KLH model 20 & turntable.

Satcom123

Satcom123

Super Member
I recently picked up a KLH model 20 turntable. Cleaned it up and it plays but with very high hum. Opened the bottom cover and black plastic pieces fell out. These were part of the cases for the capacitors. I wrote down all the numbers of any capacitor I saw in this unit. There were some transistors too.

I have been searching hi and low for these transistors or equivalents. Can't seem to find them. They are marked RCA 31267, RCA 36145, and SG 4825.

Has anyone done a recap on this turntable and had the same problem with finding substitute parts? If someone has the manual, I would appreciate that. The bottom cover has a schematic but most it torn off.

As far as the transistors. I did a Mouser and Digikey search but to no avail.

Help and comments please.
 
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You might post this over in Solid State as that's likely where you are heading. Also, I'd strongly suggest you post some pictures for the 'arm chair' bench techs to look at. They're far better than trying to describe it in words alone.

Nice little compact music systems that really helped put KLH on the map. They're getting to be 50 years old so expect some work to them. I'd also recommend you not operate it until its fixed.

Cheers,

David
 
Thank you dshoaf. Did post in solid state about transistor finding and substitutions. I will do some expounding and pics over there. Thanks again.
 
I fixed one of these for a friend. That first power cap, a big black plastic thing. cracked and there were pieces all over the interior. The guts were hanging out and it hummed like the dickens. The bottom of the unit has the schematic. IIRC, the first power cap was 10,000uf (I don't remember the voltage). Something like that at 100V might be all you need. I did not replace transistors; just the first cap and the thing stopped humming.
 
When I recapped mine several years ago, I took some notes. Hopefully it'll help you figure out which ones you need. I didn't redo the transistors -- didn't need to. And be aware that the model specs did change some over time I believe, so ymmv.

Here's what I have in my notes:

Filters:
1500 uf, 25v, radial (x2)

Board next to transformer: (this may be the ones you're looking for -- the big ones are bunched together. If the 2000 is at 10 o'clock and the 1000 is at 6 o'clock, the 3000 is the one at 2 o'clock)
1000 mfd, 15v, radial
100 mfd, 15v, radial
3000 mfd, 40v, radial
2000 uf, 15v, radial

Board with pots:
100 mfd, 6v, axial (x2)
15 mfd, 15v, axial (x4)

Pre-amp:
100mfd, 15v, axial (x4)
15uf, 15v, axial (x2)

Tuner:
100mfd, 15v, radial
10uf, 15v, radial (x3)
1uf, 15v, radial

Tiny board:
1uf, 50v, axial

2 small boards at outputs:
100 mfd, 15v, radial (x2)
2 uf, 15v, radial (x2)
10uf, 15v, radial (x4)
 
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Thank you all and thank you Bangsezmax for the list. I don't know if the transistors really need replacing. My thought was hey if I can get them then why not replace them. I took many pictures at work and will post them tonight.
 
Recap it 1st. Test. If it works, don't mess with it. Is it FM only or the AM/FM version. I've got the schematic for both.(broken down to 3 scans each). There is no known Service manual, at least that I can find (been looking for almost 3 years now). It's a fairly easy unit to recap, just getting to some of the boards can be an experience.


6-3-2014 EDIT: ALL SCHEMATICS FOR THE MODEL 20 are on the AK Database, and www.HIFIENGINE.COM



Larry
 
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Yes Larry, It does seem pretty straight forward on the re capping of this unit. All the boards seem to be chasis mounted and the connections are pin, pull outs. I have decided to just recap the unit like you say and then test. Don't fool with the transistors.

One thing though is that the cam is stuck on there and I can't get it off to get out the old grease. I don't want to damage the center pin that is already kinda loose already. I know that it's bound up because of the end of record just skips and the cam will not activate. The platter stops. Have to help it, then it works for shut off. I guess I could try heat. I put penetrating oil on the center shaft in hopes after days it would loosen up. If you could send me any info on this unit it would greatly be appreciated. It is the FM only model.
 
Pull the whole changer out of there and flush the seized grease out with a solvent. If there are any plastic parts in the area, use something like CRC electronic cleaner. Its inexpensive and available at most auto parts stores. Most importantly, it won't melt the plastic parts. You may also have some luck applying a bit of heat. Not a great deal, but careful use of a propane torch or maybe even laying the tip of a good hot soldering iron on there to get some heat in the joint will do.
 
Glad I could help with the list of caps (mine was the FM only version, by the way). The only reason I wrote everything down was the reason Larry mentioned -- no service manual anywhere, and the schematic on the bottom of min was no longer readable. Glad I kept the list.

Be sure to sanity-check the list before ordering anything! I knew a lot less about electronics then than I do now.

As I recall (it was a few years ago when I was just getting started in DIY stuff), I gave up on replacing one or two of the big caps because I didn't have a soldering iron strong enough to get the thing unmounted (I have one now -- maybe I should revisit it :scratch2:). I replaced every other electrolytic though, and it sounds great.

If you're not aware, the original matching KLH speakers were 4 ohms. They're not bad, but like a lot of vintage speakers, the highs suffer in comparison to speakers with good dome tweeters. I've had really good results running a set of original Paradigm 3se's which are rated for 6 ohms. They make that thing sing. Love that Henry Kloss-designed gear!
 
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And as far as the cam goes, let the penetrant sit for a few days and then slowly and gently try working the wheel back and forth. That loose pin worries me a bit. I've yet to have a cam on a Garrard or a BSR fail to come unstuck, but you have to be patient and gentle.
 
Here are a few pics as promised. Disregard the date stamp. It keeps getting reset when batteries run out.
 

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Satcom123 said:
Yes Larry, It does seem pretty straight forward on the re capping of this unit. All the boards seem to be chasis mounted and the connections are pin, pull outs. I have decided to just recap the unit like you say and then test. Don't fool with the transistors.

One thing though is that the cam is stuck on there and I can't get it off to get out the old grease. I don't want to damage the center pin that is already kinda loose already. I know that it's bound up because of the end of record just skips and the cam will not activate. The platter stops. Have to help it, then it works for shut off. I guess I could try heat. I put penetrating oil on the center shaft in hopes after days it would loosen up. If you could send me any info on this unit it would greatly be appreciated. It is the FM only model.
Click to expand...

I've got both versions in a zip file. PM me and leave your email address in the PM, not in the post. There are bot's that check for emails then you get all kinds of spam. Your's is identical to mine, down to the plastic knobs. DO NOT TWIST THEM to get them off, you'll break the insides and then they won't work right.

If you're talking about the cam gear to the right of the spindle under the platter on the turntable, that is a common problem with Garrards. Penetrating oil, and a heat source(NO TORCH!) Soldering iron left on for a few minutes will break it free. Vinyl engine has Service manuals , which on the 20 is a variant of the AT-6.


6-3-2014 EDIT: ALL SCHEMATICS FOR THE MODEL 20 are on the AK Database, and www.HIFIENGINE.COM





Larry
 
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Thank you Larry. I PM'd you about the file. The knobs were on there pretty tight so I used the spoon pry method. I cleaned all the pots with contact cleaner and will order some big cans of de-oxit.

I am moving next month so things will be put on the back burner until I get situated at the new house. I will try the soldering iron on the cam center pin. Once I get the cam off I will inspect the looseness of the shaft. The shaft looks like it's swedged on so I will use some force to tighten it up. JB weld maybe?
 
The cam center shaft should be a long bolt that goes thru to the bottom and holds part of the mechanism together underneath.
 
bangsezmax said:
Board next to transformer: (this may be the ones you're looking for -- the big ones are bunched together. If the 2000 is at 10 o'clock and the 1000 is at 6 o'clock, the 3000 is the one at 2 o'clock)
1000 mfd, 15v, radial
100 mfd, 15v, radial
3000 mfd, 40v, radial
2000 uf, 15v, radial
Click to expand...

Hello all. I hope some of you are still watching this thread and don't mind me resurrecting it. I recently picked up a KLH 20+ for a steal and I'm in the process of restoring it. Cabinets were a bit rough, so I've stripped them down to bare wood and re-staining.

I am a complete noob at recapping, but I have spent a lot of time reading about the process. My question is around the recapping of the power supply. I have noticed that the modern Caps are significantly smaller than than the vintage ones in the power supply. For example the 3000 uF cap is roughly 36 x 87 mm. However, the modern equivalent (at least I think) is 18 x 35.5 mm. Is this something I need to be concerned with? Or am I selecting the wrong type of cap for the power supply?
 
Not really. It just looks funny. Cap sieze for the same value and voltage have decreased by at least 60-70% since the 60's. The thing that everyone seems to forget is all of the voltages are NEGATIVE. Which means the caps are reversed for polarity. In otherwords the +(Positive side) of the cap is ground. MAKE ABSOLUTELY SURE you orient the caps correctly or at least it won't work, or at worst, the caps will blow up in your face. Not a good result. The schematics will help greatly.
 
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