Strange problem with a Technics RS1500US open reel tape recorder. The machine is in very good condition, but always shuts off some minutes before the end of a 26 cm tape reel. Not a mechanical problem, the tape pad is clean and the tension rollers stay in their middle position and are not activated when the machine shuts off prematurely. So I consulted some internet forums, and the advice is to replace all electrolytic capacitors, because more then 30 years old and so on... Reluctantly I followed this advice and replaced all old elco's of the power supply board, and measured the old ones with a quality capacitor tester.
Guess what, all old elco's measured fully O.K., some even better then the new ones. What I allready suspected, this action did not change anything. I do not, and have never believed that changing at random elco's with no visible damage is a serious repair strategy. In this case the problem was TR8, a 2SC828 transistor on the main board control section. Out of the circuit, this transistor measured O.K., but after replacing it the machine works faultless.
Guess what, all old elco's measured fully O.K., some even better then the new ones. What I allready suspected, this action did not change anything. I do not, and have never believed that changing at random elco's with no visible damage is a serious repair strategy. In this case the problem was TR8, a 2SC828 transistor on the main board control section. Out of the circuit, this transistor measured O.K., but after replacing it the machine works faultless.
Hi 968driver,
Careful with that 2SC2878. It isn't a normal transistor at all. It was designed for use in muting circuits. For that application, it has a much higher emitter base breakdown voltage That's why normal transistors don't work well in some of the same applications. A goofy fix is to put a signal diode in series with the base lead. Goofy because it doubles the forward drop voltage. The real fix is to use the same, or a new equivalent.
-Chris
I've seen that very same thing fairly often.
I agree. I need something else to go on, like some of them testing poorly, or I have a better capacitor type for the application. A customer's insistence also rates up there unfortunately as it seems like such a waste of time in some cases. The main filter capacitors rarely ever need to be replaced. Yet those are the first things to go with some of these internet reading folks.
Careful with that 2SC2878. It isn't a normal transistor at all. It was designed for use in muting circuits. For that application, it has a much higher emitter base breakdown voltage That's why normal transistors don't work well in some of the same applications. A goofy fix is to put a signal diode in series with the base lead. Goofy because it doubles the forward drop voltage. The real fix is to use the same, or a new equivalent.
-Chris
Indeed Chris...
I have to add my two cents here too... Being an old, middle-aged and well-seasoned old codger of a tech, I've sat back and watched "the trend" of this "recapping" craze build, mainly because of internet blogs like these. It's grown into a "fix-all-ills" magical procedure with mixed and over-rated results, and is totally unprofessional as far as responsible troubleshooting goes.
The individuals doing this are not techs, some don't even have a clue what Ohm's Law or resistor Color Codes are, much less knowing what capacitor polarity is all about. The "internet guru's" have fostered all this crap, causing these basement/backyard self-proclaimed "I bought a soldering iron, I'm now a full-fledged tech" geeks to flourish. In a lot of cases, it's much like "the blind, leading the blind".
And it's made people like me, a "real" service technician, a lot of additional misery in my work. Jobs that I had to try and figure out what the hell was slopped up, adding to labor time/costs, causing me to pull my hair out at times. Basically, making my work harder than it should be. For that, I certainly don't thank "the internet" for its contributions. I've even had customers walk into my shop with their "ideas" garnered by "the internet" insisting on me doing what they want, when I know better. And sometimes I've had to argue with these uneducated individuals.
Of course, this also includes a myriad of other fields, like automobiles, etc. "You can do anything if you google it up" is not what it cracks up to be.
Oh sure, I'd get arguments sometimes for stating all this, being the internet is loaded with stubborn critters, insisting that I'm wrong, or bitter, or even a troublemaker. But I'm not, I'm a down-to-earth educated technician that has done things the proper way since graduating from tech school.
This "recap craze" in many cases is, as Chris menioned, unwarranted and unneeded - don't believe everything you read "on the internet"
Because a substantial amount of it is nothing but BS.
I gradually ran the voltage up on the T-1980 over a couple of days while limiting current and monitoring the voltage on the caps (without the tubes installed).
Once I was sure they would withstand their rated voltage, I put the tubes in and brought it up.
I measured all of the DC and ripple voltages for each stage compared to the DC voltages on the schematic.
Finally I felt the cans to see if they were getting warm. There was no sense of increased temperature over the chassis.
My conclusion is that the caps are still good and I will not be changing them.
If there is any hum issue, I may add a small additional cap across the first stage following the SS rectifiers. I may also change the rectifiers to UF4007s as my experience is thy are quieter at switch off than standard rectifiers.
Once I was sure they would withstand their rated voltage, I put the tubes in and brought it up.
I measured all of the DC and ripple voltages for each stage compared to the DC voltages on the schematic.
Finally I felt the cans to see if they were getting warm. There was no sense of increased temperature over the chassis.
My conclusion is that the caps are still good and I will not be changing them.
If there is any hum issue, I may add a small additional cap across the first stage following the SS rectifiers. I may also change the rectifiers to UF4007s as my experience is thy are quieter at switch off than standard rectifiers.
Hi TheGimp,
That's great news. Excellent. Do be prepared for sudden death of a capacitor that I have experienced a couple times. It's just inconvenient, that's all. I find reformed capacitors sometimes suddenly go open, probably on startup for that first surge current.
Rectifiers. My view is that you should stay with standard recovery rectifiers and actually add some resistance in series to control the hot switching current and stretch that conduction angle out. It will be even less noisy that way.
One thing most people just don't get is the amount of engineering that goes into the "standard rectifiers". For one thing, the only reason they are not horribly expensive is that they are sold by the box car. With such a high sales volume, the price is lowered way down. Also, they are used in industry and are the most highly engineered component you can imagine. They must be reliable, and if you buy them from a reputable supplier and from a reputable manufacturer, you get reliability. The switch off times have been designed, it isn't just by chance. The UF4007 will not be your friend because they turn off more quickly which shocks the lead inductance more than the regular 1N4007 would do. It's entirely up to you, but if it where mine, I would put new 1N4007's in there and adding some resistance between the diodes and first capacitor. If you want to be really sneaky, you use a low value cap directly after the rectifiers to ground, a resistor, then your normal capacitors. That will make for a very quiet supply. The value of resistance depends on the current draw in a maximum load condition so you don't have too high a voltage drop. Our supply voltages are higher than they were, and losing some voltage will actually help your deck work at the voltages the designers expected. Because the hot switching current is reduced, your filter capacitors will last longer, especially with the lower initial surge current from switch on.
Something to think about.
-Chris
That's great news. Excellent. Do be prepared for sudden death of a capacitor that I have experienced a couple times. It's just inconvenient, that's all. I find reformed capacitors sometimes suddenly go open, probably on startup for that first surge current.
Rectifiers. My view is that you should stay with standard recovery rectifiers and actually add some resistance in series to control the hot switching current and stretch that conduction angle out. It will be even less noisy that way.
One thing most people just don't get is the amount of engineering that goes into the "standard rectifiers". For one thing, the only reason they are not horribly expensive is that they are sold by the box car. With such a high sales volume, the price is lowered way down. Also, they are used in industry and are the most highly engineered component you can imagine. They must be reliable, and if you buy them from a reputable supplier and from a reputable manufacturer, you get reliability. The switch off times have been designed, it isn't just by chance. The UF4007 will not be your friend because they turn off more quickly which shocks the lead inductance more than the regular 1N4007 would do. It's entirely up to you, but if it where mine, I would put new 1N4007's in there and adding some resistance between the diodes and first capacitor. If you want to be really sneaky, you use a low value cap directly after the rectifiers to ground, a resistor, then your normal capacitors. That will make for a very quiet supply. The value of resistance depends on the current draw in a maximum load condition so you don't have too high a voltage drop. Our supply voltages are higher than they were, and losing some voltage will actually help your deck work at the voltages the designers expected. Because the hot switching current is reduced, your filter capacitors will last longer, especially with the lower initial surge current from switch on.
Something to think about.
-Chris
Indeed, deadpool!
The customer: "It's probably something simple" Or.... "Maybe it's a loose wire"
These, and many other offerings by customers are just a way of the customer to convey to the servicer that they don't want to pay a lot for the repairs - a subtle type of "mental advice" they use to lower the cost. In hopes that the servicer will take pity on them......LOL.
Once, a guy brought in a DLP tv set - that had tiny little "sparkles" or white dots in the picture. He hit me up with the same tired line - "it works ok, maybe just needs an adjustment"
Yeah, sure, ok buddy
. Well, the set required several things... Being a couple years old, the cooling fan sucked in tons of dust - so it needed a thorough cleaning - which required major Light Engine dissasembly. But the BIG kicker - and most expensive thing was - the DLP chip was going bad, and my cost to buy a replacement chip was about $100+. In addition, after servicing, an alignment was needed - standard procedure for this type of repair.
Of course the going rate was around $330, total. Our shop listed a $75 up-front estimate fee for DLP sets, which the guy didn't like. And a few days later, when I hit him with the good news estimate, he almost fell over. But after his "heart attack" on the phone, agreed to the repairs.
What people don't seem to understand is.... A shop has expenses - overhead, payroll, stock aquisition, advertising, etc. And this ain't 1962 any more - inflation, parts costs, etc, are all up there too.
An old woman, quite miserable, brought in a GE portable phono that her kid had. Needed a cartridge, some lubrication, luckily it didn't need an idler wheel.. I gave her a $49.95 estimate..... she whined like crazy!, calling me a greedy golddigger! Heck, the cartridge cost me $25 (including shipping) - I had to order it from gary at VM in Michigan - his prices are quite reasonable. So MY final profit on that job was ONLY $25! (in 2014 yet)
Yeah, I was "greedy".
When she came to pick the phono up, she was fussy, disturbed, insisted on seeing it play. As she was getting ready to leave, another customer came in with a stereo. She attempted to stall her exit, and tried to get the guy's attention to "warn them" of my horrible pricing. She grabbed his arm to pull him aside - that's when I went off on her! I told her NO!... she was not to touch another customer in my shop, and to get the hell out before I called the cops. Some foul language from me was added, because I was majorly ticked off. All this for a lousy $25 profit.
The guy with the stereo was humored by all this, and he jokingly asked me if when he picked up his stereo once it's repaired, could he bring his old grandmother...! LOL!
I've seen and heard it ALL after decades of service.
Well, that's for sure!
Normally the worst behaved customers are the ones with the inexpensive repairs, or refused estimates. That's why I was so happy to sell my shop! I no longer had to take everyone that came through the door. I try to screen them on that initial phone call these days. Life is too short to have one of these people ruin my day when we're only trying to help them.
Even now I have large expenses. Equipment has to be maintained, and parts need to be stored to have them on hand when needed. If I added up my parts inventory, I wouldn't be able to sleep at night! Never mind the space, even though it is now my basement, it isn't free, not even close. I still have a 1,200 sq ft shop when you look at tthe space I have. More if you count the garage (my boneyard).
-Chris
Normally the worst behaved customers are the ones with the inexpensive repairs, or refused estimates. That's why I was so happy to sell my shop! I no longer had to take everyone that came through the door. I try to screen them on that initial phone call these days. Life is too short to have one of these people ruin my day when we're only trying to help them.
Even now I have large expenses. Equipment has to be maintained, and parts need to be stored to have them on hand when needed. If I added up my parts inventory, I wouldn't be able to sleep at night! Never mind the space, even though it is now my basement, it isn't free, not even close. I still have a 1,200 sq ft shop when you look at tthe space I have. More if you count the garage (my boneyard).
-Chris
That's true in so many aspects of biz and life. It's why I stopped having a webstore and only respond to direct inquiry. Life is too short to have to deal with whiners.
I only sell components to folks on DIYAUDIO, and none with a short record of participation. (Oh, I do make exceptions for ham radio guys and those folks who habitate in physics labs.)
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Right on, Chris. I as well always treated "the customer" with respect and always showed a cordial, personable attitude. After all, they're our "bread and butter" right? But as you've said, ..........sometimes....... it just isn't possible. You have to know where to cross the line.
Over the last 12 or so years, I believe I had two.... two specific "Better Business Bureau" complaints. And in each case, the customer was trying to scam me out of money with false claims. Having a video recorder of "at the front counter" recordings (with audio) by our security system, I submitted them to the BBB along with other pertinant information. I of course WON both arguments - the dumb customers naturally lost. I don't mess around, I run an honest business, yet some customers think us techs are fools. You have to protect yourselves, particularly these days.
This conversation is an interesting insight into what you face as electronics repair professionals.
I am both a terrible "customer", and a great one. Most of what I own I repair myself, including 4 vintage cars, 3 work/everyday cars, house electrical, plumbing, exterior, roof repairs, light construction, irrigation, appliance installation and repair, electronics for our business, not to mention home audio (with the help of some great folks on this forum), and much, much more. That means I rarely darken a technician's doorstep, so that doesn't help with their cashflow.
But when I do have something beyond my desire or ability to repair, I do my homework and look for a professional with a proven track record, and who doesn't treat me like an fool waiting to be parted with my money. In my youth, that happened enough times for me to develop many skills to allow me to repair, build, create many things, and it's happened plenty of times since. I communicate my needs or desires clearly to the professional, tell them my parameters of what I will and won't be satisfied with, but always do as much homework as possible to understand what is actually possible, feasible, or reasonable. I want the professional to succeed at the task, explain to me how they can accomplish it, where my expectations need to be adjusted; the success criteria must be understood by both of us.
Example: our JCW Mini Cooper needed work I just didn't have time or inclination to perform. After being treated like a fool by dealers who tried to take advantage during scheduled, covered maintenance visits, I found a skilled local specialist who performed the work quickly and perfectly at a slightly higher cost, which was not trivial - $1,700. I made sure to let them know that I understood they had done a great job, and that I appreciated it. That is how I am a great customer.
Unfortunately, most people don't know what they need or want, what they should pay, or how to judge the qualifications of a specialist. Consumers are often taken advantage of by unscrupulous businesses. It can be difficult for them to identify the high-quality, honest, talented pros like those in this discussion.
In my work, we face these same challenges and the ones being raised by you here; customers who want the infeasible, don't want to pay a fair price. After almost 29 years in this field of work, we have become more selective with clients, less egalitarian. It's just about survival. Not every professional is a good fit for every client or customer. Unfortunately, we can't rely on Chris' approach, because we have one dog who is immediately suspicious of every new person, and another who loves everyone, so it's a wash!
My recent repairs:
Audible Illusions L1 - circuit board horribly disfigured by an owner who thought he'd "improve" it by cutting traces to run Monster coax from huge stepped attenuators, new jacks he hacked in there, gargantuan output caps he hung UNDER the board by screwing on some wood to extend the chassis, oh, so much more it's sad to detail. After reconstructing the damaged traces and pads, replacing tube sockets, correcting all the bad solder joints and components, it's been functioning flawlessely for the past 2 days - listening to it now.
Audible Illusions MIIa - same owner, same horrible damage. Same repairs, plus replaced bad potentiometers, repaired the power supply, replaced some leaky electrolytics, reconnected and re-grounded the entire rear jack panel, converted to 3-wire with dedicated chassis ground, insulated fuse clip, etc. It also sounds fantastic.
That's two; I'll post more later.
I am both a terrible "customer", and a great one. Most of what I own I repair myself, including 4 vintage cars, 3 work/everyday cars, house electrical, plumbing, exterior, roof repairs, light construction, irrigation, appliance installation and repair, electronics for our business, not to mention home audio (with the help of some great folks on this forum), and much, much more. That means I rarely darken a technician's doorstep, so that doesn't help with their cashflow.
But when I do have something beyond my desire or ability to repair, I do my homework and look for a professional with a proven track record, and who doesn't treat me like an fool waiting to be parted with my money. In my youth, that happened enough times for me to develop many skills to allow me to repair, build, create many things, and it's happened plenty of times since. I communicate my needs or desires clearly to the professional, tell them my parameters of what I will and won't be satisfied with, but always do as much homework as possible to understand what is actually possible, feasible, or reasonable. I want the professional to succeed at the task, explain to me how they can accomplish it, where my expectations need to be adjusted; the success criteria must be understood by both of us.
Example: our JCW Mini Cooper needed work I just didn't have time or inclination to perform. After being treated like a fool by dealers who tried to take advantage during scheduled, covered maintenance visits, I found a skilled local specialist who performed the work quickly and perfectly at a slightly higher cost, which was not trivial - $1,700. I made sure to let them know that I understood they had done a great job, and that I appreciated it. That is how I am a great customer.
Unfortunately, most people don't know what they need or want, what they should pay, or how to judge the qualifications of a specialist. Consumers are often taken advantage of by unscrupulous businesses. It can be difficult for them to identify the high-quality, honest, talented pros like those in this discussion.
In my work, we face these same challenges and the ones being raised by you here; customers who want the infeasible, don't want to pay a fair price. After almost 29 years in this field of work, we have become more selective with clients, less egalitarian. It's just about survival. Not every professional is a good fit for every client or customer. Unfortunately, we can't rely on Chris' approach, because we have one dog who is immediately suspicious of every new person, and another who loves everyone, so it's a wash!
My recent repairs:
Audible Illusions L1 - circuit board horribly disfigured by an owner who thought he'd "improve" it by cutting traces to run Monster coax from huge stepped attenuators, new jacks he hacked in there, gargantuan output caps he hung UNDER the board by screwing on some wood to extend the chassis, oh, so much more it's sad to detail. After reconstructing the damaged traces and pads, replacing tube sockets, correcting all the bad solder joints and components, it's been functioning flawlessely for the past 2 days - listening to it now.
Audible Illusions MIIa - same owner, same horrible damage. Same repairs, plus replaced bad potentiometers, repaired the power supply, replaced some leaky electrolytics, reconnected and re-grounded the entire rear jack panel, converted to 3-wire with dedicated chassis ground, insulated fuse clip, etc. It also sounds fantastic.
That's two; I'll post more later.
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Hacked-up, butchered-up messes like that I have turned DOWN at the shop.
Turnover time is the same as money to us, and spending an incredible amount of time on something like those pieces isn't worth our time.
Perhaps a DIY'er as you can have the time to invest, but us techs have an in-flow of customers that do not like waiting weeks or months till we're done with someone else's butcher-job to finally get to their equipment.
As an example: completing 8 to 10 jobs in a week netting say, $4000, is much more practical than spending two weeks plus on one $600 "restoration", and losing several impatient customers due to the backlog it creates.
Wiseoldtech: yup, for sure. I was given these for free, and worked on them in the evenings for fun and the challenge, but certainly not for profit. Each one took me about 8 hours, but minimal cost in parts. This is how the perspectives are different and interesting between the DIY and professional engineer and technician crowd. I think we know who learns more from the other, though.