Possibly damaged OPT: Fisher X-100-2: Your thoughts?

[Patrice B]

Well, Heyboer sent me a quote too and they would make two identical replicas... Pricier as they make two instead of one for Gary.

 

[Patrice B]

Thanks to member rufleruf (Matt), I have a good working replacement ready to install...

The X-100-2 lives again!

 

[Dadbar]

By the way....it's not a good idea to remove the 12AX7 tubes on these units and run them. One some of these low priced cathode bias Fisher units, the heater string for the 12AX7 tubes serves as part of the bias resistor for your EL84 tubes. Pulling out just one tube screws up the output tube bias.

 

[rufleruf]

Dadbar, It's funny you should say that. I was looking at the schematic for my X100 (no suffix) and was trying to figure out why the heaters were all in series and connected to pin 3 of the output tube.

 

[gadget73]

The Fisher 600 works that way too, the phono tubes are the cathode resistor. Its a decent trick to get DC on the tubes that need it most, and get the heat out from under the chassis at the same time.

 

[Dadbar]

Dadbar, It's funny you should say that. I was looking at the schematic for my X100 (no suffix) and was trying to figure out why the heaters were all in series and connected to pin 3 of the output tube.

Sometimes people do this to reduce hum.....a fixed DC voltage is applied to an AC filament supply to convert it to pulsating DC which reduces hum and heater to cathode leakage.

 

[gadget73]

Thats wired slightly differently though. The cathode ends up tying to the center tap or the resistors acting as a center tap and then into the parallel wired AC heater supply. I actually like to do that as well, not sure how much it helps but it costs nothing and it must have done something or mfg's wouldn't have bothered.

 

[Patrice B]

Thanks for the advices and comments.

Done... Will post some pics tomorrow.

 

[Patrice B]

Well, in the process, I had to replace a broken socket (one lug was broken underside and when I tried to put another one, I completely damaged the socket beyond repair).

Now, it looks like that. Note the little aesthetic difference on the right OPT. BTW, one 7189 was dead once I finished the replacement. There's now a quad of Russian tubes in place.

The HK A500 could take a rest. It wasn't bad as a backup but the Fisher is better and dead silent.

Patrice

 

[rufleruf]

Looks good! I was impressed by my x 100 3 that this came from when I got it going.

 

[Patrice B]

Looks good! I was impressed by my x 100 3 that this came from when I got it going.

Oh, and thanks again for the transformer.

 

[Patrice B]

Just listened to Chicago V and wow, clarity, details, soundstage...! For sure, a fresh quad of tubes helped maybe.

 

[gadget73]

I've had that happen with sockets more than once. Seems that once one lug comes out, the whole thing is pretty much done for.

 

[Patrice B]

I'm asking myself if the broken lug and/or the dead tube could have played a role in the death of the OPT... I know Mr Gillespie talked about moisture and expansion but maybe a primary winding energized without a connection (lug, tube) is probably not good.