[ShawnMcCann]

...but the one channel that works is oh so sweeeeet!  I tested it out last night with a mono LP, Nat King Cole live at the Sands.  I got this disc used on eBay a few months ago, cleaned it manually using Disc Doctor fluid and brushes, and play it on an Audio Technica AT-PL120 turntable with Audio Technica AT-440MLa cartridge.  This copy of the LP has never sounded so good on my system.

I've checked and rechecked all connections, incoming and outgoing cables, and looked for loose or badly soldered joints on the bugle.  Also re-cleaned the bottom of the bugle pcb with alcohol and inspected it with a magnifying glass looking for any connections that might be shorted out.  Haven't found anything yet. 

Yesterday I picked up a cheap multimeter, but I'm not exactly sure what readings I'm supposed to see.  At this point my plan is to compare each component of the good channel against the bad one and assume that the problem will be wherever I see a big discrepancy.  Does that make sense or is there a better method?

Thanks in advance for any advice.

[Sarchi]

Shawn,
this happened to me also; I took a pic full size of the bottom and Jim was able to spot the cold solder joints.  If you post it I'm sure someone can help.  A decent digital pic will reveal more than you can see with the naked eye.

[ShawnMcCann]

Thanks, I'll post a picture later today.

Another question, should there be capacitors in locations C7 and C10 for the Bugle Pro?  The kit instructions indicate so in the parts list, but in the color assembly photo on the hagtech site they're missing.  A problem I'm having is that one of the rotary switches is bumping into the one in location C10.

[hagtech]

First, swap cables between L & R channels.

jh

[ShawnMcCann]

That was the first thing I did.  Also double checked the RCA jacks for shorts.  For now I've disconnected the mono/stereo switch, too.

[ShawnMcCann]

Last night there was a noticable drop in output from the working channel.  Carefully poking around I applied light pressure to one of the op amps and the volume suddenly jumped back up.  So perhaps the op amps aren't seated correctly.

This morning before work I disconnected all the wires from the bugle pcb, took out the op amps, soaked the pcb in isopropyl alcohol for a half hour, scrubbed with a soft paintbrush and dryed it with my wife's hair dryer.  Tonight I'll reinstall the op amps and keep my fingers crossed...

p.s. I also removed the capacitors from locations C7 and C10.  This didn't seem to affect operation in any way so I'll leave them out.  At least the rotary switch isn't bumping into the top of a capacitor any more.

[Sarchi]

BTW, what's a 'Bugle Pro'?

[ShawnMcCann]

The Bugle Pro half kit contains pcbs for the Bugle and the PS, along with chassis front and back panels.  This version also has variable equalization controls.  A more complete description and pictures can be found on the hagerman technology site: http://www.hagtech.com/bugle.html  Scroll down the page for a description of the Bugle Pro.

[ShawnMcCann]

I'm stumped. 

First question:  When I first fired up the bugle a few days ago the transformer got hot fast and the led didn't light up.  Quickly realized I had the diodes in backwards.  The opamps were also in backwards at that time.  Could this have fried one channel in one or all of the opamps?

Second: Is my thought process below ok?

- Since one channel is now working, I assume that means the power supply is not the problem.
- I also assume that all the components on the working side of the bugle are ok. 
- RCA jacks are not shorted.  I checked all four, inputs and outputs.  The mono/stereo switch is not connected at this time.
- Cables to/from the bugle have been swapped in two ways.  I think this can be eliminated as a possible cause.
   1) switched the L/R input cables.  sound still only in the same channel.
   2) switched the L/R output cables.  sound switches to opposite speaker.
 
- Solder joints, while not pretty, appear solid and none of them are touching. 
- I swapped both "sides" of the Cut and Turnover rotary switches.  The good channel was then a little louder, but still nothing from the bad channel.
- I am not exactly sure how to use a multimeter. What I've done is to test each individual resistor and capacitor by touching its leads to the multimeter leads.  The readings I get for the resistors and capacitors on the "good" side match the readings on the dead side. 
- Next to test the opamps, but I'm not sure what combinations of leads to measure.

At this point and with no progress for several days I'm considering buying a new PCB and parts and giving it another try.

[hagtech]

If the opamps are fried you will get dc on the outputs.  Since you have one channel working, use a voltmeter and ohm meter to track down the difference.  Both sides should be the same.

Can you post a photo we can look at.

jh

[ShawnMcCann]

Here's a picture of the underside of the Bugle pcb.  The left side of the board is the channel that is working.

Like I mentioned above, it's not pretty...

[hagtech]

Looks like a number of the holes are not filled in with solder.  Might be good to retouch these.  Also, a long shot, but the output on right channel uses inner hole as ground (all others use outer).  Any chance you have output wires backwards?

jh

[ShawnMcCann]

Found the problem.  Bad op amp in position U2. 

I went to Radio Shack to get a replacement LED (accidentally snapped one of the leads) and while I was there picked up three TLO82 op amps.  Tonight after another 5 hours futzing with the bugle I decided to try replacing the op amps, one at a time.  Success!  The op amp in the middle was the bad one.  Swapped it back in again to make sure it hadn't just been seated poorly, and again no sound in the left channel. 

So for now I have a TLO82 in the second position, and the kit-specified OPA2134 in the other two sockets.  Sounds good, but I now plan to upgrade to LM4562s based on another post here by PatOMalley.

Now to plan the next DIY project...

btw, thanks to everyone for the help!

[ecir38]

Shawn, glad to hear you got it working.

Check out these videos before your next project specifically the throughhole one.  http://www.solder.net/technical/tips.asp
These videos helped me allot for my first attemps. I am no expert here and am not sure what kind of soldering iron you are using but a good soldering station will go along way if you plan to build more kits in the future.