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Old 18th March 2014, 06:05 PM   #1
gary d. is offline gary d.  United States
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Default trace acoustic ta100r repair help

Decided to attempt repair of my dead Trace Acoustic TA100r, that I shelved several years ago. R78 on front circuit board is fried to the extent that i can't determine its value. A schematic,(if i could find one), would be very helpful and greatly appreciated.
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Old 18th March 2014, 11:13 PM   #2
Enzo is offline Enzo  United States
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Does 150 ohms 7 watts sound right?

First step, contact Peavey and ask customer service for the schematic.
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Old 18th March 2014, 11:29 PM   #3
sreten is offline sreten  United Kingdom
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Hi,

Peavey have not much to do with Trace Elliot.

150R and 7 watt seems an odd value except
in a power supply involving zeners and the like.

rgds, sreten.
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Old 19th March 2014, 03:50 AM   #4
Enzo is offline Enzo  United States
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Really? Go to the Trace website. Click on SUPPORT, and you get:


Trace Elliot
5022 Highway 493 North
Meridian, MS 39305
Phone: (877) 856-9243
Fax: (601) 486-1278
E-Mail: customerservice@traceelliot.com


That address should be familiar, it is the Peavey plant. Trace Elliot is a Peavey brand.

The schematic I have is a poor copy, I am hoping the folks at Peavey will have better. There is a low voltage power supply making +/-12vDC. The feed into it is through a 7 watt 150 ohm resistor (into a pass transistor) which APPEARS to be R78, though hard to read and might be R75.

There is another that COULD be R78, a small resistor associated with TR10, and that is a 10k. So is the burnt one a large 7w resistor or a small one?
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Old 19th March 2014, 09:34 AM   #5
teemuk is offline teemuk  Finland
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I have one TA100R schematic.

Unfortunately it seems to be either for an older or newer version than OP's model (which also Enzo refers to) since the schematic doesn't really match the desciption.

In this one the low voltage supply has its own secondary winding, and while it does have discrete regulator transistors the supply voltages are +/-15VDC instead of +/-12 volts. The component designations do not match either (no such thing as R78 or even R7x in the whole regulator circuit). It's a very basic regulator: two pass transistor with zener diodes and filter caps on their gates. Voltage division with 2K2 resistor from the high voltage supply connecting to transistor base and a 16V zener diode in shunt. Since the transistor handles all the regulation and the Zener diodes at gate draw only very low current no high power resistors (such as 7W 150R) are involved in the circuitry.

I try to browse my schematic collection because I have a faint memory that I also have much older, hand-drawn schematics for some of the TA-series amps around somewhere. (The one I have is made with CAD and very clear). I think Trace Elliot used those +/-12VDC supply voltages way back. I see what I can dig out but my collection is spread on 15 - 30 CD-R's without any sort of logical assortment other than title "schematics" written to the CD's. It's actually quite a lot of work to go thorugh that hunting just for one specific thing....

As it appears there are many different revisions of the TA100R, some obviously very different from yours, you wouldn't happen to have serial number so folks could date the proper technical documents? The schematic I have is for >1998 models.

Last edited by teemuk; 19th March 2014 at 09:39 AM.
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Old 19th March 2014, 03:12 PM   #6
Enzo is offline Enzo  United States
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My drawings are dated 3-7-90, and that appears to be the Euro date order d-m-y


For what it is worth, here is a scan.
Attached Files
File Type: pdf Trace TA100R preamp.PDF (109.5 KB, 36 views)
File Type: pdf Trace TA100R PA and PS.PDF (61.2 KB, 31 views)
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Old 22nd March 2014, 06:21 AM   #7
Enzo is offline Enzo  United States
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From his other thread, a newer schematic, I see R78 would be a 470 ohm input resistor from the XLR input. If that is the case, a burnt resistor there pretty much says to ne the IC s=will be bad or at least stressed as well. That is IC9a on that drawing.
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Old 24th March 2014, 07:52 PM   #8
gary d. is offline gary d.  United States
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Thanks for the replies. Since my initial post I have acquired 2 Trace service manuals,(no.SM00034 ISSUE 2 and no.SM00060 ISSUE 1.) The AOP and FRONT boards of my amp are ISSUE 3, though the BACK board is ISSUE 2. The ISSUE 1 manual is very different and doesn't seem to pertain to my amp. The ISSUE 2 manual appears much the same as mine.(component values,codes, and where used.) One notable difference-TR 11 according to the manual is transistor BD677. On my circuit board it is NTE 253. Are these the same kind of transistors produced by different manufacturers?
The serial number on the back of my cabinet was written in with a sharpie and has faded to the point of being illegible. There are however dates handwritten with sharpies on a couple of the boards of 12/05/91.
Thanks again for everyones help.
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Old 24th March 2014, 09:40 PM   #9
Tarzan is offline Tarzan  Belgium
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Hello Gary,
Are the schematics you received the same as these from Enzo or myself?
If different, can you post them here?
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Old 24th March 2014, 10:13 PM   #10
Enzo is offline Enzo  United States
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NTE is a replacement line. They sell parts that are supposed to be "equivalent" to the real parts. If you look up BD677 in the NTE guide, then you will find NTE253 as the replacement for it in their line. SO in other words, at some point someone repaired this unit and bought the part at some local parts house.
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