Heathkit AR1500A Stereo
Chuck Sadoian
that I build many years ago that is in good shape
except for the FM tuner. The tuner was supplied
pre-built with no schematics, and it is a maze of
point to point wiring. There's no way I can repair
the tuner, but I love the stereo and would like to
keep it around a few more years. I was wondering
if anyone had a junk AR-1500A they haven't
thrown out yet that I could talk them into giving
or selling me their FM tuner (assuming that's not
the reason it was junked!). If so, contact me
at the above email address.
Thanks,
Chuck
Jerry G.
them may have some good techs there that can service this tuner for
you...
--
Jerry Greenberg
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============ Message Separator ===============
"Chuck Sadoian" <csad...@theworks.com> wrote in message
news:390B805C...@theworks.com...
JackH35785
working on it and blew out Q701, a UC734 (FET). Then this device was still
available and replaced it with good results, even without having to re-tune the
RF section.
There are several NTE equivelants, one the 312, so it should not be too
difficul to repair. The other three bipolar transistors also have equivelant
NTE devices.
Be carefull to keep the "shorting wire" that it comes with to prevent static
problems.
Jack
Chuck Sadoian
One of the problems I have encountered when I attempted
to troubleshoot the tuner was that none of the descrete devices
appear to have numbers on them that made any sense. I stupidly
threw out my original manual just a few months ago after keeping
it in the garage for over 20 years. However, as I recall the manual
didn't have a parts list or schematic for the TUNER because it
was supplied to the kitbuilder pre assembled and aligned. So I
figured the best bet was to just find someone with a junk AR1500a
sitting in the garage that still had a good tuner.
Do you have a schematic and/or parts list for the tuner? As I
recall there are 4 transistors in the unit, plus a shitload of 1/2 resistors
and coils and such. I really doubt any of the resistors or coils are
at fault, I'm sure it is one or more of the transistors. The unit's
power supply blew up about three months ago which caused
the problem. I assume the damaged power supply sent a spike
to the tuner which blew up one or more of the transistors.
What's a good way (if any) to check a FET in circuit?
Chuck
Jeff Liebermann
wrote:
> Do you have a schematic and/or parts list for the tuner? As I
>recall there are 4 transistors in the unit, plus a shitload of 1/2 resistors
>and coils and such. I really doubt any of the resistors or coils are
>at fault, I'm sure it is one or more of the transistors. The unit's
>power supply blew up about three months ago which caused
>the problem. I assume the damaged power supply sent a spike
>to the tuner which blew up one or more of the transistors.
I have an AJ-1510 tuner with a manual that includes a schematic of the
tuner. It might be the same tuner. It has 3ea FET's and 2ea xsistors.
Unfortunately, there are no part numbers on any of the active parts inside
the tuner can. Email to me a fax number or mailing address and I'll send
you a copy of the tuner schematic etc.
--
Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
(831)421-6491 pgr (831)426-1240 fax (831)336-2558 home
http://www.cruzio.com/~jeffl WB6SSY
je...@comix.santa-cruz.ca.us je...@cruzio.com
Jim Adney
>I've got an old Heathkit AR-1500A stereo system
>that I build many years ago that is in good shape
>except for the FM tuner. The tuner was supplied
>pre-built with no schematics, and it is a maze of
>point to point wiring. There's no way I can repair
>the tuner, but I love the stereo and would like to
>keep it around a few more years.
There used to be a company that would rebuild TV tuners. Does anyone
know if they're still around and if they might do FM tuners also.
-
-----------------------------------------------
Jim Adney jad...@vwtype3.org
Madison,Wisconsin USA
-----------------------------------------------
Jeff Liebermann
>Chuck and Jeff,
>I'm not sure about the 1510, but in my schematic there is:
>The HK PN# for the "tuning unit" is 110-53
Oh-oh. The tuner part number on the AJ-1510 is 110-61.
The xsistor lineup also looks different.
>The bipolars in mine were OK but maybe Motorla could trace these down for you.
>You could use a NTE 312 (first choice) or the 453 and then just replace all the
>bipolars and pray !
http://www.heathkit-museum.com
http://www.mods.com/heath-hifi/links.html
http://members.aol.com/w3dx (See Heathkit Links).
Jim Adney
>I've got an old Heathkit AR-1500A stereo system
>that I build many years ago that is in good shape
>except for the FM tuner.
Along these same lines, I have a HK AR-15, the predecessor to the
AR-1500. Of late it has developed a static-like noise when the tuner
knob is rotated in the FM mode. I'm not used to having FM tuners do
this, but wondered if anyone had any ideas about what might cause it.
My best guess was that the grease that lubricated the bearings of the
grounded rotor on the variable cap had finally all dried up, allowing
oxides to form on the bearing surfaces. Is this a possibility and is
relubricating usually straightforward and does it cure the problem?
JackH35785
I'm not sure about the 1510, but in my schematic there is:
The HK PN# for the "tuning unit" is 110-53
RF UC 734 Q701 Single gate FET HK PN# 417-167
RF2 SE 5050 Q702 NPN Bipolar No HK PN (Motorola?)
Mixer SE 5006 Q703 NPN Bipolar No HK PN ( " " " "
)
FM Osc SE 1001 Q704 NPN Biploar No HK PN ( " " " "
)
When I opened it up it appeared that all the bipolars were Motorola. The FET
was fabricated by "Unitrode", 7 Contental Blvd., Merrimack, NH 03054-0399, FAX
603-424-3460.
I had contacted Unitrode and they told me that they haven't made this FET for
years and that is is a FET very common parameters, so any generic FET will
probably work.
The bipolars in mine were OK but maybe Motorla could trace these down for you.
You could use a NTE 312 (first choice) or the 453 and then just replace all the
bipolars and pray !
If you need a copy of my schematic leave me your address (I don't have a
scanner).
Jack
John Del
Jim Adney <jad...@vwtype3.org> wrote:
> Along these same lines, I have a HK AR-15, the predecessor to the
> AR-1500. Of late it has developed a static-like noise when the tuner
> knob is rotated in the FM mode. I'm not used to having FM tuners do
> this, but wondered if anyone had any ideas about what might cause it.
>
> My best guess was that the grease that lubricated the bearings of the
> grounded rotor on the variable cap had finally all dried up, allowing
> oxides to form on the bearing surfaces. Is this a possibility and is
> relubricating usually straightforward and does it cure the problem?
>
Yes, oxidation in the tuner bearings can cause noise as you've
described. Use "de-oxit" from Caig Labs, then one of their
preservatives.
BTW, I've been following this threat because my dad has an AR1500 he
bought new. It's now sitting in it's box because he replaced it when he
put together a home theater setup, and the rest of us never could stand
the sound quality. But in fairness, it replaced a 1962 Fisher EL34
based tube integrated, which was a real tough act to follow.
John
Sent via Deja.com http://www.deja.com/
Before you buy.
JackH35785
"29" back in 1970. I saw this variable cap suspended on ball bearings at the
end of the shaft and noticed it had some "wiggle" (play) and thought that if HK
is using the bearings as a "Ground" for this variable cap that this is bad, not
very professional. So, I took a piece beryllium copper and drilled a tiny hole
for a small ball bearing in one end and a hole for a screw in the other. I
mounted it so the ball bearing presses against the inside END of the shaft thus
the "Grnd" required for the Variable cap is not dependent on the shaft
bearings.
Got a kick out of "John" and his remark about "the rest of us never could
stand" the sound quality. There must have been something broken with it because
in the early 70's all the critics were gushing over the sound quality of the
"1500" and the "29." My "29" was used feeding a pair of 15" Tannoys in custom
cabinets for 25 years and the sound was glorious. I'm fussy: a EE and a
semi-professional orchestra musician(FHorn).
Jack
John Del
jackh...@aol.com (JackH35785) wrote:
> Got a kick out of "John" and his remark about "the rest of us never
could
> stand" the sound quality. There must have been something broken with
it because
> in the early 70's all the critics were gushing over the sound quality
of the
> "1500" and the "29." My "29" was used feeding a pair of 15" Tannoys in
custom
> cabinets for 25 years and the sound was glorious. I'm fussy: a EE and
a
> semi-professional orchestra musician(FHorn).
> Jack
Hi Jack,
Although realizing that all opinions are subjective (especially mine!),
I will stand on that comment without qualification. There was nothing
wrong with the equipment or it's construction, the problem I feel was
simply the design common to that era. You're correct about the critics
of the time praising this, indeed this was the very reason the AR1500
was purchased. But I feel this is a perfect example of early transistor
sound. Specification wise, the AR1500 had it all over the Fisher.
Output is (I believe) 75 WPC RMS, the Fisher about 50 WPC RMS. The
distortion figures and damping factor were much more impressive on the
HK compared to the tube equipped Fisher. I won't drop cliche word
descriptions that are often bandied about in HI-FI circles, but the
difference in sound was simply stunning, and we were all disappointed.
The HK was (and still is) clean, powerful, and quiet, but it simply
lacks the naturalness and fire of the Fisher. Perhaps it's not so much
an indictment of the HK, but simply an opinion that quality tube amps
were simply much more musical, especially compared to 70's SS stuff. I
would be very interested to hear your opinion if you could beg, borrow,
or steal a tube amp and give it a good auction, and I'll cheerfully
accept your critical accessment of it.
Best,
John
PS: The other thing I don't like about the HK is the 4 brass knobs are
molded off center!
Jim Adney
>Hmm. Interesting. You know, I had this very same problem when I first built the
>"29" back in 1970. I saw this variable cap suspended on ball bearings at the
>end of the shaft and noticed it had some "wiggle" (play) and thought that if HK
>is using the bearings as a "Ground" for this variable cap that this is bad, not
>very professional. So, I took a piece beryllium copper and drilled a tiny hole
>for a small ball bearing in one end and a hole for a screw in the other. I
>mounted it so the ball bearing presses against the inside END of the shaft thus
>the "Grnd" required for the Variable cap is not dependent on the shaft
>bearings.
Sounds like you recognized the potential problem, but all you did was
replace this with another sliding contact. FWIW, all air vane rotating
variable caps use this same scheme for grounding the rotor. I wondered
about adding a soldered wire that spiraled around the shaft a couple
of turns and just wound and unwound the 1/2 turn max; would that have
too much inductance?
>Got a kick out of "John" and his remark about "the rest of us never could
>stand" the sound quality. There must have been something broken with it because
>in the early 70's all the critics were gushing over the sound quality of the
>"1500" and the "29." My "29" was used feeding a pair of 15" Tannoys in custom
>cabinets for 25 years and the sound was glorious. I'm fussy: a EE and a
>semi-professional orchestra musician(FHorn).
My AR-15 has been very good to me for 32 years now. Yes, I've had to
repair quite a few things in it, mainly coupling caps, but I have
always liked the sound. While most of its life it drove a pair of
AR-2ax's, it now has a pair of AR-3s. I think it still sounds great,
but my ears are clearly not what they used to be.
Interesting, I played F horn for years, too....
John Del
John Del <ohg...@aol.com> wrote:
and give it a good auction,
uh....I meant audition. Freud would have had a good time with that
one...
John
JackH35785
Yes, I understand what you are saying about the phenomena of going from a tube
amp to a transistor amp. I had that same feeling when I went from my old HK
"Williamson" two chassis power amp and my "home brew" FET "control amp" with
preamp for a MC OrtoFon cart.
The "29" seemed even "harsh" at first but then I eventually began to like the
clarity and transient response so I efectively "rationalized" my differences
enough to enjoy the "29."
I think that the ideal system would be a "hybrid" power amp. Way back I
experimented with the old "Williamson" by changing the input/divider tube
(6SN7GT) and the driver tube (6SN7GT) with FETs and the sound was stunning. I
ended up using this configuration and sold the amp with this modification and
the fella who bought it from me in '70 is still using it !
As to the design, yes, there was the much publicized "crossover transient
distortion" but in my measurements
JackH35785
Yes, I know the phenomena of moving from a tube amp to a solid state amp. I
used to have a HK "Williamson" two chassis power amp, operating with the
modified "Ultra-Linear" circuit where the 6880 screen grid was wired to the
power transformer (mine was a Peerless) tap instead of directly to power
voltage through a "dropping" resistor.
Yes, the "new" HK 29 sounded "harsh" at first after listening to the old
"tuber" for so many years but eventually I began to like the clarity, transient
response. This was "novel" after listening to the smooth, clean 6880's.
I think the "best of both worlds" was made in the 60's when I decided to turn
my old "Williamson" to a "hybrid" power amp. I ended up removing the input
tube (6SN7GT) and the divider tube (6SN7GT) and replacing them with FET's and
the using of a "home brew" FET control amp with a preamp for my MC OrtoFon. The
resulting sound was stunning ! The fella I sold the amp to in '70 is still
using this amp/control amp combination.
Now as to what I believe you might be referring to is the "crossover transient
distortion." The circuit that HK used was a modified/updated version of the
original circuit by Motorola and HK did effectively all but eliminate this
distortion with these changes. I had the use of a "Professional" model B & K, a
HP "Distortion Analyzer and a HP "Spectrum Analyzer and spent a lot of time
looking into this after I built the "29." I was satisfied that the crossover
distortion was all but gone.
Finally, I understand what your experiencing and it could be said that the "old
saw" that "beauty is in the eyes (or ears) of the beholder" couldn't better
describe this phenomena.
Regards,
Jack
JackH35785
Enjoyed your comment on the "grounding" problem. I had even considered using an
old clock spring in a configuration similar to what you describe. I had a
friend that did try with with good results. Apparantly there were no inductive
problems.
<< Interesting, I played F horn for years, too.... >>
Yes, my horn playing began at age 11 and in '95 I "hung it up" at 69 in a
concert with a local university orchestra and went out in a "blaze of glory"
with the Bach Brandedburg #1. Great fun !
I was able to combine my "professional world" with my "musical world" and
played a lot of shows, "South Pacific", "Oklahoma', "Carousel", "Annie Get Your
Gun"(with Merman)," Kiss Me Kate", "Evita", and others as well as "subbing" in
the Hollywood Bowl Orch. During that time I was Principal in Long Beach
Symphony and the Pasadena Symphony for several years. I was accepted for a
scholarship at Tanglewood in '50 and '51 where I studied with Jim Stagliano,
BSO 1st horn, and played 1st in the "student orch" with Bernstein.
Regards,
Jack
Jim Adney
>Hi Jim,
>Enjoyed your comment on the "grounding" problem. I had even considered using an
>old clock spring in a configuration similar to what you describe. I had a
>friend that did try with with good results. Apparantly there were no inductive
>problems.
Yes, a kind of hair spring arrangement was what I had in mind, too.
><< Interesting, I played F horn for years, too.... >>
>
>Yes, my horn playing began at age 11 and in '95 I "hung it up" at 69 in a
>concert with a local university orchestra and went out in a "blaze of glory"
>with the Bach Brandedburg #1. Great fun !
>
>I was able to combine my "professional world" with my "musical world" and
>played a lot of shows, "South Pacific", "Oklahoma', "Carousel", "Annie Get Your
>Gun"(with Merman)," Kiss Me Kate", "Evita", and others as well as "subbing" in
>the Hollywood Bowl Orch. During that time I was Principal in Long Beach
>Symphony and the Pasadena Symphony for several years. I was accepted for a
>scholarship at Tanglewood in '50 and '51 where I studied with Jim Stagliano,
>BSO 1st horn, and played 1st in the "student orch" with Bernstein.
Whoa, I won't even attempt to mention my meager, and long-gone,
attempts at talent. ;-)
JackH35785
I treasure the fact that I think all horn players are a special bunch of
people. I'm not sure what it is but there is a certain cameradie among horn
players. Maybe its that horn players all understand the vagaries, treachery and
fickleness of this instrument and when they have "met the challenge" and
conquered it, they become buddies in a kinda "closed club."
Anyway, they are a great bunch of people.
Meanwhile, my old "8D" rests in an exhalted spot and adds to the decor on
bookcase !
Now, as to the spring. Yes, you are right, my friend used and old Westclock
hair spring and it works fine. I had mentioned that I would do it if I had an
old Westclock to tear apart . I didn't so I had to do something else ! I think
"the hair spring idea" is the best so someday if I can find an old clock I'll
tear the ole' HK apart and do it that way.
Best Regards,
Jack