I just contact them and they have sold all VT60 PCB and there will no other. They don't want to sell data to make it.
So I decided to do my own. There is component side of PCB on arcdb website :
ARCDB - VT60
Anadigit, do you have picture of solder side ?
Thanks,
Sébastien
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The transistor is supposed to be a MOSFET. VT100 schematic will display an example.
Hi everybody! I am repairing my VT-60 and decided to go full mod. Do you guys still have the schematic and parts list for this version? Would anyone help me out and PM me? I have some doubts. It´s almost finished! Thank you!Finaly I made my own !
I made some change :
- a 10R resistor in each 6550 cathode
- each power tube has an adjustable bias
Attachments
Mr. Appme! Are you still enjoying your VT60? Have you compared to the original? How would you describe the sound?
Would you help me with the schematics and parts list?
Thanks!
Caution:
The schematic, Post # 1, shows 6550 on Fixed bias, and g1 Rg resistors are 160K.
That is easy for the phase-inverter/driver to drive.
But . . . The maximum Rg for a fixed bias 6550 is 50k.
Be prepared for one or more of the four 6550 tubes to go into Thermal-Run-Away.
Ouch!
You can not change the 160k resistors to 50k, because . . .
The phase-inverter/driver will distort, and might not have enough voltage swing to get max output power from the 6550 tubes (their needed g1 voltage swing).
Check all the other schematics, if one of them has Rg = 50k then you are OK with that version schematic (in regards to thermal run away).
Ah, an easier and more elegant solution:
KT88 maximum Rg, with fixed bias: 100k (most tube data sheets)
Better Yet . . .
JJ KT88, maximum Rg with fixed bias is 220k, If you limit Wa+Wg2 to less than 35 Watts.
If a JJ KT88 plate + screen dissipation is less than 35 Watts, Rg 160k is adequate.
The schematic, Post # 1, shows 6550 on Fixed bias, and g1 Rg resistors are 160K.
That is easy for the phase-inverter/driver to drive.
But . . . The maximum Rg for a fixed bias 6550 is 50k.
Be prepared for one or more of the four 6550 tubes to go into Thermal-Run-Away.
Ouch!
You can not change the 160k resistors to 50k, because . . .
The phase-inverter/driver will distort, and might not have enough voltage swing to get max output power from the 6550 tubes (their needed g1 voltage swing).
Check all the other schematics, if one of them has Rg = 50k then you are OK with that version schematic (in regards to thermal run away).
Ah, an easier and more elegant solution:
KT88 maximum Rg, with fixed bias: 100k (most tube data sheets)
Better Yet . . .
JJ KT88, maximum Rg with fixed bias is 220k, If you limit Wa+Wg2 to less than 35 Watts.
If a JJ KT88 plate + screen dissipation is less than 35 Watts, Rg 160k is adequate.
Thank you, @6A3sUMMER ! In fact I had Antony´s version made. For some reason I didn´t notice the CCS o the right and since I´m following a mix of the original parts list and the mods that I made + the recomendations and discussions here, I got a bit lost in this specific area of the PCB. That´s why the schematic and parts list would help me a lot. I.e: Which transistor is used in Q2? A LM317?
Ah, a little plot twist: I drive my VT-60 with EL34s. That´s how I entered the magic DIY world.
Ah, a little plot twist: I drive my VT-60 with EL34s. That´s how I entered the magic DIY world.
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Getting answers on what parts, and what parts values to use . . .
Requires that we know what else you are changing . . .
A 6550 is one thing.
An EL34 is another thing.
There are lots of changes that probably need to be made in order to have:
Reliability
Good, if not optimal Performance.
Plug and Play
Or,
Plug and Pray
Requires that we know what else you are changing . . .
A 6550 is one thing.
An EL34 is another thing.
There are lots of changes that probably need to be made in order to have:
Reliability
Good, if not optimal Performance.
Plug and Play
Or,
Plug and Pray
I'll save those words. They apply for a lot of situations in life.
As I said, I'm not coping and pasting things. I'm trying to learn and understand everything I'm doing. Although getting the parts list and schematics for this specific board won't be a fast shortcut, it will help me to understand their choices so I can make my own.
As you said, my VT60 is another beast and a little help on this Journey would be great.
Thanks for the advice!
Oh, let me tell my story in a few words. Bought this amp about 7 years ago. Met a tube fanatic (more than 20k tubes at his apartment) that became a close friend. He helped to mod the VT60 and taught me the little I know about tube amps. Unfortunately he passed away. Right after that, my VT60 was hit by two power surges (a natural and and a stupid me one). The PCB was gone. So I decided to rebuild it.
And here I am.
Sorry for the long post!
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@geladk , thank you so much! It will help me a lot! It´s interesting to see that are many versions! I´m happy that this topic is open again. It would be interesting to know the results from different projects. This was my VT-60 two years ago:
