Starting a repair activity, need some advices :)

[yann]

Dear MEF members,

Recently, I have started a repair activity in France, mainly focused on audio equipements.
I have done such repairs from time to time since years now but only for people I know around me (a lot of musicians and sound engineers) but not as an official job.

As my current job is leaving me some free time, I have started a repair activity last month and started to build a stock of parts I may need for the job.

For tube amp, I have different set of tubes, matched or not, based on the most commonly used ones.
I also have a stock of electrolytic caps with common values used in tube amps, and also general purposes values.
For basics components like resistors, caps and diodes I already have plenty of them of different sort and this should be ok.

It would be nice if you can provide me some advices about what could be worth to have in stock, especially for power transistors, opamps or everything based on your experience.

Thanks for your kind help,

Cheers !

[Tom Phillips]

Hello yann,

We have had several discussions about the strategy of building a stock of parts to support a repair operation. Below are links to several discussions which cover the subject. This will be a good starting point for you to review and then you can ask any unanswered questions here.
https://music-electronics-forum.com/showthread.php?t=21270&styleid=12
https://music-electronics-forum.com/showthread.php?t=37758&styleid=12
https://music-electronics-forum.com/showthread.php?t=11220&styleid=12
https://music-electronics-forum.com/showthread.php?t=33751
https://music-electronics-forum.com/showthread.php?t=3898

I favor the strategy of buying extra quantity of the parts I need for a particular repair or scratch build of a common amp model. I do some internet research to verify that the part isn't an oddball one time need. I figure, if I need the part and if many other people are discussion the same repair, then I will need more in the future.

I have been doing this for many decades and I am now overloaded with lots of parts. I also have a lot of fill in parts from Ham fests which included variety boxes of high quality parts donated by local companies.

I have not bought "parts kits" from commercial electronics suppliers because:
1) The kits offered had too many parts that I would never use
2) Many kits, such as those offered by hobby supply & experimenter companies, were made up of low quality parts.

Hope this helps you get started.

Cheers,
Tom

[yann]

Hello Tom,

Thanks a lot for your answer which make sense. I totally agree with you regarding hobby electronic kits, and other component kit you can get for few bucks on *bay coming from China. I had bad experiences in the past with it so now I totally avoid it.
I will go through the threads you listed for sure.

Thanks again !

[Chuck H]

Looks like I never got involved in any of the linked threads. Probably because I'm not a repair tech. But if I have any advice from my personal experience it is this, don't stock many electrolytics unless you already have a regular need for them. Like a service contract for specific repairs that involve a certain value/rating or if you find yourself as the go to for a repair that involves them. In other words, don't stock much unless you know you'll use them soon. E caps go bad with age because the electrolyte crystallizes. I've pulled old E caps out of my stash only to have them fail in the repair soon after. One day I looked over my modest E cap inventory and realized that some were over ten years old and many others were of unknown age. So I just tossed them and now I buy new for each build. Now, as a repair guy it's too inconvenient for you and the customer to order every E cap you need. So just stock a few each of some common value/rating and, if it were me, I would mark them with dates and toss them if they weren't used in three years.

[yann]

Thanks for your inputs. I went through the links provided and I think it answered pretty much all my questions.