anatech said:
Replace it. Or at least check it for shorts and opens. I've had lots of those little guys (especially the polystyrenes) go to the big charge dump in the sky. And replacements are cheap.
I wouldn't replace any film caps unless you had evidence they
were faulty i.e. they are shorted. And if they are, you'll find out
in a hurry.
😎
were faulty i.e. they are shorted. And if they are, you'll find out
in a hurry.
😎
Old Amplifier Repairs
I thought it my be worth throwing in my $.02 on repairing these old amplifiers.
When undertaking such a project (as fixing very old equipment), be aware of the engineering involved in the power supply wire and obsolete component replacement. Many of the parts are impossible if not difficult to find. ie. 2N 3440, 2N5415, RCA1A16 and even such a thing as a NS7354 (I think A18 is a good alternative)
However, the production 400a is easier to take care of
and will yield better sound.
Unless the outputs are known good devices (read matched) you have no reason for confidence it will last any period. For 100 trasistors you may get 10% you cannot use. Accept this for a quality rebuild. Electrolytic caps wear out and should all be replaced with better quality.
Stasis II, III and model 4000 also carry the same issues.
Model Stasis I and 800a are especially interesting to repair since so many output transistors exist to fail. 20 years is about all one can expect of these devices. The Capacitors as well.
Main capacitors do not come cheap.
Bottom line:
The parts to do it right will cost $300-$500 and the labor will take 6-10 hours for the average DIY technician or Engineer.
The answers as to how to subsitute un-available parts may be able to be accomplished here.
I thought it my be worth throwing in my $.02 on repairing these old amplifiers.
When undertaking such a project (as fixing very old equipment), be aware of the engineering involved in the power supply wire and obsolete component replacement. Many of the parts are impossible if not difficult to find. ie. 2N 3440, 2N5415, RCA1A16 and even such a thing as a NS7354 (I think A18 is a good alternative)
However, the production 400a is easier to take care of
and will yield better sound.
Unless the outputs are known good devices (read matched) you have no reason for confidence it will last any period. For 100 trasistors you may get 10% you cannot use. Accept this for a quality rebuild. Electrolytic caps wear out and should all be replaced with better quality.
Stasis II, III and model 4000 also carry the same issues.
Model Stasis I and 800a are especially interesting to repair since so many output transistors exist to fail. 20 years is about all one can expect of these devices. The Capacitors as well.
Main capacitors do not come cheap.
Bottom line:
The parts to do it right will cost $300-$500 and the labor will take 6-10 hours for the average DIY technician or Engineer.
The answers as to how to subsitute un-available parts may be able to be accomplished here.
Hi SY,
Polystyrenes tend to short in cassette decks (bias oscillator section) and a few cheap low voltage ones would go open in MPX filters. The ones I see in amps may go open, but not often. They do not do well in a wave soldering enviroment.
You are right though, I do tend to check them all. Joe doesn't have the equipment for this. The best he can do is test for shorts. I do find very few bad in amps. Polyestors are another story. I tend to find them open or with reduced capacitance.
Hi Vintageamp,
Multicomp currently makes 2N3440 and 2N5415. We just need the TO-66 drivers now. 😉
Hi Joe,
You can increase the voltage rating on your replacement caps. They will then fit the board better, and you get a better capacitor. 35 ~ 63 V parts would be reasonable there.
Nelson, thanks. Are the outputs okay as a sub?
-Chris
Polystyrenes tend to short in cassette decks (bias oscillator section) and a few cheap low voltage ones would go open in MPX filters. The ones I see in amps may go open, but not often. They do not do well in a wave soldering enviroment.
You are right though, I do tend to check them all. Joe doesn't have the equipment for this. The best he can do is test for shorts. I do find very few bad in amps. Polyestors are another story. I tend to find them open or with reduced capacitance.
Hi Vintageamp,
Multicomp currently makes 2N3440 and 2N5415. We just need the TO-66 drivers now. 😉
Hi Joe,
You can increase the voltage rating on your replacement caps. They will then fit the board better, and you get a better capacitor. 35 ~ 63 V parts would be reasonable there.
Nelson, thanks. Are the outputs okay as a sub?
-Chris
Re: Old Amplifier Repairs
So to be clear; are you saying this amp cannot be reliable if the transistors are not matched? I just want to be clear on this.
I was under the impression that matching was an audio quality issue.. apparently I am very confused.
Joe
P.S. Thanks for the phone advise! You are the best! 🙂
VintageAmp said:
So to be clear; are you saying this amp cannot be reliable if the transistors are not matched? I just want to be clear on this.
I was under the impression that matching was an audio quality issue.. apparently I am very confused.
Joe
P.S. Thanks for the phone advise! You are the best! 🙂
Hi Joe,
I prefer to match outputs, Nelson disagrees for this amp design. I'll go with him on this.
I believe that as long as the outputs are within the ballpark for gain and you don't push the amp to the edge, it will be fine with new parts as you are ordering.
If you were picking old transistors (pulls) and installing them, I would totally agree with Vintageamp. I also agree with him on service time and point out that it neglects hunting for part suppliers. There is a lot to do in an older amp.
There's another $0.02. In a little while you might have enough for a coffee!
-Chris
I prefer to match outputs, Nelson disagrees for this amp design. I'll go with him on this.
I believe that as long as the outputs are within the ballpark for gain and you don't push the amp to the edge, it will be fine with new parts as you are ordering.
If you were picking old transistors (pulls) and installing them, I would totally agree with Vintageamp. I also agree with him on service time and point out that it neglects hunting for part suppliers. There is a lot to do in an older amp.
There's another $0.02. In a little while you might have enough for a coffee!
-Chris
anatech said:Hi Joe,
I prefer to match outputs, Nelson disagrees for this amp design. I'll go with him on this.
I believe that as long as the outputs are within the ballpark for gain and you don't push the amp to the edge, it will be fine with new parts as you are ordering.
If you were picking old transistors (pulls) and installing them, I would totally agree with Vintageamp. I also agree with him on service time and point out that it neglects hunting for part suppliers. There is a lot to do in an older amp.
There's another $0.02. In a little while you might have enough for a coffee!
-Chris
Well wrong or right.. all this stuff is on order!
1 13 MJ15003GOS-ND TRANS PWR NPN 20A 140V TO3 0 3.29000 $42.77000
2 13 MJ15004GOS-ND TRANS PWR PNP 20A 140V TO3 0 3.29000 $42.77000
3 1 345-1006-ND SILICON GREASE 4 GRAM 0 5.04000 $5.04000
4 12 BER122-ND HEATPAD TO-3/TO-66 .005" Q3 0 0.62900 $7.55000
5 12 P3.0W-3BK-ND RES 3.0 OHM 3W 5% METAL OXIDE 0 0.47600 $5.71000
6 12 P10W-3BK-ND RES 10 OHM 3W 5% METAL OXIDE 0 0.47600 $5.71000
7 4 P22W-2BK-ND RES 22 OHM 2W 5% METAL OXIDE 0 0.28000 $1.12000
8 20 43FR20-ND RESISTOR SILICONE .20 OHM 3W 0 1.86000 $37.20000
9 4 4236PHCT-ND CAP 50V 10UF ELECT AXIAL 0 1.47000 $5.88000
10 8 4254PHCT-ND CAP 100V 10UF ELECT AXIAL 0 1.27000 $10.16000
11 4 338-1075-ND CAP 20PF 300V MICA RADIAL 0 1.27000 $5.08000
12 4 P1287-ND CAP ELECT 470UF 50V SU BI-POLAR 0 1.73000 $6.92000
13 4 P5.1W-2BK-ND RES 5.1 OHM 2W 5% METAL OXIDE 0 0.28000 $1.12000
It literally took me about 7 hours.. which is fine.. I learned a ton.. and a BIG thank you to Anatech!!! THANK YOU THANK YOU THANK YOU!!
(FYI- Anatech also answered a bunch of my lame questions via email)..
Hi Joe,
Thanks.
In scanning your list, I was wondering about the insulators you bought. Are they mica? Normally sold in 100 lots.
Without going through the schematic I really can't comment on your part selections. Vintageamp and Nelson could probably give you more accurate answers.
So, next week you'll have grease on your fingers! Take your time and clean everything up now so it's dry and ready to go when your parts come in.
-Chris
Thanks.
In scanning your list, I was wondering about the insulators you bought. Are they mica? Normally sold in 100 lots.
Without going through the schematic I really can't comment on your part selections. Vintageamp and Nelson could probably give you more accurate answers.
So, next week you'll have grease on your fingers! Take your time and clean everything up now so it's dry and ready to go when your parts come in.
-Chris
anatech said:
Did you need any heat sink pads for t03's? Cuz I now own 1200 of them. 🙂
Also I did not expect anyone to go thru those parts.. its too much work.. I KNOW..🙂
Hi Joe,
I'll bet there is a member close to you that can use some insulators. I'm sure you got a good price when you bought them. I don't see you going through all those, but I haven't checked the Digikey site. What type did you buy?
-Chris
I'll bet there is a member close to you that can use some insulators. I'm sure you got a good price when you bought them. I don't see you going through all those, but I haven't checked the Digikey site. What type did you buy?
-Chris
anatech said:
I boughtwhat SEEMED to be the best.. this is a CRITICAL component.. They were listed as very high performance as opposed to economy..
BER122-ND: 1
HEATPAD: 122
TO-3/TO-66: 20
.005: 17106
Records matching criteria: 1
Manufacturer Part Number Q3-05
Description HEATPAD TO-3/TO-66 .005" Q3
Quantity Available 3896
All prices are in US dollars
Quantity Item Number Reference (optional)
BER122-NDQ3-05
You may submit a request for quotation on larger quantities
Technical/Catalog Information BER122-ND
Standard Package 100
Category Heat Sink Products
Family Heat Sink Pads
Vendor Bergquist
Type Very High Performance
For Use With/Related Products TO-3
Names, Registered & Trademark Names Q-PAD®3
Color Black
Thickness 0.005±"0.001"
Material Silicone/Fiberglass
Lead Free Status Lead Free
RoHS Status RoHS Compliant
Other Names BER122
I'd be happy to send 100 or so of these to you free of charge.. just email me your address.. Steve? Need any?
Also.. I am disassembling my 400a 100% today and sending parts out for anodization.. then I HOPE MR. PASS WILL SIGN MY FRONT PLATE.. HINT HINT HINT!!!!
Hi Joe,
Oh man! Are those expensive!!!!
Can you attempt to return some? I'd hate to see you stuck with that cash outlay! I normally use mica, I haven't even tried those.
See if they will take some (most) back. Explain to them that you made an error. You might be able to catch them before they ship even.
-Chris
Oh man! Are those expensive!!!!
Can you attempt to return some? I'd hate to see you stuck with that cash outlay! I normally use mica, I haven't even tried those.
See if they will take some (most) back. Explain to them that you made an error. You might be able to catch them before they ship even.
-Chris
IMPORTANT
Hey Joe,
Those are not insultors! they are completely wrong for your application. You had better return the entire lot. Use mica. They are cheap and pretty good for heat transfer.
-Chris
Hey Joe,
Those are not insultors! they are completely wrong for your application. You had better return the entire lot. Use mica. They are cheap and pretty good for heat transfer.
-Chris
Re: IMPORTANT
What are they then? The picture looks right.. says for heatsink applications.. ???
And they were only like $7.00.. for 1200. I think I can swing that.. 😉
anatech said:
What are they then? The picture looks right.. says for heatsink applications.. ???
And they were only like $7.00.. for 1200. I think I can swing that.. 😉
Those are a grease replacement. If you look real close at the Q-Pad description at the top of the Bergquist/Digikey page, it says "(Elecrically Conducting Material)". You need an insulator. I would suggest the Keystones seen below on the same page.
Okay.. I'm on it.. I must have chose the wrong one.. this one has no pic and the one I looked at had a picture.. crap.. and thanks for saving my butt.. 🙂
Hey Joe,
No one wants to see someone else have avoidable problems. I use Keystone mica insulators.
I find that a #2 artist's brush is the perfect size for applying grease. Try not to put too much on. A thin even coat.
If you get a little squeezed out around the edges of a transistor, it's about right. Don't obsess over it. Too much is actually bad. You can warp the case and crack the die. Try to tighten them down carefully. Snug, but not too tight. I think On Semi states around 8" / lbs. I could be wrong as it's been years since I read the app note.
Can anyone confirm a number?
-Chris
No one wants to see someone else have avoidable problems. I use Keystone mica insulators.
I find that a #2 artist's brush is the perfect size for applying grease. Try not to put too much on. A thin even coat.
If you get a little squeezed out around the edges of a transistor, it's about right. Don't obsess over it. Too much is actually bad. You can warp the case and crack the die. Try to tighten them down carefully. Snug, but not too tight. I think On Semi states around 8" / lbs. I could be wrong as it's been years since I read the app note.
Can anyone confirm a number?
-Chris
After reviewing that part carefully I think its right.. its a greasless heat sink pad for the t03.. should work great.. and no greasy kid stuff! LOL...
I ordered grease too but should not need it with this pad..
I'll call digikey to be sure in the morning.
I ordered grease too but should not need it with this pad..
I'll call digikey to be sure in the morning.
Man, you have a wrong part.
Here is the pdf explaining what do you have.
It is electrically conductive material used instead of [/B]"GREASE"[/B] and NOT instead of "PAD"
Since you are new here, if you didn't know - you had best of the best that this forum has to offer helping you with your problem.
Please follow literally what they say. It is very easy to make mistake when ordering from DIGI Key or Mauser. It is overwhelming amount of variables and choices, as you have experienced after 7 hours of ordering. Follow the direction and than once you gain some experience than do experiments and mods.
Here is the pdf explaining what do you have.
It is electrically conductive material used instead of [/B]"GREASE"[/B] and NOT instead of "PAD"
Since you are new here, if you didn't know - you had best of the best that this forum has to offer helping you with your problem.
Please follow literally what they say. It is very easy to make mistake when ordering from DIGI Key or Mauser. It is overwhelming amount of variables and choices, as you have experienced after 7 hours of ordering. Follow the direction and than once you gain some experience than do experiments and mods.
roddyama said:
I can confirm the statement that the QPad3 material parts are not insulators. I used some in a 200V application and they conducted so well that the arc blew holes through these pads and pitted the heatsink.
Put a meter on them. 200Ohm face-face, 750Ohm corner to corner is what I measured on some that were TO247 sized.
Bryan