Camera video problems with 4 channels

[livan74 0]

Hi to all,

I'm just try to check what is this problem that affect this DVR.

The DVR is a CPD507 with 16 channels input.

The channels from 1 to 12 are working fine but those from 13 to 16 have all the same strange problem.

The image on those channels is "squared" like a sampling error and seems like that there is a sync problem because the bad squared image "walks" from right to left.

I found that this DVR was already repaired because near the 40 pin inputs connector, on the bottom side there was a sign of hot air solder station and I see that they changed one of two multiplex HEC4051B, but the new multiplex that they have soldered is wrong because is an 74HC4051.

However, since I'm a technician and I have a hot air solder station, I take the wrong chip out and tried to turn on but the problem still the same.

I think that the problem is one of the four VLSI big chip with the heatsink on it because I checked the wiring from the 40 pin camera inputs from 13 to 16 and ONLY those 4 input goes to this chip, the other 4 inputs goes to the second big chip and so on.

No one can help me?

Thank you!

[scorpion 0]

U6 is for 1-4CH, U16 is for 5-8CH, U25 is for

9-12CH, and U34 is for 13-16CH.

 

 

Your troubles are with the following:

U34 AV083

U36 SDRAM

 

If they replaced U34 then you may need to replace U36.

 

You may need to replace RP32 and RP32.

 

What do all of the freak signals look like off of all the osc?

[livan74 0]

Thank you for the fast reply!

No, they replaced only the multiplex 74hc4051 (but the original was HEF4051D).

There are some news!!!!

So, I resoldered the 74hc4051 since the problem stills present, reassembled all the DVR, connected to TV to check and the problem stills present but I tried to connect the TV also to CALL output and the image is perfect!!!!

So if I connect the TV on MONITOR output the last 4 cameras input shows a bad image, green thick stripes and squared image, if I connect the TV on the CALL output the image is perfect like other inputs!

What the hell drives those two outputs?!?!

Since the image is perfect on the CALL output the AV083 (U34) should be ok I think.

 

Please let me know what do you think.

Do you have a schematic for this DVR?

Can you send me please?

 

Thank you man!

[scorpion 0]

For main monitor video out then you need to check U43, and U44 and R185.

 

I do not have schematics.

 

I hand traced them back in the day when I had more time in the office.

[livan74 0]

Ok, I'll check these components, but I remeber you that the problem is present only for the last four camera inputs, so these components could cause the problem?

Thank you!

[scorpion 0]

I do not think it is the monitor out circuit.

 

I only provided the info so that you would have it.

[livan74 0]

Ok, so I have to understand what path have the last four cam input!

The mainboard is multi layered and I cannot check with meter, who can have the schematics?

 

Thank you

[livan74 0]

So, I checked on the board U43 and U44 and since U43 is a multiplexer (do you remember that I said they changed??) probably you mean U43 and U45 because U44 is another SMD chip with three pin by side and R185 does not exist, there are the pads but not the resistor.

The multiplexer that they replaced is U45, probably the problem is U43!

These two multiplexers should be one for main video and the other for call output?

However now I try to take it out, better if I swap them so I can check if the problem go to the call monitor!

 

Bye

[scorpion 0]

I do not think anyone has schematics except for AVTech.

 

The DVRs are at a price point where they are not worth fixing, and most times you would just go and buy another DVR if it was out of warranty.

 

I do not think AVTech would send out the schematics to the general public unless you sign some document about sharing the schematics, and the lawyer fees would not be worth the representation unless you are a big company.

 

You could give them an email, and try.

 

If you have a rework station then replace the chip U34 again.

[livan74 0]

Chip replaced, nothing has changed.

The last four camera inputs go on U45 and AV083, at this point the problem is the AV083 chip because U45 has been replaced already.

Conclusion : New DVR.

 

Thank you!