Carver m1.5t (Attn: Anatech) - Page 2 - diyAudio
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Old 29th June 2006, 07:20 PM   #11
anatech is offline anatech  Canada
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Hi oldsthunder,
You are on the right track now. Let me know how things work out. Carver did produce a replacement cap board, one board holds four caps. They became N. L. A. as well. It was cut to fit the contour of the chassis exactly. The pins fit in where the old mounting holes were for the original caps.

My cost was about $120 (retail was much higher). I have one left only that I was saving for the next job. If you are interested I'll sell it to you for what I paid for it plus whatever shipping is. Designing and making a PCB is a real pain in the other end of a tech. My mail button works if you are interested.

-Chris
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Old 8th July 2006, 08:56 AM   #12
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Those caps are a real pain on the PM/M1.5 amplifiers. I was having trouble getting them from Carver so I started to make my own. When you add up the price of the caps (I use 8), the circuit board and all the labor involved in getting the 16 mounting pins aligned you will know why they were so expensive from Carver. I won't be making any more for for another month or two, but if you are into making one yourself and want some photos then let me know. I still have a disassembled M1.5t with the new caps sitting on the bench.
Todd
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Old 8th July 2006, 03:00 PM   #13
anatech is offline anatech  Canada
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Hi Todd,
Eight caps. Interesting. I'll bet it's easier to source two caps in the proper voltage than one.

How close am I?

It's also a real pain to get it all to fit with the contour of the chassis in the area. Mind you, I really liked the sub board when it came out. It's just a big job getting there. I usually replace a couple problem resistors when I get in there.

Anyway, I'd love to see you solution. I have but one of those Carver cap. boards left.

-Chris
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Old 8th July 2006, 03:52 PM   #14
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Hi Todd & Chris,
Todd thanks for the reply & info. I just recieved my order from Digikey (next day delivery--amazing!), and now have two new Panasonic caps, 4700 MFD, 200 VDC & four 2200 MFD , 100 VDC. Hopefully I will get them installed in the coming week. Chris, I'll let you know when they are in.
Dave
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Old 8th July 2006, 04:05 PM   #15
anatech is offline anatech  Canada
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Hi Dave,
I love Digikey. I wish they carried 100% of what I need. They are the best for shipping to Canada (Mouser fails big time there!).

Yank out those caps now and have a look at the solder joints and some resistors in the area. Now's the time while the area is clear.

-Chris
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Old 9th July 2006, 10:35 PM   #16
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4 of those caps are 120uf HF, back when I was testing for ripple on the scope they really seemed to make a difference, so I kept them in the PB design. The other caps are 2 X3300@80v and 2 X 6800@50v, sourced from Digi-Key. I pay $20 each for the boards ($60 for 3) double sided FR4 glass epoxy. PCB file I have is "expresspcb" so it wont work for Gerber or other PCB programs, you will have to order directly from expresspcb only. Let me know if you require more information.
I hope the attached photo works..

Todd
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Old 9th July 2006, 10:40 PM   #17
anatech is offline anatech  Canada
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Hi Todd,
That sure is a forest of caps you have there! I'd like to see some more details for sure. The 120 uF caps get most of the pounding I bet with that power supply design. They go a long way to smooth out teh rising edge of the waveform. Is that what you found?

-Chris
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Old 12th July 2006, 07:54 AM   #18
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Chris,

I found some old photos from some testing that was done a few year ago. Im not sure of the bias current setting during the measurement. The scope shows the low rail ripple, two DMMs show the low/mid ripple (ok, its just AC measurement on DC rails) and the third DMM shows the hi voltage rail in DC volts. I remember during one hi power/hi frequency test the little 120uf caps did get hot, never had any of them fail. Normal loud music don't really seem to change the temperature at all. I had (if I can find them) some thermal IR scans of a M1.5t running fairly hot, you can see the temperature differences in the transformers/resistors/etc. If your interested I'll see if I can find them and post them here.

Todd
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Old 12th July 2006, 07:54 AM   #19
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Same amp and measurement points, but with the ORIGINAL power supply caps. You can see a big difference with a cap change.

Todd
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Old 12th July 2006, 03:17 PM   #20
anatech is offline anatech  Canada
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Hi Todd,
Never run these at high frequency / high power. Not even to the second rail. The commutators will lock up and the amp will go into thermal runaway. So use these for full range or bass only. Mids and highs only will kill them.

I'd be interested in the thermal pics. Just for curiosity.

On the pictures, see the "pip" on the leading edge of the waveform? That's my indicator for bad capacitors. You should look at it with a real 'scope and compare.
-Chris
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