Dual 1229Q bad channel

If you take out the sub headshell (TK-14) and look where it's 4 springy pins are suppose to connect, you'll notice a thin copper tab that ground the tonearm to the right channels ground (green). Sometimes this thin copper tab bends and shorts other tracks on that micro pcb. Make sure it's dead centred and doesn't short.

tnsilver, is this the tab you are referring to?
https://imgur.com/a/1Ifzz

75i1pGH.jpg

75i1pGH.jpg
 
Yup. That's the one. Notice how at the bottom of it, there's a trace to the right channel's shield (green), which is covered in solder in this picture.
Actually, these traces look dead to me. You may want to use a DMM's continuity test to make sure they conduct all the way, and bridge them
with solder or left-over capacitor leads, if they don't.
 
Yup. That's the one. Notice how at the bottom of it, there's a trace to the right channel's shield (green), which is covered in solder in this picture.
Actually, these traces look dead to me. You may want to use a DMM's continuity test to make sure they conduct all the way, and bridge them
with solder or left-over capacitor leads, if they don't.

Thank you! Can you tell if my tab looks ok? I wonder if I bent it somehow switching out the sled. I had had a few beers.
I have a few of the TK14 sleds - I have the kind with the springy pins and the kind with the bent copper bands as connection points. When I was diagnosing this problem, I put an older Dual cart that I don't use on one of the sleds (darnit I wish I could remember which sled it was!) and I got it working. So then I think I put my good Empire cart on that sled and only got sound out of one channel.

I don't know what a trace is. Are they the four horizontal copper bands on either side of the aforementioned tab? (Actually, I guess there are five of them including the one behind the tab). To check continuity, do I just use a multimeter do I just put one probe at the top of the band and the other probe down on that tiny circle thing or the solder?

Sorry, I'm pretty new to this. Not sure exactly what "bridge them with solder or left-over capacitor leads" but I'll cross that bridge when I get to it!

Thank you very much again!
 
It's not hard to spot. It looks OK. It's straight and comes in contact by the force of it's springiness with only the central trace of the micro PCB in the HS.
Bridging the traces just means to re-flow them with molten solder instead of the old copper on the original trace that appears worn out. Sometimes, if
you can't spread enough solder over a long stretch of old trace with a soldering iron, it's easier to solder a thin capacitor lead over the old trace to fix
it. You should first test to check if it's really worn out or just appears that way.

Here, I marked one of the 5 traces for you. The yellow rectangle shows how the central trace is connected with the right channel's ground/shield trace.
For all intents and purposes, it grounds the HS, and the entire TA. Remember the traces are what comes in contact with the headshell sled 4 springy pins.
Those pins should also be cleaned and checked for continuity all the way to the cart pins.

Lito1DB.jpg
 
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The copper tab was eliminated in the 1229Q. Also, the pic of the [above] p.c. board reveals that someone 'cleaned off' the silver plate. For the copper ground tab to work properly, the trace on the p.c. board needs to be clean and polished. Matter of fact, all the traces need to be that way. Early 1219 had the p.c. board glued in. Great glue that usually will not budge. So rather than forcing and breaking the board to get it out from behind the copper tab, I remove the tab. Mind you, when I do a rebuild, the arm is out. This makes it waaaay easier to press the tab back in place, as it is held to the alloy head in a small recess and by a few crimps in the alloy. Impossible to get the tab to hold again if working on the are still installed.
When Dual replaced the glue with a plastic holder, the job became lots simpler. Tom's p.c. board is not glued in. But that board looks like it was a boat anchor at one time and does need some attention.
 
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It's not hard to spot. It looks OK. It's straight and comes in contact by the force of it's springiness with only the central trace of the micro PCB in the HS.
Bridging the traces just means to re-flow them with molten solder instead of the old copper on the original trace that appears worn out. Sometimes, if
you can't spread enough solder over a long stretch of old trace with a soldering iron, it's easier to solder a thin capacitor lead over the old trace to fix
it. You should first test to check if it's really worn out or just appears that way.

Here, I marked one of the 5 traces for you. The yellow rectangle shows how the central trace is connected with the right channel's ground/shield trace.
For all intents and purposes, it grounds the HS, and the entire TA. Remember the traces are what comes in contact with the headshell sled 4 springy pins.
Those pins should also be cleaned and checked for continuity all the way to the cart pins.

Lito1DB.jpg
This is a huge help - thank you!

I assume I check continuity by place a probe about at the tips of your two arrows? Also assume I understand correctly that the solder in the rectangle is supposed to be connected like that?
 
I just read through all the old posts and newer ones in this thread. As I read the original problem, I was pretty sure the contact between head shell and carrier was the issue...especially with the older type carrier with the bent contacts rather than the spring-loaded pins. That older carrier is a constant struggle for most tables. You need to regularly straighten and stretch them out after removing and replacing to get good contact, and even then they might not make good contact at all points. I recommend not using the older carriers/sleds. Try to use the pin type. Re-wiring seemed a bit unnecessary, but if it works for you, it works for you. A new carrier was probably needed...maybe headshell at worst. I've seen a lot of those models, and they might look messy up in there, but will a bit of cleaning, I've always gotten them to work....even on tables that had rusted quite severely from damp environments for decades.

As for the later comments...I'd still look to the contacts on the carrier first...always. That will nearly always be your culprit. If you're using the older carrier with bent contacts, straighten them and stretch them out with a small screwdriver then try again. Hum is also, very often, the result of bad contact in there. But I'm sure you all know hum can come from a dozen other issues from grounds to poor RCA contacts.
 
The copper tab was eliminated in the 1229Q. Also, the pic of the [above] p.c. board reveals that someone 'cleaned off' the silver plate. For the copper ground tab to work properly, the trace on the p.c. board needs to be clean and polished. Matter of fact, all the traces need to be that way. Early 1219 had the p.c. board glued in. Great glue that usually will not budge. So rather than forcing and breaking the board to get it out from behind the copper tab, I remove the tab. Mind you, when I do a rebuild, the arm is out. This makes it waaaay easier to press the tab back in place, as it is held to the alloy head in a small recess and by a few crimps in the alloy. Impossible to get the tab to hold again if working on the are still installed.
When Dual replaced the glue with a plastic holder, the job became lots simpler. Tom's p.c. board is not glued in. But that board looks like it was a boat anchor at one time and does need some attention.

Any tips on how to give the PC board the attention it needs? I have deoxit spray and red and gold liquid deoxit tubes. My PCB does slide out readily (not glued in).
 
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I have to reiterate....after working with a few dozen of these, I have not needed to monkey with that tiny circuit board in the head shell. I would bet dollars to donuts your issue is with the contacts on your carrier/sled. If it's one of the older style with bent wire contacts, they are a constant hassle. Try working with them and wiggling the carrier a bit as you insert it before locking it in with the lever. I suggest NOT trying to re solder or over solder any of the original circuit board. And it never hurts to check your ground at the receiver. Clean that contact and maybe expose some new, clean wire.
 
Here are two more images of the PCB with better light:

dttFgLw.jpg

i6Ih5Ki.jpg


And here is the sled:
61CHGzd.jpg


Now a question: is the tab supposed to make contact with the middle trace at all times? That is should it be in contact when the sled is not inserted?
 
I have deoxit spray and red and gold liquid deoxit tubes. My PCB does slide out readily (not glued in).
Slide it out then, work the traces with DeOxit, use a rag to polish them as much as possible and test their continuity. If they check out, inspect the sled pins as mentioned earlier. Make sure they make good contact with your traces and that they have continuity with your cart's pins (through the HS wires). You got the sled with the springy pins. Good for you. That should be easier.

The ground tab is in contact with the middle trace at all times. Once you slide that micro PCB back in place, it should make contact with the center trace, regardless of the sled.
 
Slide it out then, work the traces with DeOxit, use a rag to polish them as much as possible and test their continuity. If they check out, inspect the sled pins as mentioned earlier. Make sure they make good contact with your traces and that they have continuity with your cart's pins (through the HS wires). You got the sled with the springy pins. Good for you. That should be easier.

The ground tab is in contact with the middle trace at all times. Once you slide that micro PCB back in place, it should make contact with the center trace, regardless of the sled.
I applied deoxit oil to the sled pins and connected everything shown in the photos very carefully - only have a left channel signal. Next step is to check the continuity of the traces.
 
I agree. Try checking from the head shell to the mute switch then to the RCA plugs and so on. If it's not the carrier contacts, you'll find out pretty quickly. Those little divots in the circuit board copper make a great place to put one of the test leads. I assume you tried more than one pair of RCA cables. It shouldn't take long with a tester to locate the break.

Or...you could test from the head shell all the way to the receiver end of the RCA cables. If you have continuity there, obviously you're back to the carrier.
 
I play 'musical cartridges' a good few times per week. From the beginning, it was the sleds with spring-loaded pins that were an intermittent issue. Do not know why. Perhaps the crimps are poor. Tarnished silver plating under these crimps is a big issue. I have far fewer customers calling me about the occasional intermittent after they change a mounted cartridge since having this epiphany and changing my preference to the older sleds.
And yes, the proper Caig contact treatment product is your friend.
 
I play 'musical cartridges' a good few times per week. From the beginning, it was the sleds with spring-loaded pins that were an intermittent issue. Do not know why. Perhaps the crimps are poor. Tarnished silver plating under these crimps is a big issue. I have far fewer customers calling me about the occasional intermittent after they change a mounted cartridge since having this epiphany and changing my preference to the older sleds.
And yes, the proper Caig contact treatment product is your friend.

I have seen this too. Been lucky as a good cleaning has eliminated the problem. My "early" 1219 had broken arm with the tube not damaged! The PC was undamaged. Had a good sled holder that I put on. Didn't glue the PC in place. Cleaned the contacts with Caig. Kept this 1219 as it's an early one. Minty. Even the blushed aluminum parts aren't tarnished. Ran yesterday in the shop. No problems with channels droping out
 
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I have to reiterate....after working with a few dozen of these, I have not needed to monkey with that tiny circuit board in the head shell. I would bet dollars to donuts your issue is with the contacts on your carrier/sled. If it's one of the older style with bent wire contacts, they are a constant hassle. Try working with them and wiggling the carrier a bit as you insert it before locking it in with the lever. I suggest NOT trying to re solder or over solder any of the original circuit board. And it never hurts to check your ground at the receiver. Clean that contact and maybe expose some new, clean wire.

I have one of each sled type and I've been trying both of them. I've had a feeling since this problem started a couple days ago that the issue was with contacts. I've been trying to get the newer pin model to work. Maybe I need to get a new sled if I can't get any of these to work. This all began when I tried switching sleds. Before swapping them, I had the sled with the old bent band contacts and it was working fine. Now I can't get either to work. Eventually I'll get this!
 
Try the old carrier but stretch the contacts outward to give plenty of chance to make good contact with the shell. I've had 1219s that liked the old carriers better. there is more surface contact with them, I think, compared to the small tips of the spring-loaded type. Did you continuity test anything?
 
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