# Damn! the 7909 sounds clean just like I remember!



## jeffp (Jan 18, 2015)

I have been working a couple of decks I bought, and both of them were a total mess. So I went to work on them, and made good progress with one, and almost got the second deck up and running. I need to do all of my work again on the second deck.
BUT! I got the first deck going and the cd would not run, so after I worked for a number of days, today I decided to swap out the parts from the first deck to trouble shoot the second deck. I had previously recapped the PCB, and the first cd player needs more parts.

I swapped out the PCB hooked up the cd mech to the deck I have working, poped in Kenny G and Toni Braxton because of the lows and the highs on "that somebody was you", and the unit played the song!

This deck SOUNDS SO CLEAN I wanted to cry LOL, I am so happy now.

Now on to the second deck. A GOOD DAY TODAY!


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## jeffp (Jan 18, 2015)

So upon further testing, I came to realize the unit has only one audio output to the right channel, still sounds excellent. These decks are giving me no mercy LOL. But one is almost there.


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## 1996blackmax (Aug 29, 2007)

Pretty cool you're bringing these HU's back to life.


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## cajunner (Apr 13, 2007)

apply time and pressure, everything succumbs eventually...


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## lsm (Mar 11, 2009)

Great CD Players. Well worth the effort.


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## jeffp (Jan 18, 2015)

I was having some problems with one of the cd mech circuit boards, and it was really trying my troubleshooting experience. I decided to recap the second board and see how that went. After I did the recap, that did fix the board problem. I thought, check all of the capacitors you installed and make sure the are not backwards. They were correct, but I did find a missing cap. So I looked it up and it is a voltage stabilizer on the transistor that is the PLL loop filter control circuit. I installed the cap, ant the cd is working now. 

This unit is almost done, it sounds excellent. I have to clean, lube and put the unit back together.
I will say one thing though, this deck has been relentless to the very end, but then again, I am working on two decks, that obviously were very difficult, and pretty much trash. I think they were parts decks, put together and some sucker bought them  :laugh: LOL. Well electronics, and especially audio have always been my favorite thing to do for fun.

Eric Clapton unplugged sounds so good. You can hear his fingers sliding up and down the strings of his guitar and it sounds like he is right in front of you playing. So Cool


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## jeffp (Jan 18, 2015)

So After I recapped the unit, it was working good for a few days. I was not totally confident with the unit, so I have had it on the bench disassembled for that time. I played the unit for hours, I wanted to address some concerns with the power transistor on the cd board, it was getting hotter then I thought it should, turns out it is just the way the part runs. Ok so I keep playing the unit, besides I am waiting for a shipment of the relays in the unit. I figure they are the OEM parts, and they have been in the unit for some time and it is just good practice to replace them, just for reliability reasons. 
The unit looked good, then yesterday. I had some running around to do so I shut the deck off. When I came back home I turned the unit on and popped a cd in it and it would not start playing and ejected the cd. I cycled the cd a few times and it started playing. I was a little uneasy about that, but it played for a few hours. I shut it off and came back later, and again it would not play. I left the cd in the player both times this happened when I shut the deck off, so I was wondering, since I don't have the batteries installed yet if that was the issue, loss of memory and the cd did not know where to start again. That was not a correct assessment of the problem. Due to my inexperience with the deck I had no answers, so it was trial and error time, and I had to revert back to how do most cd players behave to give me some sort of idea as what to expect, not the best way to troubleshoot, but the only method I have. 
I went to bed and the unit was not working, and I decided it was more then likely the laser going out. 
This morning I popped a cd in the player and it worked, but only for one song and then it went out to lunch. 
I decided to replace the laser, and that is a PITA folks, really had to utilize that soldering class I took to R&R the laser and not destroy the flex board. I got the change out completed and hooked everything up and it played no problems. 
I did notice, the cd that has scratches in one spot did behave differently, in stead of getting stuck in that part of the cd, and repeating, it now just blips the audio and continues on with the track. So that appears to be an improvement, but I could be wrong, but with the over sampling of the deck, it seems more plausible that the unit would do that then just get stuck and repeat over and over again.
So starts the burn-in process all over again. The thing that bothers me is that this deck has been messed with so much, and is so old the failures could plague me for some time until I systematically replace all of the failure components, one of the problems with dealing with old equipment, so that is the reason I just shotgun components like switches, relays and the like, its just a trial in patience but I think it is still worth the trouble.
We will see how it goes.


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## jeffp (Jan 18, 2015)

I started work on the second deck, what a mess this unit is. The audio did not work, the cd palyer is trashed, and the cd circuit board. The dc converter was trashed. and it is looking like when the converter went it also took out the A/D converters, and all of the amps for the radio, and the cd player. 
I was able to steal some parts from a 7903 to get the radio portion of the deck working. I tried a transport that is working, it works except for the audio. The dc converter, I have to replace every cap, SMD and through hole, and the SMD resistors. This deck really looks like it was a parts downer deck I have bought, but I'm going to get this one working as well. I just hate waiting for parts orders what a pain.


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## jeffp (Jan 18, 2015)

*Re:hard to find parts*

I was waiting on an order from encompass to come in for the 7909 units I have been working on. The parts I really needed are NLA, the most significant part the flex pcb/cable from the laser to the cd pcb, and the bracket. I made the bracket without to much trouble from brass shim stock I have.
I was hoping I could get this part and not have to go to the extreme and make a cable myself. So I had this design in mind for the cable, and that turns out will not work. Solution, I utilized the 12 pin cable end to go into the pcb connector, then from the laser I used transformer wire, insulated, and I don't know the gauge. I have drug this roll of wire around with me for 20 years, it was used for small coupling transformers. Anyway, I started to run the wires, total pain, and got everything going that way. I used the high temp orange tape to secure the wires and make a cable. It turned out good, and I decided to buy some 1.4mil copper sheet to provide a ground shield, that is still on its way. 
I was not sure about the laser that was in the unit, so I took a chance and hooked that part up, DEAD, so I had to pull it apart, I was a little apprehensive about that, but figured if I had to start all over again, then what the heck.
I was able to get the old laser removed, and the new part installed without making a new cable, good to go. 
The cd player worked good, and I dialed it in but one thing that happened was the solenoid driver transistor smoked. I still don't know why, I was not even working on that part of the player, again total pain. I had to buy the part out of UK as it is not available here in the US, total pain. 
The player works, it just will not pull the solenoid to drop the cd, so manually, if I do it, the cd drops, and starts playing. 
So, a big PITA, but my cable works, and the cd player works, well less the solenoid but I verified the transistor was the only problem, Still pisses me off. I still can't figure out why it smoked, the board is a little loose in the player, but I could find no problems, and the player works fine, oh well, I will get the new part and everything will be good.

I am happy, the first deck got its audio cap upgrade, and is almost put back together. I just need to clean the main board, and screw it back together. The unit sounds excellent, and it is a refurbished unit that was totally trashed on. The second unit was no better, and had parts I had to manufacture, but it to will be a refurbished unit, with upgraded audio caps, total recap of the cd player, and main board for both units. 
anyway, I will get pictures of the units up when they are completed.


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## 1996blackmax (Aug 29, 2007)

Glad you are making progress! Sounds like it's been a lot of work. It will be great to have both units up & running.


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