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I have a MX113 that I have had for about 30 years. It has not been powered on for about 20 years. Is it safe to power on or should I use a variac to bring it up slowly? I assume it will need to be aligned, but what else should I consider doing once I have it up and running?

I figured the speakers were the prize also. I looked at the stuff yesterday. 2 blown drivers I passed.

My first Fisher piece was a SA300 that my father purchased new about the time I was born. His system was the 300, a Scott preamp and a Fisher tuner, Gerard turntable powering a pair of, built into the wall, AR1s. Someone gave him good advice except for the speaker location. I spun Beatles...

It was a bad solder joint R28..

My 400 is sounding wonderful but I have no FM mono output. I replaced the suspect 1 uf in the MPX and corrected the eye dance. In mono the eye retracts and does react to tuning but modulates a little. If I had to guess ( remember I am a novice) I would think the issue is after or R28 which...

Dave. I have been studying the 3 schematics you posted to familiarize myself with the modifications. I have a couple questions. On the EFB schematic, the 2 watt resistor at the top after the 410 V supply. I cannot make out its value. 15? 150? 1500? On the Input and Inverter Driver Stages...

Correct, my dyslectic mistake, 45.22 K is the correct figure.

Dave, Thank you for the explanation. I have set the combined resistance of the control and parallel resistors to 54.22 K. I now have the urge to start collecting the necessary test equipment to achieve the least possible distortion. All in time. I also want to thank you personally, and the...

Yes I moved the plate supply voltage of the AF stage to 306V ( Dave's Schematic 310v) My AF stage plate voltage 98V vs Daves 90V and My PI stage Cathode voltage 99V vs Daves 91V

Yes I check the resistor values when I remember . Both channels are close. Pin 1 resistance measures 48.97 K and 49.03 K Pin 3 fully adjusted measure 47.93 47.66. Another member had a similar problem after installing this mod on a Fisher 500. There is pair of parallel resistors just before...

Well it took me a while but I have finished up all of Dave Gillespie's mods as outlined in " Improving the Fisher 400" The unit is sounding very good. I have a question about adjusting the AC balance. I have the PI modification in place and I tried to use this quick method Posted by Larry ...

I found the culprit. It is the shielded lead from the volume control to V13 network. I hooked my meter up to the volume pot and started to poke around the area of V13. It took a while but it was obvious once I found it. Powered the unit on and I could control the right channel volume by flexing...

Poked around some more, gave some areas a shot of Deoxit. A few hours later I powered it up and the right channel is back but balance control needs to be way off center. The right channel dropped out again while playing after about 15 minutes. I have an intermittent problem I guess.

I think it is more than that but I am open to suggestions . Leads are connected , at 12 o'clock setting of volume control right channel 1.2K left channel (the working channel) 127 K

I checks most components downstream of the volume control. The resistance between the lugs of the volume control varies greatly between channels???

Ok will do, OTs were not in place. Grid resistors are good.

One problem fixed another arises. I now have very low output from the right channel. I swapped tubes 8 and 9 and also 10 and 11. Swapped output tube pairs, checked voltages across heaters in V 8,9,10,11 all about 14 volts. Looked around a lot for anything I may have nudged while connecting...

Down and dirty,, I switched the legs on the transistors and hooked up the board before mounting it. I read your suggestion about checking the transistors after I was done. I think I bought 10 transistors. With line voltage @122vac via variac I get the voltages on Dave G's schematic 435v and...

I'm Back 4:17 PM. I think I found it, Rookie mistake. I have the collector and base switched on the 2- KSA1013. I drew a drawing and had them interchanged, I do not know where I got that info. Do you think they are still good? I will check the rest of the components the best I can, and...

Ok here are some shots. If someone can spot an error I will be amazed. Not because I do not think there is one, there most likely is. I takes me quite some time to trace it looking at the schematic and flipping the board back and forth. I will start now. 3:36 PM

Thanks for the advice . Luck I will need. I will pull the board and check the build. My bet is I made a mistake somewhere. I will check the transistor orientation. I will disconnect the bis lead from the 330 ohm resistors and see if in fact there is any output with the led disconnected.

Disconnected EFB board from transformer. Still have output from board to screen grids. Slight +.2 voltage at bias output, output still connected 330k grid resistors. R138 stays at room temperature.

Output tubes are removed. I removed tubes 8-11 and brought the variac up to 67vac. R 138 starts to get hot at that voltage. My B+ is 239 volts Output to screen grids from EFB board is 170 volts Output to bias network from EFB board -1volt. It does not change while adjusting the 10k trimmer...

I did not think about it when I took the photos of the charts , they are copyrighted. I do not believe I should post them.

Everything was working fine until I cut the white lead. I do not know how hot the resistor was getting before,but it is very hot now. Rectifier voltage checked OK prior to this.