If I might also offer --
1. The large brown radial lead cap attached to C116 that you are indicating is a 10 uF cap looks by physical size to be very much bigger than 10 uF. Regardless however, it is a band-aid that never appeared in the original factory wiring. If C116 is good in all sections (which is the filter cap for the tuner circuits), then no such band-aid is needed for quiet operation. The brown radial cap shown added to C116 is the only band-aid appearing in your pic.
2. The blue axial lead cap attached to the silicon rectifier T-strip should in fact be a 10 uF cap. The one installed is obviously a replacement cap for the original, which is designated as C114 on the Z schematic. Confusion arrises from the fact that the M version of the MX-110 did not have a discrete cap in this location, so those more familiar with the M version might initially view such a cap in the Z version as an aftermarket modification -- particularly if it is a modern replacement cap as shown in your pic. In fact, its inclusion was part of the significant power supply upgrades made by Mac when the Z version was developed.
3. The other modern discrete cap shown bent down behind the rear red PEC should be a 12 uF (or larger) cap,
incorrectly labeled on the Z schematic as simply C115. Now obviously being a discrete component, it can't be part of the C115 can cap sections, so the schematic mislabeling causes confusion. As installed at the factory, the real C115 is in fact a four section cap, but has two of its sections paralleded. The two paralleled sections together make up the single 70 uF cap shown on the Z schematic as C115C, which further adds to the confusion when trying to match the schematic to the build. Finally, the highest numeric label for capacitors I could find on the Z schematic is C124. But -- as another schematic error -- there are two separate (unrelated) caps labeled as C124 on that schematic, so for at least my own purposes, I have labeled the original "C115" 12 uF cap as C126.
4. The design of the 110's HV power supply employs a CT winding in the power transformer, allowing for "full" and "half" voltage supply points. But the load attached to these points is wildly different, with far greater current flow being drawn at the half voltage supply point than at the full supply point. As a result, it is impossible to use a single resistor in the negative lead of the bridge rectifier array to compensate for the increased efficiency of the silicon versus the original selenium. A given resistance value can make one voltage tap correct, or the other, but not both. Therefore,
two resistors must be used to correctly compensate the unit when silicon replacements are installed -- one between the positive lead of the bridge and C114, and one between the transformer HV winding CT and C116A. In a correctly operating Z, a 560Ω 2W resistor at the bridge location, and a 100Ω 5W resistor at the HV CT lead will produce normal voltage levels in the Z. The negative lead of the bridge should be grounded as in the original design.
5. Your unit also shows more evidence of a significant factory wiring lead placement error I discovered through troubleshooting a client's MX-110Z hum complaint, that had symptoms nearly identical to those you describe in your unit. Apparently Mac ultimately became aware of the problem as well as once I had determined what the problem actually was, continued research (by others) then showed (through underside pic observations only) that the factory had resolved the problem in later Z units with a change in lead placement that was in a manner very similar to the one I had published here. Either way works equally well, but nobody knew about the change Mac made to correct the problem because they never offered their fix in a service bulletin -- I guess because it technically didn't represent a circuit change. The cause therefore had to be sussed out independently. In any event, with no published correction from the factory, the run of units affected never had a chance to be corrected in the field -- all the owners of those units knew is that their unit hummed. The reduction in hum made by the fix proposed is significant -- you can find the thead I published on it here:
If @monkboughtlunch is anything, he is relentlessly persistent. For nearly 4 years he has contacted me at various times regarding a hum in his MX-110Z, over which time we discussed virtually every aspect of resolving it save throwing the kitchen sink at it. It was particularly problematic when...
audiokarma.org
I hope this helps!
Dave
