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Definitely an earlier one, haven't had the privilege of working on one of those. Other than the power switch it looks to be just like the original one with meters. I don't know when GAS changed the power switch from rotary to push-button. No Fairchild transistors either so that's a plus.

I'm right behind you at 62 years young, I refuse to grow old!
 
I agree with refusing to grow old. So any recommendations. Should I just run it as is. I can't believe how clean it is. All I did was dust off the transformer. The rest is just as it was when opened. When I got it I got brave and just turned it on and voila, music.
 
The only thing I see, may or not be anything, are the two capacitors, C20 and C21, sitting dead center look as though they got roasted by the nearby resistors. Those two capacitors are in the VI limiting circuit but don't do anything in normal operation. I don't think the drive boards are plug-in on the early version so I don't know how much work it will be to replace them.

Craig
 
I looked at them up close, it looks like the wrap is just shorter on the edges, as they are equal all the way around. I looked for any heat damage, and all looks like it has been running pretty cool.

Bernie
 
I'm Looking for a full Throebe Schematic, the only one I found is the line Amp from Davids site.
 
All of the plug-in boards are the same as Thaedra so those schematics are easy to get/find. I have not yet seen a schematic for the mother board but there should be one out there somewhere. I do have a block diagram of the Thoebe.

Craig
 
GREAT AMERICAN SOUND TRANSISTOR CROSS REFERENCE
GAS 101 = 2N5631 OR MJ15022 OR 24
GAS 108B = MPS8599
GAS 101B = 2SD424 OR 2SD555
GAS 108C = 2N5401
GAS 101C = 2SC1586 OR 2SD424 (NPN)
GAS 109 = MPSU07
GAS 102 = 2N6031 OR MJ15023 0R 25
GAS 110 = MPSU57
GAS 102B = 2SB554 OR 2SB600
GAS 112 = 2N5088
GAS 102C = 2SA909 OR 2SB555 (PNP)
GAS 112C = 2N5551 (NPN) match hfe to compliment
GAS 103 = 2N6316 OR 2SD525
GAS 114 = 2N4401 (NPN)
GAS 103B = 2SD525
GAS 114A = 2N5210 match to compliment
GAS 104 = 2N6318 OR 2SB595
GAS 115 = 2N4403
GAS 104B = 2SB595
GAS 115A = 2N5087
GAS 105 = 2N3584
GAS 116 = 2SD613 OR MJ15028 low hfe <150
GAS 106 = 2N6421
GAS 117 = 2SB633 OR MJ15029 (PNP) low hfe <150
GAS 107 = MPSU06 OR 2N5551 match hfe
GAS 118 = 2SB554 (PNP)
GAS 107B = MPS8099
GAS 119 = 2SD424 (NPN)
GAS 107C = 2N5551
GAS 100 = CA3086 Transistor Array (5 NPN)
GAS 108 = MPS56 OR 2N5401 match hfe
GAS 100A = MPQ6001 OR MPQ6002 ( 4 transistor array, complimentary)

DIODES ACROSS AMPZILLA EMITTER RESISTORS ARE 1N5821

NOTE: ALL VERSIONS OF
GAS 107 CAN USE JAP 2SC2240 ( NOTE THE DIFFERENT PINOUT ) ALSO
GAS 108.. 2SA970
BEST STABILITY IS ACHIEVED WITH MATCHED QUAD SETS WITH HFE IN THE 150 TO 250 RANGE.
ALL VERSIONS OF THE
AMPZILLA CAN USE MJ15022 / MJ15023 AS THE OUTPUTS.
USE ONLY THE MOTOROLA TRANSISTORS THOUGH
DO NOT USE REPLACEMENT TYPES FOR ANY ORIGINAL TRANSISTORS IE: NTE, SK, ECG, ETC.
THE FETS USED IN THE THAEDRA/THOEBE LINE AMPLIFIER CAN BE REPLACED WITH 2N5459 N-CHANNEL 2N5462 P-CH (MATCHED AS BEST AS YOU CAN FOR FETS)
THE BIAS SETTING FOR THE AMPZILLA IS 30MV ACROSS THE EMITTER RESISTORS OF THE OUTPUT TRANSISTORS
THE SON OF 22MV SAME PLACE.
OFFSET IS ALWAYS SET FOR .000V +/- .015V
DRIVER TRANSISTOR SHOULD ALSO HAVE HFE'S LOWER THAN 200 FOR BEST STABILITY
 
Here are some pics of my Ampzilla(original) which is undergoing a rebuild.
Right now it is getting a new fan, meter bulbs converted to LED and better RCA's and binding posts.
I have heard it and it sounds good.IMG_0375.JPG IMG_0376.JPG
 
Here are some pics of my Ampzilla(original) which is undergoing a rebuild.
Right now it is getting a new fan, meter bulbs converted to LED and better RCA's and binding posts.
I have heard it and it sounds good.View attachment 1160848 View attachment 1160853
Here are some pics of my Ampzilla(original) which is undergoing a rebuild.
Right now it is getting a new fan, meter bulbs converted to LED and better RCA's and binding posts.
I have heard it and it sounds good.View attachment 1160848 View attachment 1160853


do you know what size caps are the GAS 102,103 and 104 are? and I have one that says .12 50v also
 
If it's like the son it had lamps in series (I think 4 , right across xfmr . If one went out . They all went out
. I can't get to stuff now. If no one comes up with it, reach out to me later
 
Looking for a location on information that would be helpful in tracking down the source of a120hz hum in my Thalia II preamp. It’s not super loud, if playing music it’s not noticeable. Not sure if it’s the preamp or bad power. I do have a power conditioner in-line and it’s not the amp. Wondering what the likely issues are that maybe causing this.
 
I'm not sure that has a voltage doubler I'd have to look.
Are you sure it's not 60hz. A lot more places it could come from:idea:
 
There are Thalia II service bulletins over on DIYAUDIO from a former GAS tech. Search in the Analog Line Level forum.

Craig
 
I’m new to the forum but a long-time GAS owner. I bought my Thalia and Grandson in 1980 when my younger brother was production supervisor at GAS. I just had both units gone through by Kim Hachenberger (referred by Mike Bettinger) and had Mike Bettinger refresh one of my Thoebes. I currently have 1 Grandson, 1 Thalia, 2 Sons, 2 Thoebes, and I just purchased a Thaedra...which I’ll be sending to Kim at GAS Audio Restoration soon. I’m hoping to buy or build a bridge for a Thaedra, Son, Son setup.
 
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Since my last post the Thaedra pre-amp arrived and it turns out to be an earlier model (1) when GAS was still in North Hollywood. It is off with Kim at GAS Audio Restoration getting a reference rebuild, so it should be as good as new (or better). I also got a Sumo MOAT bridge and having been talking to Kim about how to get the most out of my system as a bi-amped or tri-amped bridged system. That being said, it'll be about 9 months before I can assemble the entire system AFTER my "man-cave" is built...
 
Hi Gas friends!

I am proud owner of two Ampzilla 500 (the latest version with diods that shows the output and one of them are for sale), one Thaedra2, one Ampzilla Grand Son with Thalia and aSon of Ampzilla. I also hawe a Empire 698 turnable and a pair of JBL L112 speakers. As you understand I beliwe the

The first Gas product I owned, and still owne, is the Thaedra2 that woke my interest. It was in 1988. Both the 500:s has resently ben owerhauled by a genius in electronics and friend to me. The turn has come to the Thaedra2 that began to have it´s own life.

Here is my questions: Does anyone of you have an idea of how to find: The sliding potentiometer with the same specs as original. Onother problem is that when I adjust the basslewel there is a conemowement on the bassspeaker. Anyone that hawe the same problem or hawe found out how to fix the problem?

Beeing from Sweden i want to appologise for my spelling!

Regards TobbeC
 
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Sourcing that slide is difficult.
I have some that are electrically the same but physically narrower . That is, the mounting threaded holes on the control are at the outside edge of the original slide slot.
Same value, manufacturer, style. Even the knob (slide cap?) Fits.
It just won't go as far left to right. Center position is the same.
It's the best I could come up with after a pretty extensive search. I know I have a spare if you're interested , PM me
 
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