CFS-99 is a very complicated box. Repair guy has lot of options here even to swap boards. Good luck with the repair! 
CFS-99 Left Channel Gone On Tape Deck Only
- Thread starter Gluecifer
- Start date
Since the switches are on top maybe it was corroded enough inside and is really not making good contactGluecifer said:
Rick,
The record bar (or other switches) might need more vigorous cleaning than you might think. It could explain all your problems.
However, if you are convinced that it's not the record bar, then it's also possible, even likely, that different issues are at play and that the left channel is just a coincidence between those 3 boxes. I took a quick look at the schematic and I don't see anything remarkable with the left channel that makes it any more likely than the right to be problem prone. In fact, the left and right channels are supposed to be mirror parallel circuitry.
The record bar (or other switches) might need more vigorous cleaning than you might think. It could explain all your problems.
However, if you are convinced that it's not the record bar, then it's also possible, even likely, that different issues are at play and that the left channel is just a coincidence between those 3 boxes. I took a quick look at the schematic and I don't see anything remarkable with the left channel that makes it any more likely than the right to be problem prone. In fact, the left and right channels are supposed to be mirror parallel circuitry.
I will do a vigorous cleaning on my CFS99 record bar and see if that solves my channel problem.Superduper said:
Let me see if I can do it this weekend.
BoomboxLover48 said:Gluecifer said:
Both my meters work fine for all functions.
My mistake! When it plays tape, the left meter is not working as it should. It jumps when I move it to tape function and then goes to rest. When I slide the balance slider to left channel, I get weak sound at peak volume.
Sorry to bring this old thread to life again but there appeared to be no evident resolution and I have the same symptoms with left channel though it might be on all functions (little more testing needed) as alluded to by Glu in his first post.
its also appears closely related to the balance slider with audio coming out of both channels when sat in the middle (no left VU action) then when moved to the left, the left chan audio disappears though of course this could be a symptom rather than a cause.
Its important to note that at this point I have NOT cleaned the record bar but have cleaned all other switches and sliders (including headphones) without any slight change or alteration to the outcome leading me to focus on the record bar next (which is facing away from where there is access without removing the board/chassis of course, never straightforward is it!). As alluded to by Norm about the record bar, I want to try and audio check at the bar and see if that can provide useful info.
I am going to do a little tracing here and there and see if we can come up with something around this issue which seems to be quite common it seems, any input appreciated.
its also appears closely related to the balance slider with audio coming out of both channels when sat in the middle (no left VU action) then when moved to the left, the left chan audio disappears though of course this could be a symptom rather than a cause.
Its important to note that at this point I have NOT cleaned the record bar but have cleaned all other switches and sliders (including headphones) without any slight change or alteration to the outcome leading me to focus on the record bar next (which is facing away from where there is access without removing the board/chassis of course, never straightforward is it!). As alluded to by Norm about the record bar, I want to try and audio check at the bar and see if that can provide useful info.
I am going to do a little tracing here and there and see if we can come up with something around this issue which seems to be quite common it seems, any input appreciated.
I left that box with similar issues alone, and might work on it when I get some time. FM was sounding very low on that box.
I have a fully working CFS 99. It is a very unique box to have in the collection.
I have a fully working CFS 99. It is a very unique box to have in the collection.
Record bar cleaned which had no effect,
I've signal traced backwards from the IC103 chip all the way back to the deck playback amp but it is proving difficult at the moment due to the area of the Preamp board being covered by a metal plate soldered at four different points. Q102 for the left channel has a higher than expected voltage at the base (1.2v should be 0.6v) and when compared to q202 for the right channel.
I also haven't yet eliminated the wire from the deck head to the connection board as it is really difficult to get into the head to test continuity.
Will continue to try and isolate.
I've signal traced backwards from the IC103 chip all the way back to the deck playback amp but it is proving difficult at the moment due to the area of the Preamp board being covered by a metal plate soldered at four different points. Q102 for the left channel has a higher than expected voltage at the base (1.2v should be 0.6v) and when compared to q202 for the right channel.
I also haven't yet eliminated the wire from the deck head to the connection board as it is really difficult to get into the head to test continuity.
Will continue to try and isolate.
Certainly is!
There is no audio at the base of q102 for the left channel when compared to q202 for the right channel.
Gonna have to try and remove the metal plate soldered to the board to get at the areas required.
There is no audio at the base of q102 for the left channel when compared to q202 for the right channel.
Gonna have to try and remove the metal plate soldered to the board to get at the areas required.
I have destroyed more cfs 99 boxes than i would like to say
and saved about 30%
it is a very hard one to work on
You need to work like a ninga
I have somehow fixed and sold about 5
I have killed many more
and spent in hours years of my life
not a simple thing
you will have so many parts hanging and then in the end if they all get back
you are blesed
this box will test your ZEN
and saved about 30%
it is a very hard one to work on
You need to work like a ninga
I have somehow fixed and sold about 5
I have killed many more
and spent in hours years of my life
not a simple thing
you will have so many parts hanging and then in the end if they all get back
you are blesed
this box will test your ZEN
Agreed.
I think that tieing so many wires across the amp board is not such a good idea from Sony.
The area I have seen wrong voltage readings are on the deck transistor amps and associated components located under these wires...
Ordered some resistors I don’t have so we’ll see. I need to get the correct voltage to q102 before progressing.
I think that tieing so many wires across the amp board is not such a good idea from Sony.
The area I have seen wrong voltage readings are on the deck transistor amps and associated components located under these wires...
Ordered some resistors I don’t have so we’ll see. I need to get the correct voltage to q102 before progressing.
Well... no further along, no left meter on any input.
Signal very low at IC303 for left channel when compared to right.
Seems something common from all inputs before IC303, such as record bar or... or I dunno.. 😩
Signal very low at IC303 for left channel when compared to right.
Seems something common from all inputs before IC303, such as record bar or... or I dunno.. 😩
Been working on this today a bit more and have done a test to try and confirm the issue which was successful.
I have ordered 2 components which should arrive next week, once hopefully confirmed, I will share the fix.
I have ordered 2 components which should arrive next week, once hopefully confirmed, I will share the fix.