Early c3 comprehensive stereo testing procedure
Thread Starter
4th Gear
Joined: Mar 2017
Posts: 4
Likes: 0
From: Franklin Mass
Early c3 comprehensive stereo testing procedure
Hey folks,
I have searched and found many interesting articles but nothing quite scratching this itch I have.
situation:
1970 convertible with factory stereo, amp (single amp unit with two ds501 transistors) and 10 ohm speakers in the dash). This week I was tuning to another channel using the tuning **** and suddenly lost the right channel. Lots of twisting, and gentle tapping and removing the right lower dash to inspect wiring and everything looks fine. I am looking for a comprehensive write up on troubleshooting this stereo in the car so I can determine if it’s the head unit (I suspect it is. The fact that I was using the tuning **** which shares real estate with the r/l fader control at time of failure tells me something internal happened). But if someone else has heard this story a million times and has a strong alternative I’d love to hear it. If not I’d love a good step by step with the multi meter and what I am looking for at each component to try and rule out good from bad. Any advice much appreciated!
I have searched and found many interesting articles but nothing quite scratching this itch I have.
situation:
1970 convertible with factory stereo, amp (single amp unit with two ds501 transistors) and 10 ohm speakers in the dash). This week I was tuning to another channel using the tuning **** and suddenly lost the right channel. Lots of twisting, and gentle tapping and removing the right lower dash to inspect wiring and everything looks fine. I am looking for a comprehensive write up on troubleshooting this stereo in the car so I can determine if it’s the head unit (I suspect it is. The fact that I was using the tuning **** which shares real estate with the r/l fader control at time of failure tells me something internal happened). But if someone else has heard this story a million times and has a strong alternative I’d love to hear it. If not I’d love a good step by step with the multi meter and what I am looking for at each component to try and rule out good from bad. Any advice much appreciated!
Melting Slicks
Joined: Apr 2010
Posts: 2,314
Likes: 164
From: Broadview hts Ohio
It could very well be the speaker died. Both my dash speakers went out on my 72 LT1 stereo. I assumed it was the radio or amp as I no sound. It was the speakers and they had been replaced before.
Try a new speaker before ripping dash apart.
Joe
Try a new speaker before ripping dash apart.
Joe
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
Most likely the power transistor for that channel failed. Could it be the speaker? Maybe. You can test the speaker IN PLACE by QUICKLY touching a 1.5v battery to the two speaker leads (disconnected from the amp). Don't hold the leads on the batteryj; just tap the wire on the battery to see if you get a 'scratch' or 'pop'. If you do, the speaker is functional.
The DS-501 power amp transistors are no longer available (other than very old pieces from old radios). But replacements are readily available. Problem could also be internal to the radio head...but that is LESS likely.
The DS-501 power amp transistors are no longer available (other than very old pieces from old radios). But replacements are readily available. Problem could also be internal to the radio head...but that is LESS likely.
Thread Starter
4th Gear
Joined: Mar 2017
Posts: 4
Likes: 0
From: Franklin Mass
Thank you!
Thanks guys. I have tested the speaker and it appears to be good (appropriate resistance, makes a pop with the battery test) Is love to find a way to test the output on the stereo to isolate the amp
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
Could be a wiring issue going from head unit to the "convector" (with the big power transistors). Test all connections and remove/replace all connectors to make sure they haven't corroded/tarnished.
