sadly that didn't help much. ended up replacing all the resistors and that got it a little quieter. still not perfect.
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#1
The Wurlitzer Electric Piano / Re: rebuilding a 140b amp output problems
April 17, 2017, 03:30:06 PM #2
The Wurlitzer Electric Piano / Re: rebuilding a 140b amp output problems
February 27, 2017, 05:16:55 PM
great! i'll check there!
#3
The Wurlitzer Electric Piano / rebuilding a 140b amp output problems
February 25, 2017, 02:13:24 PM
hey all! i lurk here a lot and have gotten a lot of great info from ya'll! thanks for that!
i'm currently rebuilding a 140b that was a literal rats nest. it's all almost working again (yea!), but i am running into a problem without the output signal.
basically, it's too loud! the level control is set at it's lowest, and still it's a little distorted. it looks like the problem is at the output transistor, tr72. emitter is measuring -.6v (instead of -0.06v), base is -0.7v (instead of -0.09v), and collector -33.3v, which is fine. all transistors have been replaced with new ones from vintage vibes. The level control pot has been tested and looks pretty ok, as is the volume knob. tr71 is a bit high on emitter at 33v, and base, at 32.9v. overall, it's all pretty close considering it's a 50+ year old schematic.
the ldr has been upgraded to an LED, which also hasn't been as rich of a vibrato as a 140b with a incandescent. i assume that part of the problem is coming from this part of the circuit. it's at a beautiful volume and no distortion when the led is not in place and the LDR is uncovered to receive natural room light. is there a good source for the original incandescent bulbs out there?
i'm currently rebuilding a 140b that was a literal rats nest. it's all almost working again (yea!), but i am running into a problem without the output signal.
basically, it's too loud! the level control is set at it's lowest, and still it's a little distorted. it looks like the problem is at the output transistor, tr72. emitter is measuring -.6v (instead of -0.06v), base is -0.7v (instead of -0.09v), and collector -33.3v, which is fine. all transistors have been replaced with new ones from vintage vibes. The level control pot has been tested and looks pretty ok, as is the volume knob. tr71 is a bit high on emitter at 33v, and base, at 32.9v. overall, it's all pretty close considering it's a 50+ year old schematic.
the ldr has been upgraded to an LED, which also hasn't been as rich of a vibrato as a 140b with a incandescent. i assume that part of the problem is coming from this part of the circuit. it's at a beautiful volume and no distortion when the led is not in place and the LDR is uncovered to receive natural room light. is there a good source for the original incandescent bulbs out there?
#4
Parts, Service, Maintenance & Repairs / replacing balance rail pins
June 08, 2013, 09:41:55 PM
hey all!
so i recently got a free rhodes mkI (the joys of people who are too afraid to fix things on their own!) and i started to refurbish this beast. it's a mkI suitcase, and the big problem is that some of the keys stick when pressed down. The key section sat out in someones garage in Rhode Island for about 4 years so there is a LOT of rust all over the place, but mostly my friend and I believe it is the rust on the balance rail pins that are creating the problem. I have a source for new pins, my question is what is the best way to remove and replace the pins? a pair of pliers and pulling straight up work? or is it more like pulling up the whole balance rail and removing the pins that way? anyone have words of advice? thanks so much!
so i recently got a free rhodes mkI (the joys of people who are too afraid to fix things on their own!) and i started to refurbish this beast. it's a mkI suitcase, and the big problem is that some of the keys stick when pressed down. The key section sat out in someones garage in Rhode Island for about 4 years so there is a LOT of rust all over the place, but mostly my friend and I believe it is the rust on the balance rail pins that are creating the problem. I have a source for new pins, my question is what is the best way to remove and replace the pins? a pair of pliers and pulling straight up work? or is it more like pulling up the whole balance rail and removing the pins that way? anyone have words of advice? thanks so much!
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