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M-500 Refurb.

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bob p

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Post Wed Apr 30, 2008 1:50 am

Re: M-500 Refurb.

glad to see things are coming along, Bill.

since you went through all of the trouble to track down those panasonic chicken's foot style caps, maybe it would be worth putting the digikey or mouser part numbers in your restoration thread, for anyone who might need that info someday.

you're right -- recapping the amp isn't hard, its just tedious. i can see why Rolland would want $300 to give an amp "the treatment." there's a lot of tedium involved, even though the M-500 has got to be one of the easiest Carver amps to work on.
Carver Preamps: C-1, C-2, BillD's JVD-modded C-4000, C-9
Carver Amplifiers: BillD's C-500, M-1.5t (4) PM-1.5 (4) M-500t (2)
Repair/Restoration/Upgrade expert for all of these components.
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BillD

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Post Wed Apr 30, 2008 11:13 am

Re: M-500 Refurb.

Will do. I found something interesting while going through mine. Apparently earlier models had more parts. Two of the caps I ordered aren't in the version of the amp PCB anymore (the M-500t doesn't have them, either). Moreover, there used to be internal fuses that are gone. The board has all the connections for a pilot light, a power switch and a switched outlet that aren't used, plus a bunch of other stuff I can't figure out.

Anyway, the point is that I will list ALL the caps, but you might not need to use them all (they extra ones are really cheap anyway), depending on the build of your particular serial number. I will indicate the ones I didn't use.
It should sound like it isn't there!
There is a difference between hearing and listening...
Making life enjoyable through expensive electronics.
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Carver: C-4000 & C-1 preamps, PSC-60 preamp/tuner, TX-11a tuner, M-400 (2), C-500, M-500, M-500t, M-500t Mk.II, A-500x, AL-III loudspeakers (2 pr.)
Sunfire:Theater Grand III processor, Ultimate Receiver, Cinema Grand Signature 400 ~ seven, True Subwoofer Mk. II, D-10 Subwoofer
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BillD

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Post Sat May 03, 2008 3:21 pm

Re: M-500 Refurb.

I am done, and am listening to the M-500 right now - sounds sweet, but it's not on my AL-IIIs, just some bookshelf M&Ks. Anyway, I learned quite a bit. First off, the traces on the M-500 are very delicate. In removing a part, I actually removed the trace with it (it was at the end of a trace run). I thus had to scrape off some of the trace coating further down and solder to it. It wasn't difficult, but not something I'd ever done before. I don't know if the traces on other Carver gear is this delicate (this unit is made in Japan), but it certainly isn't like the Heathkit AR-1500 I built in 1970.

Second, I found that all the capacitors listed in the Service Manual were not needed. Actually, the M-500t was closer to what was needed than the M-500 manual (I must have had a later model). So, You should pop the lid before you order parts and check to see. Actually, it probably would have saved me less than a buck not ordering the extra parts.

Finally, I found that all the traces to make this into a M-500t were there, plus some. There was a couple of traced holes for an indicator light (if I'd had an appropriate LED, I probably would have put it on the board, just for grins). There was tracing for a switched outlet, the front power switch, an impedance switch - neat stuff.

OK, here's some picks that I haven't posted earlier.

Amp board before:
M-500 amp before.JPG
M-500 amp before.JPG (316.52 KiB) Viewed 1202 times

Amp board after:
M-500 amp after.JPG
M-500 amp after.JPG (274.91 KiB) Viewed 1204 times

Notice all the blue caps are gone. Sorry about reversing my camera angle.
M-500 Completed:
M-500 Finished.JPG
M-500 Finished.JPG (283.32 KiB) Viewed 1203 times


And finally, just now in operation:
M-500.JPG
M-500.JPG (172.45 KiB) Viewed 1208 times

Below is the list of capacitors that I bought to do this project:
  Code:
Carver Corp. # Qty Description     Panasonic #    Digi-Key # Spacing M-500 Capacitor        Cost    Total Comment
MS-16TW471M     2  470µF 16v       EEU-FC1C471L   P10247-ND    3.5   C103-C104              $0.47   $0.94
MS100TW1R0M     8  1µF 100v        EEU-FC2A1R0    P10765-ND     2    C119-C122, C135-C138   $0.24   $1.33 Buy 10
MS-50TW1R0M     3  1µF 50v         EEU-FC1H1R0    P10312-ND     2    C123-C124, C517        $0.27   $0.81
MS-25TW1R0M     1  1µF 25v (50v)   EEU-FC1H1R0    P10312-ND     2    C522                   $0.27   $0.27 Substituted 50v
MS-16TW470M     3  47µF 16v        EEU-FC1C470    P11196-ND     2    C133, C605-C606        $0.34   $1.02
MS-16TW101M     2  100µF 16v       EEU-FC1C101    P11198-ND    2.5   C134, C526             $0.34   $0.68
NP-25TW470M     1  47µF 25v        ECE-A1EN470U   P1179-ND     2.5   C201                   $0.31   $0.31
MS-16TW221M     1  220µF 16v       EEU-FC1C221    P11199-ND    2.5   C202                   $0.48   $0.48
MS-50TW470M     1  47µF 50v        EEU-FC1H470    P10321-ND    2.5   C203                   $0.28   $0.28
MS-25TW101M     1  100µF 25v       EEU-FC1E101S   P10269-ND    2.5   C525                   $0.23   $0.23
MS-16TW100M     3  10µF 16v        ECE-A1CKG100   P910-ND       2    C527, C603-C604        $0.19   $0.57
MS-25TW4R7M     1  4.7µF 25v (35v) ECE-A1VKG4R7   P920-ND       2    C528                   $0.19   $0.19 Substituted 35v
BC80682YC60GH4  2  6800µF 80v      ECE-T1KA682EA  P10642-ND    22.5  C508-C509              $9.05  $18.10
BC50682XB50CC3  2  6800µF 50v      ECO-S1HA682CA  P6686-ND      10   C510-C511              $5.20  $10.40
BC80222M250CC2  2  2200µF 80v      ECO-SIKA222BA  P7505-ND      10   C512-C513              $4.89   $9.78
                                                                                            Total  $45.39

The caps that I found that weren't used were C603 and C604. You will see that I substituted a 50v cap for a 25v cap for C522. That makes them the same as C123, C134 and C527, so you can order 4 of those. Actually, if you wanted to save a few more cents you could use the extra 2 caps you got when you bought 10 of the 100v 1µ caps for C123 and C124, and just order two 50v caps for C522 and C527. I also had to substitute a 35v cap for a 25v one for C528, because the 25v caps were only available in lots of 10.

The high dollar caps are the big ones in the power supply C-508 and C509 have four prongs (two are just for stability on the board) and look like chicken feet. Anyway, I made the substitutions because I wanted to find a single supplier for the project (save minimums and shipping charges). I got the entire project parts from Digi-Key (http://www.digikey.com/). All the caps are at least 3000 hour life and 105°C rated.
It should sound like it isn't there!
There is a difference between hearing and listening...
Making life enjoyable through expensive electronics.
_________________
Carver: C-4000 & C-1 preamps, PSC-60 preamp/tuner, TX-11a tuner, M-400 (2), C-500, M-500, M-500t, M-500t Mk.II, A-500x, AL-III loudspeakers (2 pr.)
Sunfire:Theater Grand III processor, Ultimate Receiver, Cinema Grand Signature 400 ~ seven, True Subwoofer Mk. II, D-10 Subwoofer
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RichP714

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Post Sat May 03, 2008 4:08 pm

Re: M-500 Refurb.

Very nice job! The inside of that amp is so clean compared to the two I got off of ebay; they had lots of grunge. The bias trim pots have been replaced recently too, nice.
Last edited by RichP714 on Sat May 03, 2008 5:01 pm, edited 1 time in total.
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BillD

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Post Sat May 03, 2008 4:50 pm

Re: M-500 Refurb.

Yeah, I adjusted everything to within an inch of its life. I was wishing that I had your guidelines as to how to up the output. I thought the output at 1 volt in (1000 Hz tone) was a little low. I had my tone generator on my computer into my C-4000. I adjusted the C-4000 output to 1 volt then plugged it into the amp and adjusted the meters to 100 watts. But when I measured the output it was around 27 volts. I figured that it should be a little over 28 volts [sqrt(100*8)]. So, I guess the meters are reading a little high. But, they are on zero with no signal. The input from the power supply is exactly 74 volts. The bias is exactly 6mv left and right. Oh well. I noticed the new trim pots. Probably from the guy that didn't do a very good job in there otherwise.
It should sound like it isn't there!
There is a difference between hearing and listening...
Making life enjoyable through expensive electronics.
_________________
Carver: C-4000 & C-1 preamps, PSC-60 preamp/tuner, TX-11a tuner, M-400 (2), C-500, M-500, M-500t, M-500t Mk.II, A-500x, AL-III loudspeakers (2 pr.)
Sunfire:Theater Grand III processor, Ultimate Receiver, Cinema Grand Signature 400 ~ seven, True Subwoofer Mk. II, D-10 Subwoofer
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RichP714

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Post Sat May 03, 2008 5:11 pm

Re: M-500 Refurb.

BillD wrote:....I was wishing that I had your guidelines as to how to up the output......
My project is on hold, by emperial decree, until we get moved. We move 16 May, and I'm sure I'll be plenty busy even for awhile after the lifting is done...when I get back to it and get a finalized version running I'll post everything.
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bob p

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Post Sun May 11, 2008 12:14 am

Re: M-500 Refurb.

Hey Bill, glad to hear that you've got things taken care of. So the only problems that you were having with the amp were fixed by recapping it? If that's the case, then I'm glad that we had you try the simple approach first. I bet you're REALLY happy that you didn't send it out to have someone else do the work!

I'm so glad that you were able to take care of things yourself -- fixing up your own non-working amp gives you a great feeling of accomplishment and you should feel proud. And just think how much money you saved by not having to pay 2 legs of shipping to have one of the other forum guys look at the amp for you.

I'm wondering about your meter question -- when you calibrated your meters, what kind of dummy load were you using?
Carver Preamps: C-1, C-2, BillD's JVD-modded C-4000, C-9
Carver Amplifiers: BillD's C-500, M-1.5t (4) PM-1.5 (4) M-500t (2)
Repair/Restoration/Upgrade expert for all of these components.
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BillD

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Post Sun May 11, 2008 10:00 am

Re: M-500 Refurb.

Bob p - no load except for the DMM. I was measuring voltage at the speaker out jacks. I figured it should be about 28.3 volts for 1 volt input at 1000 Hz [sqrt (100 watts x 8 ohms)], but it was actually reading around 27 volts. M-500 meters were adjusted to 100 watts with that input (1v @ 1kHz).
It should sound like it isn't there!
There is a difference between hearing and listening...
Making life enjoyable through expensive electronics.
_________________
Carver: C-4000 & C-1 preamps, PSC-60 preamp/tuner, TX-11a tuner, M-400 (2), C-500, M-500, M-500t, M-500t Mk.II, A-500x, AL-III loudspeakers (2 pr.)
Sunfire:Theater Grand III processor, Ultimate Receiver, Cinema Grand Signature 400 ~ seven, True Subwoofer Mk. II, D-10 Subwoofer
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RichP714

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Post Sun May 11, 2008 10:53 am

Re: M-500 Refurb.

BillD wrote:Bob p - no load except for the DMM. I was measuring voltage at the speaker out jacks. I figured it should be about 28.3 volts for 1 volt input at 1000 Hz [sqrt (100 watts x 8 ohms)], but it was actually reading around 27 volts. M-500 meters were adjusted to 100 watts with that input (1v @ 1kHz).
I think the meters say on the face that they represent power into an 8R load
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BillD

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Post Sun May 11, 2008 1:54 pm

Re: M-500 Refurb.

Well, I'm not sure I understand the difference. In an ideal world the voltage would remain constant regardless of load, and the current supplied by the power supply would vary until the rails start to sag (in the real world). If the manual says that the unit can supply 200W at 1kHz with a 1v input into 8R, I can calculate the voltage out. I would expect the voltage to be the same into a meter with almost zero amps being demanded of the power supply. Maybe I need to be educated more.
It should sound like it isn't there!
There is a difference between hearing and listening...
Making life enjoyable through expensive electronics.
_________________
Carver: C-4000 & C-1 preamps, PSC-60 preamp/tuner, TX-11a tuner, M-400 (2), C-500, M-500, M-500t, M-500t Mk.II, A-500x, AL-III loudspeakers (2 pr.)
Sunfire:Theater Grand III processor, Ultimate Receiver, Cinema Grand Signature 400 ~ seven, True Subwoofer Mk. II, D-10 Subwoofer
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RichP714

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Post Sun May 11, 2008 5:30 pm

Re: M-500 Refurb.

BillD wrote:Well, I'm not sure I understand the difference. In an ideal world the voltage would remain constant regardless of load, and the current supplied by the power supply would vary until the rails start to sag (in the real world). If the manual says that the unit can supply 200W at 1kHz with a 1v input into 8R, I can calculate the voltage out. I would expect the voltage to be the same into a meter with almost zero amps being demanded of the power supply. Maybe I need to be educated more.
The meter circuit responds to the voltage out, so 40V out into 8R would give you 200W. If you set for 40V out into just the DMM (basically no load at all) and then strap 8R across it the rail will sag considerably (otherwise the 74V rail would give you 683W per channel ;); at a guess 16.5V (wild guess) or about 35W. Meter movements aren't linear, so if you then crank it back up to read 200W the DMM won't read 40V anymore. The difference may not matter to you.......
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bob p

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Post Sun May 11, 2008 8:06 pm

Re: M-500 Refurb.

Bill, I don't dump "power" into open loads. I learned not to do that with tube gear. ;)

when I recalibrate the power meters on my Carver amps, I hook up an 8ohm power resistor across the amp's outputs and measure voltage on a good voltmeter. Although I admit that I've used all sorts of dummy loads, from things like space-heaters and toasters to electric clothes dryer heating elements, etc., for my fun around the house experiments (remember when I used my PM-1.5 to make toast?), whenever I do a real meter calibration I use a high wattage edgewound vitreous enamel power resistor at the proper load resistance.

to be honest, i think that Carver's specs for the M-500 lie a little bit about the amount of clean power that the amp produces before clipping. i perform all of my tests with sine wave drive into an HP distortion analyzer, and the Carver PSUs aren't really designed for that. They'll deliver their rated power for a short period, but not for anything close to an FTC-type sine wave drive test, and certainly not for any military-style continuous duty measurement.

most of us that have bench gear have gear that can measure sustained sine wave drive power. unfortunately, Carver gear isn't spec'd that way; they always spec'd their gear in incredibly short "musically significant" pulses. its a lot more difficult to measure power in instantaneous pulses. IMO Carver's claims about the real power that their amps produce have always been a bit exaggerated. i wouldn't worry too much if your 500 tests just shy of its rated numbers.
Carver Preamps: C-1, C-2, BillD's JVD-modded C-4000, C-9
Carver Amplifiers: BillD's C-500, M-1.5t (4) PM-1.5 (4) M-500t (2)
Repair/Restoration/Upgrade expert for all of these components.
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BillD

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Post Sun May 11, 2008 8:30 pm

Re: M-500 Refurb.

It was comforting that it was in a volt of what I calculated it to be, anyway. My multimeter read exactly 1000 Hz, also. Anyway, I've just been playing around with the amp an hour or so at a time. It's probably time to do some extended use testing.
It should sound like it isn't there!
There is a difference between hearing and listening...
Making life enjoyable through expensive electronics.
_________________
Carver: C-4000 & C-1 preamps, PSC-60 preamp/tuner, TX-11a tuner, M-400 (2), C-500, M-500, M-500t, M-500t Mk.II, A-500x, AL-III loudspeakers (2 pr.)
Sunfire:Theater Grand III processor, Ultimate Receiver, Cinema Grand Signature 400 ~ seven, True Subwoofer Mk. II, D-10 Subwoofer
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RichP714

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Post Sun May 11, 2008 10:54 pm

Re: M-500 Refurb.

bob p wrote:......Although I admit that I've used all sorts of dummy loads, from things like space-heaters and toasters to electric clothes dryer heating elements, etc., for my fun around the house experiments (remember when I used my PM-1.5 to make toast?), ......
That's a pretty fun experiment BobP...have you ever used marshmallows to measure the Klystron frequency in your microwave oven?
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bob p

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Post Sun May 11, 2008 11:43 pm

Re: M-500 Refurb.

Marshmallows? Please do tell.

If you've got the marshmallows, I could use a PM-1.5 and an under-sized power resistor to boil some water for hot chocolate...
Carver Preamps: C-1, C-2, BillD's JVD-modded C-4000, C-9
Carver Amplifiers: BillD's C-500, M-1.5t (4) PM-1.5 (4) M-500t (2)
Repair/Restoration/Upgrade expert for all of these components.
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