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IT SINGS! Yes, B+ voltages are higher without tubes...I put some modern tubes in to fire it up on a variac. No smoke or fumes, voltages checked good, hooked up to the mc-275 and behold beautiful music, now to put the the original telefunkens back in! So stoked there are no issues and it's...

Copy all, I found that some idiot (me) had soldered an extra 100k ohm resistor into the circuit for V2. That now checks good. I'm pretty sure that the v4 pin2 reading is due to the 330 ohm resistor soldered onto the volume pot to balance the sides/channels because when I switch the unit from...

Copy all on grounding pin 7 of V8, other pins would also read incorrectly if not done, correct? They all read good, so I don't think i messed that up. The 100K resistor attached to that pin reads at 55K in circuit but reads 100K when a leg is lifted.

Clinic-audio- very sure I have the correct diagram and each part was taken out and replaced individually for the most part. Now obviously I made a mistake somewhere so what I'm not very good at and was hoping for help on is understanding the relationships between components; in this case v2 and...

I have a C20 that I have re-capped and re-resistored and when checking pin resistance per the schematic (SC117-201) everything is great except the following: V2 pin 1 is 55K vs 130K desired (V2 pin 1 is 130K) V4 pin 2 is 345 vs <50 desired (V3 pin 2 is 34) All other pins on all other valves...

revere521, What is the nomenclature on your protection board (numbering etc)...it may be possible to find the schematic in another amp that uses that board...happens with sx 828s also.

revere521, Try this link: http://www.audiokarma.org/forums/showthread.php?t=457663&highlight=recap+list Good luck and listen to MTF (but you already know that!) highlander52

Apparently Common Swap MTF will probably answer this one but I've also rebuilt one that had the 838 protection board. I just downloaded the 838 manual and used it for that board. Unit is still working after about 3 years so I think this was a common pioneer instituted swap. Hope this helps...

The 12az7 s are running much more "lit up" than the other small tubes and the getter appears to be damaged as well... Amp has only run about 45 minutes and I'm not sure if something is wrong or if this is normal for this amp/tube? Any help would be much appreciated!

Finally finished, almost! Had a 3 week vacation and have now pretty much finished the amp refurb. Installed the last of the capacitors and checked the resistance which are all really good and even except for the 12AZ7 pin 1 and 6 which are 51-55 ohms instead of the specified 38 volts, pins 3...

jjblue84, I'm using a Mills for the 500ohm resistor you have pictured, it's smaller and doesn't show up well in the picture but it is there...thanks for checking work, I need it!

Next steps dshoaf, So I shouldn't be worried about the high resistance readings on V4 and V7? Some are almost 50% higher than spec. The paper electrolytic caps were interesting...the external case would spin freely around the body. I still need to replace the .047 bumblebees before...

MC275 Capacitor and Resistor list per SC125-109C schematic C1 0.1 Handmade 4-TFT-R1006000 C2 330PF Mouser 598-CD15FD331GO3F C3 100 Mouser 594-2222-118-18101 C4 0.22 Handmade 4-RT-R2206000 C5 15PF Mouser 598-CM05CD150J03 C6 0.047 Handmade 4-TFT-R0046000 C7 0.047 Handmade...

Progress Update So I've finished replacing all the Diodes, the rectifier, C22 and C23, C2 and C13, the multisection caps (C24-27) and C28. R60, R61, F62, R65, and R11 and R36. Finally the thermistor was replaced with a CL-50. I used 1N5408G for the Diodes and the 1N4007G for the rectifier...

Capacitor Confusion Terry, Per your book (and online sources) the stripes are white, violet, orange, orange, blue, and finally gold or maybe white, red, orange orange, blue, and gold. Either way I can't make them come out to 330pf... white is +100 or 9, red is 2 or +-2 (violet is 7 or...

Long lost capacitors Thanks again Terry and sorry for my bungling the spelling of your last name...the stripes are white, violet, orange, orange, blue, and finally gold in that order (see picture). I've removed one and as a resistor it tests around 15M ohms as a capacitor it tests 68pf. Guess...

Hello McIntosh forum, I normally am in the Pioneer forum (lurking and trying to learn) but have had the great misfortune/fortune to inherit a nearly mint MC275/C20 combo. The 275 is s/n27510033 which I believe makes it the 33rd or 34th produced. My Grandfather purchase both new in the early...

Robie, will send you $25, pm sent. Thanks for handling this for MTF. Highlander52

Best Wishes and Prayers for Health Mark, you are in my prayers and I hope you have the best doctors in the world as you certainly deserve it! Pat

Mark, Fixed the leading letter problem...got in some ksa1013s and put one in. Powered up and same problem as before. Q202 Leds light up green (q206 didn't even flicker) until about 100 volts on the variac then start to turn orange...turned off the power this time before they were fried. I'm...

Thanks Mark. That was how they were in. Can I power it up with them out and check the voltages at q201/205 emitters, q204/206 emitters etc...just thinking out loud. I'm guessing since q202 is burning itself out the current and/or voltage is too great so I'll check c205, r208/209 on down the...

Returning after some time away! Mark et al, Please forgive me for resurrecting this old thread but I foolishly was probing for voltages (back in July?) and had my probes exposed versus covered and you know what happened next...slip, sparks, smoke, :tears:. I've just now dug it back out and...

You've exhausted the level of knowledge I'm comfortable sharing due to my own lack of knowledge but it sounds like your problem is similar to the one in this thread: http://www.audiokarma.org/forums/showthread.php?t=393371 If Mark the Fixer or Echowars or a couple others I can't recall right...

The protection is actually a relay that clicks a few seconds after power on. The noise you are hearing is probably just normal switch noise. As to the speaker plugs the top/horizontal plug is the positive/red connection. Is that your question? The plugs (u shaped jumpers) connect the amp to...

LEDs fixed OK rechecked the schematic for the CCS and I had the LEDs in backwards. Fixed now. So which pin goes where? Or have I over simplified this replacement? Given that the 2sk34s both where in the same orientation I'm assuming that the CSS orientation will be the same for both.