Macintosh TV in need of repair - need advice

[maceffects]

Yes, if the Analog board doesn't fix the issue the main board needs replaced, and uniserver is right thats most likely what happened there.

 

[Bunsen]

Look at the corrosion under the tuner card:

That doesn't look too bad - it looks like mostly surface rust & deposits. It may still come up good after a clean. NB: board washing technique is something you may want to search on here if you've not attempted it before.

look at the daughter board on the tuner card. It looks fried.

Yeah, that's toast. Still, give it a clean and see how it looks afterwards. As Dennis says, you may be able to replace the individual components if the PCB itself is OK - and if you can work out or find out values for all the components :/

 

[krye]

OK, I got my hands on a new analog board. The seller couldn't test to see if it worked. He said it's been sitting on a spare parts shelf for years.

I popped it in and powered it on. Still, no green light on the front. I tried to insert the logic board, then remove it and power on. Still nothing. No green LED on the front. Is it possible that this board too is dead? Or am I doing something wrong?

 

[spiceyokooko]

That buzzing, chirping sound you hear when you switch it on suggests to me it's the power supply that isn't working.

Have you checked the voltage outputs from the psu with a multimeter for the correct voltages?

 

[Dennis Nedry]

The analog board is also the power supply if I'm not mistaken.

I guess I'm down to maybe 95% sure that the green light should turn on without a logic board... Could somebody verify this? I don't have a 5xx handy.

Have you double-checked the connection to the board containing the power LED? These noises you describe sound like a good sign to me, they kind of squeak and chirp a little, but I'm not completely sure without hearing it myself.

Also, there is a large edge connector on the analog board, is this clean and pushed in all the way? If you take some pictures of the inside and post them here, someone might notice something wrong.

Even something as simple as your power cord, a turned off power strip, or a loose power cord connection could cause this strangeness. I would never put myself above something like that, often times it's the dumbest thing wrong.

 

[krye]

I managed to score a LC 520 for $5. What a deal. I was hoping I'd be able to swap the guts out of it. The seller couldn't verify it works since he didn't have a keyboard. I took my chances for the $5 bucks.

Anyway, I got it home and plugged in my keyboard. Same thing as the Macintosh TV. There's a chirp sound when I turn it on from the mains in the back, but it does not power on with a keyboard. I have 4 different keyboards and nothing works. I've tightened all connections. Both machines do not have green LEDs on the front. I opened up the LC 520 and the analog and logic board look like they are in great shape. It's just a mystery. These machines will power on with a Keyboard II, right? It's not that I'm using the wrong keyboard?

 

[LCGuy]

Yep, any Mac should power up with any keyboard. Just out of curiousity - I notice you have a CC in your signature, have you tried booting the CC with the keyboard you're using on these machines?

 

[Dennis Nedry]

This is very confusing. It's unlikely that ALL of those parts are bad. The only common denominators are the power cord and the keyboard, but keyboard is unlikely because of no green light when you pull out the logic board. Remember that the logic board must be removed from the Mac for the green light trick to work.

On fruit colored iMacs, it was not uncommon for the power cord to not be pushed in all the way. That's probably similar for this Mac. Have you pushed on your power cord very firmly to make sure that it seated all the way in? I don't believe that a right-angle power cord will ever seat properly if you happen to be using one of those.

Other than that, I'm out of ideas.

 

[onlyonemac]

It looks like a dead power supply from what I've heard. Check it with a multimeter to see if it gives the correct voltage (I don't know what that is). Also, while you're about it, double check the PRAM battery, particularly on the mac without the "corrosion".

 

[bibilit]

I have 4 different keyboards and nothing works

Did you ever try with the remote ? as far as i know you have got one and if something is faulty in the keyboard side, you probably will be able to by-pass it.

 

[krye]

It's not the power cord or the keybaord. I have 5 or 6 keyboards that all work on my other Macs. So it's not that. The power cord is firmly seated and I can hear a slight sweak come from the analog board when I plug it in. Almost like a chirp.

 

[Alex's Apple Orchard]

Our Macintosh TV worked great last week but this week we have a similar issue like Krye. Tried everything mentioned here and still no led green light but has the same subtle chirp when switching on...our difference is when leaving it alone for a while it makes a louder sound like a regular tv sound turning on but still no screen...trying it immediately afterwards it goes back to the subtle chirping sound like that described by Krye...thanks ahead for any further thoughts/ideas.

 

[Dennis Nedry]

I am no longer convinced that the green light is supposed to turn on when you remove the logic board. I know that it does on 5500s, but we need to verify this for 5xx series Macs like the Mac TV. (The Mac TV is most equivalent to an LC 520)

 

[krye]

@alex

I'm stuck on this for now. I've had my eye on eBay for some replacemnt parts. The only thing I've found so far is an LC520 analog board and an LC520. I was hoping to swap out the analog board, but none of them work. 3 dead board sounds too hard to believe. I've tried everything else. The Mac TV and the LC520 both do the same thing. They chirp when power is applied, but that's it. They just don't turn on.

Let me know how you make out.

 

[techknight]

because..... the logicboard is at fault.

You need 3 things for an LC5XX machine to startup:

1. a good analog board, because without power, it wont do jack shit. If you hear a slight chirp when switched on/plugged in, Thats a pretty damn good indication that the power supply is starting up.

2. a good logic board, Why? because if the power management circuit isnt working, the analog board wont latch out of standby.

3. a good keyboard/cable. How else is the logic board going to get a power signal? hehe.

 

[Dennis Nedry]

It troubles me that the power light does not turn on when the logic board is removed, because I was under the strong impression that the power light turns on in this condition if the analog board is good. That would point to an analog board issue.

Can anyone verify what happens when you plug in and switch on a 5xx Mac without a logic board installed? On a known-good 5xx Mac, does the power light turn on? I'll be quite embarrassed if it doesn't.

 

[techknight]

Well my color classic does nothing with the logic board removed. Ill go plug in my LC575 and find out.

 

[techknight]

Nope, NO power light without logic board. LC575. Put the logic board back in, press power key on keyboard, bong it fires up.

 

[Dennis Nedry]

Oh my god, I am really sorry I have mislead some people in this thread.

 

[krye]

Not a problem. I'll try anything at this point.