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PA Repair – Prosound 1000

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PA Repair

This PA repair, a Pro Sound1000, was brought to me with a couple of reasonably common symptoms. One channel was producing no output, the other channel was very quiet. To be honest I’m surprised that the internal fuses hadn’t blown. The symptoms pointed towards what is probably the most common problem with solid state PA repairs – several of the output devices were short circuit in one channel. This affects the shared supply rails of the power amp, which probably caused the effects in the other channel. I replaced the transistors from the faulty channel and both channels ran fine.

Whilst fixing the amp, I noticed that the reservoir capacitors were leaking, so these were replaced as a precautionary measure to prevent future damage.

If you have a PA repair that needs some attention, please get in touch.

Laney Repair – GH100L

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Laney Repair

What is it with laney amps that makes me forget to photo them?

This Laney amp bias GH100L just needed its bias adjusting to accommodate a new set of EL34s. The GH100L is a fixed bias amp, which means the bias is adjusted (and quiescent current is fixed) by a technician. The opposite of fixed valve bias is cathode valve bias. Confusingly cathode bias is not usually adjustable. For more info, check out this article

If you have a laney repair or a valve amp bias job, please get in touch.

Dr Z Repair – Mini Z

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Dr Z Repair

Dr Z Repair – Mini Z

This Dr Z Repair was a simple job. This DR Z amp is a 2 valve class A amp with one ECC83/12AX7 and one EL84. In this case, the output EL84 valve was faulty, the heater.

The customer asked me to replace the amp with one the fancy ‘cryo’ frozen valves from Harma. I’m not entirely sure if this changes the amp’s tone or just makes Princess Leia fancy it. Maybe if you’ve tried one, you could let me know!

This repair was easily finished within the diagnostic period. When I find a quick fix for customer’s amps I always perform a routine ‘mini service’ to ensure the customer gets their money’s worth.

If you have a Dr Z Repair job that needs doing please, get in touch.

Trace Elliot Repair – GP7SM 200W

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Trace Elliot Repair

Trace Elliot Repair – GP7SM 200W

This Trace Elliot repair is actually a service. My solid state service procedure involves the following steps:

  • Cleaning of all pots and connectors
  • Re-soldering dry or suspect joints
  • Any preventative maintenance required
  • Replacement of out of tolerance or defective components
  • Output power test.

 

I’ve seen a couple of Trace Elliot repairs in a pretty sorry state. The main cause of trouble is normally the ‘bipolar bear’ (bad electronics joke by the designer) output stage. This unit uses a lateral MOSFET output stage that is more reliable, so the customer has little to worry about. I’d recommend that owners of a Trace Elliot amp with the original stage have the output stage replaced at some point if the amp gets really heavy use.

Here’s the owner’s feedback, taken from the now extinct review site ‘www.qype.co.uk’ before it merged into ‘Yelp.co.uk’ and deleted all old reviews!
“ Rowan at Ampworks very kindly serviced my Trace Elliot GSM200 solid state head at extremely short notice. He did a thorough job of making sure everything was as it should be inside, re-soldered any suspect connections, checked the electronics and pots. I can’t recommend Rowan and Ampworks enough. John (Leicester) “(pigbobman, 28-03-2013)
Thanks for the kind words John. I’m glad you were happy with your service.

If you have a Trace Elliot Repair job that needs doing please, get in touch.