Posted by DIYIdaho [ 63.24.120.142 ] on February 08, 2006 at 10:38:39:

In Reply to: Re: where are the Toshiba SD 3950's? posted by akhilesh on January 28, 2006 at 12:47:40:

well, today I finished my initial (and probably ony) mods to my spanking new Toshiba 3950. Because of the low cost of the unit and uncertain longevity I decided to go with the 'less is more' approach (a la Swensen).

Instead of removing the DAC output coupling capacitors (C910 & C912) and tapping in wires that ran outside the unit to large (physically) .47 uF caps that were attached to 'hanging RCA jacks, I decided to make internal mods that were not so homely.

First I removed C910 & C912 to disconnect the DAC from the final digital filter and OpAmp (as did Swenson). Instead of removing the circuit board (as Swenson did) I decided to make the entire mod above the board. The main reason is that the flat strap wiring harnesses are built so flimsily that I decided that taking them apart may cause permanent problems.

I removed the capacitor by grasping with flat nosed pliers and twisting them in a constant circular motion until they snapped off. The first one I tried to snip with dikes but the left over lead was a little short. By experimentation I found the twisting left enough lead to work with.

I used the same removal method to take outC918 and C20 to disconnect the OpAmp from the RCA jacks.

There are two small yellow caps next to the RCA jacks that go between the RCA jacks and ground. Another DIY post claimed by others the removal further enhance the output signal of the Swenson mod, so I performed the twisting removal of those. Starting to be fun by now!

In the (6) capacitor removal, what was left was their leads flat against the circuit board and touching each other at the center. I used a small flat blade screwdriver to pluck the remainig wire away from the board for tinning.

The inner leads of the two small yellow capacitors connect to the signal lead of the RCA jacks so I decided to take advantage of them for my added capacitor connections.

The remaining proceedure is simply to tin the capacitors, and the upright short ckt bd leads and attatch new coupling capacitors.

I ordered .68 Uf poly German made ERO's and the man on Ebay sent a couple of extra samples of ERO .47Uf caps. The .47's were somewhat smaller than the .68's so I decided to use them (they are the size Swnson used anyway). Even tho I had previously figured the .68's were more suited to my Technics SU8600's preamp in, I think the size difference justified using the .47's.

I installed the new ERO's to the short leads left from C910 & C912 and the RCA jack side of the leads left from removal od the small yellow caps.

Because the ckt bd leads were so short (about 3/16") I could not make a mechanical connection prior to soldering and had to rely on a good solder job. This is difficult with two hands and help would be advised to make sure there is no movement while the solder sets.

That's it! Initial sound trials were very satisfying. I have no good reference to what the stock 3950's great sound was like, but It seemed to me that there was a noticeable improvement. I am a opera fanatic so I put on some standards like Rene Fleming and others that I had been listening to for years and I do love what the little unit does for the.....especially when they hit their highs.

sorry for the long wind and no pic's. Every time I try to upload a pic I use way two many bits of info and get rejected. Chuck

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Last edited by AK 47 : 02-04-2006 at 08:39 PM.

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