Out of curiosity, what desk are you testing? Perhaps I can offer more specific testing.
Often, just removing modules, carefully cleaning the innards and reinserting them MIGHT clear some problems. Having the frame and a working power supply is a huge bonus for you. (sidebar....you know NOT to remove or insert modules with the power on.....)
I don't have a "new" suggestion for a generator but I used (still do) use one of these antiques:
I built the kit in the mid 1980's. Purists will SCREAM...."UGH! A function generator has horrible distortion levels on the sine wave out!" OK....maybe 0.5% THD. If you want ultra low distortion, then spend 4-figures for an Audio Precision. I like the specs of the wide frequency range, ULTRA flat frequency response, and ultra fast settling time when sweeping frequencies. Perfect for me when aligning tape machines. Plus, it's compact. And it can produce a square wave....more on that later.
I am sure my comments will ignite a flame war here...lol. "OMG You need a HP model 122342715!" "No, you need a BippityBoppityBoo model WTF47965!"
Sidebar....our own John Roberts designed a test set marketed by Loft. That was years ago and I forget the model number......TS-1? Cool unit if you can find one in good condition (but alas, no square wave out).
Again showing my age....for years I used a Tektronix 2215 scope. 60 MHz bandwidth dual trace. I recall when I bought it new in the 1980's it cost $2200 ($6600 today). Plenty of bandwidth for audio (but nowadays "lame" when probing around inside high sample rate/high bit width digital stuff). The 2215 was smallish for it's time.
I now have a much smaller Rigol (model????) with a fancy color screen, yada yada. Cost $500-ish. It does the job, but with only 8 bit sampling so waveforms are "jaggedy" (newer units are 12 bit) and a slow...think it's called refresh rate...it acts like a slug when rapidly changing levels or frequency. The other day I fired up my old 2215 to see if it still worked (yes) and I realized how painfully slow the Rigol "reacted".
Folks here will scream "well, you need faster digital scope." OK....so gift me some money for a new five-figure Tek digital scope! Christmas is coming up....lol!
Square wave signal generator along with a scope lets you quickly detect dying lytic caps in a console's signal path and also do a quick check of the action of EQ on each channel. I am really simplifying things here, but I can elaborate....and I bet others will chime in!
Bri
