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Wolfrin

Atari 7800 parts help!!!!

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I just need to know what the c57 and c56 is I know that my zener diode is shot but so isnt those other two pieces and I can't seem to find out what they are and I need then to get my Atari back up and running it's the white brown white thing20190630_221707.thumb.jpg.1395f6bd47fa6a3564214287b66f8536.jpg20190630_221656.thumb.jpg.7f04eb4e9acc027354cd55a1f19cd2be.jpg

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I destroyed one taking it off thinking it was a zener diode when it wasnt and it split in two and the other one used to read just fine but now reads nothing and the 0.1 if is it a capacitor or a diode or a zener diode I dont know what it is

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The zener diode is the black one and it is definitely gone it doesnt read anything and once i replace both c56 and c57 0.1uf whatever it is then I will order the zener diode which has a part number of in5231 in the schematics but it doesnt say what the other two are

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Those are industry standard power smoothing caps (brown black ones), you can find them in all sorts of devices.

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Is there any way you can please link some that match the picture please and thank you and thank you for the information I added a power port to my Atari so I could use it and I'm using a 9v 1000mah power supply and it was working until the zener diode blew and online it said that when the zener diode blows it wont supply power to the transistor 

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If a Zener blows, you are SOL and you need to find an exact replacement.  Which I guess you already have.

 

Not sure why you think the 104's blew though.

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Yeah I found the exact for the zener but one was torn in a half when I removed it from the board and the other one doesnt read any olms on the multimeter and I just need to replace the one I broke and I cant seem to find one can you please link a replacement for the c56 and c57 parts

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You can harvest those from cartridges, exact replacements can be found inside 5200 carts.

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Yeah outside of Atari, I've never seen capacitors that looked like resistors.  There may have been other people who used them though, as I've seen reference to the color codes for capacitors and even diodes.

 

But anyway, a capacitor is a capacitor, so whether it looks like a resistor or not, it does the same thing.

 

The zener won't give you a reliable ohm reading, even when good.  That isn't its purpose.  It controls voltage.  You have to have the device plugged in and check the voltage across the diode.  If it's the reading on the schematic, then the diode is good.

 

If you do a "diode" test using your multimeter (console not powered), it probably won't have enough voltage to read positive to negative and will show OL.  If you read it negative to positive, though, you should see around 0.5V in that mode.

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I plugged the power supply in and I tried the multimeter. I also tried the leads both ways and it read 0.00 both times. So I think the zener diode blew closed.

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Just to make sure:

   With power connected, take a VOLTAGE reading of the diode, red on the positive side and black on the negative side.  Should read the zener's rated voltage.  Make sure you also have a voltage reading on the power supply input, at least 9V.  If your power supply is dead, then it doesn't matter if the console works or not.

 

   With power DISCONNECTED, take a DIODE reading of the diode.  With the red on the positive side and the black on the negative side, you should see OL.  Backwards, you should see a fraction of a volt.

 

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With the power supply connected if you put the positive terminal on positive and negative on negative it shows that 9v are going to the power connector. I also checked the zener diode with the postive on positive and negative on negative and it reas 0.00v and when I switched the leads it was still 0.00v. With power off of the power connection both times the leads being on the right side or switched it reads nothing on the voltage meter.

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Hmmm.... then check R53.  Even when a semiconductor goes bad, you should still see a tiny voltage across it, but you're getting a completely dead circuit.  So I wonder if R53 is broken or has a bad solder joint.

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I found r53 and with the leads one way i get 0.54 and the other way i get 0.45. When I choose dcv i get nothing but in the ohms setting I get these readings.

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On 7/1/2019 at 9:18 PM, ChildOfCv said:

 

But anyway, a capacitor is a capacitor, so whether it looks like a resistor or not, it does the same thing.

  

Sorry, I missed this comment, because polarized caps are not the same thing.

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I'm trying to decode what you mean.  Well, I guess if your ohm meter is on KOhms setting, you'd get the values you did.

 

But also, in order to make sure we're checking the whole path rather than just the resistor itself:

 

1) Disconnect power.

2) Turn on ohm meter in resistance mode.  Expected resistance will be 510 ohms, in case you have range switches

3) Place one lead (doesn't matter which one for a resistor) on either lead from FB2 (the black inductor in your first picture).

4) Place the other lead on the banded side of CR5 (just to the left of the 4013 IC)

 

As noted, this should read close to 510 ohms.

 

Also in your initial picture, that's a capacitor to the left of the black inductor.  Is it the bad lighting, or is that capacitor burnt?  And if it's burnt, then just how much voltage did you shove into this system?

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Just now, CPUWIZ said:

Sorry, I missed this comment, because polarized caps are not the same thing.

True, but the ones he seems to be talking about are ceramic.

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1 minute ago, ChildOfCv said:

True, but the ones he seems to be talking about are ceramic.

 

I suggested, using ceramics, instead of the old "glass like" diode looking ones, which I probably have hundreds on popped boards of.

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