Need schematic for Soundstream MC245

[phrarod]

I have some blown diodes in the power supply and I would like to have schematic to check everything.

Also in your experience when a FED blows is it an indication of other problems?

Is it worth it to try and upgrade anything in this amp while its on the bench?

[Perry Babin]

According to Soundstream tech-support, the schematic is not available.

Sometimes the FED16BT rectifier diodes fail and there is no other damage. Sometimes they short and cause the failure of the PS FETs. Sometimes the outputs fail and cause the rectifiers to fail.

[phrarod]

I talked to a tech up north who used to work for Soundstream. He said the same thing. I'm replacing the FED with a higher rating that the tech recommended and also upgrading the output transistors as they're a combo of two different types. I guess mine was build as they were transitioning to new parts. Hopefully this will fix it. Since its so old I also replaced the caps.

[Perry Babin]

What were the replacement parts he recommended?

I don't know of any rectifiers that can handle more than 16 amps in the to-220 package.

I've seen the TIP142T and TIP147T in some of the amps. They have a slightly (depending on the datasheet you reference) higher current rating.

If that's what he recommended, make sure that you get the ones in the TO-220 case. The TIP142, TIP147, TIP142TU and the TIP147TU are in a TO-3P case.

[phrarod]

I think they are slightly higher. He said he always upgrades amps that come in with these so I imagine they'll fit. I'll let you know when they arrive next week.

[1moreamp]

The MC-245 uses TIP142 and 147 in the TO-218 case. They can be replaced with the later case style TO-220 T versions. Same device, smaller footprint package, used in Rubicon series amps A couple years back.

I know of NO replacement for the FED diode because of its "special polarity consideration", and its rather difficult to find BUT there is a fella on E-bay by the name of Jaime that sells SoundStream parts (all original) He worked for SoundStream for 10 years. Look for JandRelectronics on E-bay. The FED16BT is special the diodes do not form either common cathode or anode configuration like all the other standard packages do. Check the diode directions on it case package < its special > LINKY: http://cgi.ebay.com/ws/eBayISAPI.dll..._promot_widget

He also can repair the unit to original specs, along with sell you all the correct parts to complete the job yourself. He might even be able to dig up a print somewhere, since Soundstream seems to have lost them over the years.

He is a one stop shop for ALL Vintage SoundStream parts

Hope this help, and good luck

[Perry Babin]

The FEP16BTD has the same configuration as the original soundstream parts. It has the same specs so it wouldn't be an upgrade.

I didn't know that SS ever used TO-218 parts. Coustic switched from the TIP142/147 to the MJH110xx series transistors. I think they used the MJH11017and MJH11018. They were a direct replacement for the coustic amps. I don't know if they could be used in the SS amps.

http://www.onsemi.com/pub/Collateral/MJH11017-D.PDF

J&R electronics is definitely a good place to get SS parts. I've recieved top-notch service every time I've ordered from him.

[1moreamp]

Evening guy's, sorry had to work on a few computers. So I was away for a bit.
SoundStream used three different configuration dual diodes. The FEP, the FEN, and the FED.
The FEP is common cathode, the FEN is common anode, the FED is anode , cathode, cathode.

Yeah Jaime is the best You gotta love the guy. He is the fastest, and nicest supplier I ever had.

I agree you can use more modern outputs like you linked to, But TIP142's and 147's are plentiful everywhere. The T version is used only in the Rubicon series though it could be used in the MC series as well. Jaime has the T series, just not listed on E-bay.
I just repaired two MC-140's last week and TIP 142' and 147's were under the card, so I replaced them with the same.

hope this helps

my pic of the FED dual diode would not upload so sorry guys, I guess its too big

[phrarod]

Thanks for all the great posts! Yup all the parts are coming from Jaime. I'm replacing all the output transistors going from 101 to 102 and 106 to 107. The amp had a couple 107s in it so it was mismatched. I'm the original owner so it came this way from the factory. Jaime said they switched to the 102/107 combo later.

I don't know the part # of the dual diodes. I'll upload that when I get them.

I did find a burned resistor in one of the channel's high pass filter network. It didn't destroy the resistor just changed its resistance by about 1 Ohm. Everything else look visually ok. The only strange thing is I cannot get continuity between common ground and the neg pad for the 2200uF cap that is closest to the sub speaker connections. Before with the blown diode there was continuity between the +/- of that caps pads.

As long as I'm deep into this board are there any mods that would improve the sound of this amp? I'd love to figure out how to put tube minatures in somewhere to get a nice tubey sound.

[1moreamp]

My memory of those MC series amps is that they left little room for upgrades. Perhaps you might change out the input op-amps with AD or BB op-amps. I just did this today for a PG amp and it really changed the way the amp sound <for the better>

With the age of your amp I would possibly exchange all the outputs and see if you get a lower DC offset at the output, and don't be afraid to replace the power capacitors on the 12 volt side and the main rail for each channel.

There just isn't much else you might do, unless you find some more leaky or defective components.

The TIP 102 & 107 upgrade wont give you anything but the fact your using the highest grade of that series of transistor, But this couldn't hurt.
How many output pairs per channel ?