Metropoulos Forum

Hello all. I recently completed assembly of a 1969 100W amp and am during initial testing, I'm getting unusual readings on my meter for voltage on the tube sockets. I obtain 3.47VDC for measurements on pin 2/7 of V4, V5, V6, and V7 and have adjusted the bias trim pot to obtain -49VDC - these are fine!

Check out the photo link - the photo of the chart shows unusual readings when testing each pin.

If anyone has ideas where to take a peek or sees anything I missed, please let me know. If additional photos are necessary, please advise. Here's a link to photos: https://www.flickr.com/gp/wedinbordeaux/045Ah2

Thanks!

no0sand1s

OK whats the problem, those readings are normal.

Your heater voltage is a smidge high, but no load is ok
What selector are you using and your wall voltage?

Build looks fine to me, suggest you post the rest of your voltages before you put your tubes in.

Pins 2 and 7 are the heater filament pins so you should be reading AC voltage there. Like the fellas mentioned above, your measurements look fine. A couple extra volts at the wall outlet will cause readings to be slightly higher than expected as will testing without tubes installed.

Everyone - thanks for looking.

Please see the photo of the voltage chart (via my link) showing negative readings/vast differences in what the voltage should be vs. what I'm reading (213v vs -.6 on pin 6 of V1, 168v vs .73v on pin 1 of V2, etc.)?

Ah it would not open on Flickr before.
Yes you have a problem, your heater chain is odd between power and preamp and the HT rail is missing in action on way to v1

axeman wrote: ↑

Sat Apr 21, 2018 5:40 pm

OK whats the problem, those readings are normal.

The readings I've posted on the chart in my photos are not normal.

Kindly check out the photo link - the photo of the chart shows unusual readings when testing each pin.

If anyone has ideas where to take a peek or sees anything I missed, please let me know. If additional photos are necessary, please advise. Here's a link to photos: https://www.flickr.com/gp/wedinbordeaux/19r7my

Thanks!

no0sand1s

danman wrote: ↑

Sat Apr 21, 2018 9:13 pm

Pins 2 and 7 are the heater filament pins so you should be reading AC voltage there. Like the fellas mentioned above, your measurements look fine. A couple extra volts at the wall outlet will cause readings to be slightly higher than expected as will testing without tubes installed.

The readings I've posted on the chart in my photos are not normal.

Kindly check out the photo link - the photo of the chart shows unusual readings when testing each pin.

If anyone has ideas where to take a peek or sees anything I missed, please let me know. If additional photos are necessary, please advise. Here's a link to photos: https://www.flickr.com/gp/wedinbordeaux/19r7my
Thanks!

no0sand1s

Your flickr page says, "You need to be signed in to see this". Additionally, it states, "It appears you don't have permission to view this album". Perhaps you need to change the album settings so general viewing is allowed.

Tazin wrote: ↑

Sat Apr 28, 2018 4:54 pm

Your flickr page says, "You need to be signed in to see this". Additionally, it states, "It appears you don't have permission to view this album". Perhaps you need to change the album settings so general viewing is allowed.

thanks for letting me know. updated now. https://www.flickr.com/gp/wedinbordeaux/19r7my

For some reason I still get the same error. I can view the iPhone & Weddin' albums and photos.

Tazin wrote: ↑

Sun Apr 29, 2018 11:48 am

For some reason I still get the same error. I can view the iPhone & Weddin' albums and photos.

Ugh. Flickr has a mind of it's own. Try this: https://www.flickr.com/gp/wedinbordeaux/19r7my

no0sand1s wrote: ↑

Sun Apr 29, 2018 1:55 pm

Tazin wrote: ↑

Sun Apr 29, 2018 11:48 am

For some reason I still get the same error. I can view the iPhone & Weddin' albums and photos.

Ugh. Flickr has a mind of it's own. Try this: https://www.flickr.com/gp/wedinbordeaux/19r7my

The Flickr page works for me now. First off, a decent amount of the solder joints look terrible...They do not have that nice "flow" look to them. I also noticed that some pictures show a full potentiometer buss ground wire while others show it as piece-meal?...Which ground scheme are you using? Additionally, I did not see a voltage chart among the photos?

You've got a long piece of solder or a component lead cut off laying on V4. Also, the black heater wires at V2 are a bit long at the solder joint so you may want to cut the excess off. Why do you have two yellow wires at the 8K2 2watt B+ dropping resistor?...Are you feeding the 10K & 8K2 2watt resistors backwards (reverse order)?

Tazin wrote: ↑

Sun Apr 29, 2018 6:01 pm

You've got a long piece of solder or a component lead cut off laying on V4. Also, the black heater wires at V2 are a bit long at the solder joint so you may want to cut the excess off. Why do you have two yellow wires at the 8K2 2watt B+ dropping resistor?...Are you feeding the 10K & 8K2 2watt resistors backwards (reverse order)?

Thanks Tazin. I've gone through all solder joints as you suggested. The 2 yellow wires to the 8K2 2W resistor are from V4 pin 6 and the F3 capacitor, depicted in assembly instructions here, step 13
http://valvestorm.com/sites/default/fil ... MP_KIT.pdf

I'm using a modified grounding scheme found here:
https://drive.google.com/drive/folders/ ... EFwZHpXN3M (version #6). I intend on adding the PPMIV when the amp is working.

New link to see updated photos (conflicting photos removed), voltage chart (1st photo) still showing odd numbers. https://www.flickr.com/gp/wedinbordeaux/3ta970