C-26 Re-Cap

[skippy_ps]

Bought a near mint C-26, non working. One side of one filter cap was dead and both sides of the other filter cap were dead (both caps are 2 section). After some head scratching and em's to Terry, I pulled both filter caps and hot glued 2 470uf caps on top replacing the 2 200uf sections and used a sticky tab and tie wrap to hold down two 330 uf caps replacing the other sections which were 200uf and 50uf. The schematic says that these 2 sections are both 160uf but what the heck. Here's how it looks on top.

 

[skippy_ps]

Not quite so neat on the bottom, but, hey I'm an amateur. Even though it may not make a lot of sense to use snap-in caps here, it's actually easier as there's a ready made place to solder all those pesky wires to. Way more selection of snap-in caps than axial caps in sorta high voltage (200v) too.

Right channel phono is dead and so far no luck in finding the problem. All audio caps replaced with Nichicon Muse and Black Gate, in place of tantalum caps.

Mucho thanks to Terry for guidance in getting this going. Sounds great with MC-2002 and Vandy 1's

Murray

 

[N7SC]

Nice job! Looks like you put plenty of consideration into doing it right, neat, and well. Truely in McIntosh style.

Need to recap my C28's power supply due to failure of one of the three-section electrolytics - BUZZZZZZZZ! I'm going to try to mount all the replacement caps in the same space, above the chassis, that the original aluminum electrolytics were in. Have worked it all out on an engineering pad, in drawing form. And have played around with the new caps and confirmed measurements and fit. Now just need to get hold of some thin sheets of UHMW plastic and some phenolic (may just gut the old electrolytics and use their bases and solder lugs) to make up the mounting rig. Plan is to make them up in "bundles" with discs of the UHMW holding them all in the right place, via leads going through small holes in UHMW. Each 3-capacitor-bundle will replace one of the 3-section electrolyts. Negative leads on the top will go through a UHMW disc, and be twisted together (inside spaghetti or heat-shrink), and the support from the phenolic at the bottom, combined with another UHMW disc wherever it fits will make each 3-cap-bundle hold together kind of looking like a big wrapped piece of taffy. Without the wrapper. And it will all fit in the same space that the originals were in, with the positive leads all coming through the chassis in the same location as the originals, so no rewiring underneath.

Will post photos when done. But it may take a while - I've got a lot on my plate right now, also waiting on two power supply diodes from McIntosh. Might scan and post drawings in interem.

 

[macman007]

Skippy,

My phono section on my C28 was doing the same thing for 2 different reasons. It was a solder joint that had failed/wasnt good enough in the first place around the edge of the board where either a wire for the phono cable connects to the board or a component was soldered badly or both.I found several other questionable joints so I resoldered them as well as all the other ones I found all over the unit. Also the wiper in the selector switch may not be making contact in the phono position but this is usualy only on one phono position not both if you have 2 phono inputs like the C28.Other than that keep searching , the answers right in front of you. Its pretty easy, once you get the hang of it, to repair these older Mc's.

Artie

 

[skippy_ps]

N7SC, Thanks. I've looked at this C-28 cap replacement thing too and will post what I found out later.

Artie, Yeah, once I got oriented between the pre amp board and the schematic, the phono section is pretty simple. All the components are on one end of the board. Everything looks fine and checks out fine, it just doesn't work. Gave up yesterday, hooked it back up and have had it playing tunes thru cd and tuner. Need to take the front panel off and check the selector switch as it's hard to see otherwise. Looked at it yesterday from behind and cleaned it but no luck.

Murray

 

[N7SC]

Murray, Don't know if this applies to the C26, or even if it was more than an isolated case, but . . . Had a C28 bought new in December 1971, when only a few weeks to few months old it dropped the phono input completely for a few seconds. It just went dead, then came back on like nothing happened. After making sure that I wasn't hearing things, called the dealer. Long story short, after three trips back to the dealer's service dept, it finally demonstrated its special talent to the service manager. Mc rep said give me a new one and send that one back to Binghamton. Might want to call up there, if it was not an isolated incident, there might be some kind of service bulletin out on it, or something. It may provide some kind of help.

Scott

 

[skippy_ps]

Ok, C-28. I got this started on my C-28 and it works now but I still need to (want to) change cap C302, the one towards the front.

C301 is 2 2000uf sections in parallel so can sub 1 4000 to 8000 or so here and put in place of the original cap. Then one below chassis 50uf/200v or 100uf or so. So far pretty easy and I already did this - used a 6800uf/63v cap here and a 100uf/250v below.

My idea on C302 was to put a 1000uf or so cap on top for the 500uf section and then a 220uf/100v or whatever below for the 200uf section. The remaining 50uf/80v section connects all the way over to the center pcb and so it could be sorta be put any where that it would fit. There's very little room underneath on a 28 so lotsa planning on what goes where would seem to be in order.

Anyway, that was my idea re C302. I have all the caps, they just haven't found their way out of the box and into the preamp.

I suppose it's possible to squeeze some or all of the new caps in a cleaned out original cap but this sounds like a real bitch. :worried:

Murray

 

[oplancq]

Hello,
I'd like to recap my C26. Anybody knows where I could find the schematic diagram ? When I switch it on and move the loudness/balance button, I have a "scriccchhhhhh" coming from the left speaker. After a few seconds, it's ok. Where is it coming from ? Thanks for your help..

Olivier

 

[theodoric]

I've got the service manual. PM me and I'll send you a copy.

 

[oplancq]

OK..now I have the schematics and it looks I need to replace 7 electrolytics polarized capacitors:
- 3: 100µF - 16V
- 4: 10µF - 20V
So can be done for reasonnable price...

Anybody can advice which cap (that would fit the best) I should order ?

Thanks,

 

[skippy_ps]

The sheet that I have for the C-26 shows 35v for the 10µf caps so I would go with the higher voltage.

I use a lot of Nichicon caps (VR and HE) but everyone has their favorites:

Panasonic FC (Digikey)

Nichicon Muse and Black Gate (Michael Percy)

Nichicon standard series (VR, HE and several others) (Mouser)

Murray