Looking for a repair person

muncybob
muncybob Posts: 3,057
in Wanted (WTB) Classifieds
I'm still having trouble with the balance control on my Dynaco preamp. Thought it was was fixed locally but problem has resurfaced. I've decided to have the pot eliminated from the signal path. Looking for somebody within say 2 hours of zip 17701(central PA) that could do this while I wait. I have schematics/owners manual. I really don't want to ship this.
Yep, my name really is Bob.
Parasound HCA1500A(indoor sound) and HCA1000(outdoor sound), Dynaco PAS4, Denon DP1200 w/Shure V15 Type V and Jico SAS stylus, Marantz UD7007, Polk L600, Rythmik L12 sub.
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  • mhardy6647
    mhardy6647 Posts: 33,909
    edited July 2020
    What's it, like a PAS-3 or a PAT-5 or?
    You ought to take a road trip up to northern NH and we can bypass the balance control together! Socially distanced & with face masks, but, you know...

    :)


    EDIT: Just outta curiosity -- you are sure that the control itself is the issue and that it is not a symptom of some other problem? Just checking.

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  • VR3
    VR3 Posts: 28,749
    WILLIAM THALMANN

    MUSIC TECHNOLOGY, INC.

    5418 Port Royal Road

    Springfield, VA 22151

    703-764-7005 x106

    bill@musictechnology.com

    www.musictechnology.com

    HOURS: 11AM-6PM Mon-Fri
    - Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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  • muncybob
    muncybob Posts: 3,057
    It's a PAS4. Much better(so I'm told) than the previous Dynaco preamps. When it's right, it's RIGHT. I had it when the much more expensive Rhumba was making the rounds. I would say it was at least on par with it with a very good sounding phono stage to boot.

    I would love to see NH again(was brought up in Portsmouth) but traveling that far is not in the cards at this time.
    Yep, my name really is Bob.
    Parasound HCA1500A(indoor sound) and HCA1000(outdoor sound), Dynaco PAS4, Denon DP1200 w/Shure V15 Type V and Jico SAS stylus, Marantz UD7007, Polk L600, Rythmik L12 sub.
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  • muncybob
    muncybob Posts: 3,057
    Port Royal is also too far but if I need to I can always ship it I guess.
    Yep, my name really is Bob.
    Parasound HCA1500A(indoor sound) and HCA1000(outdoor sound), Dynaco PAS4, Denon DP1200 w/Shure V15 Type V and Jico SAS stylus, Marantz UD7007, Polk L600, Rythmik L12 sub.
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  • mhardy6647
    mhardy6647 Posts: 33,909
    muncybob wrote: »
    Port Royal is also too far but if I need to I can always ship it I guess.

    The address was Springfield (FWIW) -- I am a little rusty on my VA geography ('cept the places our son's lived, and currently lives), so I don't know if that's better or not.


    So, what does the balance do? Is the pot scratchy, or does it just cut out, or something else?

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  • Clipdat
    Clipdat Posts: 12,952
    mhardy6647 wrote: »
    So, what does the balance do? Is the pot scratchy, or does it just cut out, or something else?

    tenor.gif
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  • muncybob
    muncybob Posts: 3,057
    Yea, misread that.

    Right channel will cut out. If you put pressure on the balance knob vertically you usually can get it back but it may not stay. The pots on this unit are sealed, no way to clean. I don't think it's a corrosion problem. At first I suspected something on the board since pushing the knob up/down helped but the board checks out OK.

    Both my power amps have pots for each channel so I really don't need this one on the PAS, just want it eliminated. There are a lot of things I'll try my hand at but this ain't one of them.
    Yep, my name really is Bob.
    Parasound HCA1500A(indoor sound) and HCA1000(outdoor sound), Dynaco PAS4, Denon DP1200 w/Shure V15 Type V and Jico SAS stylus, Marantz UD7007, Polk L600, Rythmik L12 sub.
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  • mhardy6647
    mhardy6647 Posts: 33,909
    heh -- "no way to clean".
    That, ol' son is a challenge. B)

    DeOxit is really mobile stuff. Squirtin' a little "in, with and under" most controls will result in a little finagling its way in ;)

    There are also worst case scenario tactics to unseal such recalcitrant pots.

    Do you have the schematic? bet "we" could find a pot to replace it without too much difficulty.

    Again -- just sayin'.

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  • Clipdat
    Clipdat Posts: 12,952
    Bob: It's a sealed pot, it can't be fixed.

    Mark: Don't threaten me with a good time!
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  • mhardy6647
    mhardy6647 Posts: 33,909
    Clipdat wrote: »
    Bob: It's a sealed pot, it can't be fixed.

    Mark: Don't threaten me with a good time!

    Exactly!
    Man*. The tool-using animal.


    ___________
    * I mean "Man" as in H. sapiens sapiens, not "man" as in "23XY genotype" -- in case that's not abundantly clear. :|

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  • muncybob
    muncybob Posts: 3,057
    https://goldpt.com/pas4_manual.pdf
    Yep, my name really is Bob.
    Parasound HCA1500A(indoor sound) and HCA1000(outdoor sound), Dynaco PAS4, Denon DP1200 w/Shure V15 Type V and Jico SAS stylus, Marantz UD7007, Polk L600, Rythmik L12 sub.
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  • mhardy6647
    mhardy6647 Posts: 33,909
    cool -- I'll be gettin' back to you anon on this.
    thanks!
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  • mhardy6647
    mhardy6647 Posts: 33,909
    edited July 2020
    It is a sealed pot (looks like one of those Alps pots) all righty -- and a little more complicated than I was expecting, too :blush:

    oss9nae3c1t9.png
    https://therobbcollections.blogspot.com/2018/06/dynaco-given-second-life-pan-orient.html

    3ih5kqkdkfq1.png

    EDIT: I am an idiot :p
    But, yeah, it can be jumpered out fo' sho.
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  • muncybob
    muncybob Posts: 3,057
    I found a shop that specializes in older equipment. He said in order to eliminate the pot there would need to be a number of resistors installed and suggested trying to replace the pot instead. I may be making a road trip(1.5 hours) to see him Saturday morning. The last thing he said bumms me out though, they are currently swamped :(
    Yep, my name really is Bob.
    Parasound HCA1500A(indoor sound) and HCA1000(outdoor sound), Dynaco PAS4, Denon DP1200 w/Shure V15 Type V and Jico SAS stylus, Marantz UD7007, Polk L600, Rythmik L12 sub.
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  • muncybob
    muncybob Posts: 3,057
    BTW, thanks for the link!
    Yep, my name really is Bob.
    Parasound HCA1500A(indoor sound) and HCA1000(outdoor sound), Dynaco PAS4, Denon DP1200 w/Shure V15 Type V and Jico SAS stylus, Marantz UD7007, Polk L600, Rythmik L12 sub.
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  • muncybob
    muncybob Posts: 3,057
    Dropping off the pre Saturday morning. In speaking with the shop owner I think I've found the right person. He just rebuilt a ST70(he said once done it was one of the better tube amps he's ever heard) and is somewhat familiar with Dynaco although not sure if he ever worked on a PAS4. When I explained the pot is sealed and can't be cleaned he said would try a hypodermic needle with Deoxit and then somehow gets compressed air into the pot as the 1st step. I still think it's something on the board....time will tell.
    Yep, my name really is Bob.
    Parasound HCA1500A(indoor sound) and HCA1000(outdoor sound), Dynaco PAS4, Denon DP1200 w/Shure V15 Type V and Jico SAS stylus, Marantz UD7007, Polk L600, Rythmik L12 sub.
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  • mhardy6647
    mhardy6647 Posts: 33,909
    muncybob wrote: »
    ... When I explained the pot is sealed and can't be cleaned he said would try a hypodermic needle with Deoxit and then somehow gets compressed air into the pot as the 1st step.
    heh-heh-heh... ;)
    I still think it's something on the board....time will tell.

    I've gotta say, when I saw the picture of the innards of a PAS-4, I was not encouraged to see the whole shootin' match on a single big PC board. A few decades on, that's not going to improve reliability. There may well be damaged traces from the board flexing over the years. Not irreparable, but a pain to mitigate.

    We'll hope for the best.
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  • dcmeigs
    dcmeigs Posts: 708
    edited July 2020
    I’ve used DeOxIt on sealed pots with good success. Get a drill bit the same size as the plastic straw and drill a small hole in the top of the enclosure over to the side. Not in the center! Drill slowly and wipe away the plastic as you go so you don’t deposit any in the pot. Spray, rotate the pot about 2 dozen times and Bobs Your Uncle. Cover the hole with blue tape and swear it never happened.
    The world is full of answers, some are right and some are wrong. - Neil Young
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  • mhardy6647
    mhardy6647 Posts: 33,909
    dcmeigs wrote: »
    I’ve used DeOxIt on sealed pots with good success. Get a drill bit the same size as the plastic straw and drill a small hole in the top of the enclosure over to the side. Not in the center! Drill slowly and wipe away the plastic as you go so you don’t deposit any in the pot. Spray, rotate the pot about 2 dozen times and Bobs Your Uncle. Cover the hole with blue tape and swear it never happened.

    I stopped short of invoking the drill bit gambit earlier in this thread -- didn't want to freak the young lad out, you know?

    :|
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  • BlueFox
    BlueFox Posts: 15,251
    Just spray it on the shaft going into it.
    Lumin X1 file player, Westminster Labs interconnect cable
    Sony XA-5400ES SACD; Pass XP-22 pre; X600.5 amps
    Magico S5 MKII Mcast Rose speakers; SPOD spikes

    Shunyata Triton v3/Typhon QR on source, Denali 2000 (2) on amps
    Shunyata Sigma XLR analog ICs, Sigma speaker cables
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    Mapleshade Samson V.3 four shelf solid maple rack, Micropoint brass footers
    Three 20 amp circuits.
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  • pitdogg2
    pitdogg2 Posts: 25,574
    BlueFox wrote: »
    Just spray it on the shaft....

    Ummm there's a joke in there....
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  • mhardy6647
    mhardy6647 Posts: 33,909
    edited August 2020
    BlueFox wrote: »
    Just spray it on the shaft going into it.

    That's plan A.
    Plan B involves tools. :)

    0aavyji7ux1t.png

    tenor.gif?itemid=16749349

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  • muncybob
    muncybob Posts: 3,057
    Well, I dropped it of yesterday and I'm feeling good this time about who is doing the work for me. This guy is proud of his work, showed me several photos on circuits/board he's recently worked on. I drooled over the Teac reel to reel on his shelf. He works on just about anything and loves his high end customers but also realizes I ain't one of them. His friend stopped in and advised me the the wait will be well worth it. He plans to fix the problem and go over things in detail. Also told me he has 40+ years experience w/stereo equipment and loves working on vintage gear. Now the waiting game begins..........
    Yep, my name really is Bob.
    Parasound HCA1500A(indoor sound) and HCA1000(outdoor sound), Dynaco PAS4, Denon DP1200 w/Shure V15 Type V and Jico SAS stylus, Marantz UD7007, Polk L600, Rythmik L12 sub.
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  • mhardy6647
    mhardy6647 Posts: 33,909
    He's gettin' the hammer drill warmed up even now...


    ;)

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  • dcmeigs
    dcmeigs Posts: 708
    mhardy6647 wrote: »
    dcmeigs wrote: »
    I’ve used DeOxIt on sealed pots with good success. Get a drill bit the same size as the plastic straw and drill a small hole in the top of the enclosure over to the side. Not in the center! Drill slowly and wipe away the plastic as you go so you don’t deposit any in the pot. Spray, rotate the pot about 2 dozen times and Bobs Your Uncle. Cover the hole with blue tape and swear it never happened.

    I stopped short of invoking the drill bit gambit earlier in this thread -- didn't want to freak the young lad out, you know?

    :|


    As you seem to know, that technique works well on the cubic pots like the ALPS. I’m not sure there is a corner in those pots in the photo. Can you identify those?
    The world is full of answers, some are right and some are wrong. - Neil Young
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  • mhardy6647
    mhardy6647 Posts: 33,909
    dcmeigs wrote: »
    mhardy6647 wrote: »
    dcmeigs wrote: »
    I’ve used DeOxIt on sealed pots with good success. Get a drill bit the same size as the plastic straw and drill a small hole in the top of the enclosure over to the side. Not in the center! Drill slowly and wipe away the plastic as you go so you don’t deposit any in the pot. Spray, rotate the pot about 2 dozen times and Bobs Your Uncle. Cover the hole with blue tape and swear it never happened.

    I stopped short of invoking the drill bit gambit earlier in this thread -- didn't want to freak the young lad out, you know?

    :|


    As you seem to know, that technique works well on the cubic pots like the ALPS. I’m not sure there is a corner in those pots in the photo. Can you identify those?

    I thought they looked like (or at least similar to) ALPS pots to me(?).


    2gpkcdj2f8vj.png
    ou1gxl1dnawa.png
    3dgltki6p1zc.png

    Nice to see a post from you! Hope all is well.

    PS I don't think that replacing the pot with a set of fixed resistors would be too awful, either, since it's on a PCB (assuming it's a reasonably sturdy PCB to withstand desoldering without traces lifting). Of course, adjustability would be lost via that route.
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  • muncybob
    muncybob Posts: 3,057
    I thought I would tell how this turned out. After a few days I got a call from the shop to let me know what he plans to do. They are indeed ALPS pots and no drilling was needed. He found 2 very small screws that allowed him to take the pot apart. Did a good cleaning/lube job and said it seems to have fixed the problem. He wanted to hang onto the unit for at least a week to be sure oxidation does not appear. I didn't think a week would tell the tale but he wanted to at least do that. I actually think he just wanted to play with my pre along with a just rebuilt Dynaco ST70 he had on hand :)

    He did a good cleaning of some shoddy work done a few years ago when I had some caps replaced. Spent over 2 hours working on it. I appreciated this as it was not necessary but he's very particular about how a piece leaves his shop.

    So I just picked it up 2 days ago. The first listening I did was through out outdoor speakers since it was such a nice night. I really had no preconceived notions about the sound quality, I was just hoping that the right channel would not cut out like before.

    I "thought" it sounded better but then again we were outside and not really a critical listening area.....but it did sound good. Later I went indoors and switched over the the SDAs. Now at this point I thought it sounded "different" but something seemed off a bit. The it hit me...a few days ago I unplugged the interconnect cable for the 2bs, plugged it back in and all was right with the world again. What a difference!

    So I'm now a happy camper and feel I might the right choice with this shop. Now something I noticed with the SDA cable took me back a bit. I know how the SDA effect works in principle and it was very apparent that the soundstage was larger with the cable in but I also noticed a difference in the mids and bass, esp the lower end. Seemed tighter and "smoother"(this is why I don't write reviews!). Has anybody compared their SDAs with and w/o the cable in the picture and also experienced this?
    Yep, my name really is Bob.
    Parasound HCA1500A(indoor sound) and HCA1000(outdoor sound), Dynaco PAS4, Denon DP1200 w/Shure V15 Type V and Jico SAS stylus, Marantz UD7007, Polk L600, Rythmik L12 sub.
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