My Philips CD-60 (same model as Marantz CD-60) was subjected to a moderate shock (fell onto its side onto a carpeted floor) about 1 foot (0.3 meters).
Powering up, fluorescent display seems fine, and the motor tray (drawer) works fine. But when a CD tries to boot, it slightly spins forward, then backward a little, but never spins up ... it just gives up, so no reading of Table Of Contents.
A brief measurement of voltages seems to indicate all voltages are okay. I did very briefly inspect the PCB for broken joints -- none visible.
I think the laser is okay. I put my smartphones' camera right on top the laser (so I could safely watch the laser turn on). And, yes, upon hitting Play, the laser illuminates (red) and does its focus routine.
Not really sure where to go next .... any help appreciated!!
Powering up, fluorescent display seems fine, and the motor tray (drawer) works fine. But when a CD tries to boot, it slightly spins forward, then backward a little, but never spins up ... it just gives up, so no reading of Table Of Contents.
A brief measurement of voltages seems to indicate all voltages are okay. I did very briefly inspect the PCB for broken joints -- none visible.
I think the laser is okay. I put my smartphones' camera right on top the laser (so I could safely watch the laser turn on). And, yes, upon hitting Play, the laser illuminates (red) and does its focus routine.
Not really sure where to go next .... any help appreciated!!
Highly unlikely
Highly unlikely. Think about all the inertia and "shock" they go thru during normal play.
An experiment ...
Okay, here's some other weird stuff ... on the assumption that it was the Philips CD60's CDM4/19 that may have been damaged, I swapped it with another (good) CDM4/19 from a Philips CDB610 .
Both the Philips CDPs are very similar, down to PCB, and were manuf'd in late 1989.
When I swapped the CDM4/19s, both players exhibited exactly the same problem I outlined in the original post.
Next, I put the CDM4/19s back in original players (i.e., before swap). The Philps CD60 still has the same problem as reported in original post. But the CDB610 plays fine.
The only thing I can speculate is that the CD60, after the accident, developed multiple transport issues. Or maybe the laser power needs to be adjusted?
Okay, here's some other weird stuff ... on the assumption that it was the Philips CD60's CDM4/19 that may have been damaged, I swapped it with another (good) CDM4/19 from a Philips CDB610 .
Both the Philips CDPs are very similar, down to PCB, and were manuf'd in late 1989.
When I swapped the CDM4/19s, both players exhibited exactly the same problem I outlined in the original post.
Next, I put the CDM4/19s back in original players (i.e., before swap). The Philps CD60 still has the same problem as reported in original post. But the CDB610 plays fine.
The only thing I can speculate is that the CD60, after the accident, developed multiple transport issues. Or maybe the laser power needs to be adjusted?
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Hardly any shock during normal play.
Granted, they go through more shocks being thrown around by couriers/port/airport staff on their way from the Manufacturer to the end user.
Could it be the alignment pot/s have been knocked out of alignment? Worth a tweak.
P.
alignment pot/s
Never received a damaged/defective unit.
I think I see two trimmers on the PCB, just below the CDM4. I have no idea how to adjust these. In the Serv. Man., there seems to be some procedure using an o'scope?
EDIT:
I see two trim pots: Focus Offset [22k] and Laser Out. Adj. [4K7]
Which to attempt first? Is there a formal procedure?
I have several Philips/Magnavox CDPs of this vintage ... all bought used from eBay ... all shipped to me w/o transport screws ... all packaged from mediocre to poor.
Never received a damaged/defective unit.
I've read about alignment pots -- and see some trimmers on the PCB -- but have never attempted it.
I think I see two trimmers on the PCB, just below the CDM4. I have no idea how to adjust these. In the Serv. Man., there seems to be some procedure using an o'scope?
EDIT:
I see two trim pots: Focus Offset [22k] and Laser Out. Adj. [4K7]
Which to attempt first? Is there a formal procedure?
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Running out of options ...
Again:
The disc does start to spin slowly -- a few turns -- reverses rotation slightly, then stops. Most working Philips players will go thru this same routine with no disk (e.g. power up, or closing the drawer, or hitting Play with no disk).
I did the no-clock test: removed the osc. (clock) from the circuit. And the disk-spin motor spins at crazy-fast speed (charc. of no clock signal).
I did mark and slightly adjust both Laser Power and Focus Adj. But no luck.
I also re-flowed (solder) several transport-related circuits. But, no go!
Socket to what ? ... flexprint -- I doubt it. Spin motor ... nope.
Again:
The disc does start to spin slowly -- a few turns -- reverses rotation slightly, then stops. Most working Philips players will go thru this same routine with no disk (e.g. power up, or closing the drawer, or hitting Play with no disk).
I did the no-clock test: removed the osc. (clock) from the circuit. And the disk-spin motor spins at crazy-fast speed (charc. of no clock signal).
I did mark and slightly adjust both Laser Power and Focus Adj. But no luck.
I also re-flowed (solder) several transport-related circuits. But, no go!
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Symptoms for troubleshooting ...
Some other symptoms just after the accident:
I powered the CD60 only after removing the cover to make sure all "looked" okay.
Powering up, display was normal and (I think) a CD was spinning/playing fine, BUT:
- there was a loud buzz at output jacks (both channels)
- there was a mild acrid odor (like something overheating)
- TDA1541A very warm to touch (after player being on only a min. or two -- not normal. I powered off immediately. I didn't check the other ICs/components for similar heat. The smell could've been coming from anywhere. The Mains 300mA fuse never blew.
I removed the TDA1541A (a damn $$ double crown!) and checked it in another CDP -- sounded good, no heat issue.
I removed the output opamps from the CD60 (they were fine).
Then, I re-powered the CD60 sans TDA1541A and output opamps. No smell, no fuse blowing. No shorts to ground AFAICS. And all voltages tested fine.
I didn't put in a CD yet.
I re-inserted another TDA1541A, and output opamps into the CD60. No heat issue, output was quiet (no buzz).
Now, I put in a CD and ran into the topical issue!
All "look" good AFAICS.
Some other symptoms just after the accident:
I powered the CD60 only after removing the cover to make sure all "looked" okay.
Powering up, display was normal and (I think) a CD was spinning/playing fine, BUT:
- there was a loud buzz at output jacks (both channels)
- there was a mild acrid odor (like something overheating)
- TDA1541A very warm to touch (after player being on only a min. or two -- not normal. I powered off immediately. I didn't check the other ICs/components for similar heat. The smell could've been coming from anywhere. The Mains 300mA fuse never blew.
I removed the TDA1541A (a damn $$ double crown!) and checked it in another CDP -- sounded good, no heat issue.
I removed the output opamps from the CD60 (they were fine).
Then, I re-powered the CD60 sans TDA1541A and output opamps. No smell, no fuse blowing. No shorts to ground AFAICS. And all voltages tested fine.
I didn't put in a CD yet.
I re-inserted another TDA1541A, and output opamps into the CD60. No heat issue, output was quiet (no buzz).
Now, I put in a CD and ran into the topical issue!
It really could be anything. Burning could be a safety resistor cooking (Philips/Marantz used those like they were going out of fashion). Reason could be a rail problem somewhere.
You have to begin by checking ALL rails, perhaps even with a scope as well. Hum/buzz could possibly be a broken ground trace, perhaps near a corner of a board.
You have to begin by checking ALL rails, perhaps even with a scope as well. Hum/buzz could possibly be a broken ground trace, perhaps near a corner of a board.
If a safety R did burn, wouldn't it have taken down a rail or more-obvious "system"?
Maybe it didn't burnt out?
BTW: Are these the 1-10-ohm resistors found near power pins of ICs?
I thought they were noise reducers (like ferrtie beads)?
[/QUOTE]
Reason could be a rail problem somewhere.
You have to begin by checking ALL rails, perhaps even with a scope as well. Hum/buzz could possibly be a broken ground trace, perhaps near a corner of a board.[/QUOTE]Hmmm ... I'll check again but I'm skeptical. However disabling the problem is to the CDP, the problem is so "subtle". Is the CDM4 (and its supporting systems) that sensitive to power (rail) imperfections?
Safety resistors can go high in value when overloaded. 1 to 10 ohm sounds about right for the range of values, occasionally you may see a 47 or 100 ohm.
Don't loose sight of the fact that the original problem was physical impact... implying that something somewhere is cracked or open circuit.
Don't loose sight of the fact that the original problem was physical impact... implying that something somewhere is cracked or open circuit.
Going thru the PCB, I could see no broken traces.
All the low-ohm resistors (including the blue <1-ohm SMD on the solder side) are good.
Voltages are fine.
Now I have a new problem. After reassembling the player, after this latest round of troubleshooting, I'm getting fast spin on tray and disk motors. It's acting like it has no clock signal. But I scoped it to confirm a clock signal present all the back to SAA7310 decoder IC.
All the low-ohm resistors (including the blue <1-ohm SMD on the solder side) are good.
Voltages are fine.
Now I have a new problem. After reassembling the player, after this latest round of troubleshooting, I'm getting fast spin on tray and disk motors. It's acting like it has no clock signal. But I scoped it to confirm a clock signal present all the back to SAA7310 decoder IC.
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Concentrate on one definite fault. If a motor is spinning fast then begin at the motor and work back.
Why has it got voltage on it ?
Is the motor drive amp being 'told' to supply the motor with that voltage and polarity ?
If so why ? Work back. Where do the inputs to the drive amp come from ? If its a big chip then go around every pin on that chip with a scope and DVM and make sure all voltage and signal levels can be accounted for.
Why has it got voltage on it ?
Is the motor drive amp being 'told' to supply the motor with that voltage and polarity ?
If so why ? Work back. Where do the inputs to the drive amp come from ? If its a big chip then go around every pin on that chip with a scope and DVM and make sure all voltage and signal levels can be accounted for.
Upon power ON, I count three transducers (motors) going full-blast: disk-tray motor, disk-spin motor and the radial (laser-head swing-arm) motor. The laser head slams back against its back limit.
In order to troubleshoot, I've popped out just the PCB, and attached an LED to the tray-motor jack (as an indicator of rotation).
Not sure what these components have in common. Elsewhere on DIYA, there are a few threads on Philips CDPs with the disk fast-spin issue. I think a faulty the decoder chip is a popular solution:
Philips players(or cd40) why disc spins CCW
Philips CD 303 spins cd too fast and does not play
Chip failures?
I'm wondering if there was (somehow) an over-voltage possible, only for a few minutes? That might have damaged the SAA7310 and/or the uP chip (MC68HC05C8).
If you (or anyone reading this) have service experience with these vintage CDPs ...
- how common were/are "chip failures"?
- is there enough built-in protection (fuse, clean PSU design, etc) to minimize risk?
Reason for asking ... well, I'm bottoming out on patience and want to hit the solution in the next few days as I won't have time after that.
Meanwhile, still probing ....
Upon power up right after the accident, recall what I noted earlier about: (1) the burning smell, and (2) the very warm TDA1541A
I'm wondering if there was (somehow) an over-voltage possible, only for a few minutes? That might have damaged the SAA7310 and/or the uP chip (MC68HC05C8).
If you (or anyone reading this) have service experience with these vintage CDPs ...
- how common were/are "chip failures"?
- is there enough built-in protection (fuse, clean PSU design, etc) to minimize risk?
Reason for asking ... well, I'm bottoming out on patience and want to hit the solution in the next few days as I won't have time after that.
Meanwhile, still probing ....
Chip failures are incredibly rare under normal operating conditions. Whatever the fault is, it is never usually the 'big chip' you are suspecting, be that a uProcessor or some other LSI (large scale integration) type device.
If an overvolt condition occurs then all that goes out of the window and anything could happen, chips can fail, EPROM or even ROM data can get corrupted... anything.
The burning smell could suggest overvoltage, the TDA getting hot (if it really was) could be down to overvolts or it could be down to broken print causing the chip to operate in a non valid state and draw more current than normal.
No protection, resistor, fuse or CP (circuit protector type fuse) operates fast enough to protect semiconductors from damage but it is all relative... 6 or 7 volts appearing on a 5 volt rail is probably survivable for hours, whereas 20 volt transient could zap a device or corrupt its internal data look up table (EPROM/ROM) in a millisecond.
If an overvolt condition occurs then all that goes out of the window and anything could happen, chips can fail, EPROM or even ROM data can get corrupted... anything.
The burning smell could suggest overvoltage, the TDA getting hot (if it really was) could be down to overvolts or it could be down to broken print causing the chip to operate in a non valid state and draw more current than normal.
No protection, resistor, fuse or CP (circuit protector type fuse) operates fast enough to protect semiconductors from damage but it is all relative... 6 or 7 volts appearing on a 5 volt rail is probably survivable for hours, whereas 20 volt transient could zap a device or corrupt its internal data look up table (EPROM/ROM) in a millisecond.
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