verni QUASAR restoration

[vernimark]

This is a good news. On the contrary I think the TDA has gone...

[vernimark]

I ve some doubts. About the ics on the aux board 008/ca1
1=75
2=75
3=?
4=?
5=?
6=?
7=?
8=2114
9=2114
10=244
11=244
12=174
13=?
14=32
Can you help me?

[vernimark]

Yesteraday was the last day... Too much time, to much resources... I have a very long queue and I don't want to spend any other minute on that PCB and on that KT-3 chassis.
I'll continue to restore the cab because I found a glass and the right color to cancel the scratches...


I'll wait to find a new board and a new chassis. Quasar 1 - Vernimark 0

 

[PaulSwan]

It's a battle, I know
For the IC's:

3,4,5 - 2 input NAND, 74LS00
6/7 - Quad analogue switch, MC14016B (or MC14066B).
13 - inverter, open collector, 7406
Paul.

[Laszo]

I looked at your you tube. i'm not a scope specialist yet but it looks like a square wave to me. Can you adjust the picture like  the horizontal wide and the scan frequency.... I think there is a wave in there. On the other hand I worked with an anolog scope for maybe 10 minutes at school when I was 14 😉

[vernimark]

hehe thank you...
now, waiting for a new board, I'm working on my Vanguard Zac but in a short time I'll come back to this KT3

[vernimark]

Thanks to Paul now I have a working PCB.

Going back to the monitor
http://www.vernimark.com/?p=5065
removing the T465 I haven't any short. obviously nothing works.
Now I want to troubleshoot the part before the T465 in order to have good oscillograms and then I can proceed. Any suggestion is appreciated of course

[PaulSwan]

At least it's trying to do *something*, possibly trying to repeatedly start., and it might not be able to do that with T465 disconnected.

Can you get away with T465 in but with it's secondary windings disconnected from the rest of the circuit? (sleeve the pins to isolate, i.e. LINE O/P SUPPLY & SOUND SUPPLY disconnected) so the transformer is driven has no outputs connected? This would allow you to see if you have a fault on the secondary side that's blowing the power supply and if the power supply will start and regulate the voltage.

If it doesn't start but doesn't blow either, you can then try and add a dummy load to the LINE O/P SUPPLY (e.g. a 60W 240V light bulb) to verify that the supply will regulate the voltage. If you get to this point of a regulated supply with a dummy load then that points to a fault on secondary side, like the line drive transistor or related.

Have you checked to make sure that there is no primary-secondary winding short in T465? You should be able to check for that with a meter. If T465 is actually melted in the windings it'll be hard to check that without a signal generator.

Paul.

[vernimark]

At least it's trying to do *something*, possibly trying to repeatedly start., and it might not be able to do that with T465 disconnected.

Oh, I understand. It is a good point

Can you get away with T465 in but with it's secondary windings disconnected from the rest of the circuit? (sleeve the pins to isolate, i.e. LINE O/P SUPPLY & SOUND SUPPLY disconnected) so the transformer is driven has no outputs connected? This would allow you to see if you have a fault on the secondary side that's blowing the power supply and if the power supply will start and regulate the voltage.

yep, good idea

If it doesn't start but doesn't blow either, you can then try and add a dummy load to the LINE O/P SUPPLY (e.g. a 60W 240V light bulb) to verify that the supply will regulate the voltage. If you get to this point of a regulated supply with a dummy load then that points to a fault on secondary side, like the line drive transistor or related.

Have you checked to make sure that there is no primary-secondary winding short in T465? You should be able to check for that with a meter. If T465 is actually melted in the windings it'll be hard to check that without a signal generator.

Paul.

I'll let you know. In case of short I can try to count the loops and remake it.
I'm scared it can be. I found the monitor with a wire instead of the fuse, so it has been forced to burn

[vernimark]

I could recover pictures from my old broken mobile and now I can document the glass restoration 

The original one was broken so I found another one but with some damages. This is the original




and this "was" the "new" one








I found acrylic colors very similar to the original ones


and I painted filling the missing parts



The result is not bad, although I'm quite rough in my jobs so probably some of you could reach better results  :

[Etienne MacGyver]

WOW !  Massive flaking there.

Thanks for the instructions, i have a Space station Bezel that could use some TLC, although its not as flaked as this one yet.

[level42]

Great job, looks a ton better than it was !

[vernimark]

thanks  

this night I continued to troubleshoot my KT-3
If I can't have any result before friday I'll replace it with an LCD  

I followed Paul's suggestions and I connected the pins 6 and 8 only of T465. I can say It is not shorted...



Then I referred to the technical manual to troubleshoot the regulation board




So I checked points B, D, E and F

B is ok


when I checked D I had a signal that pulsed. Regulating R7317 I could stabilize it



signal after T7353 is inverted as shown in the following picture representing E



Point F, now looks like this:



this signal is compatible with the technical manual description assuming that "t2" is very close to zero

...and NOW??   hahaha

[PaulSwan]

Attach a dummy load to the transformer output, a 60W 240V light bulb may be OK.
If that lights OK and the waveforms look good, then something is wrong downstream. Blown line o/p transistor is a popular choice...

Paul.

[vernimark]

Ok, I don't know what the hell happened but I had another burn on the TV main board. Everytime I dedicate my time to this cab something happens so I decided to stop wasting my time with this cab. I will spend just a couple of hour to re assemble it, board included (thank you again Paul), and nothing else. I want to think about the possibility to use a MTC900 instead of the KT-3 or a Polo (it needs 220V so I haven't to modify anything) waiting for a future KT-3  

I found a purple paint very similar to the cabinet color, I have only to adjust it a little bit with additional black and once I have the same color I'll remove some scratches. That's all...