Amp died after shipping -- anything easy that might be wrong?

[Jeff Potter]

I inherited a Sony TA-AV480 Amp. It worked fine. I mailed it home. I thought it worked when we got it but now that I'm trying to use it again it doesn't work at all. No signs of life. No lights. No 'electric hum.' I opened it up and looked inside. I have no experience with this kind of thing, other than I've been able to take anything else apart and fix it quite easily -- computers, cars, etc. Is there something first to look at? I suppose the damage came from the well-padded shipping carton being jostled. A friend suggested I check the "thermal fuse." I don't know where or what that is but I see the power cord attachment. I see a fuse board. A see one old-type fuse, which is fine, plus other things on that board. All boards and parts seem in good shape, nothing loose. I unscrewed the front panel also and pulled it away a couple inches and peeked in there -- looks fine. I have a volt-meter thing that I can use but don't understand. Any tips appreciated!

 

[markw]

Offhand, it sounds like something was physically shifted inside during the shipping. It may or may not be easily found and from what you say about your experience with this stuff, unless it's not glaringly obvious, I'd say let a tech look at it. There's really no user serviceable parts inside these.

 

[lsiberian]

First ensure you are plugged into a working outlet properly before you go off the rails so to speak.

 

[Rickster71]

I see a fuse board. A see one old-type fuse, which is fine,

If you don't feel comfortable working inside the case or don't have a multimeter, I'd agree with Mark on this and bring it to a tech for a look.
If you do.
I'd try a continuity test on the fuse. If the damage is impact related, the fuse won't look burnt out, may be split/broken inside the fuse.
How did the box look after shipping? If the damage is from impact, it could be anywhere on the board. (I'd look first at where the power enters the board, since nothing is lighting up)
If it has a brown single sided board, the components are only soldered on one side. So there are any number of places for a broken solder joint or trace.

 

[Jeff Potter]

I tested the fuse -- good.

So my meter with a dial and "multi" options isn't a multimeter? It's not very fancy, that's for sure. But I could try some things with it.

So could I test connections from the power-in and each step of the way after that? Is there another simple test to look for other than continuity?

 

[sawzalot]

I tested the fuse -- good.

So my meter with a dial and "multi" options isn't a multimeter? It's not very fancy, that's for sure. But I could try some things with it.

So could I test connections from the power-in and each step of the way after that? Is there another simple test to look for other than continuity?

You didnt say you had a multi meter, you said you have a volt meter thing that you can use but dont understand. I suggest you let someone take a look that does understand unless you are reserved to the fact that this will be your intro into troubleshooting this piece and dont really care if it ever works again.

 

[markw]

I tested the fuse -- good.

So my meter with a dial and "multi" options isn't a multimeter? It's not very fancy, that's for sure. But I could try some things with it.

So could I test connections from the power-in and each step of the way after that? Is there another simple test to look for other than continuity?

What things do you have in mind to do with your "volt-meter thing" of yours?

Seriously, if you can't visually find the problem then, with your skills in this area, you're out of luck. Simply owning an engine analyzer and not knowing what you can do with it doesn't make you a mechanic.

 

[herbu]

Be careful poking around w/ a multi-meter. Set to Ohms for checking shorts, (ie. fuses), the multi-meter sends a current between your probe points. Indiscriminately chosen probe points can result in blowing another component. Take it to the shop.

 

[Jeff Potter]

I understand that I can only attempt basic tests. I've often been impressed by how much can be done this way.

 

[TLS Guy]

I understand that I can only attempt basic tests. I've often been impressed by how much can be done this way.

I hate to advise people who do not know what they are doing, as there are dangerous voltages in a receiver and you can get yourself killed.

However when nothing lights up, then it is usually straightforward to find the problem. You want to take on board that myself and techs use a variable voltage isolation transformer when conducting these tests for safety.

If you don't know what I'm suggesting then leave well alone.

Identify the primary connections of the power transformer. Now plug the unit in and switch it on. Now test the voltage across the primary with your meter set to the 200 volt range. It should measure your AC line voltage. If there is no voltage then the problem is the switch or the fuse. Now I do not know that unit and it may have an electronic starting circuit. These often cause problems, but you won't sort it out. If it has a straightforward switch and there is no voltage it should be easy to find the problem.

If there is voltage then measure the voltage at the secondary windings of the transformer. If there is no voltage then the power transformer has cracked internally due to shipping damage and that is the end of that unit.

If you need to ask follow up questions, then don't touch it. I will not answer follow up questions, less I hasten your half day out with the undertaker.

 

[Jeff Potter]

Thanks!

 

[Jeff Potter]

Ah ha! A friend who is observant and skilled just stopped by and took a look. He found there was power on one side of fuse board but not on other. That is, power on the two DC posts from the power-outlet. There are two AC posts next to those that are related to the transformer. No power! Then he noticed a crack across the fuse board in the dust! There's a 5" span across the board and it looks like the board sagged in the middle -- maybe due to jostling and vibration. It looks like a solder joint under there may well be broken. I'll unmount the board and take a look... We have hopes! Maybe I can reconnect the solder joint and then reinstall and support the board with something nonconductive and we'll be good! Here goes...

 

[Jeff Potter]

Sheesh. I now have the green fuse board loosened and turned over. It sure is cracked across. Any way for home repair of these kinds of connections? It's not regular solder. There's a coating.

I see this exact board recently sold on eBay for $13. Someone has dismantled one of these and has all the parts for sale -- and the power board sold. Rats.

 

[slipperybidness]

Cracked traces on a board SOMETIMES could be repaired. "Sometimes" and "Could" being the key words.

It is not a job for an amateur and it depends on where the crack is and how bad it is.

The idea is to remove some of the material covering the trace on either side of the crack, and solder a new jumper wire across the crack.

Like I said, not for a noob. And, in general, not recommended. I have never tried it myself. I guess the only reason I would try is if the gear had sentimental value or if it were very valuable or collectable. Honestly, if that was the situation, I might be more inclined to build a complete new power supply board--also not a job for a noob.

Your best bets
1) Cut your losses
2) Take it to a pro
3) Keep looking for the exact replacement board

Personally, I don't care for Sony, so it would be off to recycling if it were mine.

 

[markw]

Sheesh. I now have the green fuse board loosened and turned over. It sure is cracked across. Any way for home repair of these kinds of connections? It's not regular solder. There's a coating.

I see this exact board recently sold on eBay for $13. Someone has dismantled one of these and has all the parts for sale -- and the power board sold. Rats.

It would seem that this is not an uncommon problem with this unit. You might want to strongly reconsider the above post.

 

[Jeff Potter]

Well, that's not my deduction from that example of one. We'll see what kind of luck I have with the home repair.

 

[Rickster71]

Sheesh. I now have the green fuse board loosened and turned over. It sure is cracked across. Any way for home repair of these kinds of connections? It's not regular solder. There's a coating.

That's what I was getting at in my earlier post, broken solder joint or trace. Meaning copper routing trace.

The coating you see is solder mask. You can carefully scrape it away and try to solder it back together,
Your better bet is to follow the path work back to a via or component through hole and add a wire.
This problem sounds impact related. How was the packing job?

 

[markw]

Well, that's not my deduction from that example of one. We'll see what kind of luck I have with the home repair.

I'd say it more an example of at least two and, given it's age and how many have been tossed already, may be telling. But, if the board is physically salvageable you might get away following Rick's advice.

 

[herbu]

Your better bet is to follow the path work back to a via or component through hole and add a wire.

Agree. It is VERY difficult even for a professional to solder to a trace. The trace is too thin to handle the heat of a soldering iron. (And do you know what is in the 2nd, 3rd, 4th layer below where you would solder?) We never, NEVER, executed that kind of repair in our mfg lines, or allowed it in our circuit card lines.

 

[Jeff Potter]

Well, I fixed 4 broken traces on the fuse board at power source. I used solder and jumper wires on two of them (that were close together). For 2 others I scraped the epoxy off to copper then I flowed solder only in a longish 'capsule' across the break -- is that OK? My continuity checker says I made good connections. The break was just a crack. Well, it seems it should be good for testing, anyway.

So, I have it on my bench, no components plugged into it. I plugged it into the wall and it clicked nice twice. A red lite came on for "CD" -- the last mode used -- plus a green light in the volume knob. I clicked thru the other mode buttons and the red lite moved along -- to phono, tape, etc. Happy day!

Then I clicked the power button and the red lite went out. Green stayed on. Clicked power again and a dim yellow lite came on over the first mode (video). Pushing power button again makes that yellow lite get bright when I'm pressing then it goes back to normal when I release the power button. But the power button doesn't really do anything more. None of the other buttons light up when pressed. No more red light.

I plugged a CD player into a couple different mode-ports and that didn't change anything.

So, it worked once.

It seems like the switch was on when I plugged it into the wall the first time. The switch then worked good enough to turn things off pretty much. But now it won't work again.

Green lite still goes on for the volume knob. When I pull the wall-plug in and out the two clicks still happen (relays I guess).

I notice it looks like the front part of the metal sub-frame (where the buttons-panel attaches) is bent a bit on the ends and in the middle -- so it might've taken some knocks in transport. When I took the screws out and removed the buttons-panel to take a peek it didn't reinstall very easily or in great alignment without some prodding. I don't see any cracks on circuit boards back there.

So anything commonly happen when front ends get whacked?

I suppose I can unscrew and remove the circuit board for the switch and test it better.