SAE 3022 Integrated/2200 amp.

[eetechTom]

I recently purchased an SAE 3022 integrated amp in need of repair. My understanding is this is a 3000 pre amp, and 2200 amp in one box. I haven’t received the amp yet, but I have some general questions regarding amp repair. Can you tell I’m anxious to get this running Lol!

First a little background about myself. I was an audio tech from 1981 to 1994, and worked on a few 2400L’s and the like. Believe it or not this the first separate I have ever purchased. It was receivers only for me, and I owned a SX1250 receiver for many years.

There is a post on this website regarding DC offset issues. llwhtt I believe had the following response:
The DC offset will have to be dealt with by replacing the input diff. transistors. The VAS stage quiescent current is adjusted by "selecting" R21/22 until you get approx. 1.6-1.7VDC across R35/35 and/or R37/38.

My question is do you always recommend adjusting the VAS Q current while the amp is apart, or only if you have problems.

Thanks,
Tom

 

[llwhtt]

Checking the VAS current is usually part of the check out procedure in the service manual, if wrong it needs to be addressed. I just did this on a MKIIICM I rebuild. This is an early version with no adjustment pot., had to tack the appropriate resistor on the back of the board.

Craig

 

[eetechTom]

Thanks Craig,
Hoping to dig into this amp soon. I have an old Harmony guitar amp I need to finish up and sell so I have some play money.

 

[Klascala]

I once owned that amp. The preamp section was dead and I was only using the power amp. lovely beast! I sold it a couple years ago for a very decent amount.

 

[eetechTom]

I was told the preamp on mine works, but the power amp is dead. Might be time to stock up on solder wick!

 

[llwhtt]

Is that the funny shaped unit with the RCA connections in the middle?

 

[eetechTom]

That’s it, kind of an SAE starter kit I guess.

 

[sregor]

Lots of non magnetic screws....

 

[eetechTom]

I had forgotten about that. Aren’t most of those sheet metal screws too?

 

[sregor]

I had forgotten about that. Aren’t most of those sheet metal screws too?

yep

 

[eetechTom]

Here are a couple of pics of the driver board. The schematic notes that all resistors are 1/4 w. Are the orange resistors like R60 really 1/4 w?
Since my schematic is the one with npn /pnp’s swapped, I’m not inclined to trust it. A couple others look a little large to be 1/4 w as well.
I found the cross reference on the SAE World website, but I don’t have p/n’s for the resistors.

 

[llwhtt]

Are you referring to the reddish brown resistors on the left next to the TO-220 transistors? Can you read any numbers or letters on them. That type of resistor in SAE equipment is usually metal film, 1W, 2W or 3W. SAE also used a lot of 1/3W carbon film resistors.

Craig

 

[eetechTom]

All of the output transistors look original.Two outputs are shorted, one driver transistor is shorted, and the other is open. The other channel looks good so far. A couple of small signal transistors are gone, a couple of 1N4148, and a few resistors. Time to order some parts.

This is in very good cosmetic condition, one slider knob is not original. The rest of the slider knobs look brown, thought they would be black?

 

[eetechTom]

Craig, yes the reddish brown ones. One is R60, 62 ohms.

 

[eetechTom]

All I see on them are the values.

 

[eetechTom]

Certain resistors on the schematic show the wattage, like the 2W output emitter resistors. R60 does not list a wattage, sure looks bigger than 1/4 watt. Maybe that type of resistor was larger back in the 70’s?

 

[llwhtt]

There should be some numbers like RS1B or RL1B on them, those are 1W. The 62 Ohm resistor between the emitters of the drivers usually listed as 1/2W but there's usually 1W there. I don't think I've seen one of those red resistors below 1W. I'm rebuilding a 2400 at the moment and the boards says 1/2W for that 62 Ohm resistor but actually has RL1B 1W in that location.

 

[eetechTom]

I’ll pull it a couple of them and take look tonight. I found 62 ohm, 1W modern resistors that were about the same size.

 

[llwhtt]

Make sure you use a Metal Film in those locations if you are going to replace them. SAE used them for their "flame proof" characteristics. Metal Oxide should be OK also. I've been using the Vishay PR01, 2, or 3 series for any of the larger metal films. They are only 5% so I order more than needed to get them to 1%, those red ones are 2% I believe.

Craig

 

[eetechTom]

I can’t see any numbers on these, other than the value. I did notice that some of the other resistors that are the same color, and size are labeled 1/2 w on the schematic. Think I’ll order PR01 replacements to be safe. Only one of those is damaged, the 62 ohm resistor that connects the driver emitters. I think I’ll replace the one in the other channel too. I’m going to use your recommendations from another post for drivers and outputs, bias transistors etc. I stumbled across a Philips cross reference online that lists a BC237B subs to a BC547B, and a BC307B sub of BC557B. The specs look good so I might try those, Mouser has them.

Thanks Craig, how many SAE, GAS, SUMO’s do you fix in year?