OK, Anatech, thanks!
So the two single caps in the picture, if connected with common ground to the middle connector and their positives to one of the two positive leads won´t work then. Too bad...
I´ll have to see see my way to ordering online, but it may take a while to set up if my daughter skives from helping me with an on-line order like this.
Meanwhile I´ll test the other units´ innards.
Let´s see what happens, said the blind man...
Cheers,
Aleatorylamp
So the two single caps in the picture, if connected with common ground to the middle connector and their positives to one of the two positive leads won´t work then. Too bad...
I´ll have to see see my way to ordering online, but it may take a while to set up if my daughter skives from helping me with an on-line order like this.
Meanwhile I´ll test the other units´ innards.
Let´s see what happens, said the blind man...
Cheers,
Aleatorylamp
They will work. They are just poor quality. You need to look at ripple current ratings at elevated temperatures inside the case.
Each component is designed in a certain way for a reason.
Each component is designed in a certain way for a reason.
You should be able to get the parts you need from digikey, mouser, or another reputable supplier. Don’t get parts off eBay or AliExpress.
The crackling in the preamp is likely dirty pots. The volume control on the 22 is a really hard part to work with since it combines volume, balance, and the on/off switch. Get some good contact cleaner (not wd-40!) and clean them up.
I would avoid doing any intrusive work on the 22 unless you absolutely have to.
If you haven’t already been warned, voltages inside the amp can be lethal, even when turned off. If you power the amp up you absolutely need to verify the power caps are discharged before you stick your hands in. Best to get a cheap second multimeter and hook it up to the caps and leave it while you’re working on it.
The crackling in the preamp is likely dirty pots. The volume control on the 22 is a really hard part to work with since it combines volume, balance, and the on/off switch. Get some good contact cleaner (not wd-40!) and clean them up.
I would avoid doing any intrusive work on the 22 unless you absolutely have to.
If you haven’t already been warned, voltages inside the amp can be lethal, even when turned off. If you power the amp up you absolutely need to verify the power caps are discharged before you stick your hands in. Best to get a cheap second multimeter and hook it up to the caps and leave it while you’re working on it.
Any DC potential across a good control will make it noisy. Just fixed a Sansui AU-111 with that exact issue. Leaky coupling caps are very, very common. I always estimate for them.
I wonder if a 100W soldering iron is a bit of a liability. I bought my Weller WECP-20 thermostaically controlled soldering iron 2nd hand, and it will probably fetch a similar sum to what I paid if I was to advertise it again. I have it set to a warm 360deg Fahrenheit, and I use a good quality Kester leaded solder with a roisin core
Similarly a variac is just about essential for slowly ramping up the voltages in long dormant or modified valve elctronics. Ultimately the job is a lot more fun if you have the right tools, even trivial bits like long nosed pliars and wire cutters.
You mentioned your multimeter does not function on all scales. A cheap digital multimeter will take a lot of uncertainty away when you need to debug voltages at a later stage.
Similarly a variac is just about essential for slowly ramping up the voltages in long dormant or modified valve elctronics. Ultimately the job is a lot more fun if you have the right tools, even trivial bits like long nosed pliars and wire cutters.
You mentioned your multimeter does not function on all scales. A cheap digital multimeter will take a lot of uncertainty away when you need to debug voltages at a later stage.
A cheap multimeter is a liability, period. So is a 100 watt soldering pencil or gun. KSGER stations are less than $100 Canadian. Temperature controlled, no leakage from tip. They will handle most needs and are adaptable with many different tips.
Hello again,
Many thanks ahankinson, for the list of possible online suppliers, for your warnings about eBay, AliExpress, and lethal voltages, and for the dirty pot solution!
I was wondering whether it is possible to try out the power amplifier on its own, without the control unit.
Hi OldHector,
Many thanks for your recommendations. I got a digital multimeter yesterday, and I could now identify that all resistors were fine, within their tolerance limits. Obviously, I discarded my misleading, defective voltmeter after that.
Then, when I de-soldered one side of the resistors to ensure proper measurements, it also turned out that the 470 Ohm resistor wasn´t cracked after all! - it was a grease streak or soldering flux that looked like a crack... Brown marks elsewhere seem to be this as well.
Hi Anatech,
"Each component is designed in a certain way for a reason."
Thanks! OK, I understand.
"No longer can you assume the parts people know what they are doing like the old days."
Yes, the shop assistants yesterday were adamant that their modern, small capacitators (photo in Post #59) were perfect for the current job - ignorant lot!
Thanks also for the info on the KSGER station. I´ll see if I can get one somehow.
Anyway: It is impossible to get the 32 mu 450v dual cap, and a reasonably priced soldering station (not 300 euros) locally, and this rather complicates things, as online purchases here are not as straight forward as in other countries.
Firstly, for security reasons, a separate bank account is best for such things, which includes the now normalized predatory banking charges.
Secondly, and worse than that, still too many ignorant suppliers refrain from shipping to Canary Islands - they think this is Hicksville, or some African ex-colony at civil war. Thus, a forwarding agent on the Spanish Mainland is required.
For a one-off thing, all this rigmarole just doesn´t seem worthwhile, I´m afraid.
My daughter often gets different things online, so it pays off for her to have a separate bank account. She uses suppliers who have discovered this is Europe here, but she´s abroad for the time being, so for now, I must make do with what there is here.
Anyway, I´ll see if any of the suppliers listed by ahankinson ship to Canary Islands.
Cheers,
Aleatorylamp
Many thanks ahankinson, for the list of possible online suppliers, for your warnings about eBay, AliExpress, and lethal voltages, and for the dirty pot solution!
I was wondering whether it is possible to try out the power amplifier on its own, without the control unit.
Hi OldHector,
Many thanks for your recommendations. I got a digital multimeter yesterday, and I could now identify that all resistors were fine, within their tolerance limits. Obviously, I discarded my misleading, defective voltmeter after that.
Then, when I de-soldered one side of the resistors to ensure proper measurements, it also turned out that the 470 Ohm resistor wasn´t cracked after all! - it was a grease streak or soldering flux that looked like a crack... Brown marks elsewhere seem to be this as well.
Hi Anatech,
"Each component is designed in a certain way for a reason."
Thanks! OK, I understand.
"No longer can you assume the parts people know what they are doing like the old days."
Yes, the shop assistants yesterday were adamant that their modern, small capacitators (photo in Post #59) were perfect for the current job - ignorant lot!
Thanks also for the info on the KSGER station. I´ll see if I can get one somehow.
Anyway: It is impossible to get the 32 mu 450v dual cap, and a reasonably priced soldering station (not 300 euros) locally, and this rather complicates things, as online purchases here are not as straight forward as in other countries.
Firstly, for security reasons, a separate bank account is best for such things, which includes the now normalized predatory banking charges.
Secondly, and worse than that, still too many ignorant suppliers refrain from shipping to Canary Islands - they think this is Hicksville, or some African ex-colony at civil war. Thus, a forwarding agent on the Spanish Mainland is required.
For a one-off thing, all this rigmarole just doesn´t seem worthwhile, I´m afraid.
My daughter often gets different things online, so it pays off for her to have a separate bank account. She uses suppliers who have discovered this is Europe here, but she´s abroad for the time being, so for now, I must make do with what there is here.
Anyway, I´ll see if any of the suppliers listed by ahankinson ship to Canary Islands.
Cheers,
Aleatorylamp
Might be worth introducing yourself over on the UK site UK Vintage Radio Repair and Restoration, since there may be local enthusiasts who could help with the equipment and parts to get started.
Hello everybody!
I have been learning a lot from all of you these days - my warmest thanks!
Given the circumstances, I proceeded to re-solder and mount everything as it was on the main amplifier.
Other than a thorough and careful cleaning job, and tightening one of the power connector nuts which was loose (!!!)🙁, nothing else was done.
Then, I cleaned the QCII selector contacts (without WD40!!), and saw nothing else suspicious, so I closed that one as well.
On the AMII tuner, nothing looked amiss, so I cleaned it a bit here and there, and closed it as well.
Now I have just been trying out the set again, and it works much better than before😀, except from the very annoying volume control crackle🤔. Even the cat´s eye seems to work fine, as do all the filters.
In LW, there are only automatic radio beacons to be heard.
In MW, 5 stations can be heard, and interference noises stop once fine-tuned reception is established.
In SW, there are many radio beacons, but on 15.5 metres in the little 19m bracket, there´s a French station clearly to be heard, that sometimes gives music. At times an East European folk music station mixes with the signal.
BTW, the antenna is a 10-metre cable hanging down from the window outside the building, held at 1 metre from the wall with a wooden pole that has the antenna taped to it at both ends.
So the problem seems to have been accumulated grit and the loose nut on one of the power studs inside the main amplifier.☕
Now I have to see about the main volume pot!😎 - probably not going to be very easy!
Thanks to all, and have a lovely day!
Aleatorylamp
I have been learning a lot from all of you these days - my warmest thanks!
Given the circumstances, I proceeded to re-solder and mount everything as it was on the main amplifier.
Other than a thorough and careful cleaning job, and tightening one of the power connector nuts which was loose (!!!)🙁, nothing else was done.
Then, I cleaned the QCII selector contacts (without WD40!!), and saw nothing else suspicious, so I closed that one as well.
On the AMII tuner, nothing looked amiss, so I cleaned it a bit here and there, and closed it as well.
Now I have just been trying out the set again, and it works much better than before😀, except from the very annoying volume control crackle🤔. Even the cat´s eye seems to work fine, as do all the filters.
In LW, there are only automatic radio beacons to be heard.
In MW, 5 stations can be heard, and interference noises stop once fine-tuned reception is established.
In SW, there are many radio beacons, but on 15.5 metres in the little 19m bracket, there´s a French station clearly to be heard, that sometimes gives music. At times an East European folk music station mixes with the signal.
BTW, the antenna is a 10-metre cable hanging down from the window outside the building, held at 1 metre from the wall with a wooden pole that has the antenna taped to it at both ends.
So the problem seems to have been accumulated grit and the loose nut on one of the power studs inside the main amplifier.☕
Now I have to see about the main volume pot!😎 - probably not going to be very easy!
Thanks to all, and have a lovely day!
Aleatorylamp
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Hi Aleatorylamp,
That's great news!
All I will say about service is, do it right. Get the correct parts (sorry it is difficult for you). The simple reason is this. Your repair is for decades, not a few months. The wrong part can cause a failure that ultimately destroys the output and / or power transformer. Total loss.
It would be such a shame to lose the equipment due to being in a rush, or for convenience. Doing things the right way is seldom the easy way - in all aspects of life.
Edit: Yes, the amplifier can be used alone. The input signal is on the rectangular plug where the preamp plugs in, however there is also high voltage in that location. Use your meter and be careful. That's why I modified some for an RCA input jack. I lost my pictures of how that was done, it isn't difficult.
That's great news!
All I will say about service is, do it right. Get the correct parts (sorry it is difficult for you). The simple reason is this. Your repair is for decades, not a few months. The wrong part can cause a failure that ultimately destroys the output and / or power transformer. Total loss.
It would be such a shame to lose the equipment due to being in a rush, or for convenience. Doing things the right way is seldom the easy way - in all aspects of life.
Edit: Yes, the amplifier can be used alone. The input signal is on the rectangular plug where the preamp plugs in, however there is also high voltage in that location. Use your meter and be careful. That's why I modified some for an RCA input jack. I lost my pictures of how that was done, it isn't difficult.
It is possible to use it without the pre-amp; that's how I use mine. However, you should be aware of the following:
- You can modify a power cable to add the two-pin power connector. However, this will not include any safety earth.
- The amplifiers depend on the connection to the pre-amp for earth / ground connection.
- My approach is to attach a spade terminal to the earth wire and then attach that to one of the screws next to the AC input on the amplifier
- The amplifiers do not have a DC blocking capacitor on the audio input, since it relies on the preamp for this. It's probably not a big deal, but if your line source presents a DC offset it can affect the bias on the preamp tubes.
- As @anatech notes, be careful with the pins on the 6-pin connector. Going against my previous advice, it is possible to find a 6-pin Jones to RCA adapter on eBay.
- This might be obvious, but your amp will amplify the signal at full bore, since there is no volume control. If you hook a CD player up to the amp directly, it will happily send that straight to your speakers. So make sure you have some sort of volume control.
Hi ahankinson, Hi Anatech,
Thank you very much!
The reason for my question was to be able to test the amplifier alone, but that is not necessary anymore.
Then, just after posting the question, I realized - "Oh, the amplifier won´t have volume control! How will that go, and how safe can a hook-up like this be?" - it always takes me time until the penny drops!
At any rate, use of SW and LW radio nowadays is at best limited, or rather nil, and AM is fine as a curiosity. My plan is to amplify the weak audio coming out of a source that is barely capable of driving a small 2W 8-Ohm speaker, and has no volume control. I expect that using the QUADII set will be easier than trying to build a two-transistor amplifier for it!!
Judging by this, if I use the QUADII plus the QCII, one of the rear-panel inputs on the latter might just do the trick very nicely.
Time to experiment some more!! Let´s see how it goes...
Cheers,
Aleatorylamp
Thank you very much!
The reason for my question was to be able to test the amplifier alone, but that is not necessary anymore.
Then, just after posting the question, I realized - "Oh, the amplifier won´t have volume control! How will that go, and how safe can a hook-up like this be?" - it always takes me time until the penny drops!
At any rate, use of SW and LW radio nowadays is at best limited, or rather nil, and AM is fine as a curiosity. My plan is to amplify the weak audio coming out of a source that is barely capable of driving a small 2W 8-Ohm speaker, and has no volume control. I expect that using the QUADII set will be easier than trying to build a two-transistor amplifier for it!!
Judging by this, if I use the QUADII plus the QCII, one of the rear-panel inputs on the latter might just do the trick very nicely.
Time to experiment some more!! Let´s see how it goes...
Cheers,
Aleatorylamp
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