Diagram for Zendrive included.

[Rob Strand]

Looks like everything is pretty solid 0! Expect maybe 200Mv on pin 3

I'd start working on that one.  No need to put in the IC yet.

Pin 8 has the full power supply voltage. 15VDC today

Are you running from a power supply or 1 x 9V battery or 2x 9V battery?
You previous measurements looked like just 1x9V battery. 
You can't get 15VDC from 1x 9V battery.

4) Last resort.   Remove the IC from the socket.  and measure
   pin 8: 10.8V
   pin 3: between 1.7V and 5.2V
   pin 4 solid 0V
   other pins should be zero but they might flicker.

(From my previous post.) These are what you should expect.
One unknown is how much your meter is loading the 470k on pin 3.

It would be a good idea to check the voltage on R8/C7.   
It should be at half the supply voltage ie.
   9V ->  4.5V
  10.8V -> 5.4V
  15V -> 7.5V.

[Zenbend]

 two 9volt battery's nope. It is a power supply ( possibly  meter is  loading around 2volts for the 10.8-11 VDC )
It would make the most sense to me.  15 volts was on my other meter: high loading meter it seems.

I checked the board and it measures about 10.8VCD on pin 8
(All other pins do read a high 7-8 volts  which makes the Ic get Hot)

Without the Ic Installed I get 0 - Volts for all pins ( exempt Pin

The C7 45uf cap reads 1.2VDC or thereabouts (But is not steady!!)

Pin 3 also measures about the same 1.2-1.5VDC
Hope I just missed something obvious maybe there's a short somewhere.

And Ps, Hope all is Great in The New Year for y'all

[Rob Strand]

Throughout the thread there's a lot of voltages which are inconsistent. Are you sure your meters are OK?
Try wiggling the switches on your meter and make sure the measurements are stable.  Another source of problems is breaks in the meter leads.   Beyond that are bad solder joints on the meter PCB.

The C7 45uf cap reads 1.2VDC or thereabouts (But is not steady!!)

Pin 3 also measures about the same 1.2-1.5VDC
Hope I just missed something obvious maybe there's a short somewhere.

The whole circuit depends on the voltage on C7/R8 to be correct and stable.   Without that there is no point continuing.  It is *very* important.  I would not put the IC back in until you can get that part of the circuit working 100%. 

There's only 3 parts involved:  R7, R8 and C7.     Check that part of the PCB very carefully by eye.   Make sure you have C7 in the right way.  If C7 is reversed you may see the problem you have now.

[Zenbend]

Hi Rob, thanks for your help.
C7 was good , I tried a different cap also in its place, I thought It might be burnt out. Still same reading after checking the cap was correctly installed.

(on this thread you asked about the voltage on the Ic with 9volts directly to the PBC board)maybe what I need to do it put a 9Volt battery directly for lower B+

I just checked the meter leads throughout both its a good connection.
it seems not to be the prob, possibly  I might be doing my reading wrong though.
I place the tip to pin 3 and other to pin 2 ?

I took the previous readings with positive (pin) and negative (ground) on the PCB

[Rob Strand]

(on this thread you asked about the voltage on the Ic with 9volts directly to the PBC board)maybe what I need to do it put a 9Volt battery directly for lower B+

I think it would help a lot to solder the battery connect wires directly to the PCB.

When I look at this photo,
https://postimg.cc/zLsw4GH0

I have a feeling one or more solder joints are no making contact.  That would cause a lot of weird behaviour and it might also explain why you measurements aren't consistent - sometimes a bad connection will connect and other times it will not.

Can I ask a question about the PCB?   Before you soldered the parts onto the PCB  were there silver "pads" around each hole, or, was it all white?

Look at this pic you can see the silver pads:
http://www.diyforums.org/SSMH/construction/PCB-5.jpg

[Zenbend]

👋 been away for a few weeks, had some time to rest. Since I hade an 7 month old just started crawling, been a test on how much I can concentrate on projects in and around the house.

Yes. The solder connections are all making contact with silver pads on each Eyelet on the board .
( I have gone over the board and the continuity function on the meter made this simpler to test for any shorts!)

Ps. I'll post some Voltage readings have a 9volt battery connected, now!
Without Ic installed this time. correct Pin layout 1,2,3,4,5,6,7,8 clockwise from the top.

[Zenbend]

Looks like everything is pretty solid 0! Expect maybe 200Mv on pin 3

I'd start working on that one.  No need to put in the IC yet.

Ic removed for these next measurments.

Pin 8 has the full power supply voltage. 15VDC today

Are you running from a power supply or 1 x 9V battery or 2x 9V battery?
You previous measurements looked like just 1x9V battery. 
You can't get 15VDC from 1x 9V battery.

Because of the high voltage, inconsistent readings I've Attached a 9volt battery

4) Last resort.   Remove the IC from the socket.  and measure
   pin 8: 10.8V
   pin 3: between 1.7V and 5.2V
   pin 4 solid 0V
   other pins should be zero but they might flicker.

Pin 8: 8.4V
Pin 3: 4.2V
Other pins are zero (0V)

(From my previous post.) These are what you should expect.
One unknown is how much your meter is loading the 470k on pin 3.

It would be a good idea to check the voltage on R8/C7.   
It should be at half the supply voltage ie.
   9V ->  4.5V
  10.8V -> 5.4V
  15V -> 7.5V.

Measured R8/C7

R8/C7 both read out same half the B+: 4.2V

[Zenbend]

Any new insight would be welcome...
I've checked  Voltage with 9v battery which seems to have a fixed the problems with weird pin readings. All looks good now. Still no sound unless bypassing effect,  Not even a weak signal coming through, on to the board for any suggestions. ?

[Marcos - Munky]

Have you tried an andio probe?

[Zenbend]

Hi, I haven't tried an Audio probe yet. Thx

[Marcos - Munky]

So try the audio probe, to find where's the signal stopping.

[Zenbend]

I've replaced the Ic chip and used a battery for power, circuit check with Audio probe done.
The signal is flowing through but it stops at the output

Here are my findings:
It's very clearly audible through the first components (into the Ic sounds full and deep)
As the (sound  passes through  pin 2  it's distorting and becomes about half in volume)
Finally near the output pot there wasn't any audible sound. (no output on the 100k pot)

I maybe had some battery issues by the end of this search as I had been repairing a part of the board. Luckily I did have a spare board to help me with circuit layout, as I would be the first to say "on a sircuit board I have little experience so far" so appreciate all the help so far!!

Thank you,

[Zenbend]

Still interested in learning how to troubleshoot.learning curve . Just haven't figured out how to check everything especially finding the last bugs around the Ic chip. Any further help would be groovy!