Water Damaged Diseqc Sat Switch

[DJ_MIX]

Guys need help to pinpoint problem

Worked great til water damage at bottom. I reflowed with flux affected area still not working.

I then try to look for shorts, I believe I found one on smt resistor labeled
1RO..

How do I tested this component I removed it still shows short on continuity and on ohms shows 1.4 K ohms.

[CapLeaker]

Re: Water Damaged Diseqc Sat Switch

1R0 = 1 Ohm. It would show as a short. So that isn't the problem.
If the through holes are good, the diodes or one of the chip capacitors aren't shorted, plus the 3 legged SMD transistors, it has to be the TINY13V IC. Check for VCC on pin 8. GND is pin 4. 5cw and the CEC are PNP's.

[stj]

Re: Water Damaged Diseqc Sat Switch

CEC is probably a voltage regulator.

[CapLeaker]

Re: Water Damaged Diseqc Sat Switch

I guess you are correct. I traced pin 8 of the IC and it goes there.

[fzabkar]

Re: Water Damaged Diseqc Sat Switch

"CEC" is a BC869 PNP transistor (20V, 1A).

[DJ_MIX]

Re: Water Damaged Diseqc Sat Switch

guys thanks for help. I do notice burn mark near TINY13V.

I looked at datasheet and it appears to be programmed chip? can I buy replacement and not have to program it?

Of course I will have to check VCC and GND when I get a chance.

[DJ_MIX]

Re: Water Damaged Diseqc Sat Switch

Also want to add:

Port1 works I get signal on sat,

Port 2, 3 and 4 I get no signal

[R_J]

Re: Water Damaged Diseqc Sat Switch

I'm not sure what brand that one is but you can usually buy them new for around $5.00 -$20.00

[DJ_MIX]

Re: Water Damaged Diseqc Sat Switch

I'm not sure what brand that one is but you can usually buy them new for around $5.00 -$20.00

it's a EMP P164IW

I would like to save it, it was a great switch too bad I had big storm and water got into it

Also it's a learning thing for me to see how circuits work.

[DJ_MIX]

Re: Water Damaged Diseqc Sat Switch

I took some measurements It's attach in photo.

Check for VCC on pin 8. GND is pin 4, Pin 4 does not go to ground for me.
I used continuity between one of the connectors and pin 4

[fzabkar]

Re: Water Damaged Diseqc Sat Switch

The datasheet states that the ATtiny13V chip's supply has an upper limit of 5.5V. Therefore I think that your measurements should use pin #4 as the ground reference for the circuit. Then the voltage measurements would make sense.

https://cdn.badcaps-static.com/pdfs/...349050191c.pdf

It would help if you were to trace the circuit. At least determine which pins of the CPU drive the base pins of the various transistors.

5CW = BC807-40 PNP transistor:

[R_J]

Re: Water Damaged Diseqc Sat Switch

A couple "general" schematics here http://www.juras-projects.org/eng/hardware.php and some other information that might be usefull here http://www.juras-projects.org/eng/projects.php
I would check the feed-through's where the water damage was, the one beside the cec transistor looks a bit tarnished.

[fzabkar]

Re: Water Damaged Diseqc Sat Switch

A couple "general" schematics here http://www.juras-projects.org/eng/hardware.php and some other information that might be usefull here http://www.juras-projects.org/eng/projects.php

That's a great resource. Thanks.

[fzabkar]

Re: Water Damaged Diseqc Sat Switch

ISTM that pins 2,3,5, and 7 of the microcontroller may be doing the port switching. Three of these pins are high, which would be consistent with the corresponding PNP transistors being switched off. The other pin is low which suggests that it is switching port #1 on.

I would think that if the micro were dead, then it would be unlikely for it to be behaving as it is.

[stj]

Re: Water Damaged Diseqc Sat Switch

is it getting 3-5v - that's the first question.

[CapLeaker]

Re: Water Damaged Diseqc Sat Switch

if it isn't switching between the ports and only port 1 works, then I think that the Tiny13V is at fault. Either it isn't getting any power, or the IC is bad. If it is bad, you are SOL unless you can program another one.

[fzabkar]

Re: Water Damaged Diseqc Sat Switch

is it getting 3-5v - that's the first question.

The chip's Vcc pin is about 5V higher than its ground pin, so, yes, it is getting the correct power.

This is what the power section looks like to me:

   13V
  Analogue
   VCC  = digital 5V
    +
    |
    +---------------------------.
    |              |
    |    .--------.     |
  13V +--------|Vcc   |    |<
    |    |D5V   |-->-R--|  4 x outputs to LNBs
 5V  |    |    |    |\
 Zener z    |Tiny13V |     |
    A    |    |
    |    |    |
    |    |DGND  |
  8V +------+-|Gnd   |--------< Drx input
    |   | '--------'     for LNB selection
    |   |
   .-.   |
  R | |  ===
   | |  Digital
   '-'  Ground = digital 0V
    |
    |
   ===
  Analogue
  Ground

The digital supply is "floating".

[fzabkar]

Re: Water Damaged Diseqc Sat Switch

if it isn't switching between the ports and only port 1 works, then I think that the Tiny13V is at fault.

ISTM that if the micro were bad, then more than 1 port could be switched on. The fact that only the first port is switched on would suggest that the micro has powered up in its default, programmed state. It now needs a DRX signal from the receiver before it can switch to a different LNB. I would be checking the circuit between the DRX input and the receiver.

[Per Hansson]

Re: Water Damaged Diseqc Sat Switch

DJ_MIX: Are you sure the problem is with the Diseqc switch?
Maybe this thread could be an interesting read for you:
https://www.badcaps.net/forum/showthread.php?t=21033

Coincidentally my apartment is getting painted.
So they washed the outside walls and you can imagine what happened to my Diseqc switch. (If not see attachment).
So I washed it and then heated it to 50°C to dry it, it then worked for ca 2 weeks before failing again.
Looking at the underside a VIA hole had rusted up... How this $40 switch does not have any conformal coating is beyond me!
I now replaced it with a $5 switch and it's working great again

[stj]

Re: Water Damaged Diseqc Sat Switch

diseq switches should be on the back of the dish - or even slung under the lnb-arm.
and should be sealed the same way you seal the lnb - i use GEL-LOCKS when i work on them - much better than amalgamating tape and you can remove & refit them!