Odd Sumo The Nine Plus

I've got a bit of an oddball, here.

A disjointed album of photos can be found here: http://imgur.com/a/O95G4

I've been chatting with Craig here (llwhtt) and he's provided me with some documentation to try and help, but I still can't figure out what's going on, here.

I've had this amp for a few years and I'm now finding time to get into restoring it... but I've found a few oddities.

The transistors in the right channel are all Sanken 2SC1116A but the left channel is all Fujitsu (?) 2SC2522. The right channel has C2238 drivers while the left has TIP31C drivers. There are a couple extra diodes on the solder side of the left channel's PCB, and all the quick disconnects are soldered in place. The torroid is unshielded, from what I understand, indicates that this is a later model amp.

Of the three schematics I have, I can't find a single channel that matches anything of what I've got here.

My best guess is that this is a late-model amp, with the left channel being stock, and a repair was done with an old right channel swapped in as a module.

After verifying that replacement output devices are available (unlike The Nine, from what I understand) I tried powering the amp up while measuring the DC bias, no load. I saw -15 VDC in each channel, which slowly increased to -13.7 VDC, and that's when I smelt that burning smell, and turned it off. All the fuses are their suggested value, and all the fuses are intact.

Ultimately I'd like to thoroughly restore this amp, giving it the best I can buy, I just need a few pointers on where to start. I'm fine with stripping this back to bare PCBs and changing out all the output devices should that be what needs doing.

I appreciate any insight and input.


Thanks!
Philip.
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Hi Philip,
Looks like a crappy repair was done.

Take the amp apart and rebuild the badly repaired channel. Do not touch the good channel until the bad one is running. DO NOT use any parts from the good channel to "try" in the bad one. While you have the channel apart, test the resistors (disconnect at least one lead before attempting to measure it). Check the capacitors as well, or just replace them. You may find that the bad channel now works after your hard work restoring it. Also, make sure the trimmer controls were not damaged, or replaced with the wrong part (like 10 - turn controls).

These amplifiers are easier to strip and take apart than they are to service in a normal way. The soldered tags and connectors are a real PITA to deal with. Try to desolder them, clean the blades up and replace the push-on connectors.

Take pictures of everything before you disconnect each section. These will be your record of how it goes back together. However, with this amplifier, compare it as much as you can with the working channel.

I'm sorry to hear an idiot was in there before you got the amp. That just makes life harder. You will need both a desoldering tool, the large pump models with recoil. You will also need desoldering braid and some liquid solder flux would help too. That's available from Sayal. Your soldering station should be a temperature controlled type - not a soldering "pencil" or "iron". Having selectable temperature is a real help, use a fat tip. If you try this with a 25 watt or 40 watt iron, you'll probably wreck the circuit board (more).

Use transistors from On-Semi for replacements. Those will be known parts instead of fake or remarked parts. The MJL series is what to look at. Both On Semi and Fairchild make suitable replacements for the other transistors in there.

Good luck on this one, Chris
 

llwhtt

Member
2008-06-12 3:43 am
SoCal
I recently rebuilt a dead NINE+ I picked up. Like Anatech said these are a PITA to repair due to the physical layout, you can't do anything with the board without yanking all of the output transistors. Mine had several problems, one 20VDC supply was fried, there was a teeny tiny solder bridge in the area that wiped out the MPSU55 pass transistor, there were two parallel .1uf ceramic caps that were shorted, and several leaky ARC (Fujitsu) output transistors.

I replaced everything that was bad, all of the electrolytics, and installed 20 ONSemi MJ21194 output transistors. The only problem after that was I couldn't get the idle current high enough. I ended up replacing R14/29 with 300 Ohm resistors and still had plenty of leeway on the trim pot when set to the JB recommended 1A across one of the fuse holders.

Just follow the schematic, use MJ21194 outputs and you'll be fine. Don't do any opamp rolling, just use the LF412A opamp, it must an A version because of the high PS voltages involved.

Craig
 
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llwhtt

Member
2008-06-12 3:43 am
SoCal
I forgot another problem I found on the amp, most if not all of the output stage secondary leads from the xfmr had broken solder joints on the PS board. The secondaries leads are very stiff mag wire and if you're not careful reinstalling the PS board the joints may break.

Craig
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Hi Craig,
Yeah, isn't that a fun amp to work on? I desolder those as I tear it down since you may well have to repair them anyhow. Because someone else was in there, those wires might be close to letting go. Also, I mis-typed the transistor series. It is MJ rather than MJL (plastic case). The MJ1502x outputs are also good replacements and are a little faster than the (excellent) MJ21194 parts.

-Chris
 

llwhtt

Member
2008-06-12 3:43 am
SoCal
The MJ21194s were recommended by JB before he passed away. I think he recommended the 93/94 for all TO-3 replacements in HIS designs IF the Sankens were bad. Obviously these won't work as replacements for the 2SC1831s or any amp using Darlingtons as in his early designs.

Many of JB's designs are a bit challenging mechanics-wise but sure beats working on receivers. There are just no short cuts, you just have to disassemble it completely, check everything, replace what find bad/questionable, reassemble, and align. Well worth the effort I think.

Craig
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Hi Craig,
The MJ1502x series replace normal Japanese outputs more closely than the MJ2119x parts.

After working on just about everything out there, I find the Sumo 9 completely stupid to work on. It didn't have to be that hard, and every time you take one of these apart you risk ending up with a pile of junk. A piece of equipment so full of intermittent and early failures that releasing one as they get older is a gamble. There are tons of receivers much easier to work with than these. I might even prefer working on a Marantz 4400 to a Sumo 9! I hate working on Marantz 4400's, they are a nightmare. But, at least when you send it out there are normally no surprises.

Honestly, this amplifier could have been made easy to service. The owners pay for this silly fact every single time they have to service it out of warranty.

I'm not talking ill of the dead, but just pointing out that this product could have been engineered to service instead. Easy to service electronics are always in better condition over the long term than nightmares. Work done is more neatly completed because nothing gets stressed as areas are accessed for service. Not so for the Sumo 9 (and other amps out there).

-Chris
 

llwhtt

Member
2008-06-12 3:43 am
SoCal
Yes, both the Andromeda I and the NINEs could have been better designed for servicing but both were budget designs utilizing the circuit design of the much bigger and more expensive GOLD and POWER amplifiers. They all use the same heatsinks and maybe this is where the compromise started.

I know you are very knowledgeable on the Carver mag amps and you'll have to admit those are kind of a mechanical nightmare also, the 400 cube for instance.

As far as the receiver comment goes, after all the work done to a receiver you still just have a receiver, a compromise at best. I did complete rebuild of a Sansui QRX-7001? for an ebay seller. WWWWWAAAAAYYYYY too much work for the end result. FM pretty much sucks these days anyway.

Craig
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Hi Craig,
The M400 and it's variants are a nightmare to service too. But the M400 isn't likely to have nasty failures due to removing the boards for service. This is another one that has to come completely apart and can not run apart. People breaking the TO-3 sockets are the worst problem. The PM200 and PM-2.0t are both ugly to work on (the 2.0 in the switching power supply enclosure).

Then you can look at the Marantz 500. An animal that comes apart easily except it weighs 80 lbs. That one is an extremely nice sounding amp once it has been set up properly.

-Chris

I've done receiver rebuilds that have turned out fantastic for sound quality. There are receivers out there that will stand with separate any day. Marantz 2385 is one for example. The 2500 / 2600 would but they need different spacers. These feed the outputs via buss bars and will make many separates look like poor cousins by comparison.
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Hi Philip,
Sorry, normally faults come in single channel failures. Given your status, the method doesn't change too much. You still have to strip it down. You just have to check both channels instead of one. Still, take lots of pictures as you work to answer questions that come up as your reassemble it.

The output transistors that On Semi sells these days are fairly close in characteristics. In the old days, the characteristics between transistors were all over the map. Today they will probably fall within 10 % of each other. I haven't a clue how they would match the parts though. This is a service I didn't know they offered. Cool.

You should probably replace the differential pairs as well as the newer transistors of the same number are improved over what we had way back when. Fairchild makes some, replacing the 2SA part of the number with KSA.

You should be fine as long as you check everything. You really don't want to have to go in there again. What you might want to do is to replace the gain setting resistors with Dale metal film types at a higher wattage rating. Favor lower thermal coefficients. Normally you have 250 ppm, 100 ppm, 50 ppm and 25 ppm. This is the resistance change per °C, lower being better. 100 ppm and lower is usually an improvement over stock parts. This amplifier is using metal film parts if you are curious about that. Also check the 1N5250B zener diodes as they can run hot and go bad over time. Bad as in noisy and sometimes they short. Just have a good hard look at anything that was running hot. Watch the traces as they also weaken if run hot over time as well.

-Chris
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Hi Philip,
Ceramic capacitors that are C0G / NP0 types are good, no need to replace any. If you do, go for silver mica (300 VDC is fine). You can also use the plastic types, but keep them away from heat.

All electrolytic capacitors should be rater for 105° or better. Use any of the good brands, I avoid BC components if possible.

-Chris
 

llwhtt

Member
2008-06-12 3:43 am
SoCal
My two visits to see James Bongiorno were all about the NINE, especially the alignment of the NINE, not the +. As for capacitor replacement, pf caps changed to silvered mica, .01, .1 changed to polyester films, he used Panasonics. I don't remember what eletrolytics he used, I used Panasonic FCs because I stock a lot of them. The four big filter capacitors are probably OK, but for few bucks I would replace them. The PCB was set up for several different type pin outs so you'll just have to replace them with what you can find. I bumped mine up to 10,000uf/80v so I could use the Panasonics with four pins. Your PCB could be different. I would also replace all of the diodes and bridges with like parts. The only hard part to find will be the Motorola MPSU55/56, Motorola is the only part that will fit the board as the tab is screwed to the board. I have a bunch of non-Motorolas but the tabs are different, they could be used under the little heatsink that the TIPs are screwed to.

Just strip the amp down to the bare bones, take lots of notes, pictures. Clean everything, inspect everything, order your parts, and then start the fun.

Craig
 

anatech

Administrator
Paid Member
2004-06-06 8:31 pm
Georgetown, On
Hi Craig,
The official replacements for the uniwatt devices are the "W" series parts, so for the MPSU10, you would use the MPSW42. No more tab, no screwing it to anything.

I do really balk at the idea of replacing rectifiers and the like. Those and the filter caps should be good, and replacing them while they may still be good is a problem for me. Likewise, check the MPSU parts. If they are good with no leakage, I'd keep them as long as they aren't cooked.

-Chris
 

llwhtt

Member
2008-06-12 3:43 am
SoCal
I had a bad MPSU55 so that why I mentioned it, if they check OK no need to replace. The series pass MPSU55 screws to the board which has a nutsert in big part of the copper cladding for a heatsink.

As for replacing good parts I'll explain for this particular NINE+. There are two eras of SUMO, JB and post JB. This is a post JB and there were corners cut, from the power xfmr on down. I have JB era NINE and a post JB NINE+, there a pretty good difference in the build quality. Could be why his two channels don't match each other also.

I was given a dead Andromeda II that SUMO repaired before it died, it was a mess. I couldn't believe that it came from the factory. I stripped it and made a PASS A40 out of it.

Craig
 
I had a bad MPSU55 so that why I mentioned it, if they check OK no need to replace. The series pass MPSU55 screws to the board which has a nutsert in big part of the copper cladding for a heatsink.

As for replacing good parts I'll explain for this particular NINE+. There are two eras of SUMO, JB and post JB. This is a post JB and there were corners cut, from the power xfmr on down. I have JB era NINE and a post JB NINE+, there a pretty good difference in the build quality. Could be why his two channels don't match each other also.

I was given a dead Andromeda II that SUMO repaired before it died, it was a mess. I couldn't believe that it came from the factory. I stripped it and made a PASS A40 out of it.

Craig

That would be interesting, if my amp came from the factory with mismatched channels.

I've got one channel sitting on the bench now. Snapping photos and taking notes, scribbling out my shopping list.

I'd love to see the comparison of pre- and post-JB Nines if you've got any! I'm wrapping up a bespoke project at work and now the axemen are coming in for cost control... :xeye:


P.
 
I hope this work was home-brew, and not factory...

We're got, AC wire soldered to one tab on the temperature switch with the transformer primary magnet wire soldered to the other, and 'that'll hold' bonding to the output terminals.

Was lamp cord the standard kit for the fan supply?


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