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Need help fixing a Dual 701 turntable

P

Parisian man

New Member
Hi everyone!

I am new on this forum and really dig all the topics discussed here!
I have to say that I am pretty ignorant in electronics so please be kind with me if I use the non appropriate terminologies!
I am trying to fix my Dual 701 that suddenly stopped working last week.
After taking it apart, I found that one of the pin that brings the current to the transformer is not welded anymore to the tiny plate. (please see pictures attached)
I tried to solder it but it does not stay in place and the plastic that surrounds the area started to melt! Not so good.
I went to an electronic shop and they advised me that it needs to be welded back to the plate.
Question is: how to do that in such a tiny place like this one? They recommended spot welding but I don't have access to the bottom part of the plate since it is attached to the plastic frame.
Do you guys have encountered the same issue in the past?
Any tips on how I could fix this would be greatly appreciated!

Thank you in advance! Cheers!
 

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You should be able to remove the junction box from the chassis and re insert the pin from the bottom and create a proper flare to hold it/make contact mechanically before soldering. From the service manual looks like screws 109 and 113 on the opposite side of the plate chassis.
 
ps... mrow22 on ebay has an excellent service guide I recommend buying if you don't have it already.

No affiliation, other than a purchaser of his guide, grease and steuerpimpel package.
 
I solder those mother-......... all the time.
The switch box does not melt when you first coat the pin bottom with solder.
If anything gets hit by the heat of the solder pencil, it might be the divider between pins.
 
Some of the pins might only be a junction for the other wires slid onto it. In other words there is no connection other than between the wires you see above. If so, then you don't even need it to be attached. I have had those pins come off once in a while and have resoldered them but realised on one job I didn't need to as the wires only needed to contact the same conductive pin. Since they have the dividers and box cover to protect it can work fine.

However the pin in question here looks like it needs to be attached. I once slid a short piece of wire down into the hole the broken pin exposed and soldered that first. Then I slid the hollow pin over it and applied more solder and it held.
 
Hey guys!

Thank y'all for the replies!
@Music2Myear here's a closer look at that plate on this picture.

@Sam08861 I did not know I could remove that box. I'll take another look tomorrow. Thanks for that tip about the service guide. Looks very detailed. I'll get one for sure.

@NoTransistors I tried that but it did not work. You totally right, I melted the divider
I could try again with a pencil tip but I am just not sure if the solder would hold that pin in place over time.

@Montycat that is an excellent idea, I did not think of that! Do you remember by any chance what gauge you used? I will definitely try that and let you guys know if it worked!

Thanks again for your support. Cheers!
 

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So, I was able to solder the pin to the plate by putting a copper wire inside. Thanks @Montycat for the tip!

I replaced the fuse. Put it back together but...no luck! Still no power.

Do you guys have any idea what I should do or troubleshoot?

Thanks a lot!
 

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Assuming you're getting power from the AC connection . . .

You probably need to replace the cruddy Frako capacitor in the power supply. It will be the one that has the casing cracked on half.

Should be C52, 0.047uf. I use the WIMA MKP-X2 275v ones. Snip the leads near the old cap. The WIMA is a bit smaller and the leads are short so you'll need to solder the new leads to the old ones.

Some folks on AK say C3 may need to be replaced as well. Haven't had to do that myself. Just C52.

And don't forget to order extra fuses while you're at it.
 
Last edited:
bangsezmax said:
Assuming you're getting power from the AC connection . . .

You probably need to replace the cruddy Frako capacitor in the power supply. It will be the one that has the casing cracked on half.

Should be C52, 0.047uf. I use the WIMA MKP-X2 275v ones. Snip the leads near the old cap. The WIMA is a bit smaller and the leads are short so you'll need to solder the new leads to the old ones.

Some folks on AK say C3 may need to be replaced as well. Haven't had to do that myself. Just C52.

And don't forget to order extra fuses while you're at it.
Click to expand...

I read on different posts and forums that this capacitor has to be changed when experiencing no power issue.
In my case, it does not seem to be physically damaged. (please see pictures)
I don't have a capacitor tester right now so I cannot test it. I have to order a tester soon...
I'll go get another cap at the shop.

Could you please confirm if C3 is this silver capacitor? (20200306... picture) I cannot find the answer online...
Thanks very much!
 

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It appears to me from the schematic C 52 it across the 110 v line ,so its a spark suppressor cap . You will need a meter to help diagnose this get one with a continuity buzzer feature. The black wires in first pic look a bit suspect. Have you downloaded the service manual from vinylengine, it has voltages labeled on schematic. C3 is on schematic 470uf after the bridge rectifier.I would be looking at connections and solder joints first off.

its at bottom. https://www.vinylengine.com/library/dual/701.shtml
 
Music2Myear said:
It appears to me from the schematic C 52 it across the 110 v line ,so its a spark suppressor cap . You will need a meter to help diagnose this get one with a continuity buzzer feature. The black wires in first pic look a bit suspect. Have you downloaded the service manual from vinylengine, it has voltages labeled on schematic. C3 is on schematic 470uf after the bridge rectifier.I would be looking at connections and solder joints first off.

its at bottom. https://www.vinylengine.com/library/dual/701.shtml
Click to expand...

I'll get a capacitor tester asap!
Yes I downloaded the service manual, very helpful even if I don't understand everything!
The black wire looked strange to me too. This would be D51 based on the SM, correct?
And yes, I replaced the fuse. When I turned the turntable on, i saw for a second the strombo light on then nothing else. The fuse is still ok though!

How do you take apart the power board?

Thanks!
 

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This is tricky trying to get info across , I have a 1019 and it only has a spark capacitor to worry about.
The D51 is a Diode, the wire is at those two spots with arrows pointing left.
A digital multi meter with a continuity buzzer feature is what would be of help here to test if you have a path from point to point .Checking capacitors you need to lift one pin to get a proper reading. Once you have the path ok then I would just recap one at a time . there cheap enough. Best to get it working first.
 
Sam08861 said:
ps... mrow22 on ebay has an excellent service guide I recommend buying if you don't have it already.

No affiliation, other than a purchaser of his guide, grease and steuerpimpel package.
Click to expand...
Hi, he no longer has these items up for grabs anymore on ebay. Any way you could shoot it my way / put me in contact with him?
 
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