Hoffman Amplifiers Tube Amplifier Forum

Other Stuff => Solid State => Topic started by: Stankfut on January 05, 2014, 09:35:42 pm

Title: Schematic for Ibanez GTA15R
Post by: Stankfut on January 05, 2014, 09:35:42 pm: Any one know where to find one? Did a Google search but didn't come up with anything. A friend asked me to take a look at it. He says its probably trash,and I'm resisting the urge to gut it to build something useful, but I think it may be a nice experience to try to learn while repairing it. It has been hacked at, so I'm not sure about some connections, so I can't really reverse engineer it, especially since my knowledge of SS is almost nil. It actually has a nice chassis for what it is. I could see a SE EL84 amp fitting nicely in there...... :angel
Title: Re: Schematic for Ibanez GTA15R
Post by: Stankfut on January 07, 2014, 01:30:54 pm: No one? I guess I'll try to hand draw it, but I'm not going to waste a lot of time on it......gutting it looks better all the time!
Title: Re: Schematic for Ibanez GTA15R
Post by: kagliostro on January 07, 2014, 03:24:31 pm: I give a try on searching for the GTA15R schematic

and effectively I've find one

unluckily it is a russian Yerasov GTA15R amp

http://www.mediafire.com/view/v0g53ic79lbsxeg/GTA-15R.pdf (http://www.mediafire.com/view/v0g53ic79lbsxeg/GTA-15R.pdf)

K
Title: Re: Schematic for Ibanez GTA15R
Post by: smackoj on January 07, 2014, 06:23:06 pm: before you give up the search, you might try contacting Ibanez for a schemo. Some of the companies out there still believe in customer "service" although it's not unusual to never hear back from some either.

good luck. :icon_biggrin:
Title: Re: Schematic for Ibanez GTA15R
Post by: Stankfut on January 07, 2014, 09:19:30 pm: kagliostro, :l2: I wish it had tubes, I can halfway understand that!

smackoj, I'll give their customer service a try
Title: Re: Schematic for Ibanez GTA15R
Post by: Stankfut on January 09, 2014, 12:02:58 pm: Hey, what do ya know! They actually sent me a schematic. Now i've got to learn about op amps and transistors. Great. :BangHead:
Title: Re: Schematic for Ibanez GTA15R
Post by: teletubetone on April 12, 2014, 08:43:55 am: Hey Stankfut would you mind passing along the schematic for that Ibanez GTA15R? My email is teletubetone@gmail.com. I would be very appreciative. BTW, this is my first post on any type of web forum ever so forgive me if there are any errors in my approach. Thank you sir!
Title: Re: Schematic for Ibanez GTA15R
Post by: smackoj on April 15, 2014, 05:55:34 am: someone said, "the only dumb question is the one you don't ask" Ibanez has been one of those hit and miss companies IMO. I don't know if it's even still the orig. company or just another 'Loud Technology' wannabe chasing a hand full of money?

good luck with it either way.

:icon_biggrin:
Title: Re: Schematic for Ibanez GTA15R
Post by: Stankfut on April 18, 2014, 10:27:20 am: Sorry, schem is on my office computer and I've been out of the office! :l2:

Here ya go!
Title: Re: Schematic for Ibanez GTA15R
Post by: Stankfut on April 18, 2014, 10:28:38 am: I am not able to repair the one I have, someone tried to "fix" it and put the wrong "power" transformer in.

Going to rebuild as tube amp soon!
Title: Re: Schematic for Ibanez GTA15R
Post by: PRR on April 19, 2014, 12:27:22 am: Power transformer *should* be 24V AC CT (1 Amp), to give +/-18V DC at caps C20 C21.

It seems unlikely C20 C21 would be blown by any "reasonable" PT swap. But if they have pooped, replace them.

Given +/-18V going to the TDA2030, it should make sound, at least a low hiss/hum. If not, replace the 2030.

If they really went crazy, the NJM4558 chips may be blown. They are cheap; TL072 is a bit cheaper and will work.

It is mostly: do I get power here? And here? Are the output pins of all amplifier chips sitting at zero Volts DC (+/-0.1V)?

I agree it is an un-inspired design, but it should be a handy bench utility amp.