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Messages - Jazz P Bass

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31
Amplifier Discussion / Re: 1988 Randall RG100ES
« on: December 31, 2019, 06:13:29 PM »
What does "Q8 is irregular pattern" this mean?


32
First of all, you need to be aware that this amplifier configuration is called 'The Widow Maker'.
The ac mains voltage is directly coupled to the rectifier.
There is not a transformer to supply the secondary voltages.
To work on and operate these safely you must have an isolation transformer that would separate the mains voltage from the amp (110-110Vac)

33
Amplifier Discussion / Re: 1988 Randall RG100ES
« on: December 31, 2019, 02:35:06 PM »
Follow the signal into the power amp.
You do have a scope, correct?
What does the signal look like at the base of Q8?
Q10?
Q11?
Q12?

34
Amplifier Discussion / Re: 1988 Randall RG100ES
« on: December 30, 2019, 05:24:49 PM »
So you feel the output is 'low'.
What is the maximum Vac out into an 8 ohm load before clipping?

35
Amplifier Discussion / Re: 1988 Randall RG100ES
« on: December 30, 2019, 12:25:26 PM »
Other than having the designators wrong on the outputs and the leg assignments wrong on the Negative outputs, I see nothing majorly wrong with the static voltages.

The schematic indicates a 225mv AC signal entering the amplifier.
What value do you read coming in there?

36
Amplifier Discussion / Re: 1988 Randall RG100ES
« on: December 29, 2019, 09:42:57 PM »
Where is the schematic?
Can you please post it?
On the last three transistors, what are the designated 'Q' numbers?

37
Amplifier Discussion / Re: Gallien Kruger GT200
« on: December 25, 2019, 08:26:43 PM »
Not too sure what you are attempting to fix here.

Yes there is a small x over notch at higher settings.
I really doubt that you could here that.

What I see from the image is a gross mismatch in the top & bottom width of the waveform.
THAT will be noticeable.


38
Amplifier Discussion / Re: Gallien Kruger GT200
« on: December 20, 2019, 01:06:31 AM »
Can you take a picture of the distortion as it appears on a scope?

If so, upload it.

39
The Newcomer's Forum / Re: Fender Mustang II v.2
« on: December 08, 2019, 03:28:54 PM »
The issue needs be to better defined.
Shuts off as in the front indicator goes out?

40
The Newcomer's Forum / Re: Eight Audio Kit TDA7294 and TDA2050 from India
« on: December 04, 2019, 09:45:34 AM »
The rear tab on both ic's, both boards, is connected to the B- power supply.

If the heat sink is 'floating' and not at ground potential then there is no need to isolate the tabs.

As to bridge mode, I am not sure.
They appear to be stereo amplifiers.

41
Amplifier Discussion / Re: Gallien Kruger GT200
« on: December 02, 2019, 11:06:49 PM »
According to the schematic, there are two pots that need to be adjusted.

42
Schematics and Layouts / Re: Schematic sites for different brands of amps
« on: November 14, 2019, 11:48:19 AM »
Have you attempted to contact Rocktron?

http://www.rocktron.com/contact.html

43
Amplifier Discussion / Re: Ibanez TSA30 - buzzing
« on: November 10, 2019, 06:07:15 PM »
I believe that the OP is referring to the Foot Switch jack.

44
Schematics and Layouts / Re: Randall RGP-1000, FS-6 Footswitch Schematic
« on: October 28, 2019, 11:48:03 PM »
Can't seem to find a schematic for that amp.

My first thought is try to find the correct plug.


45
Amplifier Discussion / Re: Anyone try a KA2206 ?
« on: October 28, 2019, 11:46:49 PM »
The KA2206 is a 2 channel power amp.
It is rated at 4 watts output with a 12Vdc supply , into a 4 ohm load x2.

I have seen them on keyboards.

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