Poineer A-209R

Karl vd Berg · 2013-05-27 1:26 am

Houston, we've got a problem.

(Hi all!)

Poineer A-209R (Direct Energy MOS)

I've got this amp for a few coins today... because it's dead.

No sign of life. Well, just checked external fuses, etc, and they're ok.

The Trafo's secondary doesn't supply anything. It's supposed to provide 14, 16, 18 VAC (Brown, Black and Gray, respct.)

Already measured for continuity across all the points. Everything "beeps" regurlarly.

An externally hosted image should be here but it was not working when we last tested it.

Any idea?

overall feedback · 2013-05-27 5:06 am

Karl vd Berg said:
Houston, we've got a problem.

(Hi all!)

Poineer A-209R (Direct Energy MOS)

I've got this amp for a few coins today... because it's dead.

No sign of life. Well, just checked external fuses, etc, and they're ok.

The Trafo's secondary doesn't supply anything. It's supposed to provide 14, 16, 18 VAC (Brown, Black and Gray, respct.)

Already measured for continuity across all the points. Everything "beeps" regurlarly.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.

Any idea?

Can you measure primary AC voltage? Secondary AC voltage? Can you check rectifier? Could be power cord problem too.

Karl vd Berg · 2013-05-27 6:05 am

overall feedback said:
Can you measure primary AC voltage? Secondary AC voltage? Can you check rectifier? Could be power cord problem too.

Hi!

Primary AC is 230V across white and yellow wires. No AC output from secondary whatsoever.

overall feedback · 2013-05-27 6:30 am

Karl vd Berg said:
Hi!

Primary AC is 230V across white and yellow wires. No AC output from secondary whatsoever.

Than there is problem in transformer. It can be proved with another supply (same voltages). But if you are not experienced enough better ask for help in electronic service or so.

srh · 2013-05-27 6:37 am

Most likely the thermal fuse in the transformer primary winding has blown.

Bibliophile · 2013-05-27 6:38 am

I see the transformer has an internal fuse.
Did you confirm continuity of the primary?

Edit: Beat me to it

Karl vd Berg · 2013-05-27 1:54 pm

Indeed could be the thermal fuse. There's 230V across the points, but no continuity across them.

I have no idea how to open the transformer to see/look for this thermal fuse...

How does it look like? And what's the function of it? Sometimes we have AC reaching 250V...

Mooly · 2013-05-27 2:11 pm

It will be buried in the windings (usually non replaceable). You should get a low ohms continuity between L and N terminals. You might "see" the fuse or deduce its location from any extra wires going into the transformer from the existing pins.

If its failed it could be anything from no fault other than the fuse to a short (such as a rectifier or outputs)

dentarthur · 2013-05-27 2:16 pm

Thermal fuse

The thermal fuse is part of the trafo - hidden somewhere under the insulation stuff. Can you take pictures of the trafo from the sides?

jaycee · 2013-05-27 2:37 pm

Elektrotanya has the service manual. I'd say the secondaries are 25-0-25VAC, so you can fit an off-the-shelf transformer in there.

Mooly · 2013-05-27 2:49 pm

This looks like the fuse. It should read zero ohms between these points

Karl vd Berg · 2013-05-27 2:59 pm

Mooly said:
It will be buried in the windings (usually non replaceable). You should get a low ohms continuity between L and N terminals. You might "see" the fuse or deduce its location from any extra wires going into the transformer from the existing pins.

If its failed it could be anything from no fault other than the fuse to a short (such as a rectifier or outputs)

I only hope I don't have to replace thr trafo, bacause it's suppose to cost something around 120 euros!! I had the same thing while ago with a Rotel amp reported here. But that was easy to replace with a common black and two 18VAC red wires from secondary.

Here instead we have three different outputs 14, 16 and 18 from the brown, black and grey's secondary...

Pictures below showing primary and secondary and from top:

An externally hosted image should be here but it was not working when we last tested it.

Karl vd Berg · 2013-05-27 3:05 pm

Mooly said:
This looks like the fuse. It should read zero ohms between these points

Oh, it is open.

jaycee · 2013-05-27 3:08 pm

There aren't 3 different outputs. It's just a centre tapped transformer the same as the Rotel was. While the service manual doesnt state the secondary voltages, from looking at the power supply capacitors and the voltage rails mentioned on the power amp side, it looks like 25-0-25VAC to me. It'd certainly get the amp working using those voltages.

jaycee · 2013-05-27 3:10 pm

My guess on why this has failed would be the same as that Rotel - your mains should be 230V but it is actually more like 250V. The extra power could well be responsible for making the transformer overheat and blow the thermal fuse. If you can get transformers rated for 240V primary, it may be better.

Also, commercial stuff tends to cut corners on this sort of thing. You may find a good quality toroid transformer will not have a problem compared to a cheaply made EI.

Mooly · 2013-05-27 3:11 pm

Thought so. You could put a 100 watt bulb across those points and test the rest of the amp

Karl vd Berg · 2013-05-27 3:22 pm

jaycee said:
My guess on why this has failed would be the same as that Rotel - your mains should be 230V but it is actually more like 250V. The extra power could well be responsible for making the transformer overheat and blow the thermal fuse. If you can get transformers rated for 240V primary, it may be better.

Yes, I guess it was the spikes of voltage at that time that blown the Rotel's trafo away. 230VAC seems to be stable since then.

Mooly said:
Thought so. You could put a 100 watt bulb across those points and test the rest of the amp

I have to build my dim bulb tester yet

Any chance of fix this transformer or replacement is the only solution?

iaxxaxxai · 2013-05-27 4:13 pm

The large power supply filter caps look possibly bad as well. I can't say for certain from the photo, but they look like their cases have expanded. Usually a sign they should be replaced.

jaycee · 2013-05-27 4:28 pm

The only direct fix for the transformer would be to bypass it's thermal fuse. I would not recommend this. If the transformer has gotten hot enough to blow the fuse, the primary winding could be damaged.

Karl vd Berg · 2013-05-27 5:04 pm

Pioneer A-209R

jaycee said:
The only direct fix for the transformer would be to bypass it's thermal fuse. I would not recommend this. If the transformer has gotten hot enough to blow the fuse, the primary winding could be damaged.

I just took the main PCB off to desolder the rectifier bridge and check if it's still OK, before take action with a new trafo.

An externally hosted image should be here but it was not working when we last tested it.

iaxxaxxai said:
The large power supply filter caps look possibly bad as well. I can't say for certain from the photo, but they look like their cases have expanded. Usually a sign they should be replaced.

Here is a close-up of them

An externally hosted image should be here but it was not working when we last tested it.

Poineer A-209R

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