Amplifier found under dash of 1976?
07-04-2004, 10:24 PM
#1
Intermediate
Thread Starter
Member Since: Jun 2004
Location: Essexville MI
Posts: 26
Likes: 0
Received 0 Likes
on
0 Posts
Amplifier found under dash of 1976?
I found what looks to be a very simple amplifier mounted under the windshield today when I pulled the dash to install some new speakers. It was not connected to anything. It has three pairs of wires coming from it that were just dangling under the dash. The two round electronic components that have the following information printed on them - DELCO DS-501 / 7537. The entire unit is about 6" long by 4" wide by 2-1/2" deep. It is made from aluminum and has fins similar to modern amplifiers. If it is something that is needed to keep the car stock later down the road I will keep it but otherwise it will be going out in the trash.
Thanks
Thanks
07-04-2004, 10:32 PM
#2
Le Mans Master
Member Since: Aug 2000
Location: Semper ubi, sub ubi
Posts: 9,662
Likes: 0
Received 6 Likes
on
6 Posts
Cruise-In VI Veteran
Cruise-In VII Veteran
Re: Amplifier found under dash of 1976? (Captbachus)
If the amplifier isn't bothering anything, then leave it there. You are somebody else might want to return it to a factory style radio in the future.
07-04-2004, 10:32 PM
#3
Burning Brakes
Re: Amplifier found under dash of 1976? (Captbachus)
That would be the outboard amplifier output transistors and heat sink for the stock Delco AM-FM stereo radio. If you ever decide to install an original stereo radio, it would be nice to have. Many of the original radios for sale do not have this item because it was left in the car as in your case..
07-04-2004, 10:35 PM
#4
Burning Brakes
Member Since: Apr 2000
Location: trumbull ct
Posts: 870
Likes: 0
Received 0 Likes
on
0 Posts
Re: Amplifier found under dash of 1976? (Captbachus)
Your car was originally equipped with am/fm stereo, and the part you are talking about is commonly called a multiplex box. It was used to provide stereo sound from the stock radio. Cars that were equipped with a mono radio had a smaller, but similar looking piece mounted in the same place, and its called a convector.
I would keep it. If you remove it from the car, be sure to plug the screw holes in the birdcage to keep the water out.
George
I would keep it. If you remove it from the car, be sure to plug the screw holes in the birdcage to keep the water out.
George
07-04-2004, 10:56 PM
#5
Intermediate
Thread Starter
Member Since: Jun 2004
Location: Essexville MI
Posts: 26
Likes: 0
Received 0 Likes
on
0 Posts
Re: Amplifier found under dash of 1976? (Smokehouse69)
Thanks for the feedback. I have pulled it but will make sure I keep it on the shelf.
Thanks again,
Mark
Thanks again,
Mark
07-04-2004, 11:59 PM
#6
Race Director
Re: Amplifier found under dash of 1976? (Captbachus)
If I may be allowed to semi-hijack this thread, is this item found in '79 models? If so, does it cause any problems if left intact when an aftermarket stereo is installed? I am not as happy as I'd like to be with the sound of my new stereo and speakers, and wondering if this box could be the root of my problems.
07-05-2004, 12:00 AM
#7
Team Owner
Member Since: Apr 2001
Location: S.W. Ohio. . . . . . NRA Life Member
Posts: 54,199
Received 173 Likes
on
107 Posts
Re: Amplifier found under dash of 1976? (Captbachus)
Your car was originally equipped with am/fm stereo, and the part you are talking about is commonly called a multiplex box. It was used to provide stereo sound from the stock radio. Cars that were equipped with a mono radio had a smaller, but similar looking piece mounted in the same place, and its called a convector.
The mono Am/FM radio was missing more circuitry than just an extra output transistor located on the remote convector assembly. There would be no benefit trying to wire in a stereo convector to the Delco mono radio.
Delco Electronics themselves called both the single transistor and dual transistor remote unit "Convectors". One was the mono-convector and the other was a stereo convector.
the DS-501 was a common final output transistor used by Delco Electronics. It had a center threaded mounting stud. Delco actually made their own transistors and integrated circuits. They grew the silicone right in the Kokomo Indianna factory.
the "multiplex box" you speak of was the stereo circuitry and extra audio output stage (for the second channel) . It was housed in a metal chassis about the size of a cigar box. The Delco stereo radio that used the multiplex box was in production in the late 1960's... maybe the last year for the multiplex box was 1970 ??? It'sd been a long time.
It's easy to determine if you have a convector assembly or an actual multiplex remote mount box. The "Convector" is only the heatsink and a single (or dual) transistor; with no other circuitry.
The multiplex adapter was enclosed in a metal chassis with a single heat-sinked transistor attached to the outside of the enclosure (thanks Tom for reviving my memory
), and connected to the related Delco radio via a jacketed cable with a round multi-pin connector (8 pins, if I remember correctly)..
[Modified by Mike Mercury, 11:02 AM 7/5/2004]
07-03-2011, 10:27 PM
#10
I was contracted with Delco Electronics back then. The Y bodied Corvette dash (thru 1977) did not have room to handle the complete Delco FM and stereo FM radios. So, the output transistors alogn with their heat sinks were remotely mounted.
The mono Am/FM radio was missing more circuitry than just an extra output transistor located on the remote convector assembly. There would be no benefit trying to wire in a stereo convector to the Delco mono radio.
Delco Electronics themselves called both the single transistor and dual transistor remote unit "Convectors". One was the mono-convector and the other was a stereo convector.
the DS-501 was a common final output transistor used by Delco Electronics. It had a center threaded mounting stud. Delco actually made their own transistors and integrated circuits. They grew the silicone right in the Kokomo Indianna factory.
the "multiplex box" you speak of was the stereo circuitry and extra audio output stage (for the second channel) . It was housed in a metal chassis about the size of a cigar box. The Delco stereo radio that used the multiplex box was in production in the late 1960's... maybe the last year for the multiplex box was 1970 ??? It'sd been a long time.
It's easy to determine if you have a convector assembly or an actual multiplex remote mount box. The "Convector" is only the heatsink and a single (or dual) transistor; with no other circuitry.
The multiplex adapter was enclosed in a metal chassis with a single heat-sinked transistor attached to the outside of the enclosure (thanks Tom for reviving my memory ), and connected to the related Delco radio via a jacketed cable with a round multi-pin connector (8 pins, if I remember correctly).
.
[Modified by Mike Mercury, 11:02 AM 7/5/2004]
The mono Am/FM radio was missing more circuitry than just an extra output transistor located on the remote convector assembly. There would be no benefit trying to wire in a stereo convector to the Delco mono radio.
Delco Electronics themselves called both the single transistor and dual transistor remote unit "Convectors". One was the mono-convector and the other was a stereo convector.
the DS-501 was a common final output transistor used by Delco Electronics. It had a center threaded mounting stud. Delco actually made their own transistors and integrated circuits. They grew the silicone right in the Kokomo Indianna factory.
the "multiplex box" you speak of was the stereo circuitry and extra audio output stage (for the second channel) . It was housed in a metal chassis about the size of a cigar box. The Delco stereo radio that used the multiplex box was in production in the late 1960's... maybe the last year for the multiplex box was 1970 ??? It'sd been a long time.
It's easy to determine if you have a convector assembly or an actual multiplex remote mount box. The "Convector" is only the heatsink and a single (or dual) transistor; with no other circuitry.
The multiplex adapter was enclosed in a metal chassis with a single heat-sinked transistor attached to the outside of the enclosure (thanks Tom for reviving my memory
), and connected to the related Delco radio via a jacketed cable with a round multi-pin connector (8 pins, if I remember correctly)..
[Modified by Mike Mercury, 11:02 AM 7/5/2004]
I was wondering if I can play the stock radio without this module. It appears that it has gone bad but some sound still gets to the speakers if I turn the volume all the way up.
Does anyone have a diagram for the wiring of this module, and does anyone know if a standard, low powered two channel amplifier can be used to replace this module(I've had problems finding the dual transistor one for my Stereo Delco).
05-12-2016, 08:01 AM
#12
2nd Gear
Member Since: May 2016
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
Mono amp testing
Mike is there a way to test the mono amp I believe either the amp or the radio has died radio lights up but no sound I removed the amp. Can you test for resistance I am getting power to the yellow wire (to the remote amp) when the radio is switched on. Thank you
QUOTE=Mike Mercury;1547728364]I was contracted with Delco Electronics back then. The Y bodied Corvette dash (thru 1977) did not have room to handle the complete Delco FM and stereo FM radios. So, the output transistors alogn with their heat sinks were remotely mounted.
The mono Am/FM radio was missing more circuitry than just an extra output transistor located on the remote convector assembly. There would be no benefit trying to wire in a stereo convector to the Delco mono radio.
Delco Electronics themselves called both the single transistor and dual transistor remote unit "Convectors". One was the mono-convector and the other was a stereo convector.
the DS-501 was a common final output transistor used by Delco Electronics. It had a center threaded mounting stud. Delco actually made their own transistors and integrated circuits. They grew the silicone right in the Kokomo Indianna factory.
the "multiplex box" you speak of was the stereo circuitry and extra audio output stage (for the second channel) . It was housed in a metal chassis about the size of a cigar box. The Delco stereo radio that used the multiplex box was in production in the late 1960's... maybe the last year for the multiplex box was 1970 ??? It'sd been a long time.
It's easy to determine if you have a convector assembly or an actual multiplex remote mount box. The "Convector" is only the heatsink and a single (or dual) transistor; with no other circuitry.
The multiplex adapter was enclosed in a metal chassis with a single heat-sinked transistor attached to the outside of the enclosure (thanks Tom for reviving my memory ), and connected to the related Delco radio via a jacketed cable with a round multi-pin connector (8 pins, if I remember correctly).
Mike is there a way to test the mono amp I believe either the amp or the radio has died radio lights up but no sound I removed the amp. Can you test for resistance I am getting power to the yellow wire (to the remote amp) when the radio is switched on. Thank you
[Modified by Mike Mercury, 11:02 AM 7/5/2004][/QUOTE]
QUOTE=Mike Mercury;1547728364]I was contracted with Delco Electronics back then. The Y bodied Corvette dash (thru 1977) did not have room to handle the complete Delco FM and stereo FM radios. So, the output transistors alogn with their heat sinks were remotely mounted.
The mono Am/FM radio was missing more circuitry than just an extra output transistor located on the remote convector assembly. There would be no benefit trying to wire in a stereo convector to the Delco mono radio.
Delco Electronics themselves called both the single transistor and dual transistor remote unit "Convectors". One was the mono-convector and the other was a stereo convector.
the DS-501 was a common final output transistor used by Delco Electronics. It had a center threaded mounting stud. Delco actually made their own transistors and integrated circuits. They grew the silicone right in the Kokomo Indianna factory.
the "multiplex box" you speak of was the stereo circuitry and extra audio output stage (for the second channel) . It was housed in a metal chassis about the size of a cigar box. The Delco stereo radio that used the multiplex box was in production in the late 1960's... maybe the last year for the multiplex box was 1970 ??? It'sd been a long time.
It's easy to determine if you have a convector assembly or an actual multiplex remote mount box. The "Convector" is only the heatsink and a single (or dual) transistor; with no other circuitry.
The multiplex adapter was enclosed in a metal chassis with a single heat-sinked transistor attached to the outside of the enclosure (thanks Tom for reviving my memory
), and connected to the related Delco radio via a jacketed cable with a round multi-pin connector (8 pins, if I remember correctly).Mike is there a way to test the mono amp I believe either the amp or the radio has died radio lights up but no sound I removed the amp. Can you test for resistance I am getting power to the yellow wire (to the remote amp) when the radio is switched on. Thank you
[Modified by Mike Mercury, 11:02 AM 7/5/2004][/QUOTE]
05-27-2016, 10:10 AM
#15
Advanced
Note that the pix of speakers indicate 10 ohms. My radio man advises that for the old radios, only 10 ohm units should be used to replace the originals. The radio in the '69 I'm working on is stamped "8 ohm minimum". Reason is that the 4 ohm replacements sold through 'Vette suppliers and others now will eat transistors in a hurry, ruining your original radio. Unfortunately, about the only place to get 10 ohm speakers are from a salvage yard. I've found them in 2000's GM wrecks in various sizes. Just FYI..
08-01-2016, 10:43 PM
#16
Team Owner
Member Since: Apr 2001
Location: S.W. Ohio. . . . . . NRA Life Member
Posts: 54,199
Received 173 Likes
on
107 Posts
barely alive though 
a quick test of the output transistor is to use a multimeter that has a diode checker built in. Should read voltage drop from B-C, and B-E,,, one direction only. Reverse the leads and it should read open
Final test is between E-C, should read open both ways here.
Those DS-501 transistors (if that is what you have) are severe overkill; mega beefy part. Very rarely failed.
The factory speakers (Delco actually mfgrd their own speakers back then) were indeed 10 ohms. but 8 ohm speakers were just fine & safe to use.
4 ohm speakers (and Fords 3.2 ohm speakers) would be a no-no.
a quick test of the output transistor is to use a multimeter that has a diode checker built in. Should read voltage drop from B-C, and B-E,,, one direction only. Reverse the leads and it should read open
Final test is between E-C, should read open both ways here.
Those DS-501 transistors (if that is what you have) are severe overkill; mega beefy part. Very rarely failed.
The factory speakers (Delco actually mfgrd their own speakers back then) were indeed 10 ohms. but 8 ohm speakers were just fine & safe to use.
4 ohm speakers (and Fords 3.2 ohm speakers) would be a no-no.
08-01-2016, 11:10 PM
#17
Team Owner
I take it you have an aftermarket sound system in the car now. Just remove the "convector" [final stage of amplification for your original Delco head unit] and put it up on eBay. Yours is a stereo unit and will work for 1971-1977 units. Those power transistors are no longer made and folks are in need of good convector units...especially stereo units. Check going prices on eBay and set price accordingly. Good luck!
08-02-2016, 06:17 AM
#18
Drifting
Or sale it to me....I have a Delco stereo unit that I'm going to install soon....My car only has a mono convector so I either need a stereo unit or another mono unit.
Brian
Brian
08-02-2016, 08:34 AM
#19
Burning Brakes
Note that the pix of speakers indicate 10 ohms. My radio man advises that for the old radios, only 10 ohm units should be used to replace the originals. The radio in the '69 I'm working on is stamped "8 ohm minimum". Reason is that the 4 ohm replacements sold through 'Vette suppliers and others now will eat transistors in a hurry, ruining your original radio. Unfortunately, about the only place to get 10 ohm speakers are from a salvage yard. I've found them in 2000's GM wrecks in various sizes. Just FYI..
Recommended to me by Jerry Rudbeck when he was doing radio work for me.
Regards,
Jimmy
Last edited by Tooch1; 08-02-2016 at 08:40 AM.
08-02-2016, 10:02 AM
#20
Advanced
Right on!
They are very courteous and prompt. After I last posted, I ordered the 4x10 Slimline in 10 ohm. It fits nicely and has good sound. I can highly recommend this outfit. Thanks, everybody!