Hi I'm trying to fix an old hu i got for cheap the problems I'm having are that it doesn't out put any sound through the pre amp and it wont load Cd's i have another old alpine cd only hu that has a lot of the same parts
dose any one know where to start and what component i should be testing .
pic is the unit
dose any one know where to start and what component i should be testing .
pic is the unit
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OK start by considering that Alpine most probably does not carry parts for that 1991-93 era HU. < just a FYI > Call Pacific Coast Parts or look them up online and ask to be for sure.
Then as I recall this HU has a common problem of needing the CD mechanisms switch's replaced. It won't load could be dirty rollers, and bad switch's on the mechanism that sense where the CD is as it loads into the position to drop into play mode. Dirty rollers can be cleaned with alcohol and clean wipes, and operating the load servo and allowing the rollers to rub themselves clean on the alcohol wetted wipes. and or Q-tips.
As for no sound out, well that's a good one but here again the HU might not be able to decide which source to use (i.e, radio or CD) due to bad sensors in the CD unit, or the CD Radio selector circuitry has failed or is confused possibly by incorrect signals from the CD mechanism.
With a HU this old I would be asking if the CD drive motor and the Laser assembly are still available from PCP. As these parts along with position sensor switch's were the big failures I saw on these long ago...Also ask PCP if they have the service document on this model still as your gonna need it to order and get parts you might need..Hope this helps....
Then as I recall this HU has a common problem of needing the CD mechanisms switch's replaced. It won't load could be dirty rollers, and bad switch's on the mechanism that sense where the CD is as it loads into the position to drop into play mode. Dirty rollers can be cleaned with alcohol and clean wipes, and operating the load servo and allowing the rollers to rub themselves clean on the alcohol wetted wipes. and or Q-tips.
As for no sound out, well that's a good one but here again the HU might not be able to decide which source to use (i.e, radio or CD) due to bad sensors in the CD unit, or the CD Radio selector circuitry has failed or is confused possibly by incorrect signals from the CD mechanism.
With a HU this old I would be asking if the CD drive motor and the Laser assembly are still available from PCP. As these parts along with position sensor switch's were the big failures I saw on these long ago...Also ask PCP if they have the service document on this model still as your gonna need it to order and get parts you might need..Hope this helps....
I did repair on at least 50+ of the 7903/4's . The most common problem that I remember is the worm gear getting trash on it. Since the 7903 is the pullout model, it would get turned sideways when pulled out. Any specs of trash, grass, dust balls, ect. would get stuck in the worm gear and cause a switch to malfunction. This was not always the case, but was the most memorable of that unit. I remember aligning the optical pickup. Bad vol-pot's. Soda under the buttons, and LOTS of burned traces. Being a pullout made this model go through a lot of problems with the dirty worm gear. Clean it, and you might get lucky.
anatech said:
Hey Chris, 1more amp, ect. I was just wondering. (or any former service techs). Do you or anyone else remember the Sony CDX-77 ? Did anyone do service work on those? 3rd CD unit Sony made. Worst CD unit ever. I remember wondering about the poor tech that had to do warranty work on these. Horrible design ALL-OVER... I did what I could for that model, but wondered what the return rate was on them. I stopped working on them. Could not get the gremlins out. Fix one problem, and another would start. Awful units... Was it just me, or did anyone have the same experience with the CDX-77 ?
Hi tomtomjr,
Those Sony units were no fun at all. Luckily, I didn't do warranty on Sony, but had many out of warranty. One major problem is that the Sony Service manager up here did not tell the truth. Then there was Sony Corp. They would never admit when they had a problem - ever! Everything was swept under the rug. Like most Japanese companies of that time, they were too proud to admit to their problems. Some, like Teac, would come out with bulletins like " Hey, we've discovered <problem> and here is the fix we have worked out". This after you've been dealing with this fault and been told they don't experience that problem. Oh, and their fix was something you or another shop had suggested.
Alpine was much better about service issues, at least in Canada. I only saw a few worm gear issues up here though, switches ruled even in their cassette mechanisms.
I still deal with the old service manager from the Alpine days. Super guy that distributes Cyrus and Creek in Canada, possibly all North America for Cyrus. We went through a lot, but he was always honest and fair.
-Chris
Those Sony units were no fun at all. Luckily, I didn't do warranty on Sony, but had many out of warranty. One major problem is that the Sony Service manager up here did not tell the truth. Then there was Sony Corp. They would never admit when they had a problem - ever! Everything was swept under the rug. Like most Japanese companies of that time, they were too proud to admit to their problems. Some, like Teac, would come out with bulletins like " Hey, we've discovered <problem> and here is the fix we have worked out". This after you've been dealing with this fault and been told they don't experience that problem. Oh, and their fix was something you or another shop had suggested.
Alpine was much better about service issues, at least in Canada. I only saw a few worm gear issues up here though, switches ruled even in their cassette mechanisms.
How do customers get most of a cup of coke (or coffee) inside a dash mount unit??? Happened a lot. Then the destruction caused by installers, or worse yet, owners friends.
I still deal with the old service manager from the Alpine days. Super guy that distributes Cyrus and Creek in Canada, possibly all North America for Cyrus. We went through a lot, but he was always honest and fair.
-Chris
Hi weesatron,
When I used to get these in out of warranty, I would quote for all switches and a complete clean. A setup was also done as the unit would always perform better afterwards. The factory setup was okay, but not great. That was true with all machines really, including home machines.
-Chris
That means it didn't read the TOC. This could be due to switches, there are a couple in the CDM itself also. Could be a loading switch (probable) or a dead laser assembly. If you continuously hear the loading motor running, you have a problem in the CD loading mechanism for sure. If you hear it stop, then the fault is in the CDM. It is possible there are more than one fault. Heck, that is very likely.
When I used to get these in out of warranty, I would quote for all switches and a complete clean. A setup was also done as the unit would always perform better afterwards. The factory setup was okay, but not great. That was true with all machines really, including home machines.
-Chris
Cupholder or conveniently flat area under/in front of the head unit.
It's very satisfying to show the sticky mess left inside to that customer who's absolutely ranting about the pitiful reliability of your products.
Also found a bit of loose change in cassette decks. Every one had a curious child within arms reach. Maybe they thought it was a jukebox...
1moreamp, anatech, tomtomjr, thanks for the information -there's a well-loved and working 7904 in my dash.
weesatron, I have some portion of a tech paper on the 7903/04. Seems like it's schematics and part numbers. I'll look them up tomorrow.
anatech said:
Well, At least I know now I wasn't the only one who had issues with Sony. I collect yellow-box Sony units. (shaft cass, amps, speakers, eq's, ect made in the early to mid 80's) . For me, it seemed like the Sony quality went away after they made the CDX-R88/66 CD unit. 1988 or so.
Hey Tim. Got my Zapco 40V Power supply today!!! Now I can complete a System 200 3 piece in 40V. (like I really needed another) . Nice that you have a 7904 in your dash too. I sure need that. Where do you park your car?tsmith1315 said:
I worked on a few 7909's. Only owned one. The 7903/4 is the best made back then for SQ. Had several. Nothing could compare. But only making tech money back then, so when I needed cash, they were sold off quickly.
Now, strangest things pulled out of tuners... Raisins (pioneer 3000 cass) , small gumball toys , gum, bullet (22), homemade porno (2 times from camcorders, plus a hidden cam video once) , change (lots of change) , a 3-1/2 floppy a guy put in his brand new Lincoln (very old guy thought it would record his songs) , Soft drink residue, paper, business cards, hard candy, and even one where someone peed in this guys Pioneer (pullout model, didn't work on that one, stinky!!!) ... Well, that is all I can think of at the moment for things I took out of tuners. Sure there is more. I used to keep a cup above my bench with all the crap taken out of tuners. Anyway, glad to see other techs, and former techs on here. Last thing... I still have a service manual for the 7903. Will dig this weekend and see if I can find it. If I do, I will post a link to some hi-res pics for you...
Gave it a good clean. Some of the ir LED's that sense where the disc is look a bit cruddy so ill replace all them and the switches. Hopefully it not the laser assembly
"and even one where someone peed in this guys Pioneer (pullout model, didn't work on that one, stinky!!!"
Why would any one pee in a hu?
"and even one where someone peed in this guys Pioneer (pullout model, didn't work on that one, stinky!!!"
Why would any one pee in a hu?
weesatron said:
Story was that someone got mad at the owner (of radio) at a party. Back then, the pullouts were kept in little purse/pouches. So the one guy gets mad and pees in the other guys purse/pouch that had the Pioneer Cass in it. Smell was awful...
The above problem is actually one of the lighter ones.
I have lots of horror stories from the Cell , Home Audio, Big Screen TV's, ect. But they get kind of gross. So I won't post them here. Noobs, before you open something that does not belong to you, smell first.
Keep us posted on what you find wrong with the 7903. If I find the 7903 service manual over the weekend, I will let you know.
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