Let's Restore a Dynaco PAT-5!

Great write-up and review. The dexa opamps I'm using are the special editions. They have quite a bit more output than the standards. The upper range is quite clearer and "sparkly" with the special editions. My main reason for going with the dexa ops was cost. I got them for $25 or so each, and I'm very happy with them. I also like the leds while they're running :)

Mr.Jim...PAT5 redo parts list . ..I posted some where back if you could post your update parts list at a higher scan rate or original document as a attachment or copy and paste to WORD....not sure how to get clearer...I cant read the one on site.......
thanks gray
 
Great write-up and review. The dexa opamps I'm using are the special editions. They have quite a bit more output than the standards. The upper range is quite clearer and "sparkly" with the special editions. My main reason for going with the dexa ops was cost. I got them for $25 or so each, and I'm very happy with them. I also like the leds while they're running :)
Looks like China is on the retro Op amp gig.......$8.99 of course never know on china parts..........but a note on what they said
"
"We are professional Audio-hifi Team! We have professional technicists and we love&enjoy DIY audio. We are not only reseller!"

If above is true and to make audio junk and a opamp on top of that dont know how long a op-amp scam could go on........china parts people have brought this feeling on by doing just that........Of course their has to be real China DIY stereo dudes I would think.........are they listening to "black sabbath" in China just heard
wu-man-by-stephen-kahn-3_wide-b31c9d1831f128179b57e38d074f7b7d4ff2c503-s800-c85.jpg


Wu Man is recognized as the world's greatest virtuoso on an instrument that is over 2000 years old: the Chinese pipa. Throughout her career, she's brought the pear-shaped, 24-fret instrument into the 21st century by collaborating with world class orchestras like the New York Philharmonic and groups like the Kronos Quartet and Yo-Yo Ma's Silk Road Ensemble.


Tiny Desk
Wu Man: Tiny Desk Concert

"Jump out the box — I always wanted to do [that] as a musician," Wu Man tells NPR's Scott Simon before playing the main riff to Black Sabbath's "Iron Man." "I personally really enjoy [trying] something different ... to use my instrument to communicate with the audience." She hopes her music will teach the world more about Chinese music and culture.



Full Discrete Single OP AMP Replace AD797 OPA627 NE5534 for Headphone Amplifier ebay

s-l400.jpg

HDAM full discrete Single, with Marantz HDAM circuit modeled on the production, uses a FET input precision pairing warmest sound, more than before because the number of components can only be used in a separate preamp, the board is very large, now often carefully design, base area and single op amp to do the same, familiar pin is fully compatible NE5534 LME49710 OPA627 AD797 op amp, etc.

Warm Reminder : if you need Dual OP AMP module , pls you buy it in link:
HTTPS://www.ebay.com/itm/201532144224

Op amp features:

1.no low open-loop gain, it is not necessary that the depth of the op amp negative feedback, sound more natural and delicate

2.op-amp power supply may be higher, up to + -28V can work under more dynamic (+ -V well at work, too)

3.higher output current, generally within about op amp output current 40MA, this op amp maximum output current 100MA

4.can be transferred through a single dual-board adapter dual op amp

 
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Full Discrete Single OP AMP Replace AD797 OPA627 NE5534...
I recently replaced the OPA2604/OPA2134 op amps with Burson V5 FET discretes in a Music Hall DAC. They deliver decidedly improved transparency and focus. Red modules in the pic below:

burson2.jpg


Owned a PAT-5 back in the mid 70s. Ok, but nothing to write home about. Sent it to Frank VanAlstine for the FET-5 upgrade which transformed its performance in many ways.
 
I recently replaced the OPA2604/OPA2134 op amps with Burson V5 FET discretes in a Music Hall DAC. They deliver decidedly improved transparency and focus. Red modules in the pic below:

burson2.jpg


Owned a PAT-5 back in the mid 70s. Ok, but nothing to write home about. Sent it to Frank VanAlstine for the FET-5 upgrade which transformed its performance in many ways.

Thanks for the post on the Burson V5 FET discretes in a Music Hall DAC......nice unit..........thanks gray....

Will be sending 6 boxes of mint chocolate cookies.........for post
 
I did a Full Monty updatemydynaco overhaul of my PAT5. New power supply, line level boards and phono board. I’m very happy with the results. It’s transparent and very quiet.
 
I did a Full Monty updatemydynaco overhaul of my PAT5. New power supply, line level boards and phono board. I’m very happy with the results. It’s transparent and very quiet.

Uh......Respighi....I dont remember you asking Jim Marantz if you could do this update..........The AK Hi-Fi police will have to confiscate what you have done
with out a permit. and you're going to have to be locked in your garage for 2 weeks on the matter of no audio permit....Respighi just picking on you ......Jim made me do it.......
To your PAT 5 update.....What new line level boards did use....or did you use the stock new
dynaco boards with fresh reload of parts...Or.....I'm referring to updatemydynaco new designed line level PAT 5 boards, look quite impressive.......
Oh what op-amp did use........look forward to your response......Oh the power supply ..item was that ..updatemydynaco new PAT 5 new design power S.board also impressive........

thanks gray......
64714-slap.gif
 
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I also did the PAT 5 BiFet upgrades with the Updatemydynaco goodies, I did not do the phono board because I'm using an outboard preamp, but I did the line stage boards, and the power supply, and changed out the balance control with a NOS unit, and installed an Alps volume control. I also got ambitious and did the RCA jacks upgrade.
The P5 looks mint, sounds very smooth and quiet, and I plan on keeping it around as it's my main preamp, matched up with my Citation 12.
Like everything, it takes way more hours than desired, but there is only one way to do it, and that is carefully and paying attention all the time, every minute.
 
I used the following

Updatemydynaco Dynaco PAT5 Parts

PAT4PPR, phono board
PAT4PPR2P5A, phono board adapter for PAT5
PAT5RCAJ, Gold inputs
PATLS, Line Level Boards
IC sockets + LME49720
PAT5PWR, PAT5 Power supply

It takes time, but I enjoy the kit building. The results are terrific.
 
I also did the PAT 5 BiFet upgrades with the Updatemydynaco goodies, I did not do the phono board because I'm using an outboard preamp, but I did the line stage boards, and the power supply, and changed out the balance control with a NOS unit, and installed an Alps volume control. I also got ambitious and did the RCA jacks upgrade.
The P5 looks mint, sounds very smooth and quiet, and I plan on keeping it around as it's my main preamp, matched up with my Citation 12.
Like everything, it takes way more hours than desired, but there is only one way to do it, and that is carefully and paying attention all the time, every minute.

CTJim..........Just how big of a pain was the RCA update, Im going to do basically what you did or the line boards were out and not that bad? ...........what op-amp are you using in the PAT 5 ????
thanks CT........gray....have a good 4th.....................
 
I used the following

Updatemydynaco Dynaco PAT5 Parts

PAT4PPR, phono board
PAT4PPR2P5A, phono board adapter for PAT5
PAT5RCAJ, Gold inputs
PATLS, Line Level Boards
IC sockets + LME49720
PAT5PWR, PAT5 Power supply

It takes time, but I enjoy the kit building. The results are terrific.
****************************************************************************
Thanks for your update list Respighi, Im sure the PAT 5 sound very nice after your update..............................gray
 
The RCA jacks took me about 2.5 hrs, the wires don't have a lot of play, so sometimes you need to sit back and think, before you unsolder or simply cut the wire at the old jacks. Dan suggested to me to do the RCAs first, make sure everything tests out ok, then continue one upgrade at a time.My line boards remained in place until after the power supply upgrade was installed and tested.

I used the "gold-plated sockets", (GPS4) and went up one notch for the opamps to the LME49720 units.
I did not install the ops that came with the unit, I'm simply keeping them with the manual in the event of needing a replacement, for some reason.
 
I did another PAT5 for someone. It was a pleasure because I got to do it all at once. I pulled out all the boards. Did the Gold jacks first, then the phono board, the line level boards next and the power supply last. There is much more room to work when the power supply and metal divider are missing. I’ve done enough updatemydynaco kits that I’m very confident the boards will work. Everything worked and it sounded great.
 
I did another PAT5 for someone. It was a pleasure because I got to do it all at once. I pulled out all the boards. Did the Gold jacks first, then the phono board, the line level boards next and the power supply last. There is much more room to work when the power supply and metal divider are missing. I’ve done enough updatemydynaco kits that I’m very confident the boards will work. Everything worked and it sounded great.
thanks Respighi for your response...........gray
 
I am sitting listening to my Dynaco 410...
Nice work! Same but easier to fix stuff. Fatigued mind of mine....
 
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Did you redo some items on the 416..........
I have not done a thing on this other than enjoy it. I opened it up when it came home and all looked like it had been assembled yesterday. It has been in use daily 10 to 12 hours. I love it and am very likely picking another that will be gone over with a rebuild/upgrade. I have found it difficult to find a filler even a temporary to get me through the period while this 410 would be out of service. I have a model 400 but Its not the same. I am hooked on all my dynaco above the others in my stable. So hope that helps. At night I can fill the bill with tubes from also dynaco but days it my coffee. And coffee in order to get me moving has to have kick! In a nut shell there is no substitute for cubic inches and the 416 brings it. :banana:Nemo
"I started out with nothing and still have most of it left "
 

You might want to pull this full page up concerning the 416.....I have one that is like new after reading this not going use until doing this update.....very good analyst by Kervin and his write up the 416 fix.......very good...
gray .........

Dead Channel Fix — Dynaco Power Amps
by Kevin Boales — January, 2002
Applies to: Stereo-400, ST-150 and ST-410 Amps. These models (and the ST-416) each contain a pair of Dynaco PC-28 Amplifier PCBs — one board per channel.

Overview
These power amplifiers can often be found in on-line auctions or local classifieds. I've found that a surprising number of these models are offered for sale "as-is," with the seller citing that the unit has only one "good" channel. I recently saw a Stereo 410 in fine condition — except for a dead channel — for less than fifty bucks at www.eBay.com.

It would appear that many of these amplifiers developed channel failures after they had accrued some time in service. The failures are often intermittent in nature and defy logical cause-and-effect troubleshooting. When these channel failures occur, there are usually no obvious clues as to what happened. All the fuses will be intact, and there will be no smoke or death-fizzle noises. Most of the time, the circuit boards and wiring will look fine.

In fact, most of these mysterious failures have a common cause that can be corrected by anyone who is reasonably familiar with handling printed circuit boards, knows how to use a 25W-40W soldering iron, and has about five bucks for a handful of new parts.

These models are each equipped with a pair of Dynaco PC-28 amplifier circuit boards. One edge of the board has eyelets for the wires connecting it to the rest of the amp's circuitry. Near each corner at either end of this edge are a pair of 2-Watt, carbon composition resistors. On earlier boards, they are mounted vertically; on later boards they are mounted horizontally and tightly against the board.

The Problem
Each resistor pair consists of a 750-ohm (purple-green-brown-gold) and a 1k-ohm (brown-black-red-gold) 5% resistor. In retrospect, it seems that their 2-Watt power rating may have been inadequate for the job. They function as emitter bleeds for the driver transistors, which are mounted to the aluminum heat sink/mounting bracket attached to the PCB.

The four resistors (two pair) on each PC-28 board run fairly hot even at modest power levels. Over time, this takes a toll on their phenolic outer shell and the integrity of the carbon compound resistance medium inside. The thermal cycling of these resistors can result in invisible hairline cracks in the carbon compound or phenolic shell. If the resistor does not crack, its expansion from the heat can put enough pressure on the trace pads to crack them — sometimes lifting them off the board entirely.

Either way, the emitter circuit is broken and the channel stops working.

About The Replacement Parts
Resistor technology has come a long way since the mid-seventies. This progress was driven by many factors, primarily the advances in miniaturization and a quest for thermal stability. Carbon compound resistors are massive compared with today's wire-wound and metal-film replacements. As such, carbon resistors tend to retain heat to a greater degree than the newer, smaller parts.

In addition, a carbon compound resistor operated constantly near the upper end of its power rating tends to gain in resistance value due to the effects of time and elevated temperature. In the case of the resistors in question, even a slight change in their value can wreak havoc with one of the amplifier's critical operating parameters: power section bias current.

In the Procedure section that follows, you'll be replacing these original carbon compound resistors with high-temperature, silicone-coated, wire-wound power resistors. You will need a total of four 750-ohm, and another four 1k-ohm (not 1.1k) 5% resistors to upgrade both PC-28 boards in your amplifier. These parts should have a power rating of at least 3-Watts. I ordered mine from Mouser Electronics on-line. The catalog listed their rating at 3-Watts, but the parts arrived with markings indicating a 3.75-Watt power rating – nearly twice the power rating of the originals. Mouser also carries 5-Watt versions — use them if you want a little extra insurance.

Required Tools and Supplies:
  • Flat-blade screwdriver(s) for chassis screws
  • Needle-nose pliers
  • Sharp side-cutters or dykes
  • Small, bright flashlight
  • Small magnifying glass or folding loupe
  • Soldering iron (25W to 40W, small tip)
  • Fresh rosin-core solder, small diameter
  • De-soldering braid
  • Can of rosin flux
  • Spray can of electronics cleaner with extension tube
  • 4 ea. Vishay/Dale 750-ohm silicone power resistor, wire-wound 3-Watt (Mouser p/n 71-CW2B-750) or equivalent
  • 4 ea. Vishay/Dale 1k-ohm silicone power resistor, wire-wound 3-Watt (Mouser p/n 71-CW2B-1.0K) or equivalent
  • 6 ea. Fast-blo 6-amp, 8AG fuses (1/4- by 1-inch)
  • 4 ea. Fast-blo 1-amp, 3AG fuses (1/4- by 1-1/4-inch)
The Procedure

http://home.indy.net/~gregdunn/dynaco/components/ST400/chnl_fix.html
 
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I appreciate the Info I will investigate further and do have other sources thankfully to fall back on in the meantime. When in doubt remember to keep your back up st-70 near
By for days like that. :naughty:
 
I appreciate the Info I will investigate further and do have other sources thankfully to fall back on in the meantime. When in doubt remember to keep your back up st-70 near
By for days like that. :naughty:

Im using a Mitsubishi DA 15 PAmp Until the 416 can be updated
upload_2018-8-1_18-0-7.jpeg
 
I sadly am using all my old dynaco gear. I currently running my 410 with my pat 5. And in a little bit I will be featuring my early sca-35 complete with the original dynaco tubes the ones it came with.. all of em.
 
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