Valley People Dynamite Compressor: Repair

[eddie_ruff_]

Hi,

Does anyone have a Valley People Dynamite compressor (19" rack version with silver edges)? I purchased one and noticed some oscillation/noise on both channels. I opened it up, and I'm a bit troubled by the PCB. I see two jumper wires and several cut traces per channel...was this factory?

Pictures are here https://drive.google.com/drive/folders/11wg5FtlcXyYY-atHXNgB7ATeoVIVXWTp?usp=sharing

 

[eddie_ruff_]

After probing everything out and checking the schematic it appears to in fact be factory modifications. Interesting...

 

[scott2000]

Old Mytek converters are the same deal ....  Guess they were figuring stuff out......

 

[Monte McGuire]

Sometimes people get PCBs wrong and don't catch it until they've already manufactured some. Cut traces and jumpers aren't a guarantee of problems, and maybe only an indication that you have an early rev. of the device. Sometimes the early rev's of a device are preferable, since the cost cutting process hasn't yet been applied to the device, which may actually degrade its performance compared to the original design.

Good luck in your troubleshooting!

 

[eddie_ruff_]

Replaced all the electrolytics with Nichicon caps and upped the PSU filtering to decrease the ripple...just tested on some drums and all appears to be well. Nice n quiet too 

Still need to clean up some scratchy pots and maybe swap out some opamps...

 

[pvision]

The power transformer on those is tiny. I'm having a real problem finding a 220 volt replacement that will fit in the small cutout in the PCB

I haven't found a source for replacement pots ether - IIRC they have 1/8" shafts

The respond very well to recapping!

Nick Froome

 

[eddie_ruff_]

Yeah i thought about rebuilding the power area with an AnTek toroidal transformer laying flat. But it is working great as is!

 

[scott2000]

I haven't found a source for replacement pots ether - IIRC they have 1/8" shafts

There are a few small pots scattered in here... not sure what you're looking for though.....

https://www.eyguitarmusic.com/Potentiometers_c_93.html

 

[pvision]

I thought of using an external power supply but then then I'd have to fit some kind of latching power connector. The back panel is plastic - and very brittle - so I worry about damage

One of those laptop-style Meanwell 15-0-15 power supplies might be ideal

Nick Froome

 

[thecr4ne]

The power transformer on those is tiny. I'm having a real problem finding a 220 volt replacement that will fit in the small cutout in the PCB

In the original schematic (available in the manual on valley people's website) the PSU specs a DST-4-36 transformer, which is available from Digi-key, and there are plenty on ebay. It's a PCB mount style, but has split primary for 110/220V. Secondary is 36V center tapped, not sure if other mods would be necessary to accommodate it in the later rev PSU.

 

[thecr4ne]

...upped the PSU filtering to decrease the ripple...

What value did you replace the filter caps with?

Also,  if you ever open this up again, could you take a pic of how the ribbon cable interfaces with the PSU? I got a unit missing the power supply and am trying to recreate one as best I can. Finding pics of these opened up has been a challenge.
Cheers.

 

[eddie_ruff_]

What value did you replace the filter caps with?

Also,  if you ever open this up again, could you take a pic of how the ribbon cable interfaces with the PSU? I got a unit missing the power supply and am trying to recreate one as best I can. Finding pics of these opened up has been a challenge.
Cheers.

Apologies for the delay! The unit is racked and in use right now, so I don't have any additional gutshots. The original google drive link has been updated. I've added the schematics I used. Below are my notes from the repair.

C1, C2 are now 4700uF 35V United Chemi-con KYB
C15, C16 are now 0.033uF 63V WIMA
C17 is now a 150uF 50V Nichicon
C6, C7, C12, C18, C19 are now 4.7uF 50V ELNA
C9, C20, C21 are now 0.47uF 50V WIMA
C10 is now 0.068uF 63V WIMA
U10 is now LME49710

 

[thecr4ne]

Many Thanks! I ended up getting another single unit with the PSU in the chassis, so I am just working on making a dual faceplate to accommodate both. I did take some pics of the psu, in case anyone else is interested.

 

[allergies.for.all]

@eddie_ruff_ Do you still have that google drive info? The link no longer works.
Just picked a busted one and the transformer looks like it's been sitting at the bottom of the San Francisco Bay for a decade, so I'm assuming that's part of the problem. Super bad hum on the left channel and it sounds like the voltage is low, kinda like a dying pedal. Upped the filter caps to 50v from 35, hoping that would help, but no dice. Wiring is strange on yours @thecr4ne - positive from the power cord doesn't go to the on/off switch? That's how mine is. Also what's up with all the traces that go nowhere? These guys made some strange decisions, esp in choosing this super brittle acrylic faceplate.

 

[thecr4ne]

@allergies.for.all I'm not sure about the wiring on mine, I'll have to have a look and let you know. Also if you need a new power transformer, I have a spare. The traces that go nowhere I assume are there so the same board can be used for a different purpose. Not super uncommon. As for the acrylic faceplate, sadly I lost the ones I had, but I was smart enough to have scanned them. I was able to re-create the layout digitally using Inkscape. The files probably need to be converted to actually make a faceplate, but if you're interested, they are here:
https://drive.google.com/drive/folders/1hSj0ZJnmI9v0UZ25_WT0WrcafuiR3ZW2?usp=sharing

 

[allergies.for.all]

@thecr4ne Thanks for those scans!

I've checked the voltage coming after the rectifier, and I'm only getting +6v on the problematic side ( channel 1 ), so that explains the distortions/ low power sound. Checked the rectifier diodes and they're all good so it's gotta be the transformer. Could I grab that extra from you? DM me!