[rsaavedra]

The Brown-dog arrived today!!! Hot rodding of the Toshiba about to continue. Check out the parts in the photo:

1) Brown-dog adapter

2) Heat sinks for the large IC's on the audio board of the Toshiba

3) JB Weld (heat resistant epoxy) for gluing those heat sinks to the IC's

4) Panasonic caps to replace stock C904 and C905

5) On the back you can see an "HD-14" (Home Depot Gauge 14 outdoors power cord extension), a.k.a. the "Halloween powercord" for its orange and black colors, the one recommended by TAS to make DIY speaker cables and power cords. I'll use it to hardwire a new power cord in the Toshiba (see http://db.audioasylum.com/cgi/m.mpl?...14&r=&session=).

6) Static-shielded bags on the left contain the OPA627's, haven't opened those yet.
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[ITZBITZ]

Be sure to get the dog in the hole correctly. If I recall, looking at the adapter with the IC1 side facing you and the pins on the bottom, the left pin is pin 1. You can verify by comparing the OPA2604 and OPA604 pin outputs and checking continuity on the traces before mounting the chips.

 

[rsaavedra]

Thanks Itzbitz. So if I understand correctly, to place the browndog properly on the toshiba, the IC1 side will end up facing C905 and the fat capacitor of the audio board, right?

By the way, I noticed we've been incorrectly calling one of the capacitors 904. There is no such thing as a C904 on this board, its actual number is C901. From the top it looks as if it says 904 because of a little hole, but from the bottom it's clear what the real label is:

I unsoldered the opamp I had placed a few weeks ago, and guess what? After it was out I realized one of the tiny resistors next to the opamp area was completely loose, the one next to the second pad from top to bottom on the right of the opamp area.

I guess the heating nearby took hold of the soldering that was holding it in place. It took me hours to solder the tiny little thing back on. It is so small that aiming the huge soldering iron tip next to it was very difficult, and I had to keep the tiny resistor in place with my other hand using sharp tweezers, talk about microscopic acrobatics. Finally it got soldered, and I checked with the magnifying glass from several angles, it seems the contacts are fine, even though the resistor ended up a bit crooked. I hope the heat this resistor endured won't affect its performance, and that the contacs are ok. If I hear something weird in one channel after these mods I know what the problem is. Wish me luck!
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[rsaavedra]

Finished soldering the opa627's to the Browndog, then the Browndog to the Toshiba, and then the capacitors. Placed the board back in the player and wanted to try it right away, even before the rest of the mods (heat sinks and power cord) because I was anxious to make sure everything was ok. AND IT'S WORKING AND SOUNDING GREAT!!!!!!

Gee what a relief!! So the tiny resistor temporarily going loose caused no problem. That got me really very scared thinking I was going to be forced to bypass this whole opamp mod with the Swenson version, fortunately everything is sounding great. Here some pics:

The Browndog with the OPA627's, IC1 side, once soldered to the Toshiba board:

Browndog, IC2 side. Interestingly, IC2 needs to get soldered upside down with respect to IC1:

The completed mods, soldering back the Blackgates, and replacing 901 and 905 with Panasonic caps:

Now the player is getting unplugged again, will continue with the heat sinks and power cord right away...
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[ServinginEcuador]

You have a good excuse: waiting for some eagerly awaited parts to install into your unit. Understandable.

 

[rsaavedra]

Mods completed!!! Here's a summary of everything.

Audio PCB: all caps listed in the Vinnie Rossi mods replaced, plus C901 and C905 with Panasonics (same values as in C902); clock dampened with "white tack"; opamp now replaced with a Browndog adapter holding 2 OPA627's as suggested by Itzbitz (thanks again Itzbitz!); large ic's with heat sinks on them glued with J-B Weld as suggested by Audiosold (thanks again Audiosold!); for completeness I should probably mention the cuts I had made on top side edges of the chassis for better ventilation:

Power supply: all Rossi mods done on it, plus stock power cord now replaced with an "HD-14" (no AC grounding of the chassis to avoid groundloops, see this posting). This "Halloween" power cord is exactly thick enough so that its own girth keeps it very tighly fixed to the chassis opening, but I added a little fastener inside for extra anchoring. Outside added RFI filters on each end of the cable. Chose to keep it 6 feet long, same as the stock:

And now the top cover is back on, hopefully for a long long time

Player is already going through break in of these last changes, and it's sounding truly beautiful. I'm taking this player to the upcoming FL meet so other Headfiers can check it out.
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[tortie]

Nice work! Maybe you should start your own Toshiba 3950 DIY shop

 

[Budgie]

Nice job rsaavedr! Great pictures too. I am looking forward to the reviews from the Florida meet!

 

[ITZBITZ]

Glad you got it all done and working. Close call on the resistor, glad you were able to get it fixed up without any problems.

Hopefully at the meet in FL you can get the little "Toshiba that could with $100 in modifications" some respect.

 

[rsaavedra]

Quote:

Originally Posted by ITZBITZ Glad you got it all done and working. Close call on the resistor, glad you were able to get it fixed up without any problems.

Well I really wouldn't call it "without any problems"

It really took me about 3 hours of trials till I got it in place satisfactorily. Originally I was trying placing the resistor in place and then using a large piece of cork on it while leaving one end of the resistor visible, so I could solder it. But the cork wouldn't hold the resistor at all once the soldering iron and solder had touched the resistor. So tweezers and a steady hand was the only way to keep it in place while soldering one end. And that was very tricky because any microscopic movement of the hand sent the resistor off the pads too easily. A very tough task it was. That grain of salt sized little rectangle is just so small, definitely to be soldered by machines, we are too giant creatures to work reliably with those dimensions.

Quote:

Originally Posted by Itzbitz Hopefully at the meet in FL you can get the little "Toshiba that could with $100 in modifications" some respect.

Quote:

Originally Posted by Budgie I am looking forward to the reviews from the Florida meet!

Yes, I'm also bringing my SACDmodded NS500V to add to the participants in this source comparison.

 

[rsaavedra]

Quote:

Originally Posted by tortie Nice work! Maybe you should start your own Toshiba 3950 DIY shop

Well, I need to rest from opamp replacements for a long time

 

[morrowaudio]

Good job on the mod. Thanks for taking my advice on heat sinking the chips. Your unit will last much longer. With mass market on this level Toshiba dosent care that it would only last about 2-4 years without the heat sinks.

I have been in electronics for 26 years now and have done many mods on McIntosh, etc. I even sell mod kits for some of the McIntosh vintage units like the MR71, etc.

I started modding my own stuff and before long people were wanting me to mod theirs.

I just put up an article about modding your tube amplifier with oil capacitors, removing the electroylitics.

www.audiosold.com

 

[morrowaudio]

I would get at least 16 volt BlackGates since I noticed that on some the DC voltage across them is 5 volts. 6 Volt caps would be taking a chance there.

 

[rsaavedra]

Realized have not indicated the part number for the heatsinks, someone from audioasylum asked me about them. Got them from Digikey.com, the part number was HS273-ND, cost=$0.73/piece, very inexpensive.

OPA627's = $18.38 each, also from Digikey. These opamps are the most expensive part of all these mods.

Browndog adapter = $6.95+($4.85 S/H) = $11.80

Halloween power cord from Home Depot was $16.35 for the 25 feet version. Used 6 feet for the Toshiba, so the effective cost of the power cord mod was about $4. Will use the remaining length of this cord to replace the PC's of some of my other components.

 

[CBMC]

where did you get those heatsinks?