Interesting Model Thirteen. Prototype?

[JKent]

Just acquired another Model Thirteen stereo adapter to pair up with a Model Eight table radio. This one may be an early prototype.

As shown in the photos, the back of this one does not have the printed lettering (it has Dymo labels instead) or serial number label (one of my other Thirteens is shown for comparison) and the layout was apparently done by hand, as shown by the scribe lines. Finally, the SCA filter switch looks to be an afterthought. The cutout is crudely made, it is too close to the AC outlet (in fact the flanges overlap inside the case) and it is attached with machine screws instead of rivets.

Don't have this working yet. One of the PC boards was shattered and wires were broken, pointing out another clue. On my other Thirteens, the machine screws holding the transformer in place go through to standoffs on the chassis and serve double duty attaching the PC board to the chassis. On this one, the board is attached at the 4 corners, so the heavy xformer in the middle is supported by nothing but the board. No wonder it broke!

So far I've removed everything from the broken board, laminated a piece of fiberglass cloth to the top with epoxy, rebuilt the board with new caps and diodes and reinstalled it. Still needs work though--the sound is badly distorted.

Will post my progress (assuming there IS any )

Kent

[Andy]

Yet another interesting piece of KLH history found by kent. It seems that every once in awhile a pre-production, or production variation item surfaces with the KLH label. Never seen that.....thanks for sharing the photos.

As I posted a couple of years ago - I bid on a model Thirteen with a solid walnut cabinet that was factory labeled "model eight stereophonic adapter" on the front panel ! Left a crazy bid of about $450., but was outbid *%#!

Andy

[JKent]

"Progress" to date:

POWER SUPPLY BOARD

1. Removed all components from PS board, laminated fiberglass cloth to board with epoxy. Replaced separated pieces

2. Repopulated board with original transformer and inductor. Other components new.

3. Replaced 470 ohm resistor with new 470/1 watt flameproof

4. Replaced two 1N2859 diodes with new equivalents

5. Replaced missing fuse clip and fuse.

6. Repaired broken green, red leads from transformer.

7. Replaced 500uF 30v cap with 470uF 35v

8. Replaced 1000uF 15v with 1000uF 25v

9. Replaced 1000uF 30v with 1000uF 35v

PHONO BOARD

1. Replaced 100uF 3v lytic with 100uF 10v

EQ AMP BOARD

1. Replaced 400uF 30v lytic with 470uF 35v

MX BOARD

1. Replaced 100uF 3v lytic with 100uF 10v

STEREO PHONE PLUG/WIRE

This is the connection to the Eight and there seemed to be a short, so I replaced the plug with a new Switchcraft brand and also replaced th cable.

The transformer on the power supply board buzzes loudly. Squeezing the frame with pliers had little or no effect. I'd like to replace the transformer but not sure of the specs. This is all the info from the schematic:

I'll also go ahead and replace all of the remaining electrolytics: 4 more 100/10 and seven 16/16. Those will be tricky to find I think.

Here are some photos. First the broken PS board Here's the chassis from the top showing the repaired PS board, MPX board and Phono board Next is the new phone plug and the underside of the chassis, showing the EQ Amp board Finally, the buzzing xformer with its several spliced leads

Any suggestions welcome. John has been extremely helpful, as always, but other input would be great. Any thoughts on that transformer?

Kent

[bjornklh]

"Progress" to date:

POWER SUPPLY BOARD

1. Removed all components from PS board, laminated fiberglass cloth to board with epoxy. Replaced separated pieces

2. Repopulated board with original transformer and inductor. Other components new.

3. Replaced 470 ohm resistor with new 470/1 watt flameproof

4. Replaced two 1N2859 diodes with new equivalents

5. Replaced missing fuse clip and fuse.

6. Repaired broken green, red leads from transformer.

7. Replaced 500uF 30v cap with 470uF 35v

8. Replaced 1000uF 15v with 1000uF 25v

9. Replaced 1000uF 30v with 1000uF 35v

PHONO BOARD

1. Replaced 100uF 3v lytic with 100uF 10v

EQ AMP BOARD

1. Replaced 400uF 30v

MX BOARD

1. Replaced 100uF 3v lytic with 100uF 10v

Wow that board definately has some issues. As far as the transformer hum if it's not too loud it may be fine my 8 has always had some hum and hasn't failed me yet(knock on wood) plus my tech said it was fine. It's intesesting to see inside one of these surprsingly simple circut. Hehe I'm sure that's not what you want to hear after working on her you are ambitious but seriously why can't they make stuff like this anymore? Anywho good luck with her all the best

STEREO PHONE PLUG/WIRE

This is the connection to the Eight and there seemed to be a short, so I replaced the plug with a new Switchcraft brand and also replaced th cable.

The transformer on the power supply board buzzes loudly. Squeezing the frame with pliers had little or no effect. I'd like to replace the transformer but not sure of the specs. This is all the info from the schematic:

I'll also go ahead and replace all of the remaining electrolytics: 4 more 100/10 and seven 16/16. Those will be tricky to find I think.

Here are some photos. First the broken PS board Here's the chassis from the top showing the repaired PS board, MPX board and Phono board Next is the new phone plug and the underside of the chassis, showing the EQ Amp board Finally, the buzzing xformer with its several spliced leads

Any suggestions welcome. John has been extremely helpful, as always, but other input would be great. Any thoughts on that transformer?

Kent

[bjornklh]

Hey sorry my response is in the middle of that last post it's not all copied message there is a message in the middle of all that. So sorry I thought I deleted all the copied text hope I didn't make too much of a mess of the post.

[bjornklh]

Hey sorry my response is in the middle of that last post it's not all copied message there is a message in the middle of all that. So sorry I thought I deleted all the copied text hope I didn't make too much of a mess of the post.

[JKent]

Progress report:

A voltage problem was driving me crazy but with a lot of help from John finally traced it to a broken hair-thin transformer lead. Getting the right readings now.

Replaced all of the electrolytic caps. There were a bunch of 16uF/16v that I replaced with 22uF/25v (closest I could get locally). The old ones were OK--tested about 19-20uF. Also replaced a few 100uF/4v caps with 100uF/16v. The old ones were ALL shot.

Gave the transformer another squeeze with water pump pliers.

Plugged it in--MUCH less hum from the transformer.

Sound through the speaker attached to the 13 is garbled and staticky and with the 13 connected the 8 doesn't sound too good.

Hooked up a KLH 18 tuner to the Aux input and get the same garbled/staticky result. Ditto if the 18 is hooked up to the Phono input.

Here are some more pics. One shows the chassis top, with the 4 PC boards labeled. The other is the chassis bottom, where the EQ Amp board is.

And a copy of the schematic.

All suggestions welcome.

Kent

[Pete B]

Can you provide EBC voltage readings for all the transistors in the amplifier section,

with no signal applied.

You need to use a meter with a high input impedance, a DVM or VTVM.

Also, check the polarity on all the caps.

The unit uses Germanium transistors, these have very poor performance. Just keep

this in mind.

[JKent]

Hi Pete

Thanks for the help. Please bear in mind I'm a hobbyist and not a pro, so my 1st question is, "what's EBC?"

I was pretty careful with polarity when I replaced all the electrolytics, but will re-check. Fortunately I have a working Thirteen for comparison.

Are the germanium transistors those little round ones marked TS192? Think the replacement for that is 2N406.

Kent

[Pete B]

No problem Kent,

See the symbols section here for E B and C: http://en.wikipedia.org/wiki/Transistor

Forgot to mention ground the negative meter lead and measure each pin with respect

to ground. Be careful not to slip and short anything, transistors burn out instantly.

This measurement is going to tell us the DC operating point for each transistor and we

should be able to find one that is not biased correctly or defective.

You could put a current limiting resistor in series with the main supply, say 100 or

1K ohm depending on how high the idle current is; this would help protect from

accidents during debugging. That resistor can drop 1 or 2 volts without upsetting

the bias, any more and the resistor is too big. This would be very important if you

had a big amp that could blow $100 worth of output devices. Also consider that you

cannot get the Germaniums easily today.

Yes those stood out right away as Germanium, the rest might be also I didn't

check carefully:

http://semiconductormuseum.com/MuseumStore...2N109_Index.htm

The first pre amp I built as a very young kid from Popular Electronics used the similar

2N404 and it had a pathetic signal to noise ratio. It did work, I even etched the PC board.

[JKent]

No problem Kent,

See the symbols section here for E B and C: http://en.wikipedia.org/wiki/Transistor

Forgot to mention ground the negative meter lead and measure each pin with respect

to ground. Be careful not to slip and short anything, transistors burn out instantly.

This measurement is going to tell us the DC operating point for each transistor and we

should be able to find one that is not biased correctly or defective.

You could put a current limiting resistor in series with the main supply, say 100 or

1K ohm depending on how high the idle current is; this would help protect from

accidents during debugging. That resistor can drop 1 or 2 volts without upsetting

the bias, any more and the resistor is too big. This would be very important if you

had a big amp that could blow $100 worth of output devices. Also consider that you

cannot get the Germaniums easily today.

Yes those stood out right away as Germanium, the rest might be also I didn't

check carefully:

http://semiconductormuseum.com/MuseumStore...2N109_Index.htm

The first pre amp I built as a very young kid from Popular Electronics used the similar

2N404 and it had a pathetic signal to noise ratio. It did work, I even etched the PC board.

Thanks Pete

Hope to get on that today.

I see there are modern replacements for the germanium transistors. Of course that brings up an anxiety in the back of my mind: This is an early and rare Model Thirteen. Probably a prototype. By now I've replaced all the electrolytics with modern ones and the 2 diodes on the power supply board with modern replacements. I'm just wondering how big a deal it is if the components no longer look original. But that's sort of an aside. First concern is to get it working!

I'll visually check the polarity of each new cap by comparing them to a working Model Thirteen. Then I'll try to test all those transistors. Think there are about a dozen.

Kent

[Pete B]

I'm not suggesting that you change them, just know that they are a weakness.

I also forgot to mention that the Emitter, is the pin close to the small tab on the

metal case, Collector is opposite, and Base is in the middle.

You only have to do the line and poweramp section as long as you are sure that

is where the problem is.

[JKent]

Not sure which transistor is which (Q1 through Q13) so maybe this info is useless, but here’s what I got:

EQ Amp Board

E B C

-0.9 -0.9 -9.0

-6.9 -7.0 -15.0

-1.5 -1.5 -9.0

-6.9 -15.0 -7.0

MX Board

E B C

-4.9 -15.0 -4.9

-4.9 -15.0 -4.9

-1.4 -1.5 -15.0

-4.0 -6.8 -15.0

Does that make sense or do I need to figure out which transistor is Q1 etc? Also, I’m not absolutely certain I always identified E B and C correctly. In fact, I checked the readings yesterday then rechecked today and got some different readings. Damn amateur!

thanx

Kent

hmmm.. those "were" tables. Hope they are clear enough

[Pete B]

The format is fine as long as you add the transistor identifier.

I need Q11 - Q14. Please also measure the -12 and -27 supplies.

Start at the volume control and the .1 uF cap, follow it to Q11, then

from Q11 to the next transistor, etc.

[JKent]

Thanks Pete.

I've been getting a lot of behind-the-scene help from forum member johnieo. After much learning and a lot of false assumptions on my part, turned out there was ANOTHER voltage problem . The pin on the power supply board that was supposed to be -27V was dead. And of course the wire from there to the phono amp board carried nada, making those transistors look weird.

Pulled the power supply board AGAIN and underneath, where the pin went thru a hole to the trace, there was no solder. It "looked" like it made contact but it didn't. Some flux & solder and the contact is good.

Put it all together and plugged it in. It works! Only problems now are:

1. a hum through the speaker that is connected to the Thirteen when I move the input selector to Phono or Aux, or if I turn down the FM on the Eight. Speaker connected to the Eight does not seem to hum. Hum should mean a bad power supply cap but those are new.

2. sound is not hi fi. I'm sure the Thirteen needs adjustment and alignment. It has to be aligned with a Model Eight, as a system. Will take this to Bristol Electronics for that.

Any ideas about that hum?

thanx again

Kent

[JKent]

A strange turn of events...

The Thirteen is basically working. It needs alignment, which will require taking it to a pro, and there's that slight hum, which John says is most likely a bad ground somewhere. But it works

This is my third Thirteen. The first one is on a shelf, displayed. The second one was in storage but I pulled it out to serve as a model when checking #3. So I decided to hook up #2 to see how it sounds, compared to #3. Bad news--the FM sound from the Thirteen is so faint it is almost inaudible. And the sound from the attached Eight is poor. A separate KLH Model Eighteen tuner, that sounded GREAT plugged into the Aux inputs of Thirteen #3 did not play at all. And the infamous 3-position selector switch seems to have 4 positions. Never noticed that before and it sure ain't right

Pretty disappointing. Think I'll take THIS one back to the repair shop.

[JKent]

Here's an update on the "prototype" Thirteen.

Took it to Bristol Electronics and Tim said there wasn't much he could do with adjustment, because the adjusting screws are all glued in place! BUT he checked it out, cleaned up a couple of solder goofs and ran it for 6 hours, and it works!

The Thirteen is mostly a collector's item and not the highest of fi. The circuit is a bit primitive. Too bad Kloss decided to go with the "modern" transistors for this instead of sticking with tubes like the Eight.

But it works, and has very good stereo separation. Have not tried the phono section yet.

Here are photos of front and back, with the matching white knob Eight. Speaker on the right goes with the Eight and has dual 3" drivers and one of my linen grilles. The one on the left is the Thirteen speaker with the single 4" driver. Have not made a new grille yet.

btw--a revised version of my KLH Eight repair manual is complete, so I'll send it out to Mark to post in the Library. Stay tuned

Oh--and I just bought KLH Thirteen number 4. Plan to recap it, have it aligned, then sell two or three of these. Can't keep EVERYTHING! Tim asked if I have all of the Model Eights still in existence

I just enjoy finding them and restoring them. Only plan to keep two (a black knob and a white knob)

[JKent]

Quick update. I received an email from a fellow who asked whether I was a former KLH employee like himself (I'm not). He went on to say he worked at KLH starting in 1962, later went to Advent with Kloss. He said if I have a prototype, he probably built it! So I sent photos and got this reply:

I think I did build this one. Memories grow hazy over time, of course, but I remember using that color Dymo tape on some projects. The inside looks familiar - I remember having to spend a lot of time getting the multiplex decoder to work – it was new technology then! That whole pcb would be in a single chip today.

Cool! I asked about the non-adjustable adjustments and got this:

I remember using hand soap on the ferrite slugs in the adjustable coils so I could adjust them without “stick-slip”, then using hot melt as there was some suspicion that they were moving in shipping. After the first 100 or so of any product was built, I didn’t have much to do with it, so I don’t remember stopping the hot melt sealing operation.

I Love this hobby! Happy Thanksgiving to all fellow enthusiasts!

Kent