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  #1  
Old 09-08-2012, 06:01 PM
Crawford Tillinghast Crawford Tillinghast is offline
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Teac A-3440 power supply problem

Hello.
I'm hoping someone can help me. I got my Teac A-3440 out of storage, I haven't used it in 8 years. I switched it on and nothing happened. It worked fine before. I have a very limited knowledge of electronics, but I thought I'd see what I could do. The fuses are ok. I checked the primary coil of the transformer with an ohm meter and got no reading. This I don't understand: I get a voltage reading on the power wires to the transformer even when it is switched off. There is a black gizmo on the switch attached to the in and out wires of the switch. I am guessing this is a device to prevent the switch
and transformer coil from voltage spiking/arcing when it is switched on or off? Does this thing normally leak a tiny bit of 110 volt current?
Might there be some other problem, or does it sound like it is just the transformer and maybe the switch gizmo?

Thanks,
Tom
  #2  
Old 09-08-2012, 07:44 PM
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BeatleFred BeatleFred is offline
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Hi Tom,

The A-3440 is a really great recorder, hope you can get it up & running again. Its tough to say exactly whats causing the problem. I'm sure some other knowledgeable folks will chime in soon and be able to offer some assistance.

In the meantime, here is some good info on the circuitry of the A-3440 that you might find interesting, as I did. I hope to be able to contact Les Carpenter and express my gratitude for the excellent information he took the time to write-up and make freely available:

http://homepage.ntlworld.com/lez/Tea...0circuitry.pdf
  #3  
Old 09-09-2012, 12:55 PM
jeddak jeddak is offline
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Far out! Thank you for that link, BeatleFred. And yes, a big tip o' the hat to Les Carpenter.
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  #4  
Old 09-09-2012, 02:02 PM
Crawford Tillinghast Crawford Tillinghast is offline
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Excellent info, BeatleFred, thanks. So the "switch gizmo" is a capacitor and resistor, and some types of capacitors leak a few microamps. I guess that's ok then.
  #5  
Old 09-09-2012, 02:56 PM
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Skywavebe Skywavebe is offline
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Hello Crawford Tillinghast ,

You are in a fix in that either the power switch has opened up which I have never seen happen or the fuse in the transformer has opened up and the next thing you need to do is get a new transformer or have it fixed.
There is another website related to a person who was kicked out of here that sounds like Feanix tape. The typing of the actual word is blocked. The reason that I mention this is not to get anyone mad but that there is a detailed procedure I put on there some time back on how to fix the transformer and it has pictures. Now you can replace the fuse in the transformer but what I usually do is short the link, then place an inline fuse holder in the transformer primary to do the same job. However, you should determine what cause that fuse to blow as it can do it again. If you were near by I would just say bring it to me but many times people are in places like Bulgaria, the UK or even Malaysia that I give E mails to and there is no way they will walk over from there.
If the Primary of the transformer is open these are the options. I discovered this way back when at Teac and I have done about 8 of them so far.
Funny thing is the very model I did the instructions on was the one that the pictures were taken of and the feedback left on my Thumbtack website was the machine the guy was talking about.
The procedure requires take the transformer apart to an extent and being careful not to break any wires that are in there. Then putting it all back together again.
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Sam Palermo, BSEE , ProSquad Member
Skywave Tape Deck Repair- Chicago area
(630)616-0932 Office/ Email skywavebe@sbcglobal.net
Past Teac/Tascam Lead Service Technician at Chicago Factory Service still doing repairs.
http://s609729863.onlinehome.us/tape...uipment-repair
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  #6  
Old 09-09-2012, 04:41 PM
Crawford Tillinghast Crawford Tillinghast is offline
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Skywavebe,
Thanks for the instructions. The fuse is blown. Also, you mentioned double digits for the primary coil, but I get only 2 ohms. Is this a short in the coil?

-- I found a post of yours to answer that:
"IF the reading is 0 to 5 ohms- you better have a fuse in the line as the transformer COULD have a shorted primary and the fuse will pop."
"In that case the fuse link will not be the only problem. At this point the power supply should be examined for defective capacitors and blown out wire wound power resistors."

So I guess the next step is to replace the transformer fuse with a 2 amp fuse, turn it on, see if it works? Or is 2 ohms obviously wrong for an a-3440?

I'm in San Francisco, CA BTW. It's a U.S. model.

Last edited by Crawford Tillinghast; 09-09-2012 at 06:25 PM.
  #7  
Old 09-09-2012, 07:19 PM
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Skywavebe Skywavebe is offline
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Hi Crawford,
I just measured a Power cord with the switch turned on and I got 9 ohms using a Fluke 79 III unit. Remember that DC resistance is not the same as the impedance of the primary at 60 Hz.
You measure it to see if there is an open or a short. If the primary measures 2 ohms, that is a bit low. Maybe the 6 ohms I got came from the switch and power cable. The internal fuse is not blown if you can measure the primary. What were the conditions when this happened- was the machine very hot?
Is the machine set for 120 Vac like it should be? Did any fuse in the unit blow catastrophically or did it just simply break. These all give hints as to what when wrong. If the fuse has a little break in it that could be from mechanical stress. If the fuse is seen to have the element inside it vaporized and the glass is all black then there was a major short somewhere. You could prepare a coed to have a in line fuse if there is not one in the deck already and put a 3 A fuse in the 2.5A fuse in the cable. Then plug it in for a second or two- note if the lights in the meters come on or if the fuse just vaporizes. If it blows big time then you may have a shorted Primary and that will require either a new transformer or to have the primary side of this one rewound. We have not had a lot of these transformers fail often so far I have only worked on one recently and I do not remember a lot of transformer replacement in the past. NJFSDigital may have some further insight as he is a long time Teac Technician as well. His name is Russ.
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Best regards,

Sam Palermo, BSEE , ProSquad Member
Skywave Tape Deck Repair- Chicago area
(630)616-0932 Office/ Email skywavebe@sbcglobal.net
Past Teac/Tascam Lead Service Technician at Chicago Factory Service still doing repairs.
http://s609729863.onlinehome.us/tape...uipment-repair
Now accepting MC, Visa, Amex & Discover Cards!
  #8  
Old 09-09-2012, 08:47 PM
Crawford Tillinghast Crawford Tillinghast is offline
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Skywavbe,
Thank you so much for the help.
Measuring across the fuse, from the brown input/power wire to the twisted white wires on the other side gave me no reading.
No reading on brown to white power wires.
Measuring from the fuse output (the twisted white wires) to the white power wire gives me 2 ohms through the coil.
Then when trying to push the plastic tube out, I heard a snap and the fuse broke. It's really hard to tell, but it looks like a silvery wire/rod inside that maybe has a few spots of black on the glass.
The machine worked when I put it away 8 years ago. It was moved in that time.
So the problem occurred either right as I last turned it off, during the move, or right as I turned it on.
When I turned it on, I did not see anything - the lights did not come on even for a moment, nothing.
There's no switch to change the 120 Vac. The 7 fuses are ok.
  #9  
Old 09-09-2012, 10:21 PM
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Skywavebe Skywavebe is offline
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I am getting a little confused by some of your descriptions. The plastic tube and a fuse is this inside the transformer- are you in there yet or are you talking about the fuse somewhere else? The A3440 by schematic is not suppose to have a fuse like some decks in the incoming power line- that fuse is inside the transformer. Another issue is that if something is shorted on a secondary then the primary will draw high current. In my diagnosis and I use a power strip with a switch to turn power on with control. The one thing you can do is find each secondary set and make sure there is no short on any of them at the output. What that means is that in a secondary coil one end goes to the bridge rectifier and the other end goes through the fuse. What you want to do is lift the fuse so that you are not measuring the secondary coil but the load that is placed on it. If there are shorted diodes in the Bridge rectifier or individual diodes or in a Electrolytic cap, then you should find this right away.
Another thought comes to mind is that when I buy stuff off E bay on occasion, I get the units and previous to applying power I turn the unit over and shake with a cover off to get any strange or inappropriate item out that could cause a short- I have found screws, pennies and paperclips in decks.
Maybe something got into yours and that might be a thing to check first off.

If you find no secondary load shorts- still leave all the fuses out and rig a 2 amp fuse in line with the input power of the deck. Put a 2 Amp fuse in it. Power up the unit for a second or two with no loads on the transformer- this is the case when all fuses are out so now this will tell you if the Primary winding is shorted. If the fuse blows fast and with a large black explosion you may even hear a pop. there is something shorted in the primary, If it does not blow, you can start to check AC readings on the secondaries.
Once all these check good, I would unplug the capstan motor servo plug and with power off start installing one fuse at a time. If the outside fuse blows
when one fuse on the inside is put back then that circuit section need looking into. Sometimes, there are shorts that have a dynamic condition rather than a static condition- these are shorts that only happen when voltage is applied. The ohm meter test would not show those.
Give me feedback on what else you see- the Primary transformer wire leads from the USA schematic are suppose to be Brown and White.
__________________
Best regards,

Sam Palermo, BSEE , ProSquad Member
Skywave Tape Deck Repair- Chicago area
(630)616-0932 Office/ Email skywavebe@sbcglobal.net
Past Teac/Tascam Lead Service Technician at Chicago Factory Service still doing repairs.
http://s609729863.onlinehome.us/tape...uipment-repair
Now accepting MC, Visa, Amex & Discover Cards!
  #10  
Old 09-10-2012, 03:49 PM
Crawford Tillinghast Crawford Tillinghast is offline
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Sorry about my lack of clarity. Here's what I have done:

The 7 fuses on the fuse PCB are ok.

There's no foriegn items inside that could cause a short. The capstan belt turned to goo and fell apart, but that wouldn't be conductive.

I opened up the transformer to get to the fuse inside. From inside the transformer I checked the fuse, which is blown or broken, and the primary coil which reads 2 ohms.

I removed the 7 fuses and checked the loads placed on the secondary coils for shorts and did not find any.

With the 7 fuses removed, I rigged up a 2 amp fuse in line with the input power (at the same place the transformer fuse was) then switched it on. The fuse did not blow.

I then checked the AC readings on the secondary coils. OK.

I unplugged the connector to the capstan servo PCB, then powered it up with one fuse in at a time. No problems.

I'm hoping this means the transformer fuse simply broke?

And yes, the primary transformer wire leads are brown and white.
  #11  
Old 09-11-2012, 04:11 PM
Crawford Tillinghast Crawford Tillinghast is offline
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IT WORKS! ...at least I think it works. I installed an inline fuse on the transformer. I checked what I could without a capstan belt.
Thanks, Sam, for your help.
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