Proton D1200 Advice

[LHMAudio]

I have a Proton D1200 100W amp that has been in my attic for a good 10 years. Prior to that it saw very little use. The attic does not get very hot or cold (55F to 90F). I would assume that the power supply caps need to be replaced. Is there anything else that I should look at? It has quite a few what appear to be Panasonic electrolytic caps. Would those still be OK?

It is an interesting design with dual power supplies and appears to be very well built. Any info about how it should sound would be welcome.

Lindsay

[LHMAudio]

It is beginning to look like I cannot replace the PS caps as I cannot find any 15,000mfd caps at 120VDC with the form factor of the originals. Is there any chance the originals are still good? There are four of them!

There are also four 22,000mfd at 63VDC. There is a lot of capacitance in this thing!

Any suggestions for sources for these types of capacitors?

Thanks for any help.

Lindsay

[1965GTO]

Yes those capacitors were made for Proton by the brand NICHICON. I can see no one offering a 15000uF at 120v. Unless you go to a screw terminal. I am not sure what type of mounting they used, but I would bet it was a screw terminal type. These days 160v is the norm, but the can size is too big for the D1200 Chassis. On the 22000uF they too were made by NICHICON but again the smallest size I could find was 35mm dia X 120mm Hght, again too big for the D1200 Chassis. Those capacitors were rated for 85 degrees C, so that is 185 degress F. I would say they are "ok", just when you fire it up, there will be a large amount of leakage current from the capacitors as they reform the electrolyte. I say turn it on with no load for an hour and let it warm up and get the bugs out. The company I work for, when customer have requested product that has a date code that is 3 years or older we test and 99% of the time they test good after the reformation process. I too have a D1200, and they sit for awhile and I just plug them in and warm them up and then they are good to go. My date code on my Proton is March 1988 and they still work fantastic. I will keep searching and let you know if I come up with a cap manufacture.

[LHMAudio]

1965GTO - Thanks for the response. I did pretty much what you suggested, but was a little more conservative. I used a light bulb in series with the power input and brought the voltage up slowly over two days using larger and larger wattage bulbs. That worked fine and the capacitors reformed without a problem. I was not so lucky with an older Marantz amp and had to replace the caps. One had some leakage from what looked like a pressure relief plug. Fortunately I was able to find equivalents readily available.

Lindsay

[dougman2011]

Hey there Lindsay, et al.,

I have a Proton D1200 inherited from my father which has worked great for a long time, but out of nowhere this week the right VU meter went dark and no sound comes out of either channel.

I generally keep it plugged in and on indefinitely. I'm a musician and love the great sound but unfortunately don't know much about fixing audio equipment, especially vintage hifi stuff like this.

My questions are:

1. From what I mentioned, might you have a guess as to what's wrong with it? The right VU meter is dark and nonfunctional, the left one seems to be okay. There is no sound coming out, no response to input even on the meter. Disassembling the box, there is no visible damage (i.e. rust, burnout), but there is a good bit of dust. Can't see anything obviously broken.

2. Is this fixable, and what level of expertise will it need? Would I even be able to find the parts?

Thanks very much,

Doug