Wanted Phase Linear DRS400 (for parts or working)

[Tech19642020]

I'm new to this forum looking for some help.
Like many here I've been doing hi-fi and electronic work both for a living and as a hobby for almost 40 years.
I own a Phase Linear DRS400 with a defective power transformer. Will pay top dollar for a unit (for parts or complete). Also any leads or ideas would be greatly appreciated! Thanks so much for your time!

 

[mlucitt]

Welcome! We are Phase Linear fans here but more for the earlier amplifiers, before Pioneer purchased Phase Linear in 1979 and rolled out the DRS line. I'm sure there is someone on the Forum that will be able to help you source a replacement transformer. These units are fairly robust, do you know why the transformer failed?
I was trying to find a DRS900 for several years, but gave up and stuck with an old PL700B that smelled like beer inside. I rebuilt it and it still keeps the neighbors awake at night.

 

[Tech19642020]

Hello!

Thank you for the warm welcome! I kind figured it's more for the older PL equipment which was really why I purchased this amp back in '83 hoping it was of the quality of the orriginal older PL but couldn't afford. I do really like it and that PL "clean sound" I happened to see this in a CMC hi-fi store (back when they were still around) and bought the tuner, P3800 preamp and this DRS 400 that matched it, all as a complete set. As for why it failed, one of the bridges was also shorted and it failed while playing. To your point transformers so rarely fail it does give me pause but I've confirmed all other loads and there's no issue so, potentially it was a surge or the primary laminations just weakened over time. Thanks again for your response and welcoming to the group. Hopefully someone out there has one (or leads to one) . Incidentally this was orignally posted in "amps and preamps" so I'll delete it there to prevent confusion.

 

[WOPL Sniffer]

so, with nothing connected, the transformer is dead? Everything disconnected?

 

[WOPL Sniffer]

Post a pic of the transformer, there is a possibility that another transformer may fit. I haven't looked at the schematic yet. nor the specs

 

[Tech19642020]

Hello,

Thank you for the reply. It blows the 10A line fuse with all secondary loads disconnected. It's a dual primary Xformer 120/240 VAC switable series - parallel and one primary is shorted (as a test I used a lower voltage, measured current, did the math and came up with a Z of 2.13 ohms. So, I'm sure it's shorted. Thanks again for your interest and any leads. Take care.

 

[Tech19642020]

Will do! thank you!

 

[Tech19642020]

Hello,

Here is the schematic. It's a fairly complex secondary. I've looked into a quote (to build one) through "Controlled Magetics" but haven't heard back from them yet. Thank you.

 

[WOPL Sniffer]

To build you a new transformer???? Those amps are not worth that.

 

[Tech19642020]

Haha, yes I know..it's a sentimental thing. That's why I'm happy to pay top dollar for a parts or complete unit.

 

[WOPL Sniffer]

They are rare, because they were disposable. But I wish you luck in your search. I bet you could find a suitable sub for the transformer.

 

[Tech19642020]

Hopefully there's one out there somewhere. Thanks very much for your kind wishes!

 

[WOPL Sniffer]

I didn't even see a manual for it except the guys trying to sell them.

 

[Gepetto]

Have you tried running it from just one of the 2 primaries? One may turn out to be OK. Depending on how the primary failed (and you do not really know that the primary failed) you may be able to run it on one of the 2. You won't get full power output but it may suffice for your listening needs.

 

[Tech19642020]

Hello,

Thank you for the reply. Yes I kicked that idea around just to make it somewhat workable and I can limp it along but since my son is wanting to use it I really need full power Thank you very much for the input though..it validated my thinking

 

[Gepetto]

Hello,

Thank you for the reply. It blows the 10A line fuse with all secondary loads disconnected. It's a dual primary Xformer 120/240 VAC switable series - parallel and one primary is shorted (as a test I used a lower voltage, measured current, did the math and came up with a Z of 2.13 ohms. So, I'm sure it's shorted. Thanks again for your interest and any leads. Take care.

And you are sure that the 120/240V switch did not short over?

 

[Tech19642020]

Hello,

Thank you very much for the reply. Yes I measured each primary independently using the same method. The "good" primary measured about 0.5A at idle but I'm sorry I don't remember the actual Z at that point.

 

[laatsch55]

Time for a WOPL !!

 

[WOPL Sniffer]

yep I just ordered some parts for 2

 

[wattsabundant]

Tech1964...Was there a blown fuses in it when you got it? Was it the right one?

To blow fuses with nothing on the secondary suggests shorted turns. If you use the light bulb test set (series 100 watt incandescent light bulb) with one of the primaries you can snoop around and look at the other primary and secondary voltages. You would need a precision ohmmeter or micro ohmmeter to get any relevant resistance readings. The primary on a 120V P/L 400 is less than 2 ohms.

When a transformer fails it almost always make a stink. The stench is unmistakable. Give it the nose treatment. If it doesn't stink keep looking elsewhere.

I hate to be a buzz kill but I don't like the totem pole output design of this amp. Dynaco and somebody like Sound Craftsman, or GAS used that concept. The advantage is the lower voltage drop across the transistors results in less heat dissipation. Something about series bipolar transistors just doesn't sit well with me.