Harbinger, SHS, other more generic Powered speakers

[guitardad]

Are most of those units amp boards found having universal designs?

trying to find some prints for SHS powered speaker. No model on the unit anywhere, but its a powered 15" in ABS cab. Looks just like a Harbinger version or Pyle.

Has a slight dc offset on the amp (294mv). All transistors check ok. resistors and caps ok. Swapped out questionable 4148 diodes.

I know these are pretty much crap in most opinions, but the unit was free. Might work enough for a monitor.

Thx in advance

edit , looks to be an SHS Audio S-215-A

[olddawg]

SHS S-215-A G2 POWERED 15 SPEAKER CABINET They have a 5 year warranty. One trick is to order one from a reputable supplier. Swap the board. Send it back as defective and ask for a refund. Or... Tell them it was a gift. Will they cover it under warranty. You never know. Give them a call.

[Enzo]

Is there an actual problem? SOme defect in performance? I don't necessarily consider a couple hundred millivolts offset a problem.

[guitardad]

Is there an actual problem? SOme defect in performance? I don't necessarily consider a couple hundred millivolts offset a problem.

It has really bad distortion and a slight hum. Clean at the front of the diff amp. Rails clean and full, I swapped out the 4-5551's and a 5401 since they are cheap anyway, and it came down to about 180mv offset. Distortion still there. I haven't cranked it for any period of time though. I don't see it pulling excess current, but there is a slight hum.

On the output pairs (C5200/A1943) I have .75v on one B and -.2 on the other B (pnp pair). That's not good. I've had several amps in the past where the 4148's were leaky creating bias and other offset issues, so I just swapped those out first.

IDK, might just swap the transistors out later. If any are leaky who knows. They checked fine on a meter even reversed high scale, but that doesn't always mean they are good. This has 4 drivers (2-2SA940, 2- 2SC2073) as well as a bias Xist 2SC2800.

[Enzo]

ANy op amps? Look at their output pins, see if any have DC offset. And I mean like several volts or more, not just millivolts.

[guitardad]

No, this is the standard stuff. Looks like a diff amp pair, current pr, drivers, and darlington configured op prs.

I was just pm'd too that the unit is more than likely an SP15 than the newer S215A. They look similar, just one is a much older version.

[The Dude]

Just an FYI- not sure if it's related or not, but I've had 4 of these in the shop recently with shorted coils on the 15" driver. It's not something you see often. Possibly your speaker has started to crap out and may have shorted coil windings. I would measure the coil resistance and see if it's anywhere close to correct. I believe these have 4 ohm drivers.

[olddawg]

Tickle the diff pair with some freeze mist and monitor the the DC offset. If the hfe of either transistor has changed it will cause an offset. Btw...I have a Harbinger 15" powered monitor like his. I took the badge off. Everyone thinks it's great.