Restored Grundig SV2000 Amplifier
I got this Grundig SV2000 Amplifier with the complaint that it has crackling noises in all modes and one channel is weak. Confirmed the complaint on pre-check-up.
On opening the set and visual inspection, I noticed that there were a few very flimsy resistors soldered, keeping it elevated on the boards, and if I use the blower, it surely will get bent and there is a possibility of these resistors ‘falling in love’ with the nearby component and ‘kiss’ each other! See pictures of a couple of these from a visible portion of the PCB. There are a few more like that, which are in inaccessible area and hidden by other boards from easy view.
So, I cleaned the inside with soft, long bristled brushes only. Then observed that there were several dry solder spots such as these:
Noticed that the board has heavy coating of varnish on it. First thing is to remove it. Otherwise, the varnish will melt together with the lead and form bubbles, causing unseen dry solder inside! So, used denatured spirit, brushed the board thoroughly. Repeated it with turpentine and again with spirit. After third rubbing, most of the varnish coating got removed. Nevertheless, in some places, I had to desolder, clean and resolder the joints. Here is the view of the set after completion of the work:
Checked ESRs of capacitors at random. A few showed out of range. But decided to go after it, only if these are causing some problems. Switched on and the set was working very well on all modes, except tuner. In the tuner mode, there were disturbances, possibly caused by some semiconductors, most probably PNP transistors (from my experience!). When the customer was informed about the progress made, he did not want the tuner mode and asked me not to bother! Here is the set working on final test:
After running the set on for several hours, closed the covers and retested it:
Another job completed, satisfactory to the customer, but not me! (Customers such as these are ardent users as well as traders of old and antique models and do not want overloading of service charges, lest they should never be able to sell or it may have to be sold at very low margins).
This article was prepared for you by Parasuraman Subramanian from India. He is 66 years old and has more than 30 years’ experience in handling antiques equipment Valve Radio, Amps, Reel Tape Recorders and currently studying latest techs classes conduct by Kerala State Electronics Technicians’ Association. He was a BBA graduate, retired as MD of a USA company.
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You may check on his previous repair article below:
https://www.jestineyong.com/restoring-mr-light-mr-680v6-emergency-light/
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Bernie Scott
May 16, 2016 at 10:49 pm
Good job.....I agree with you totally....I have customers that only want the unit working good enough to sell it to somebody else....at first I got caught up in that situation.....but now I tell them that if they want me to do it everything has to be repaired.....because they are going to tell the buyer that so and so just overhauled this for me.....and then it breaks shortly after and I am the one who gets the bad reputation....so I put my foot down...my reputation is worth more than a few quick bucks....Very good article....And it looks like the previous tech wasn`t very concerned about the quality of the work...
Parasuraman S
May 18, 2016 at 2:32 pm
The scene here is different from your country, I assume. I had on many occassions, convinced the customers about the need for a total restoration, but they are disinclined and sometimes opt for return without repair! They will then sell the 'good' equipment at throw away prices to those who take junk and rebuild, or sell to to scrap dealers. Knowing its value very much gnaws my heart, when I knew that dedicated service would have brought it back. Such situation is similar to a sick animal turned to slaughter house, when a good treatment would bring it back to normal condition!
Paris Azis
May 17, 2016 at 1:47 am
Well done Parasuraman!
albert van bemmelen
May 17, 2016 at 3:21 am
Thank you Parasuraman Subramanian. Although the Customer was happy the
repair was not made at too high costs, I'm sure it will work for a
considerable long time after your repair. And if the e-caps in the
Grundig Audio Amplifier Set in time do get worse, you no doubt are able
to fix the set again. As no other repair Engineer is as devoted to a
level of quality as you are!
Robert Calk
May 17, 2016 at 4:30 am
Thanks for sharing the repair with us. But it is not restored. I hope the customer doesn't tell people that you "restored" it and give you a bad name.
Parasuraman S
May 18, 2016 at 2:21 pm
In the present scenario here, there is hardly a guy who will bring another because of a satisfied service. Most of them are all very possessive and would like to take 'private sips' as long as possible! Especially, those who are users and traders, will never divulge info about where they got it serviced for obvious reasons! So, it does not matter to me. In the other cases, even if others want to get something repaired, it will be routed through these known people, keeping me in 'oblivion', which suits me and decreases my pressure! This does not mean that there is no mouth to mouth publicity; it is there, but in lower percentage.
Kevin Hall
May 17, 2016 at 4:54 am
I have enjoyed your posts. We are about the same age. I got into electronics as a child about 12 years old, with some old 20's radios and parts given to me along with a 1929 home study course from the National Radio Institute. I was a tech for years and then an engineer for 40 plus more. You are probably as busy if not more so than me, but if you have room on your social card I would like to strike up a friendship with you. my best regards. "Papa Joe"
Parasuraman S
May 18, 2016 at 2:34 pm
Glad to know you.
beh
May 17, 2016 at 2:38 pm
thanks for this super article .
Yogesh Panchal
May 17, 2016 at 2:43 pm
Yes some time "Romantic mood" of components creates Problem.
thanks for sharing the article.
Humberto
May 17, 2016 at 11:40 pm
Hi Parasuraman, you have done other professional repair again, as usual. Congratulations and keep up sharing your experiencies.
David Towers
May 19, 2016 at 10:11 am
Yes India has a bad reputation for low quality work and poor repairs - good to see you are not one of them - everything done on the cheap , theft of electricity - yet your government can spend millions on Space rockets and political campaigns - At least its not as bad as it is in other country where I worked - I was regularly threatened by customers but they are all mouth and no action as we say in blighty - i only ever had to hit a customer once after he tried to hit me with a baseball bat for not allowing him to take his repaired computer away before paying!
suranga bandara, Suranga Electronics
May 19, 2016 at 12:28 pm
Hi Mr, Audio Expert,
Great and a clever repair job.
Thanks Expert.!