Carver CM-1090

[Frazzled]

Hello everyone...

I am new to this forum and was very happy to find it as i have been an audio electronics enthusiast for years and it is nice to see so many other with so much experience to share, thanks for allowing me into this community.

I will be receiving very shortly a Carver CM-1090 amplifier in non working condition. Does anyone have any repair experience with this amplifier, I also have a service manual coming too but what I am looking for is some insight from this vast pool of knowledge.

Thank you for your time and consideration.

[Frazzled]

Well that's ok. I received the "service manual" yesterday which really other than schematics and parts list there is no other service information contained within, but I think I have enough to go on.

The amplifier should arrive this week and I will have more info at that time.

BTW what a great forum!

[Frazzled]

OK here is what I have so far...

Input is 1.5v p/p @ 1khz
Output at 2SC3281 responds to the volume control up to about 112v p/p before clipping @ 1khz

However at the speaker outputs I get a very low volume output that tracks the volume control but very distorted output!

Then when I turn on the sonic hologram suddenly I have output at the speakers.

Anyone have any thoughts, I can provide the repair manual in pdf format to anyone willing to help me out.

Thanks for your time.

[Frazzled]

Well I think this is one of a few rare threads were only one person has started and finished the thread.

After a lot of hunting around, damn I hate integrated amps; give me a regular old amplifier any day, I found the whole problem came down to a balance pot.

It is a taiwan made ALPS 150K stereo pot but it is different than any other potentiometer I have ever seen, let me explain...
it has a center detent, on one wafer right of center is 0 ohms while left of center is 140K to zero as you turn it, the other wafer is the same only reversed and it's maximum impedance is 127K but is very eratic.

Any way this bad pot was apparently enough to keep the amp from operating properly.

It turn out the sonic holography bypasses the balance control altogether therefore restoring output, I have just bypassed the pot temporarily until I can find a suitable replacement. Guess I will call Carver on Monday put I am not very hopeful that old BOB will have one of these in stock.

[destroyer X]

Something may be happened with forum people, maybe the timing, related other people sleeping, maybe the subject.

Let i try to explain the little things i start to understand here....just starting, not a real problems, but some characteristics of the forum personalitty.

I do not read forum yet.... i am out around 12 hours, and i saw some of that never ending discussions.... sometimes start very well, and in the middle became a little hot, and when too much pages sometimes overheat a little.

There are subjects that everyone of us can, in a easy way, create a lot of discussions that have not a clear decision.

If you entered, with good heart and ask about simetrical input, will start a crowded change of ideas... and if you are not to good man, and beeing bad decide to make them figth (this is theorical, not really practical or precise) You can start with some polemic and never ending stories here. As an example, if you start a thread and with strong energy say clear and loud that Bootstrap method is better than other method of design amplifiers.

And, this way start the thing, reading all forum twice, i found some good change of ideas sometimes, a small strike someday, i heavy combat one nigth, and people nervous other time.

If you are completely ignorant, no knowledge, not a qualified technician or a skilled repair man, or an old enginner....here, a complete Democracy, you can face, you can discuss, and you can create a damn confusion, because the one that have 35 years working hard with such a thing, the one that design 104447984 equipmentos, the one that is the big boss of an International or multi national big company, the one that is the Responsible of Nasa controls design.... they are here, all of them as kids, sharing their toys.... and them, appear one beginner, someone that read yesterday a text and say that bootstrap is a damn bull s---!

And this magnificent man, skilled Engineer, deep knowledge, full of books written, respected wide world, teacher of Universities have enter in a never ending discussion related some matter. Things that mix subjectivity with technology... and hard to face because if you write, inside a discussion, that could never see Scopes walking in the street to go shopping and buy amplifier, as i write somewhere, but not inside a hard discussion that you can feel hot inside, ...but if you say.... I hell with those damn formulas... i do not like.... all this is a ..................... (do not know exactly what can be said) you completely send dirty to 30 years experience, give a lame shower to a very well respected man and start a big competition, with no winner, and no result, no conclusion and some hurt mids, and hit hearts.

Our matter is also subjective.... our ears are the main instrument.... if someone calculates deeply and avoid, lets see, 5 order distortions, because he made tests in laboratory, and based in books, in ideas an in experiments, he nows, clear and without doubts, that this fifth order distortions is awfull to humans (i do not know, just one idea...just to think about it... i could no sleep, so lets talk an talk)... do not keep my words as God words, i am not God.... and not an experienced man, also not the forum voice...just one common user that is discovering slowly the stones in my way, the good , the bad and the evil )

And someones start to discuss this matter, knowing nothing about the hard study donne related to subject and say.... damn S...! Bull S---! of course people became controled but nervous. And they tried to explain, and is misunderstood with someone with this purpose, and misunderstood agains with other without the evil purpose, and also a lot of people saying, good!.... Yes!.... thanks!....great!..... and also Aaaagh!....baaaah! and things alike.

I do not know...but somewhere in forum may be happened a bad discussion, the one start with some delicated offense... forum big, many places to discuss, you can start a combat in off topic and all the army will strike in another place.

95 percent are good intentions, 4 percent are the ones that do not really understood, and 1 percent is treating of confuse all the others and put them to figth.

You start is the one with some problems, i imagine that have some problems to put schematics.... some copyrigths laws turns hard to ask you....hey!...put schematics!.... because without it.... people will make magic to discover something.

And start with a problem without giving us the good tools to help you..... if you put some link to the schematic...if the schematic is already in internet, or if you do not tell the name, the brand and the factory.... and show only a small part of the schematic, related to the most probable damaged circuit.... or if you make the amplifiers schematic in a Workbench, or some Spice image....this way..... one certain circuit..... one thopology....my personal problem.... things became easier to the people help....hey!... check here, or there... and they will be very helpfull.

But this way... this is a Rodde ans Schwartz, registered under 098226664878 as a property by William and Sons factory unlimited limited... some problem, you know.

Not sure if i am rigth... i am to new in this forum, and i can be dreaming out of my bed!

And there are some competitions here.... the long tail team, and the CCS team and the Double simetric team.... and no conclusions... and i need those alike you and everyone...but difficult because mixed technology with subjectivity... i love some stupid distorted amplifiers.... and now?.... complicated.

I imagine people must make a Chart... some Excel work and put the characteristics measured in laboratory.... subjectivities appart... and long tail has good woooming..... bad buuuuuufle.... clear smiddles..... some leack deepneck..... some distortions in buuuuuufle!... and put all the new and some old together to comparison... this is bad here and good there... and you make your technological choice and go to hear to decide that your "good Thopology" is upp side down cascooding with unsimetrical short tails". of course cascode is not cascooding...only as an example...my english is not so bad this way.

There are some small comercial interests too.... we have inside our forum wonderfull PC boards factories, magnificent Kits, and some bad one can make them fitgh only to wait diggestion of lunch of the time to go out to have fun.

This way, someone that is drunk... and enter here, can face the big brain enginners and send it to space!... and this is terrible... loose of respect, ignorance and no sense.

too many people talks Maths.... and distortions.... and i assemble sometimes and awfull sound (subjectivity!, the one that only heard poor sound can dislike a precise equipment)... this way, i think in write that distortion analiser do not buy amplifier...and i put it somewhere....i was completely rigth, and completely wrong! at the same time.... you can not measure and classified subjectivities....so, go to measurements.... thats the only way to say good or bad.

Start a thread this way.

Here's my new amplifier..... and put schematic made in some Spice.... i am having problems this or that, put pictures (people love pictures, i love them too).... people will appear and help you


But, something that can be everything at same time.... starting from a fuse and ending with a damaged voice coils.... and in the middle some bad solder...it is hard to help

If i could be rigth in 0.000000005 percent, i was a good man, and giving you a friendly reception

This is our place, we love this place, but, as whole manking, we have some small problems and characteristics and personallity... you will find gentle moderators...you will find crazy ones, you will reach panzer people, bombers, strickers, confusers and anjos too.

Welcome to our happy meeting,

Carlos

[destroyer X]

I could see Mr Curl on line.... also Rodd Elliot passes here sometimes, Mr Hugh Dean, Mr Jan Dupont, Mr Nelson Pass... and others qualified people that can help a lot.

Here, we have those man helping the beginner, teaching them as to hold a soldering iron... this is great!

Carlos

[Frazzled]

Well it was an excellent weekend.
I epaired the following, Technics SL-P3 CD player, Carver TX-8, Carver CM-1090. (must clean off all the fingerprints!)

All Ebay purchases (except CD, garage sale, $1)

You already know about the amp, the tuner had no power(bad voltage regulator) and the CD player needed two new belts and the switch that detects that the tray is closed was non functioning so the tray motor kept spinning and burned out one belt before I realized what was going on.

Anyway everything is working perfectly (except I still need a balance pot for the amp) and it has been a fruitful weekend!

[macebobo]

Frazzled,

Would you by chance still have the PDF for the Carver CM-1090? If so, I would be in your debt if you would be so kind to send me a copy. My 20+ year old 1090 just started having some clipping issues the first 15 minutes of operation (so bad it makes my wife jump in her chair when it happens!)

If you don't have the manual any longer, how about suggestions where I should look first. I love this amp and this is the first time I've had any issues with it, other than a VU bulb burning out.

Thanks,
Mac

[anatech]

Hi Frazzled,
I just caught you thread. I used to be the Canadian Factory service for Carver. My manuals all went with the shop when I sold it, so I can't give you detailed information.

Your balance control can possibly be saved. A small shot of WD-40 on the slip ring area should restore it. I would prefer that you use De-Ox-Id, or De-Oxide (Caig or General Cement products). Radio Shack cleaners should be avoided. Don't use tuner cleaners - ever! Use as little as you can, it washes out the lubricants.

I'll get notifications on your thread now if you have any questions. If you are going to send out PDF's, I wouldn't mind a copy. Use bhomester at gmail dot com.

Good job Frazzled! That holography circuit really confuses most technicians.

-Chris