Gretsch Amps

Rogue 7157 Tremolo / Magic Echo Repair

1

I have been working on a Gretsch Rogue model 7157 to fix an issue with the tremolo / magic echo. First of all are there any schematics for this amp?

The tremolo can sometimes be barely heard, but the magic echo there is no change in sound. I have tested the transistors and all have tested in good condition. are there any suggestions on what might be the issue?

2

I think Magic Echo was also used in the larger version of the Safari solid state model. Glad someone is willing to take this on!

3

You can find a Rogue schematic on the Schematic Heaven site here:

https://schematicheaven.net...

Scroll to the bottom of the Gretsch amp section. Hopefully it's what you need.

I owned a Rogue back in the 70s and the impression I had at that time was that the tremolo used a sine wave and the magic echo was tremolo but using a square wave for a more abrupt echo-like effect. I'd be interested to know if that was the case.

4

That's not a complete schematic though....it's the power supply, power amp, and tremolo oscillator...but none of the parts we actually want to see.

5

We want to know what's in these rectacgular boxes!

6

You can find a Rogue schematic on the Schematic Heaven site here:

https://schematicheaven.net...

Scroll to the bottom of the Gretsch amp section. Hopefully it's what you need.

I owned a Rogue back in the 70s and the impression I had at that time was that the tremolo used a sine wave and the magic echo was tremolo but using a square wave for a more abrupt echo-like effect. I'd be interested to know if that was the case.

– Mij

I have a copy of that schematic and it is not what the Tremolo/Magic echo circuit looks like. I have made a schematic of the circuit and tested every component, there was a transistor that was replaced before I got into it, and I'm thinking it was replaced with the wrong transistor, therefore I would need an original schematic to determine what transistor was used. The problem is, all the transistors are obsolete and some you can't find a replacement for.


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