TelRay 1001 oil can delay screen voltage
Moderators: pompeiisneaks, Colossal
TelRay 1001 oil can delay screen voltage
Does anyone have a service manual or any information on how the screen pot is supposed to be set? I have a schematic for a similar fender model with added voltages but don't know what the optimal setting would be. Is this more or less a set by ear kinda thing like the other trim pots?
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Re: TelRay 1001 oil can delay screen voltage
I'd suggest it would be an 'ear' adjustment to suit your playing style. A can has a fairly restrictive frequency and dynamic range response, which are aspects of what the screen adjustment would modify. The input stage is grid leak biased, so is already going to be dependent on the playing style you have, and on the actual valve you are using. The Reverb 2 schematic indicates the screen voltage may be down towards 15V, although the actual voltage is suspect due to the high resistance node being measured, and the meter that may have been used to measure '15V'.
The Standel Duette 2 was pretty much another copy of that unit.
Have you checked your oil level and condition ?
The Standel Duette 2 was pretty much another copy of that unit.
Have you checked your oil level and condition ?
Re: TelRay 1001 oil can delay screen voltage
Thanks! Haven’t checked the oil yet; the owner said he put new oil in. One of the heads had significantly lower signal than the other so I probably will take a peek in there. Hopefully that’s just an oil level problem.
Another local tech worked on this before me and made a mess of things so i’m re-re capping it, adding a mains fuse, and cleaning up some weirdness before I do anything else.
Another local tech worked on this before me and made a mess of things so i’m re-re capping it, adding a mains fuse, and cleaning up some weirdness before I do anything else.
Re: TelRay 1001 oil can delay screen voltage
Another question: The Standel schematic says 35v zeners, the other two schematics say they think they have zeners, the one I'm working on appears to have germanium. It also looks like they might not be original. Should I replace them with 35v zeners? Are they just knocking down voltage spikes from the magic electrostatic disc?
Re: TelRay 1001 oil can delay screen voltage
I don't have a Standel schematic that include any zener diodes - can you provide a link please.
The back-to-back diodes in the two schematics in the first post could plausibly have been two back to back zeners, or a diode and a zener, as I'd anticipate their function would be to avoid any high voltage transient at turn-on or turn-off due to the 10nF coupling cap from the input stage triode. The electrostatic disk is effectively an aluminium insulator capacitor, and insulation degradation/damage may have been observed by Telray/etc at some point - perhaps not a concern for solid-state oilcan pedals (I have a Morley RSE).
There are a few paths that could be taken to confirm the protection diode types. For example, you could carefully test each diode's forward and reverse conduction characteristics, assuming they are original parts. Another option is to remove them, and bring the pedal up with a variac (to avoid the need for transient protection), and measure the signal voltage at that node with at least a 10Meg probe/meter for different uses and with different Echo levels. Based on a peak voltage that exceeds the normal usable signal level, then select suitable protection parts.
The back-to-back diodes in the two schematics in the first post could plausibly have been two back to back zeners, or a diode and a zener, as I'd anticipate their function would be to avoid any high voltage transient at turn-on or turn-off due to the 10nF coupling cap from the input stage triode. The electrostatic disk is effectively an aluminium insulator capacitor, and insulation degradation/damage may have been observed by Telray/etc at some point - perhaps not a concern for solid-state oilcan pedals (I have a Morley RSE).
There are a few paths that could be taken to confirm the protection diode types. For example, you could carefully test each diode's forward and reverse conduction characteristics, assuming they are original parts. Another option is to remove them, and bring the pedal up with a variac (to avoid the need for transient protection), and measure the signal voltage at that node with at least a 10Meg probe/meter for different uses and with different Echo levels. Based on a peak voltage that exceeds the normal usable signal level, then select suitable protection parts.
Re: TelRay 1001 oil can delay screen voltage
The diodes on mine look like germanium and measure like germanium. Sloppy soldering to the chassis with a not strong enough iron leads me to believe they are unoriginal or have been messed with. I don't have the unit handy at the moment or I would post a picture.
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Re: TelRay 1001 oil can delay screen voltage
Ta - I missed seeing those parts, doh!
Possible that they are 3.5V or 35V. Another aspect of restricting the peak signal voltage being applied to the disk could be related to time 'smear', for example where the applied voltage is sufficient to leak across to nearby stripe of disk that has, or is, about to the recorded onto. I'd anticipate that the higher the applied voltage, the greater the leakage, in which case the manufacturer may have been trying to improve their product's clarity, or similar audible aspect.
Possible that they are 3.5V or 35V. Another aspect of restricting the peak signal voltage being applied to the disk could be related to time 'smear', for example where the applied voltage is sufficient to leak across to nearby stripe of disk that has, or is, about to the recorded onto. I'd anticipate that the higher the applied voltage, the greater the leakage, in which case the manufacturer may have been trying to improve their product's clarity, or similar audible aspect.
Re: TelRay 1001 oil can delay screen voltage
I believe they are germanium zeners. I didn't realize that was a thing, but I guess it would have to be... 3.5v makes a distortion pedal, 35v is inaudible compared to no diodes. Guessing it is to knock down voltage spikes. I replaced the diodes just to be cautious, someone had tampered with them so better safe. Everything seems to be working fine, thanks for the help!
Apologies if everyone has already heard this. While reading up on telray/ morley, I learned Morley was named to compete with Leslie. That's better than the Ampeg name origin!
Apologies if everyone has already heard this. While reading up on telray/ morley, I learned Morley was named to compete with Leslie. That's better than the Ampeg name origin!