Well I also just have to ask what are the symptoms of the amp failure? What is wrong with this beast? xP

What amp are we referring to here on this thread, out of curiosity? I understand the question on the thread but feel some example of reference would be nice.  8|

Also checking out this site and messaging this poster might be a way to get the right schematic. Maybe I will try just as I am curious. It is an old thread so who knows we might have missed the train...  :afro:

http://www.mtsforum.grailtone.com/viewtopic.php?t=1629

It's all about being aggressive and very careful all at the same time. Many times you'll get the sucker out, but yeah it will leave some markings. Work on getting the orange back board out first... Then you can get your hands on other parts of the chassis to wiggle it free. I some times use a flat wood tool or something to lightly separate the stuck parts as I wiggle. It's fun stuff!!  :trouble

Well yeah they Mickey Mouse colored the stems on the pots from many Crate amps. That is not a sure way to figure which one goes where on the pre-amp board. There is a G-60 schematic online but no G-60xl... So best bet is to call Loud Tech. who own Crate and Ampeg amps. All you need is your serial number and model name to give to the service/parts department. It won't cost any money at all when you call them...

http://www.crateamps.com/support/

I have a few of Epiphone Valve Jr 5 watt tube amps. I bought two working amps for $75 each and a non-working one for $40. These amps are easy to mod and are cheaper than most of any of the tube amps out there... Still not the greatest sounding, but still can be modded in so many ways. I also have an attenuator for Epi Valve Jr. to make it breakup at lower volumes. Sure you can spend money on a kit and build a Fender Champ or something. I found a sweet deal on three Gretsch Electromatic G5222 amps for $50 each. Those amps are basically like the Fender Champion 600 type amps. My point is that given some patience and research on craigslist, 5 watt tube amps are easy to find at a great price. 

Is there a way to detach the power board wires that carry 15v rails to the other boards? I mean at least then we could test the voltage at the source just to make sure it is good. That way we can then start looking at opamps etc etc... Well then again... So far it sounds like the +/-15v rails are being bogged down by something upstream. Are any opamps getting hot in conjunction with the regulator getting hot?

Yeah sure the regulator could be the problem but I think Ed said that he had replaced the 78M15 part. In this case I would be checking zener diodes or resistors for shorts. ZD3-6 and all zeners need to be tested. Also, voltage check of the 24volts rails needs to be established as well.

Here are the schematics for the Taurus Elite amp... Ed sent them over to post up here for convenience. Thnx Ed!

This is a 10" option that allows you to control how you want to wire it up, battery or plug.
http://www.ebay.com/itm/Red-24CM-LED-Strip-Car-Auto-Motorcycle-Flexible-Grill-Light-Lamp-Bulb-12V-LED-/161110711710?pt=US_Car_Lighting&hash=item2582f25d9e

Trust me that you do not want to try to tap the amps power supplies. Rather if you must, mount a 1:10 step down transformer from the 120v already entering your amplifier. Now this is not the greatest idea but I think it better than trying find a way to tap into the power supply of the amplifier itself. Mounting this transformer will prove to be a hassle and it needs to be positioned in the chassis perfectly so it won't add hum to the amp.

Personally, a battery powered or wall wart powered alternative is much more practical and easier to remove if you ever want to get rid of the decorative item on the amp. For example, here is a product that would be easy to copy. http://monkeydream.com/led_bar_sale.html

Right there on the schematic it says "Mod from 12-9-86  s/n u29600 onwards c14 + c18 removed." Also s/n u29600 could read 029600 just can't tell really. Check if that mod is present and the serial number etc. It all relates in circuit to VR4 so it made me wonder. Let us know if your amp already has that mod too.

Here's some info that I have found so far...

http://www.justanswer.com/electronic-musical-instruments/6jbbv-burned-resistors-circuit-board-roland.html

On this site the poster uploaded the KC-300 schematic... Now I am posting that image here... Does your pcb board say PWB = G2927124??

Yeah you should not be having problems just plugging in something to the amp while it is on. However, what are WE plugging in EXACTLY? Please explain how this latest problem might be related to the previous problem... That is to say again.. What are we plugging in to the amp while it is on?

Also, pls look at this schematic I have attached and figure out if it really is the KC300 schematic. It might be, but you never know. I post it anyhow with the link the website I found it on. I hope this might help.

Here is the power schematic for a mini-brute and I am pretty sure they are very close. Look on the board for where the transformer plugs into the power board. Should be easy to start checking for voltages around caps too. Look at the regulators to provide other various voltages to the preamp...

P.S. I could not find the thread where I got these pics... I searched but could not find it... Thanks to that poster for these pics and schematics.

Double P.S. The 378B looks more like it here it is...

Well it is good to have the pictures online so everyone has an idea to see the Rat's nest we are working on here. I love Polytone amps but looking inside of them it is always a wonder how they sound so good... I follow all the advice given thus far from Juan and others... However looking at the pics I have to question what caused the browning of the circuit board here... Did you inspect the traces on this part and test the mylar film cap for any damage?