Quad 34 Acting Up

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09-Nov-2017 06:31 PM

Navydiver

Navydiver

Posts: 27

Just acquired a Quad 34 and 306 Pre-amp and Power Amp. The 306 works great as I have also been using it with my Quad 44. Basically what happens is the Quad 34 makes a loud buzzing sound on power up which momentarily distends the drivers on my speakers. It also turns on the F1 and F2 filter lights (sometimes randomly only one but mostly two red lights) each time on power up. Here is a video I made showing/explaining the issue:  

https://youtu.be/7ISzTXpj30E

The amp works fine with my quad 44 on the 1.6V Output (have not tried it on the others yet as I was in a hurry to get to work) so I am assuming the amp is operating correctly. Before I bought the preamp there was an issue off an A/V guy, he did say one channel was not working on the pre. He had is technician look at it and apparently it was the balance control that was problematic. When he shipped he said it was fixed. After this power on issue occurs the preamp sounds absolutely fine - clean, no background noise. 

I guess my questions are:

1. Has anyone run into this issue before and if so what was the cause?

2. If I were to order the upgrade kit for this pre (which I will likely do anyway), would this solve the problem?

3. Is there a long lead special part I will need to order to solve this that anyone is aware of?

I believe the main circuit board inside the 34 is a V7 but could be wrong. Here are the pics of it:

https://s6.postimg.org/6l8j7xkb5/Quad_34_Main_Board_1.jpg

and

https://s6.postimg.org/mw8n494ip/Quad_34_Main_Board_2.jpg

Thank you
Tim

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09-Nov-2017 06:34 PM

Navydiver

Navydiver

Posts: 27

Oh yeah, serial is: Q 037374

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09-Nov-2017 06:37 PM

Navydiver

Navydiver

Posts: 27

image of back of units

https://s6.postimg.org/qfuku4k41/Quad_34_and_306_rear.jpg

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10-Nov-2017 01:46 AM

EJP

EJP

Posts: 1405

If it was the balance control you would have a balance problem.

If it comes from the preamp, I would investigate the muting circuit. A 34 is supposed to mute for a few seconds while it sorts itself out internally. This is controlled by the timing capacitor C69 and associated components, which include T14 and T15 right at the final output. You should also check that the green LED D33 is illuminated. It's inside the power cage.

F1 and F2 coming on at power-up is not normal, it is a separate fault, somewhere in the area of C68 and C79 respectively. Check the soldering on the whole of IC15 and IC16.

I hope you're not going to paint this one :-|

EJP
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10-Nov-2017 04:35 AM

Navydiver

Navydiver

Posts: 27

Thank you EJP
I just mentioned the balance issue for historical reasons to indicate there was a previous issue that was noted when I bought the unit. The technician fixed that but when I received it in the mail these other issues showed their ugly heads. I have to believe a decent tech would not let the unit go with these overt issues so maybe the shipping from Alberta to British Columbia (not far by North American Standards of distance) shook something up - who knows?

Anyway, pretty sure the issue is with the preamp as the 306 behave marvelously when I use it with my "painted" but beautiful sounding Quad 44. Concur with not painting the grey unit which is what I was actually trying to achieve through conversion with the Olive Drab Quad 44. I was trying to match it with my 405-2 and FM4. I did order a "grey" faceplate and "grey" chassis from Dada E here on their webstore to convert it to grey as my original plan. Unfortunately after a 2 month wait for them to arrive here in the far west of North America, they finally showed up and they were completely the wrong colour as per:  https://s6.postimg.org/xn1bmz3vl/IMG_20170823_1717129.jpg
note in the image the grey FM4 that I was hoping that the faceplate and the case would match and the bad cosmetic condition of the original 44 case. Anyway, mistakes do happen and I soon got over it. The flag scheme was always in my plan to try as I had planned to have two cases and two faceplates with which to experiment - that I achieved. This colour faux pas really just forced my hand into going with the flag scheme because it would not otherwise match my grey FM4 and 405-2 (with smokin' great Dada Upgrade applied I might add) and look worse. Quite honestly I like the flag - but someone unfortunately likes it more and is buying it from me which is why I really got the grey 34 - to match the other gear). I was really torn about selling it but when the right price is offered you say yes and then "perhaps" turn around and do a better job than the first - know anyone with an old inexpensive 44 kicking around? Already got faceplate number 2 and case number 2  half way done in the same schema...
;-)

All because it was a non-starter to take 2 months to ship back and then hope they had the right colour to do the conversion which I don't believe they had at the time  and wait a further 2 months to get the new set back. That was when I had to commit to do the paint scheme - it was either that or the ugly olive drab which I had already looked at with my previous Quad 44/405-2 set. The grey I really like!

Will absolutely check out the suggestions with a Tech as soon as I can because soon I will be without the 44....
:-(
Many thanks for your input.
Tim

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10-Nov-2017 06:03 AM

Navydiver

Navydiver

Posts: 27

Update on my post above. Beginning to think it is a combination of issues that the seller was not completely honest about. This explains: 

https://youtu.be/1w3D_PPeTtY

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10-Nov-2017 04:27 PM

Luke

Luke

Posts: 92

I have a unit with simmilar random filter and slope issues, on mine I know the problem is the PCB where the 10uf electrolytics leaked and destroyed the copper tracks under the laquer. The only way I found it was from the frustration of not getting it to work at all I eventually scratched the laquer off where the colour had gone slightly darker and thats when I found the copper was completely degraded. I patched it up with point to point wiring under the pcb, it now works most of the time (good enough for my workshop setup).
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10-Nov-2017 06:20 PM

Navydiver

Navydiver

Posts: 27

Thank you Luke

Do you have a photo or a drawing to show where you shunted the PCB? I ran out of time to open it up and see if there are any brown spots I missed in the photo that the previous owner sent. Will open her up tonight. Those photos I posted at: 

Photo 1:  https://s6.postimg.org/6l8j7xkb5/Quad_34_Main_Board_1.jpg

and

Photo 2:  
https://s6.postimg.org/mw8n494ip/Quad_34_Main_Board_2.jpg

Tim

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10-Nov-2017 06:27 PM

Navydiver

Navydiver

Posts: 27

Also 

For those experiencing similar problems to mine, EJP provided a good assessment via SEPCOR on what he thinks is going on with my setup. I happen to agree with him given all the troubleshooting I have done so far. Here is his assessment based on my less than technical desrciptions of the problems:

There are three problems. 1. 34 muting circuit inoperative, causing initial buzz. 2. F1/2 coming on at power up. 3. 306 thump at power on. (3) is normal, and is distinct from (1). A newly renovated one won't do it, because the PSU caps are well matched, but it comes back over time. All 405, 306, 606, 707, 909 etc., do it. 303s too.

A separate comment:
The thump comes from the 306. It isn't surprising that you didn't get it from the 34 with the power amp already on. The 34 doesn't remember its buttons across power cycles.

Thank you EJP

Hopefully this may be of help to anyone experiencing similar issues....

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11-Nov-2017 10:40 AM

nixie

nixie

Posts: 32

HI i have tried to view the photos but had no luck can some one tell me how to view them
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11-Nov-2017 11:41 AM

Joost Plugge

Joost Plugge

Posts: 938

The repair of the damaged tracks, which is responsible for the switching problems, due to leakage of the cheap elco's Quad used is fully described in the upgrade manual of the 34. 

Joost Plugge

DaDa Engineering

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15-Nov-2017 06:48 AM

Navydiver

Navydiver

Posts: 27

Looking at page 8 of the Quad 34 DIY v3.5 guidelines, my circuit board (V7 I think) looks virtually pristine. I don't see any of the scoring or capacitor leak issues etched in the board at all to cause F1 and F2 to go wonky on me. Am I looking at the wrong part of the board? The circuit diagrams in the service manual are very bad at showing where on the double sided board these things are located I think. I have looked at the board all over except the under side of the input select daughter board with no sides of leakage and bad traces anywhere. Puzzling as I thought the last board they made up (V7 I think) was their best????

I think I will order the upgrade kit tomorrow and see if that might sort some of the issues out...

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15-Nov-2017 06:49 AM

Navydiver

Navydiver

Posts: 27

here are some better pics of the condition of my boards:

https://timothyflath.smugmug.com/Stereo/Quad-34/

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15-Nov-2017 07:25 AM

EJP

EJP

Posts: 1405

You're not going to shotgun the F1/F2 problem with any kit. You are going to have to get down and dirty with the schematic and a voltmeter and examine the appropriate pins of IC15/16. Possibly you may have to replace one of both of those 4013 chips: it's been known. There's a good description of the filter switching on page 6 of the service manual.
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15-Nov-2017 05:20 PM

Navydiver

Navydiver

Posts: 27

Thank you EJP - are those IC's commonly available or are they unobtanium like a lot of old vintage stuff? Would it be worth trying to re-flow the solder connections on the IC's just in case it is a cold solder joint messing things up. The board looks great with no discoloured areas that I can see. Will open it up again tonight after work and have a look closer in the vicinity of the two IC's that you mentioned (if I can find them). Because it is a doubled sided board it is wonky in that the ID characters are on the opposite side of the board to where the devices are. I do see the IC 15 and IC 16 locations on the back of the board and as near as I can tell all the copper traces look pristine so it has to be the chips or the solder connections I think if those are the logic chips for the for the F1/2 buttons. If I could get the two ICs at a reasonable cost somewhere I am inclined to just replace them as I have to replace the FM4 battery with a memory chip that I got from Dada as well. It also won't hurt to to the upgrade kit me thinks as well??? Now I am thinking I should hold off on the upgrade kit because if I can't sort out the F key problems I may just have a parting out unit on my hands????

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15-Nov-2017 06:15 PM

Navydiver

Navydiver

Posts: 27

I am thinking this would be the right chipset when going by the photos I posted earlier?

https://www.ebay.com/itm/1PCS-MC14013BCP-Dual-Type-D-Flip-Flop-/320937465708


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16-Nov-2017 12:08 AM

Ton

Ton

Posts: 18

Perhaps this one  ? 

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16-Nov-2017 01:16 AM

EJP

EJP

Posts: 1405

4013 ICs are jelly-bean parts, easily available. But get some voltage readings first, find out what's going on.
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16-Nov-2017 07:43 AM

Navydiver

Navydiver

Posts: 27

Ton 

I would prefer to get from Dada but the last three items I ordered from them took almost two months to get here to the west coast of Canada. Items ordered from China usually get here in well under 30 days. Geography is against me on this one...

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16-Nov-2017 07:55 AM

Navydiver

Navydiver

Posts: 27

EJP
I think you are misunderstanding my electronics skillsets. I am no ET and would probably electrocute myself with a multi-tester. Not saying I don't want to learn. Just bought and old beater QUAD 303 ser 76047 here locally and am going to try tacking the install of the kit as per: http://www.dadaelectronics.eu/shop/quad-upgrade-kits/quad-303-upgrade-and-revision-kit

Photos are here: https://timothyflath.smugmug.com/Stereo/Quad-303/

What I can't figure out is if the previous owner did any work on it as the caps look pretty new - can anyone tell from the images if this is in original condition based on the ser number and the images?  If original I will order the kit...

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16-Nov-2017 08:24 AM

Navydiver

Navydiver

Posts: 27

I should have mentioned that the 303 amp does work but sounds kind of flat compared to my 405-2 and 306. Maybe just because it is an older solid state unit although the ser # indicates it was made towards the end of the production run of the 303. What baffles me as well is there is no light behind the red power indicator on the back (or is it the front) which indicates to me somebody had gone in and worked on it at some point. I don't even see anywhere on the insides where the lighting leads would have come from????

Oh, and naturally I have someone on this end to assist me when I get out of my depth.

;-)

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16-Nov-2017 08:34 AM

EJP

EJP

Posts: 1405

Well this is a DIY forum. If you need it fixed, send it to one of us, depending on your location.
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19-Nov-2017 08:33 PM

Navydiver

Navydiver

Posts: 27

I am in Victoria, British Columbia. The 303 is going to be a learning project for me. It is pretty beat up so if I botch the job it won't be a big loss. The 34  repair was going to be uber-expensive with DaDa America wanting a much higher cost than I paid for the 34 and the 306 together so will explore another means on that one with a local tech. Shipping is always a killer in time and money. anyway I do have a question about the 303 amp. My amp has four large blue capacitors which can be seen in a link in one of my posts above. The upgrade manual and parts list only lists 3 large size capacitors as per the diagram in the install instructions? Why only three and if I do the basic kit install am I losing performance besides the obvious upgrade to older components?
Tim

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19-Nov-2017 11:15 PM

EJP

EJP

Posts: 1405

Well that's a new question but the simple answer is that the 303 kit replaces 4 x 2000uF capacitors with 3x4700uF capacitors, so the overall capacitance is increased.
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20-Nov-2017 01:30 AM

Navydiver

Navydiver

Posts: 27

I suppose - just kind of seems lop-sided and odd that it wouldn't be a one for one exchange of caps with larger capacities. It does mean a circuit/wiring change I would assume. Oh well, will go for it 

:-)

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20-Nov-2017 03:30 AM

EJP

EJP

Posts: 1405

There is a slight wiring simplification around the now single PSU capacitor. Some people use four capacitors, and indeed my own 303 has four from an upgrade many years ago, which doubles both the output coupling capacitance and the PSU capacitance, but there are other issues to consider when doubling PSU capacitance, and the decision on the kit was not to do it.
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20-Nov-2017 06:09 AM

Navydiver

Navydiver

Posts: 27

Just ordered the 34 and 304 kits - now for the long wait...

;-(

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20-Nov-2017 06:10 AM

Navydiver

Navydiver

Posts: 27

I meant 303 of course...

;-)

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