Tremelo parts (light bulb) [message #3161] |
Tue, 14 October 2003 01:43 ![Go to next message Go to next message](/FUDforum/theme/vk30/images/down.png) |
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Hi,
I'm resurrecting a Frankenstein head, and it seems that the light bulb that controls the optical resistor, in the tremelo circuit is completely open (infinite resistance). The oscillator circuit seems to be working OK. Has anyone ever replaced those parts (the bulb and opto-resistor inside heatshrink)? And, if so, what did you use for replacements? I think I might have to jerry-rig this whole opto-isolator apparatus. I'm doing all of this without a schematic. Any help would be appreciated.
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Re: Tremelo parts (light bulb) [message #3165 is a reply to message #3161] |
Wed, 15 October 2003 14:11 ![Go to previous message Go to previous message](/FUDforum/theme/vk30/images/up.png) ![Go to next message Go to next message](/FUDforum/theme/vk30/images/down.png) |
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I recently rebuilt the vibrato in one of these heads. The light bulb was a #48. It had wires soldered to the threaded base. My book says that a #48 bulb is 2 volts at 0.06 amps. If you can't find one, a #49 is the same specs but with a bayonet base.
The CdS photocell was a Clairex CL-603. The vibrato was very weak, so I replaced the photocell with one that I had around. I tried 5 or 6 different cells to find the one that worked best. Hope this helps. Bill from Chicago.
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Re: Tremelo parts (light bulb) [message #3166 is a reply to message #3161] |
Wed, 15 October 2003 14:13 ![Go to previous message Go to previous message](/FUDforum/theme/vk30/images/up.png) ![Go to next message Go to next message](/FUDforum/theme/vk30/images/down.png) |
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I recently rebuilt the vibrato in one of these heads. The light bulb was a #48. It had wires soldered to the threaded base. My book says that a #48 bulb is 2 volts at 0.06 amps. If you can't find one, a #49 is the same specs but with a bayonet base.
The CdS photocell was a Clairex CL-603. The vibrato was very weak, so I replaced the photocell with one that I had around. I tried 5 or 6 different cells to find the one that worked best. Hope this helps. Bill from Chicago.
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Re: Tremelo parts (light bulb) [message #3196 is a reply to message #3195] |
Wed, 29 October 2003 11:18 ![Go to previous message Go to previous message](/FUDforum/theme/vk30/images/up.png) ![Go to next message Go to next message](/FUDforum/theme/vk30/images/down.png) |
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Roy,
Glad I could help. Mine is true vibrato (pitch shift), which was very weak until I changed the photocell. The new one made a big difference.
What kind of noise is your amp making?
Bill
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Re: Tremelo parts (light bulb) [message #3296 is a reply to message #3199] |
Wed, 03 December 2003 13:43 ![Go to previous message Go to previous message](/FUDforum/theme/vk30/images/up.png) ![Go to next message Go to next message](/FUDforum/theme/vk30/images/down.png) |
John
Messages: 1 Registered: December 2003
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Junior Member |
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Hi-I'm trying to fix an old Frankenstein head M/n J595 RV S/N 10948. The problems I,m having are just as people on the site have described-reverb that reduces volume without any reverb effect and intensity and speed knobs that do nothing. Thanks to what I learned on the site I've purchased a Clairex CL-603 photocell and a # 49 lamp from Mouser. I haven't opened up the amp yet and I believe schematics are non-existent. Any words of advice before I begin? Thanks
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Re: Tremelo parts (light bulb) [message #3297 is a reply to message #3296] |
Thu, 04 December 2003 12:09 ![Go to previous message Go to previous message](/FUDforum/theme/vk30/images/up.png) ![Go to next message Go to next message](/FUDforum/theme/vk30/images/down.png) |
chicagobill
Messages: 2005 Registered: April 2003
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Senior Member |
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In 595 RV heads, the reverb and vibrato circuits are both located on one circuit board located on the left side (when viewed from the front) of the amp. The reverb control works differently from most amps, as it is really a balance control. Full counter-clockwise all straight signal, full-clockwise all reverb signal. Therefore what happens when you turn up the reverb, you turn down the straight signal. If you've already checked the tank and wiring, check the transistors and the caps in the reverb circuit. Good Luck! Bill from Chicago.
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Re: Tremelo parts (light bulb) [message #3298 is a reply to message #3161] |
Thu, 04 December 2003 14:04 ![Go to previous message Go to previous message](/FUDforum/theme/vk30/images/up.png) |
beagle
Messages: 12 Registered: September 2003
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Junior Member |
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I have a similiar problem with my K-200 head. I get reverb when i turn the pot up, but when I combine that with the speed pot turned up, all I get is dramatically reduced volume levels. Can anyone tell me what's wrong?
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