Paramour troubleshooting

[jmathers]

I recently won a pair of original Paramours with the iron and cap upgrade kits.  They arrived yesterday.  A choke had come loose from its standoffs in one monoblock but I was able to reattach it.  And it looked like no major damage was done.

I started by checking all the resistances as per the manual.  They were off at the following points:  terminal 2 = 199 ohms; terminal 25  = 1.4K ohms!  Resistances on both amps matched, which I took as a good sign.  One fuse was blown, which I replaced.

When I put tubes in and powered both amps up, they produced no sound.  The monoblock with a replaced fuse, makes an audible high pitched hum - not through the speakers but from one of the transformers I believe.  This amp did not have the loose choke.

Any tips on where to continue troubleshooting?  I see that the connection at terminal 25 is a coupling cap and primary of output transformer, I think.  This may have changed with the iron and cap upgrade - instructions for which I do not have.  If anyone has these can you let me know?

Any help much appreciated.

Jeff

[Paul Birkeland]

How do the power transformers test?  This was the first and last time we used Hammond to wind our power transformers, as they had  a reputation for not lasting very long.

I'd have to go digging for my Paramour I manual, but you could spec out resistances and voltages in terms of the tube socket pins.  DC voltages on each of the 4 pins on the 4 pin socket, for example, would be helpful.

[jmathers]

Thanks for the reply!

Yes, I can check DC voltages on the 4 pin socket.  I'll do that tonight when i get home.

The reading on terminal 25 should be 200 ohms according to the manual.  It's at 1.4K ohms.  So that may tell us something.  I'm not sure what though.

Well, I'd hate it to be power transformers.  Probably can't get an off the shelf replacement anymore.

I've also emailed the seller about this. 

[Paul Birkeland]

We did have a replacement made by our current winder, which goes by the PT-2 designation.  These are out of production but we have done a small run here and there in the past.  When I run into this problem on the repair side, I have a way to get our current PT-7 power transformer to work in the circuit, with the added bonus of DC heating.  Still, your transformers could be just fine and I would certainly take some time to see if you can get them running.

[jmathers]

I found an old post about testing the resistance of the power transformer windings.  So I can try that as well.

I couldn't find anything in the manual about PT values but I'm assuming that these values would be correct (keep in mind I have Paramours with the upgrade iron and caps)?:

"Check the resistance of the power transformer high-voltage windings. You should have the Hammond power transformer (label on the back side of the core). The black and white wires are the primary and should read about 10 ohms. The high voltage secondary are the orange, brown, and violet wires. You should read about 200 ohms brown to orange, 220 ohms violet to orange, and 420 ohms brown to violet."

[Paul Joppa]

T25 is OK. The original output transformer had the primary "common" grounded, so the 200 ohm primary DCR shows up. The upgrade output transformer (I assume this is the one we sold for a while, one of the three labels says Bottlehead EM0551.) was rated for some DC voltage so the common goes to the top of the 1200 ohm cathode resistor - so T25 to ground is 1400 ohms.

[jmathers]

T25 is OK. The original output transformer had the primary "common" grounded, so the 200 ohm primary DCR shows up. The upgrade output transformer (I assume this is the one we sold for a while, one of the three labels says Bottlehead EM0551.) was rated for some DC voltage so the common goes to the top of the 1200 ohm cathode resistor - so T25 to ground is 1400 ohms.

Yes, it's the Bottlehead EM0551 output transformer that I have. 

Excellent info.  Thank you!

[jmathers]

It appears that the transformer resistance readings of both amps are within the above specs (amp1/amp2):

Black to White:  10 ohms/10 ohms
Brown to Orange:  197 ohms/204 ohms
Violet to Orange: 208 ohms/216 ohms
Brown to Violet: 405 ohms/418 ohms

What's next?

[jmathers]

Well, it looks like it was a loose wire on a pair of interconnects that was the culprit.   

Swapped out the interconnects and we're making music.  Thanks so much for all the help here.  Really helped me rule out a bunch of things and understand a bunch more. 

[jmathers]

And just to add a few weeks later.  These things make lovely music.  Wish that kit was still available.  And at the original offering price!      A great way into SET amplification.

[Paul Birkeland]

And just to add a few weeks later.  These things make lovely music.  Wish that kit was still available.  And at the original offering price!      A great way into SET amplification.

The kit is still available, the Paramour evolved into the current Stereomour, but the Stereomour is an improvement over its ancestor in bandwidth, power, noisefloor, and output impedance flexibility.  When you consider the price of the original Paramours plus the iron upgrade, the price of the Stereomour looks quite attractive.