My Scott 222D has been idled for the summer but now the phono stage is FUBAR! Signal is very weak -with hum- and as the volume is increased, the amp bursts into oscillation!
Line-level inputs are AOK! I have a Schiit Mani in place feeding into the "Tuner" input for Vinyl playback and that sounds very nice indeed but, what might have gone bad in the EQ stage of the Scott? It used to be OK...
The only change made to the unit before storage was to replace the 6U8A's in the Voltage Gain/ Phase Splitter which had developed hum.
* I have limited test gear: a DVM and my Ears. ;-)
Rick
Line-level inputs are AOK! I have a Schiit Mani in place feeding into the "Tuner" input for Vinyl playback and that sounds very nice indeed but, what might have gone bad in the EQ stage of the Scott? It used to be OK...
The only change made to the unit before storage was to replace the 6U8A's in the Voltage Gain/ Phase Splitter which had developed hum.
* I have limited test gear: a DVM and my Ears. ;-)
Rick
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- Good advice: I have tried all those things to no effect. Gain is huge now. So by 12 o'clock on the volume knob the amp is completely out of control using any Mag. input. Really strange!
Maybe those 2.2 megohm grid-leak resistors have gone bad? I'll have to wait for today's mail for new test probes and some resistors. I was getting intermittent and crazy readings with my cheap meter and dodgy leads.
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Your symptoms appear to be the same that I've once encountered with an accidentally miswired (confusion of both channels' hot and ground leads) Dual 1226 TT. But you didn't alter anything at your TT?
Has your Scott unit got RCA input terminals? If so, are the GND sleeves clean?
Best regards!
Has your Scott unit got RCA input terminals? If so, are the GND sleeves clean?
Best regards!
Well!
1) Phono Stage issue.
2) Both channels affected equally.
and: too many switch points (with 55 years of of age) to deal with, so... I'm going to go with the Schiit Audio "Mani" Phono EQ into the "Extra" line input and the Schiit "Modi-Multibit" DAC into "Tuner" input as i have been. The Mani is very accurate +- 0.2 db and sounds very nice through the Scott Amp circuit. Thanks for all the input! ;-)
1) Phono Stage issue.
2) Both channels affected equally.
and: too many switch points (with 55 years of of age) to deal with, so... I'm going to go with the Schiit Audio "Mani" Phono EQ into the "Extra" line input and the Schiit "Modi-Multibit" DAC into "Tuner" input as i have been. The Mani is very accurate +- 0.2 db and sounds very nice through the Scott Amp circuit. Thanks for all the input! ;-)
I just finished putting the HH Scott back together and I will hook it up tomorrow - it is 2:11 A.M. here.
Here is a picture of the Amplifier on my kitchen work table: I love the Reflektor 6n14n output tubes
DSC_0128 | Rick Ganan | Flickr
Here is a picture of the Amplifier on my kitchen work table: I love the Reflektor 6n14n output tubes
DSC_0128 | Rick Ganan | Flickr
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* I think I already did check the 12AX7's connections and resister values but it can't hurt to check again.
* Your tip to by-pass the EQ switch looks like an item of interest.
The switch does have a poor 'feel' as it is moved between positions and could have loose bits inside.
I'll update this thread when I have time to try this out.
PS. Stay warm, eh! It must be getting cold up there in Alberta
* Your tip to by-pass the EQ switch looks like an item of interest.
The switch does have a poor 'feel' as it is moved between positions and could have loose bits inside.
I'll update this thread when I have time to try this out.
PS. Stay warm, eh! It must be getting cold up there in Alberta
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I have a soldering iron I got at Radio Shack in their final days and it is ridiculously hot!
I need to get a proper one and some basic electronic tools before doing any further work.
I once had a complete tool kit in a Attache case when I was a tech - but everything had to go after the Great Recession!
And, Jeez! The schematic diagram - especially all the switching and routing - gives me a headache.
I'm listening to some vinyl: Holiday stuff - "Don't Eat The Yellow Snow" - using the Schiit 'Mani' into "Extra" (line level) input right now and it sounds mighty fine!
I need to get a proper one and some basic electronic tools before doing any further work.
I once had a complete tool kit in a Attache case when I was a tech - but everything had to go after the Great Recession!
And, Jeez! The schematic diagram - especially all the switching and routing - gives me a headache.
I'm listening to some vinyl: Holiday stuff - "Don't Eat The Yellow Snow" - using the Schiit 'Mani' into "Extra" (line level) input right now and it sounds mighty fine!
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To keep these old parties running, you'll need a good switch and control cleaner. I can recommend the CAIG products (although their spray cans get worse every generation) in a very light application. Discretion is the better part of valor.
"Pretty loud" at 12:00 on the volume control is quite possibly normal for a classic era Scott, or others. Fashion maybe.
All good fortune,
Chris
"Pretty loud" at 12:00 on the volume control is quite possibly normal for a classic era Scott, or others. Fashion maybe.
All good fortune,
Chris
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