Is this a Van Alstine Dynaco Pat5 Preamp?

Lyndon · « **on:** 16 Sep 2011, 10:13 pm »

I was thinking of picking this up locally, and wrote to Frank, but I can't see the four tubes that should be there.
I'm a bit confused. I will try to link the photos in the ad.
Transcendence Series Two

And the serial number
Is this a solid state model???

Sorry, but I thought the Van Alstine group could help me on this older model. Is the Transcendence Two a
solid state preamp concoction? Digging on the 'net, I can't get anything on this unit.

dlparker · « **Reply #1 on:** 16 Sep 2011, 11:29 pm »

Quote from: Lyndon on 16 Sep 2011, 10:13 pm

I was thinking of picking this up locally, and wrote to Frank, but I can't see the four tubes that should be there.
I'm a bit confused. I will try to link the photos in the ad.
Transcendence Series Two

And the serial number Is this a solid state model???

Sorry, but I thought the Van Alstine group could help me on this older model. Is the Transcendence Two a solid state preamp concoction? Digging on the 'net, I can't get anything on this unit.

Not meaning to sound flippant, but if there aren't any tubes it must be solid state, and anyway, I'm pretty sure the PAT5 series were all solid state. In fact, I can only remember the PAT4 and PAT5 being solid state.

At any rate, it's a good looking amp, and I'll bet it sounds great! If the price is right, I'd say go for it!

I'm sure Frank will report in soon with particulars on it.

mark funk · « **Reply #2 on:** 16 Sep 2011, 11:57 pm »

No, Frank use to build Fet/Valve pre amps in the Pat-5 chesse also

Lyndon · « **Reply #3 on:** 17 Sep 2011, 12:04 am »

Thanks, Mark.
I thought so as well, though in that photo, I don't see any valves.
I thought the serial number would give Frank a heads up.

Power switch is broken off, but Frank told me he has NOS switches. But I don't know if he opened the photos
to look at this unit from my email.
Lyndon

JakeJ · « **Reply #4 on:** 17 Sep 2011, 12:09 am »

Not trying to a nattering neybob of negativity....but, that board in the right rear of the chassis looks very well cooked to me and would hesitate to buy it until I had it checked out

Just my .02.

Lyndon · « **Reply #5 on:** 17 Sep 2011, 12:26 am »

JakeJ,
I wish that photo was more clear.
And how does one test it with the power switch broken. Hmmm.....

Lefty052347 · « **Reply #6 on:** 17 Sep 2011, 12:30 am »

T-2 is discrete solid state pre-amp from 1986. No op-amps. Working properly, a nice unit.

That board contains the raw power supply. On the back of the board are dropping resistors (probably 3 watt). Normally they are off the board, so I would question the discoloration.

Regards,
Dean

Lyndon · « **Reply #7 on:** 17 Sep 2011, 12:36 am »

Thanks, Dean
Much appreciated. Seller has not responded to two emails, and two phone messages in the last week.

dlparker · « **Reply #8 on:** 17 Sep 2011, 02:38 am »

Quote from: Lyndon on 17 Sep 2011, 12:36 am

Thanks, Dean
Much appreciated. Seller has not responded to two emails, and two phone messages in the last week.

WOOPS! I missed the fry job near the cap on that board.

I love my PAT5/FET-II. My first AVA unit, been loving it since I got it July of last year. To say that I was ecstatic at the difference these tired, old (65+ years), trebly (as in 3 - old age, loud music, and numerous childhood ear infections) abused, ears could hear would be a gross understatement. I've now got a used Insight+ 250 Hafler rebuild as the PA, driving a pair of Hsu Research HB-1 MKII speakers with single Hsu STF-2 that I rarely use because the bass is so good on the PAT5-FETII/Insight+/HB-1s combo. I've got an Omega III 260 sitting in the shipping box that the Insight+ 250 was shipped in. At some point I plan to trade it in on an AVA DAC, or maybe one of the preamps that occasionally show up on Frank's used eqpt list but never last very long.

JerryM · « **Reply #9 on:** 17 Sep 2011, 03:02 am »

If the seller doesn't respond, maybe you can work a deal with this guy. You'd have shipping from the greater So Cal area, but it may work out well nonetheless. Oddly enough, this T2 has a broken switch, as well.

Have fun,

Jerry

avahifi · « **Reply #10 on:** 17 Sep 2011, 11:49 am »

Whoops, my mistake in identifying this unit. It indeed is all solid state with all AVA circuits, a discrete design done way before we did the hybrid tube circuits. The serial number tells us it was built in 1986.

The power supply board discoloration is probably nothing much to worry about, just from the heat of a couple of high wattage power supply resistors over the years.

We do still have original replacement power switches for any Dyna Pat-5. It is not a big deal to replace them.

Regards,

Frank Van Alstine

Lyndon · « **Reply #11 on:** 3 Nov 2011, 01:26 am »

Frank,
Ordered the NOS power switch from you Monday.
Dean said:

Quote

That board contains the raw power supply. On the back of the board are dropping resistors (probably 3 watt). Normally they are off the board, so I would question the discoloration.

And Frank said not to worry about it, but I am wondering if I should replace them, and mount them down on the chassis, or further away from that board.
I think its those two white electrolytic resistors that are causing the high heat.
I have these posted on my flickr page, and wish I could make them larger, but don't know how.

avahifi · « **Reply #12 on:** 3 Nov 2011, 02:38 pm »

I would not worry about the large power resistors. You might want to resolder their connections to the PC card however. The connections can oxidize from the heat over the years. These resistors are dropping the raw plus and minus 60V power supply down to plus and minus 15V (along with zener regulators). That means they are dissipating 2-3 watts each depending upon their value. That does not seem like much, but over the years it can cause board discoloration. We have never seen one of these fail, or cause the power supply itself to fail. Not a major worry.

Dyna originally needed the high voltage supply for its really crummy two transistor phono section. We salvaged the source of the high voltage, the power transformer, in our rebuilds to keep the price down. We just needed to throw away some of the voltage as heat as our circuits were all linear op amp designs back then and needed only plus and minus 15 volts throughout.

Later we found a better way of getting rid of the excess voltage and heat. We simply wired the power transformer for 240V operation. Then when used on 120V as intended, this cut the operating voltage in half and made the output of the power transformer much easier to manage without the need for huge high wattage hot running power resistors.

Regards,

Frank Van Alstine

Lyndon · « **Reply #13 on:** 3 Nov 2011, 03:26 pm »

Thank you, Frank.
Much appreciated!
Can't wait to get this baby up and running in the system.
Lyndon

Lyndon · « **Reply #14 on:** 26 Nov 2011, 12:52 am »

Got the power switch installed, broke the orange drop cap, but will get that replaced.

Frank, you posted above:

Quote

I would not worry about the large power resistors. You might want to resolder their connections to the PC card however. The connections can oxidize from the heat over the years. These resistors are dropping the raw plus and minus 60V power supply down to plus and minus 15V (along with zener regulators). That means they are dissipating 2-3 watts each depending upon their value. That does not seem like much, but over the years it can cause board discoloration. We have never seen one of these fail, or cause the power supply itself to fail. Not a major worry.

Dyna originally needed the high voltage supply for its really crummy two transistor phono section. We salvaged the source of the high voltage, the power transformer, in our rebuilds to keep the price down. We just needed to throw away some of the voltage as heat as our circuits were all linear op amp designs back then and needed only plus and minus 15 volts throughout.

Later we found a better way of getting rid of the excess voltage and heat. We simply wired the power transformer for 240V operation. Then when used on 120V as intended, this cut the operating voltage in half and made the output of the power transformer much easier to manage without the need for huge high wattage hot running power resistors.

Frank, a friend said:
I suspect that if you drop the power transformer output voltage, then you'll want to reduce the value of the power resistors as well. Did Frank give you new values for that?
Finally, is there any way I can get a pdf file of the manual for this unit?
Thanks so much,
Lyndon
Salt Lake City

PSB Guy · « **Reply #15 on:** 26 Nov 2011, 02:35 am »

Link to a manual:
http://akdatabase.org/AKview/displayimage.php?album=41&pos=15

Cornelis

Lyndon · « **Reply #16 on:** 26 Nov 2011, 05:55 am »

Cornelis,
I have the PAT-5 manual. Aside from the tranny, knobs and chassis, it it mostly Frank's boards.
Thanks,
Lyndon
I guess I meant schematics, to follow through Frank's suggestions above. So I worded it wrong.
Thanks again, Cornelis.

PSB Guy · « **Reply #17 on:** 26 Nov 2011, 06:53 pm »

Sorry, misunderstood. This link has the schematics, but I guess they'd be for the Dynaco boards. Might help anyway.
http://www.dvq.com/hifi/html/hframe.htm

Cornelis

Lyndon · « **Reply #18 on:** 26 Nov 2011, 07:02 pm »

Yep, I got that as well.
Frank said:

Quote

Later we found a better way of getting rid of the excess voltage and heat. We simply wired the power transformer for 240V operation. Then when used on 120V as intended, this cut the operating voltage in half and made the output of the power transformer much easier to manage without the need for huge high wattage hot running power resistors.

Which I think my electronic friend and I can figure partly, but he had the question for Frank:

Quote

I suspect that if you drop the power transformer output voltage, then you'll want to reduce the value of the power resistors as well. Did Frank give you new values for that?

And I am heading up to Bountiful in the hour, and sure wish I knew this. Also, we broke off the little cap on the power switch, a cap which on the old one said:
Z5U .01m
And on the NOS said:
BC Z5U 1.03M 1 kV
Correction: BC Z5U 103M 1 kV (no decimal point)
Of course, the ONLY decent electronics shop in Utah took the entire weekend off Thurs-Sun, leaving me with the Shack. Went to the Shack, they didn't have it, and while I was in there, some little old lady backed into my truck in the parking lot-estimate $1000, just not my day.

Wish Frank would catch this thread and let me know about the tranny question above, as I am about to take it up to Bountiful and try to figure it out.
Lyndon

Lyndon · « **Reply #19 on:** 27 Nov 2011, 04:06 am »

Big thanks to Frank for sending me a PM for ideas about the transformer conversion.
HUGE difference in heat from the previous setup!

Up and running and it sure sounded good through my friends Krell KSA-50 and Dynaudio Audience 9 towers.

Thanks again, Frank! It was much appreciated!

Lyndon