Audio issue a couple of weeks after Moreplay Upgrade [resolved]

[Galluch57]

Hello -
  I wanted to ask some advise as I find myself in a pickle. I built a Moreplay preamp a couple of years ago and it was a very successful build! Been sounding beautiful w/ my Dynaco ST-70. So as soon as I saw the upgrade kit, I jumped on it! I meticulously installed the upgrade over the course of a couple of nights, tested and when I put the Moreplay back in my system the improvement was SIGNIFICANT!!
NOW...here's the bummer part   - the other night I fired up the system and the audio was low and distorted in both channels and seemed to get worse if I tried to turn it up louder. I tried both outputs from the Moreplay with my ST-70 as well as my headphone amp with every source input and it seems to come down to the Moreplay. My problem is that I AM mechanical, have soldering skills and was meticulous and extremely careful with the build but I don't possess the electrical knowledge or have the experience to troubleshoot the issue. Can you help me with that? I'd be so depressed if I had to put my Moreplay on a shelf as decoration (gorgeous as it may be!!Lol)...pride of building aside, it sounds incredible and I hope I can find the problem and repair it without spending a ton to involve a technician - thank you all for any help you can offer!!
Paul Gallucci

 

[Paul Birkeland]

There are voltage checks in the manual on pages 25 and 28, I would start by double checking that those are all correct, and posting what you find there.

 

[Galluch57]

Will do tonight, thank you!

 

[Galluch57]

I’m having trouble with my Moreplay a couple of weeks after installing the upgrade - was working beautifully for two weeks and now low volume distorted audio through both channels. I’m doing the voltage checks to begin troubleshooting but wanted to ask where I should clip the negative lead for the high voltage check now that the volume pot has been upgraded to the board mounted type?

 

[Paul Birkeland]

If it fits, you can clip it to either of the black wires where they connect to the input selector switch.

 

[Galluch57]

Excellent, thank you - I was thinking that but wanted to be certain. I will post voltages  in a few minutes.

 

[Galluch57]

Here are my checks on the Moreplay w/ Upgrade:

Low Voltage Check:
A2 - A7 - 6.26v
B2 - B7 - 6.25 v

High Voltage Check:
6U/16U - 174.3v & 174.4v
B+ Reg TP on PC board - 177.5v
4U/14U - 10.85v & 10.69v

 

[Paul Birkeland]

Can you tell me about the 6V6 tubes you're using?  You have the correct heater voltages to allow the tubes to work, the bias voltage isn't super far off, but the plates aren't pulling down.  As you built the kit, were the voltages correct at that time?  Do you have the ground jumpers on the volume/balance upgrade board?

 

[Galluch57]

They are Marconi 6V6 G - they’ve worked beautifully for maybe a year + before the upgrade. All voltage checks were within spec when I built the upgrade and the ground jumpers are installed on the potentiometer board.

 

[Galluch57]

I’d like to post pics but the jpeg’s from my phone aren’t an accepted file type

 

[hmbscott]

Try this. Change the file name from .jpeg to .jpg.

 

[Paul Birkeland]

Can you put the stock tubes in just to double check?

 

[Galluch57]

Yes, I'm going to. I had to go out of town for a couple of days.

 

[Galluch57]

Here are the Morconi Tubes I've been using.

 

[Galluch57]

...and thank you Paul, changing the file name worked.

 

[Galluch57]

Moreplay Upgrade Pic 1

 

[Galluch57]

Moreply Upgrade Pic 2

 

[Galluch57]

Moreplay Upgrade Pic 3

 

[Paul Birkeland]

Can you measure 6 and 16 with the tubes we provided?

 

[Galluch57]

6U - 172.6v
16U - 172.6v