Pretty much impossible to troubleshoot without a look at the schematic. What the TP is connected to might be helpful.
jeff
jeff
TP 2 is 1 leg of a 2K2 resistor that is fed directly from the output tx, It in turn connects to a 20 ohm res.. The 2K2 resistor is shunted(?) by a 330u cap.
If that's an offer, I can PM tomorrow.
Thx 6L6, this site is great, I have learned a lot in a short time. Unfortunately a lot of what I've learned is how much I have to learn! LOL
Ok, this is a 12AU7 or 12BH7A input voltage amplifier, which is direct coupled to a 12AU7 or 12BH7A cathode follower,
capacitor coupled to the single ended, self biased output tube. Pretty simple. The secret sauce is in the parts quality.
Just measure the DC voltages (plate, grid, cathode) of each tube, with respect to ground.
Once for the good channel, and again for the bad channel. That's about all you need.
And list them here.
V1 plate =
V1 grid =
V1 cathode =
V2 plate =
V2 grid =
V2 cathode =
V3 plate =
V3 grid =
V3 cathode =
One thing, is it possible to install the tube sockets wrong on the board, are they keyed? That does happen.
Here's an approximate schematic from publicly available information, but the optional feedback is not shown.
capacitor coupled to the single ended, self biased output tube. Pretty simple. The secret sauce is in the parts quality.
Just measure the DC voltages (plate, grid, cathode) of each tube, with respect to ground.
Once for the good channel, and again for the bad channel. That's about all you need.
And list them here.
V1 plate =
V1 grid =
V1 cathode =
V2 plate =
V2 grid =
V2 cathode =
V3 plate =
V3 grid =
V3 cathode =
One thing, is it possible to install the tube sockets wrong on the board, are they keyed? That does happen.
Here's an approximate schematic from publicly available information, but the optional feedback is not shown.
Another thing that might be measured are power supply voltages. Tube amp power supplies often look something like this:
There is typically a transformer, then a rectifier, then some stages of RC or LC filtering. At each stage of filtering the voltage is a little lower (as indicated in purple numbers in this example). If there is a power supply that looks something like one in above pic, you could measure the voltages at each point similar to the example.
Of course, this assumes you know how to measure high voltages safely. Do you know how?
There is typically a transformer, then a rectifier, then some stages of RC or LC filtering. At each stage of filtering the voltage is a little lower (as indicated in purple numbers in this example). If there is a power supply that looks something like one in above pic, you could measure the voltages at each point similar to the example.
Of course, this assumes you know how to measure high voltages safely. Do you know how?
He wants all possible info at once to reduce the back and forth. Perfectly understandable.
Don't get too frustrated, these things happen. Lots of kits from the golden era started out not working.
And they were often much more complicated to troubleshoot point to point wiring.
Want to feel better? See Sheldon's rebuilt HK Citation 1 kit.
https://www.quadesl.com/photo/cit1_photos/rebuilt3.jpg
https://www.quadesl.com/photo/cit1_photos/rebuilt2.jpg
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That is not unreasonable, but at some point he should just (only) sell factory assembled units,
and avoid the trauma on both sides. If it's only an extra 10% of the kit price, why bother?
You would not believe some of the atrocious work I've seen on audio kits. It makes you weep.
Soldering guns, huge solder blobs, long untrimmed leads, crooked parts, etc.
Dynaco hired local housewives to do all of their factory assembled units.
They were meticulous and beautiful (the kits).
and avoid the trauma on both sides. If it's only an extra 10% of the kit price, why bother?
You would not believe some of the atrocious work I've seen on audio kits. It makes you weep.
Soldering guns, huge solder blobs, long untrimmed leads, crooked parts, etc.
Dynaco hired local housewives to do all of their factory assembled units.
They were meticulous and beautiful (the kits).
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He does offer assembled units, but I was intrigued by building kits, what he should have done is pointed me in the right direction. He has the schematics, has built several from what I can tell and with just a few posts and minimal info you guys cut right to the point.
I really fell down the rabbit hole of DIY, started with an Eros 2, completed 2 ACA Minis and waiting for the Pearl 3. Building the kits is a lot of fun, a great learning opportunity and enhances my listening enjoyment immensely!
I really fell down the rabbit hole of DIY, started with an Eros 2, completed 2 ACA Minis and waiting for the Pearl 3. Building the kits is a lot of fun, a great learning opportunity and enhances my listening enjoyment immensely!
Actually, as I think about it this is an excellent learning opportunity. I have a hard time learning if there's no hands on and have slowly been learning about tubes. This will help me connect the dots, or in this case pins 😉 to the inners.
Sounds like you have more than enough practical experience to do a good job.
It will be interesting to see what the problem turns out to be.
It will be interesting to see what the problem turns out to be.
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