Magnavox CDB-460 Measurements and Review (CD Player)

[tpd]

Here's a link to the June 1987 issue of Audio in which Walt Jung discusses the CDB-650 and offers some starter modifications: https://www.worldradiohistory.com/Archive-All-Audio/Archive-Audio/80s/Audio-1987-06.pdf

I would love to see both parts of the POOGE-4 articles if anyone has the originals to scan. Those issues (The Audio Amateur 1988 issues 1 and 2) have been difficult to track down.

 

[tpd]

Re-measured using the suggested technique:

 

[AnalogSteph]

That's more like it.

 

[tpd]

Revised measurements here. I'll add a link in the first post to these new measurements for clarity.

 

[tpd]

And here are measurements for my second CDB-460. This was also re-capped and cleaned up, and is identical except: I removed the original filter op amps, soldered in sockets, and have a pair of Burr Brown OPA2132 op amps in there now. I don't think it makes a measurable or audible difference.

 

[tpd]

PS: RCA output for the second CDB-460 is...

Right: 2.002Vrms
Left: 2.041Vrms

 

[DMS-MN]

There are some power supply capacitors known to go off on, particularly on the driver board. The symptom is inability to detect the TOC. Unless there's a good reason to do otherwise, I often take the shotgun approach of replacing all electrolytics in any gear 30+ years old. They are all well past their rated lifetimes and post-replacement measurements frequently show elevated ESR.

Unlike Sony-based CD mechanisms, the Philips CDM drives seem to be pretty robust and often just need cleaning and a new belt. If they don't read, it's usually because the power supply is wonky. At least that's my experience across 5 Philips/Magnavox players so far.

Hoping to tag along on this reply, since Cap replacement was commented on as well as the CDM2 robust-ness. I have a CDB-650 also with a CDM2 drive (not sure which CDM2-x variant). Mine has started to NOT recognize all brands of burned-disks that formerly worked just fine. It's been back and forth to a shop with a set of various CD brands all ripped from the same audio files - the shop says the laser diode is getting weaker, but if that drive is considered "robust," I'm wondering isn't more likely a power supply issue as was stated. I've rebuilt and recapped a lot of audio gear and have standard tools like a capacitor ESR meter, oscilloscope, etc. I'm really hoping that it is NOT the laser diode itself and sure would appreciate hearing more about known successes in re-capping the CDM2 driver board AND/OR the CDM-650 mainboard itself.

 

[tpd]

Hoping to tag along on this reply, since Cap replacement was commented on as well as the CDM2 robust-ness. I have a CDB-650 also with a CDM2 drive (not sure which CDM2-x variant). Mine has started to NOT recognize all brands of burned-disks that formerly worked just fine. It's been back and forth to a shop with a set of various CD brands all ripped from the same audio files - the shop says the laser diode is getting weaker, but if that drive is considered "robust," I'm wondering isn't more likely a power supply issue as was stated. I've rebuilt and recapped a lot of audio gear and have standard tools like a capacitor ESR meter, oscilloscope, etc. I'm really hoping that it is NOT the laser diode itself and sure would appreciate hearing more about known successes in re-capping the CDM2 driver board AND/OR the CDM-650 mainboard itself.

Unfortunately, I have only anecdotal evidence to offer so take from it what you will.

Neither of my CDB-460s could read any disk consistently until I recapped them. One of them still has occasional issues reading CD-Rs. I'm not sure why. Could be dust on the lens. Could be an aging laser. Could be bad/failing disks. I've retired that player for the moment to do no further harm.

My CDB-650 is not yet recapped and has issues reading some disks when cold. If I give it a few hours idling to warm up, whatever aging component is the problem seems to sort itself and it reads CDs and CD-Rs fine. This one is to be recapped anyway at this point and I'll retest the CD-R read issue then.

I had a spindle of old (2010s), budget CD-R blanks that started failing. Newly burned disks on those blanks would only read on my newer players if at all. Some research across other forums suggested that other people are encountering similar problems with blanks of that era, even from "trusted" brands. IIRC it had something to do with one of the US manufacturing facilities shutting down. I spent some time looking for vintage Verbatim and TDK blanks and those seem to be working well across my CD players. Sorry that is sadly vague advice. If I can find my notes from that search I will post them.

 

[tpd]

There's some clues in this old sh thread: https://forums.stevehoffman.tv/threads/since-ty-death-what-brand-of-cd-r-do-you-buy.595221/

OLD Verbatim has been relatively easy to find. JVC-branded TY/CMC discs are still around new.

 

[rockrink]

Hoping to tag along on this reply, since Cap replacement was commented on as well as the CDM2 robust-ness. I have a CDB-650 also with a CDM2 drive (not sure which CDM2-x variant). Mine has started to NOT recognize all brands of burned-disks that formerly worked just fine. It's been back and forth to a shop with a set of various CD brands all ripped from the same audio files - the shop says the laser diode is getting weaker, but if that drive is considered "robust," I'm wondering isn't more likely a power supply issue as was stated. I've rebuilt and recapped a lot of audio gear and have standard tools like a capacitor ESR meter, oscilloscope, etc. I'm really hoping that it is NOT the laser diode itself and sure would appreciate hearing more about known successes in re-capping the CDM2 driver board AND/OR the CDM-650 mainboard itself.

Whenever I get one of the 650s, I take a look at the blue axial capacitors on the servo board. That is the board that is physically attached to the Mech unit. I would warn to be very careful of the flex cable if you dig in to this. The schematic for that servo board is part of the documentation for the CDM, not the 650. The one cap that always seems bad is 2103. It is supposed to be 33uf. Generally, unless already replaced, these will measure less than 12 uf and have an ESR of over 20 ohms. In my opinion, this cap is the first thing to be checked on any 650 that is showing symptoms. I usually just replace this with a Vishay series 021 axial cap of the same value, though some recommend increasing the value to 47uf.