Quad 33 no sound after revision

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07-Feb-2019 06:11 PM

J-O

J-O

Posts: 4

Hi,

I have applied the revision kit on my Quad 33 and now it's not working at all, I get no sound out of it. It was not working perfectly before though, I had sound from the right channel and just hiss from the other, but now it's dead quiet. The only thing that is working is the light on the front panel. I have been looking through the changes I have made and all seems OK and in line with the instructions. Last night I applied some contact spray on various controls and contacts and tried to tighten the connector sockets, but nothing came out of that - still no sound. I have 15.88 volts on the pcb so I am getting close to the expected 16 volts that was one of the goals of the update. I am using a Quad 303 which is working fine with my other preamplifier and I am using the interconnects I bought from DaDa ...

I know this in not much to go on, but do anyone have any ideas what could be going on here? The revision I did on my 303 was a great success, this on the other hand, is looking like a disaster ...
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26-Jun-2019 09:48 AM

Karl

Karl

Posts: 3

Sorry this isn't a solution, but I have exactly the same problem. Mine is a 33 with serial 16...something (apologies - away from the workshop at the moment) and Rev 3 Amplifier boards.  

It was working ok before the revision and now has no sound at all.  I'm pretty sure it's the amplifier boards I've messed up somehow, but I've checked and rechecked my soldering and all looks OK.

I tested the voltage from the red wire on pin 4 after doing the PSU upgrade and before moving on to the amp boards.  It read 15.8v.  I have also performed all the upgrades on the phono-preamp; disc input and tape input boards and the two caps on the motherboard, and double-checked all the soldering which looks OK.  I found a couple of loose joints 1st time around which I rectified.

I've tried radio 1 and 2 inputs and with the cancel in and out, and nothing.  

I've put my upgraded amp boards into another (not upgraded) known good 33 and they don't work there either.  I didn't want to try the good amp boards from the other 33 in the now non-working one in case there is something I've done that could damage them.

Any further troubleshooting advice would be really helpful if anyone has any ideas.  Can I check outputs from the amp boards with a multimeter and somehow isolate the problem?  I'm not very experienced with troubleshooting but keen to learn.
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16-Nov-2019 08:29 PM

J-O

J-O

Posts: 4

Mine is now working fine though I did not get any help from DaDA electronics. I turned out that the transistors I received with the revision kit were not the "Low Noise BC550" stated in the webshop. Don't remember now what I received but though they were compatible with BC550 they were not pin compatible. So after removing them and soldering them in again (after checking the data sheet for the item in question) everything worked like a charm ...

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16-Nov-2019 09:47 PM

Karl

Karl

Posts: 3

Ah OK.  That sounds worth a try.  Thanks.  So you had to reverse the pins i.e. solder them in the other way around.  Is that correct?  Many thanks.  Karl.

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16-Nov-2019 10:04 PM

J-O

J-O

Posts: 4

Yeah,

That's exactly what I did! Look at the transistors first and find a data sheet with the help of Google ... 

Good luck

Jan-Olov

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16-Nov-2019 11:07 PM

Karl

Karl

Posts: 3

Thank you!..  I will try soon.

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17-Nov-2019 04:36 AM

EJP

EJP

Posts: 1676

I'm sorry to hear this. What transistor type were you supplied?

EJP

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17-Nov-2019 10:43 AM

J-O

J-O

Posts: 4

It says C1845 on the casing which I believe is short for 2SC1845, a good low noise transistor like BC550. The BC550 is cbe pin out and the 2SC1845 is bce which I found out the hard way ...

Jan-Olov

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17-Nov-2019 10:22 PM

Joost Plugge

Joost Plugge

Posts: 971

Sorry to hear this, the KSC1845, labelled SC1845, is a transistor I used in my 405 HE board design, indeed it will work in a 33 but the pinning layout is different. There must be a mix up in the shop during packing.

Joost Plugge

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