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Need radio service info

M

MoFo

NAXJA Forum User
NAXJA Memorial Lifetime Member
Location
Near Rochester NY
I have a 1987 XJ Laredo with the OEM Radio / Cassette player. The tape deck and radio work just fine and I would like to keep them.

However, the radio will not hold the station memory when I start the engine. I have checked the preset stations while letting the battery voltage drop to 10.0 volts, too low to start the engine.

However, when the starter cranks, the voltage drops to about 9 volts. I figure this is when the memory is lost. I think there is probably an electrolytic capacitor in the radio to hold the memory through these drops, but nothing is obvious. I hear these caps can go bad in 20 years. I would like to fix the radio, rather than rig something externally to hold the power. The clock holds the time just fine.

Does anybody have a schematic, or know where I can find one for a

1987 AMC model 8956001910 cassette player?

TIA
 
First it sounds like you might want to clean all your connections from battery to stereo hot and ground. Those voltages sound a bit low. a wire brush and some contact cleaner/lubricant should help. Also if you have any crimped on connections, replace with direct solder terminations or solder on connectors. The working voltage of most 12v DC stuff is usually from high 9 to about 15 depeding on the powersupply in the unit. Caps can go bad so do you see any liquid that is a strange color or sticky/slimmy/smells like burned crap. Caps are usually pretty strong at least in my field. Good luck
 
The connections look fine. I did use a little De-oxit as a matter of course. The power lead that supplies the battery voltage to the memory carries less than 5 mA at 13.6 volts. My 40 years experience in various electronics service positions tells me that it is unlikely to be a bad connection. Ohms law tells me it would take 720 ohms at a bad connector to get the voltage to 10 volts. A bad ground would prevent the tape deck and amplifiers form operating.

Anybody know where I can find a schematic?
 
You'll probably spend more money on an old OEM radio than you would on a new aftermarket CD player. If your tape collection is just that great I think I saw an aftermarket tape player at wal-mart the other night. If you have your heart set on it I know of 86 and 88 XJ's at my U-pull it I can check for you when I go on sunday. PM me if your interested, Cost is $25 plus ship.
 
Thanks for the offer pierce. I had a friend tonight remind me of the books that Sams Photofacts published that covered car radios. The local library used to have Sams, but I heard they have transfered them to microfilm to save space. I will check there tomorrow.

I know I can get an aftermarket CD player cheap. I have a nice Kenwood player in my '90 XJ hanger queen that I could pull out. But, if I go aftermarket, I would want HD radio, MP3 and USB ports. I am trying to resist that.

I would like to keep everything on the body and in the cabin stock. The suspension is quite a different matter.
 
I just tested my battery / starter on an 89 Renix I picked up a few days ago, and it held a constant steady 10.69 volts with an old battery while cranking the 4.0 engine for 30 seconds straight.

MoFo said:
I have a 1987 XJ Laredo with the OEM Radio / Cassette player. The tape deck and radio work just fine and I would like to keep them.

However, the radio will not hold the station memory when I start the engine. I have checked the preset stations while letting the battery voltage drop to 10.0 volts, too low to start the engine.

However, when the starter cranks, the voltage drops to about 9 volts. I figure this is when the memory is lost. I think there is probably an electrolytic capacitor in the radio to hold the memory through these drops, but nothing is obvious. I hear these caps can go bad in 20 years. I would like to fix the radio, rather than rig something externally to hold the power. The clock holds the time just fine.

Does anybody have a schematic, or know where I can find one for a

1987 AMC model 8956001910 cassette player?

TIA
Click to expand...
 
Thanks Ecomike.

The cranking voltage reading I quoted was with a DMM in Peak Hold Low mode. The actual reading I got was a peak low of 9.12 volts. The engine cranks and starts just fine. When I look at the average, it is about 10.4 while cranking.
 
I seem to remember a company called S&S Automotive in chicago that specializes in factory stereo repairs. Sorry I don't have a ph # though. Maybe do a search... Hopefully they might be some help...
 
Nice to see someone still out there repairing electronic stuff instead of just tossing it. I try to dabble in that type of stuff and keep as much going as I can. A little patience and a soldering iron can do wonders sometimes.
 
MoFo said:
However, the radio will not hold the station memory when I start the engine. I have checked the preset stations while letting the battery voltage drop to 10.0 volts, too low to start the engine.
Click to expand...

Just so I understand, after you set your presets, they work while your jeep is running. Do they work after you shut off and then turn the key accessory? Do they work if you turn the key from off to Run (don't start)? Then go away once you turn to Start?
 
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