the faulty one.
Any idea or favorite place to... -
Re: Aiwa CA-P50, low power output
HI Piotr
thanks for the reply.
I Learn that my question was a bit "stupid".
a metal foil resistor 100 ohms 1/4W will do the job.
i ordered them and will change them.
i'll keep you posted of the result.
You've lall been of great help. I learned a lot on the process to analyse such failed apparatus and what "not to do".
Best regards
JMLeave a comment:
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Re: Aiwa CA-P50, low power output
Hello everybody
I've googled a lot and the only option seems to use a 10 ohms 1.4W and add it a 90 ohms.
Nothing at Mouser, nor Franell, nor Digikey.
will it do the job ?
Best Regards
JMLeave a comment:
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Re: Aiwa CA-P50, low power output
Hello again
Q7, 9, 11 and 13 and their counterparts on the other channels are OK.
So do I change the fusible resistors?
It look like 100 ohms 1/4w fuse resistors are not that easy to find. I had a loon at mouser and farnell, but not found them. Any recommendations if changing them is the try to make?
Best regards
JmLeave a comment:
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Re: Aiwa CA-P50, low power output
Hi gentlemen
@piotr. Done the test
Cb1 and 2 are OK. 0 ohm resistance.
S4 looks OK. It closes.do I unsolder it or clean contacts?
Voltage on r51 and 52 close to zero.
R53 and 54 have been adjsuted as written in the manual 5mv. But the idling current cannot be adjusted on both channels.
I'll check other transistors now
Best regards.. JmLeave a comment:
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Re: Aiwa CA-P50, low power output
HI Budm
Sorry my english can be improved.
when I've discovered the two units they were complete.
I tested them and get the bad sound out of it.
Then I had to open the box to try to discover the root cause of the problem.
As you can see on the picture, the amp is a small format factor and accessing boards means removing all surrounding parts.
But I've not unsoldered any board. so ground is connected . When I've tested Voltages point my ground was on the main board and...Leave a comment:
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Re: Aiwa CA-P50, low power output
Hi budm
Here are pictures.
Unfortunately, no real story available.
This unit was dropped to waste by one of my neighbors.
Whenever there is a single pop when turning the volume pot, they put the all stuff to waste without further questions.
Hi have saved many tv and audio units over passed years.
But I never faced this type of problem and I can't decide to put to waste something that can be saved.
Jm...Leave a comment:
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Re: Aiwa CA-P50, low power output
Hello everybody
Will do it.
- pictures of the front panel, there is no back panel (just connectors)
you have the main board (where the big power source is located ), two side panels for each channel and one front that hold display leds.
- test on Q7, 9, 11 and 13.
this evening. Now its time for business.
many thanks for your help.
JMLeave a comment:
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Re: Aiwa CA-P50, low power output
Sorry R47 to R50 are 100 ohm on my model. But whatever scale I use they are open.
JMLeave a comment:
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Re: Aiwa CA-P50, low power output
Hello everybody
Tested power transistors and resistor around. All seems to be OK. None open.
I've also had a look on fuse resistors on each channel board. R47 R47, R49 and R50 who are supposed to be 200 ohms. It looks like they are all opened.
Tested Q11 to Q14 and they are looking OK.
From there, where is the next step?
Best regards
JMLeave a comment:
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Re: Aiwa CA-P50, low power output
Hello everybody
sorry for my silence, i was travelling for buisness.
thanks for all your input.
i'll check power transistors today.
@momaka. just to avoid any "wrong path", sound on speaker is low and always distorded as long as I can hear something at less than 1/4 of the volume pot.
on headset, yes sound is correct, but you must turn the volume at more than half of the max to hear at normal volume in the headset.
thanks again. i post you the outcome of power transistor...Leave a comment:
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Re: Aiwa CA-P50, low power output
Hi Budm
Tested all test points as described in the service manual except the zero and idle values.
All values seems to be ok (or in the range).
Best
JMLeave a comment:
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Re: Aiwa CA-P50, low power output
Hi andrew.
I'll check them this evening.
I was just balancing between testing on the unit, active way and as a stand alone transistor.
Best regards
JMLeave a comment:
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Re: Aiwa CA-P50, low power output
Hello.
@andrew. I'm a newbie on this exercise. How to test them?
@piotr.
I will check them specifically this evening
Thanks for your input and advices.
I keep you informed of the outcome.
Best regards from France
JmLeave a comment:
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Re: Aiwa CA-P50, low power output
Hi everybody
tech info.
JM...Leave a comment:
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Aiwa CA-P50, low power output
hello
I've got an old Aiwa CA-P50 power amplifier with its preamp.
when connected to HP, the sound power is very low and full of distortion. Both channels are in the same state
I've tested with another preamp (and vice-versa) that the problem is in the amplifier.
what I've done so far
- checked all ref voltages. OK
- changed all electrolytic caps
- not changed 4 electrolytic bipolar ones.
- not touched the zero power and any other adjustment
- checked and/or resolder questionnable ones.
...
No activity results to display
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