Columbia Masterworks Model M500 Audio High-Fidelity Series???

[WannabeAudiophile]

Hi everyone! This is my first post here! I came across this Columbia Masterworks Model M500 Audio High-Fidelity Series Stereo w/TT in a thrift store, I've got two weeks to return it, does anyone think it's worth the trouble to work on? It works, powers on, but the left channel is out on both the A and B channels. I found an old thread on here with the same problem and I might try some of those solutions, but is this worth anything? Are they desirable, rare, collectible? Anyone know the quality? Made by Columbia Records in the 60's? It's got a fairly nice BSR TT, and I know the TT works because it has RCA jacks that connect it to the amp, so I connected those to my Technics stereo and both channels work, although the bass seems over-pronounced and distorts on heavy bass notes. In order to get any further I'll have to tear it down some more and, again, just wondering if it's worth the effort.

Thanks!!!!!

p.s.-- I've also got a newer but vintage Sony with one channel out on both A and B as well. It was working great and then one day, no left channel. Did a cap blow? Diode? Can I use parts from the Sony to fix the Columbia?

Thanks again!!

[WannabeAudiophile]

OK, after tearing it down, (which was pretty easy, it was made to be worked on!) I found a blown cap directly in line with the left channel, it has to be the problem, but could that be the only problem? Could something else cause the cap to blow, or do they just go bad?

[Hyfi]

I am guessing no members here have experience with the item you asked questions about. Unfortunately, no response may be better than useless responses. Sounds like a fun project and pics would be nice.

[WannabeAudiophile]

98409843984298419844 Of course, I was being silly, sorry to waste your time. I'll try to make it more interesting with some groovy, far-out photos!

OK, you can see the top shell of the Masterwork unit with the TT, and then you have the green blown cap, with markings only on one side and it just says "250V" --so this blue one is the closest I could find locally without doing a lot more searching, it's a 1µF 250WVDC max. You guys think the green one is a 1µF?? You can also see what part of the amplifier board it came from (the pretty blue on the corner, it's not soldered in yet), it's the very last component the signal goes through on the left channel side, and the first one I came across working backwards, luckily! I can't wait to try it! What will happen to the board if it's the wrong value? Hopefully it will just blow the cap, right?!?!?

Oh, and what will happen if I use a 2.33V, .5A Krypton flashlight bulb in place of a regular flashlight-type 3V, .25A bulb? 2 of those light up the tuning dial.

[Mr Peabody]

What input did you plug the turntable into when seeing if it would work? If you plugged into a phono input and got distortion then try an AUX or CD input to see what happens. If it sounds more correct the table may have a ceramic cartridge which would indicate the Columbia is an entry level piece. Another way to check is if the table has a ground along with the red/white RCA's. If no ground another indicator it's ceramic. If there would be a ground wire it may be moving magnet and just need adjustments to the set up.

[WannabeAudiophile]

Wow, great info, thanks! I did plug it into the phono input, and I did think about plugging it into a different input but then I guess I just forgot. There is no ground wire, it's not surprising that it's an entry-level piece since I believe they gave these away if you bought a set of albums or something. I'm still an entry-level audiophile so it's a good match for me, I guess. I'll have to wait until I get the board soldered back together (which I have been procrastinating, waiting to see if anyone here would give me info about that capacitor) to try the TT again since it also relies on the power from the main unit, maybe the ground you speak of is in the power plug, it does have 4 leads? Wishful thinking, I'm sure it shows my inexperience.

[Mr Peabody]

Nothing wrong with good deals on hi fi, but I would not use a ceramic cartridge on my albums. Depends on how much you care about them. One of these cheap USB turntables would be better or look for another turntable at the thrift. Sometimes you actually find some real gems at the thrift. I'm not sure who hear has tech experience to answer your cap question, maybe Smokey. I'm pretty much plug-in-play, LOL

[Mr Peabody]

Moving magnet cartridges have a lower output than other sources like CD player or tape etc. so your phono input has a built in additional preamp to step the signal up. A ceramic cart wouldn't need this. That's what I suspect your distortion is from, overloading the phono input. The table may play fine through one of the other inputs. As I stated though ceramic is terrible sound and not even so good for your records. Some of the USB tables have the phono stage built in so if you get the Columbia to work you might want to just get another turntable to go with it. Some of these like Numark on Amazon are not very expensive.

[WannabeAudiophile]

Awesome, thanks! So anyway, I just found a loose ground wire, but I don't think it's long enough to have been the TT ground, but it could have been. Wait, does the TT ground have to come directly from the TT? If it does then this is for something else, I'd kill for a schematic... The ground wire is clipped off and looks like the end is tinned with solder, like it was attached to something... aaaanyway, I've got the cap soldered in and am ready to see if the left channel will work now, and if it does it may even help the sound problems...I'd say wish me luck but I don't believe in it :)

[WannabeAudiophile]

by the way, I don't really have any albums worthy of a nice TT, I mostly find vg+ records, listen to them one time and put them up for sale or trade. I'm just now getting back into records, I used to help my brother copy his albums back in the late 70's but haven't messed with them until now. I did sell an incredible copy of Grateful Dead Live in Europe when I was low on cash and I'm still kicking myself for it. I'm going to make sure I have a nice TT before I try to play anything better than thrift store vg records!