Seeking Guidance - 1965 Fisher Ambassador VII A-690

bodenzord

New Member
Hello,

This is my first post. I signed up, because I discovered this website during my initial research in restoring a 1965 Fisher Ambassador VII A-690 stereo console.

This is my father-in-law's stereo that he's asked me to restore. He's the original owner, and the unit is in really good condition. However, it's not working at the moment, and I'm unaware of how long it's been this way. His console includes a L-22 reel-to-reel tape recorder and a Dual 1228 turntable, which replaced the original Dual 1009.

2015-10-20_1965FisherAmbassadorVII_Z2A6002_web600.jpg


The power supply and amplifier is 59-A.

2015-10-20_1965FisherAmbassadorVII_Z2A6050_web600.jpg


2015-10-20_1965FisherAmbassadorVII_Z2A6065_web600.jpg


2015-10-20_1965FisherAmbassadorVII_Z2A6015_web600.jpg


The tuner is 59-T.

2015-10-20_1965FisherAmbassadorVII_Z2A6042_web600.jpg


2015-10-20_1965FisherAmbassadorVII_Z2A6040_web600.jpg


2015-10-20_1965FisherAmbassadorVII_Z2A6030_web600.jpg


A little history:

On 10-25-1976:
  • Audio Hospital in Canoga Park, CA replaced both 6HU8 tubes and one 12AX7.
  • Audio Hospital replaced output transistors for the left channel, Q1, Q2, Q3, & Q4, with ECG121 transistors.
On 12-2-1977:
  • Audio Hospital did a complete dis-assembly, cleaning, lubrication, and reassembly. I'm not exactly sure what this means.
Sometime a few years ago:
  • My brother-in-law replaced many tubes. There are no notes indicating which ones or why.

I'd also like to point out that my father-in-law had the turntable replaced some time ago. I'm not sure of the exact date. The original turntable was a Dual 1009. He replaced it with a Dual 1228. I mention this detail, because there's been a modification to some of the wiring. The following picture shows that the changer connector has been modified. Wiring to pins 2 & 4 have been cut. In their place, an AC receptacal has been wired. This is where the turntable and reel-to-reel are plugged in. At the moment, I have no idea why this was done. So further investigation is needed.

2015-10-20_1965FisherAmbassadorVII_Z2A6058_web600.jpg


1965FisherAmbassador_Schematic_ChangerConnector.jpg



This is what I've done so far:
  • Inspected the fuses - main power 3.2A slo-blo fuse is blown. Remaining fuses are good.
  • Tested the tubes - all tubes are good except one: 12AT7.
  • Inquired with Jim McShane and Metalbone for restoration kits. Neither are able to supply me with a restoration kit. Therefore, I'll be sourcing new components individually.
At this point, I'm planning on replacing all electrolytic and film capacitors unless someone advises against this. I'll also order new diodes and rectifiers. But before I order parts, I have a few questions.
  1. The main fuse is blown. I'm presuming this is due to a short and that it's one of the capacitors. Can anyone suggest any troubleshooting techniques aside from component replacement?
  2. What is the size of the fuses? 6mm x 32mm? or 6.3mm x 32mm?
  3. When looking for a new main fuse, I cannot find a 3.2A 125v slo-blo fuse. Will a 5A 125v work? This is the closest fuse I can find at Mouser.
  4. In this post on Audio Karma, Larry recommends using Nichicon UPW capacitors for replacement filter caps and Nichicon UKL capacitors for all remaining electrolytics. When sourcing parts, it appears that UKL capacitors are radial and not axial. When replacing axial capacitors, are people able to install radial without and spacing issues? Otherwise, I've been able to find replacement Nichicon TVX axial capacitors. Will these be acceptable in this situation instead of UKL?
  5. I'm planning on replacing film capacitors with Orange Drops. When sourcing them, do I spec out the voltage rating as AC or DC? For example, capacitor C1 in the power supply is .022uF, 250V. Is this voltage rating AC or DC?
  6. What are the recommended replacement parts for the diodes and rectifiers?
  7. Can someone recommend a good terminal strip?
  8. Should I install a thermistor? If so, recommended size?
  9. It looks like all four of the Left channel output transistors, Q1, Q2, Q3, & Q4, were replaced in 1976 with ECG121. According to the schematic, Q1 and Q3 are different than Q2 and Q4. Now that they're all the same, is this a problem?
If anyone could offer some guidance through this project, I'd be very appreciative.

Thank you,

Mike
 
Beautiful console and welcome to AK. Theres a couple guys in here that are experts on Fisher consoles, they will be along I'm sure. AL
 
Welcome to AK. I too am a newish member. I have the same Ambassador VII and love it. Mine has been restored electronically and operates and sounds great. Hard to believe they are 50 years old and still looking great. I found mine in Falls Church, VA about six months ago and had it shipped to my home. I have the original Dual 1009 and the vintage Pickering. Enjoy your vintage console.
 
Mike; I'll take your questions in order, and answers will be after each question.

Most likely one or more of the ECG transistors blew. They were junk then and they are still junk. Bets are one or more of them is blown. Pull the perforated covers off and mark them 1 thru 8 and mark the location on the chassis. DO NOT MIX THEM UP. TEST using Mark the Fixer's procedure in post 11 of this thread...... Bi-Polar Junction Transistor Testing

Now for the rest of it......


The main fuse is blown. I'm presuming this is due to a short and that it's one of the capacitors. Can anyone suggest any troubleshooting techniques aside from component replacement? Don't plug it in until all the output transistors have been tested and proved good.

What is the size of the fuses? 6mm x 32mm? or 6.3mm x 32mm? (I HATE METRICS!!!)

Take the fuse down to Home Depot and match it up for size. 3AG size should work OK.


When looking for a new main fuse, I cannot find a 3.2A 125v slo-blo fuse. Will a 5A 125v work? This is the closest fuse I can find at Mouser.

3.0A 250V @ Home Depot. It should be fine without the CL-80's. My Futura doesn't have thermistors in it. and haven't blown a fuse since I rebuilt it in 2010.


In this post on Audio Karma, Larry recommends using Nichicon UPW capacitors for replacement filter caps and Nichicon UKL capacitors for all remaining electrolytics.
When sourcing parts, it appears that UKL capacitors are radial and not axial. When replacing axial capacitors, are people able to install radial without and spacing issues?
Otherwise, I've been able to find replacement Nichicon TVX axial capacitors. Will these be acceptable in this situation instead of UKL?

I replaced axials with radials due to price and the fact that the UPW and UKL are better caps for the duty. You can use theTVX, but it will be a bit noisier. I had no fitment problems except for 2 caps needed longer leads. These were covered with heatshrink tubing. No problems. (I've done 2 59-A's and 4 49-A's this way.)


I'm planning on replacing film capacitors with Orange Drops. When sourcing them, do I spec out the voltage rating as AC or DC? For example, capacitor C1 in the power supply is .022uF, 250V. Is this voltage rating AC or DC?

DC VOLTAGE.

What are the recommended replacement parts for the diodes and rectifiers?
1n4007

Can someone recommend a good terminal strip?
Antique Electronic Supply in Az. www.tubesandmore.com they have different sizes

Should I install a thermistor? If so, recommended size?
CL-80 on each AC LEG if you use them. I've found with the 59-A no problems with it. But DO use a X-Y rated cap to replace the 1st .1uf cap off the power cord in the amp.


It looks like all four of the Left channel output transistors, Q1, Q2, Q3, & Q4, were replaced in 1976 with ECG121. According to the schematic, Q1 and Q3 are different than Q2 and Q4. Now that they're all the same, is this a problem?

No, they are close enough in spec it doesn't matter. I would recommend you pull all the ECG's and check them. Bets are one of them is blown which blowing the fuse. They are germanium, and very expensive.($30+ each) Cost of 8 replacements are going to be more than the unit is worth, and more than likely will be NTE which are worse than ECG(They bought ECG 15 years ago and their transistors are crap). Unless you can find a working 59A to transplant into it.


The original bias circuit in these is very touchy. The adjusting pots are the culprit, along with a lousy design. one goes open for a second and will take out at least 2 if not more transistors.
OPTION1: replace the pots with NEW 10 ohm pots.

OPTION 2:
FISHER did have a fix, and your's doesn't have it. There is a thread in here somewhere (search ain't working too good right now) about it. One of the guys has a A690 and he replaced the parts with new ones. 2n2923 or something like that. It's a temperature compensating diode
that RCA made for a few years and is now about unobtainable. If you can find them they are about $30.00 each.

OPTION 3: a redesign of the bias circuit is the 3rd option. Fred Soop has done it, with the 600-T which uses the same basic circuit.

OPTION 4: Find a WORKING 59-A / 59T combo in a FUTURA or AMBASSADOR from 1965 with a beat up cabinet.

The 1228 did not have the MOLEX connector to plug in to the FISHER cable. So someone bastardized the power cables for the Turntable/R2R. The R2R should have a standard plug that would plug into the amp. NO POWER until the main switch is thrown.

Larry
 
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AlTinkster92 & fisher1965,

Thanks for the welcome.

Larry,

Thank you for the detailed response. After seeing your replys on other threads, I was hoping you'd respond here.

It looks like I've got some work ahead of me. But you've helped me formulate a gameplan. I'm sure I'll have more questions, so I'll ask when they pop up. Additionally, I'll keep this thread updated with my progress and photos as I proceed.

Mike
 
For a quick test that eliminates the output transistors (to see if there are additional power supply problems), you can pull the transistors and replace with 100 ohm resistors between the emitter and collector terminals of each transistor. This allows for measuring the voltage applied to those transistors and if it still blows the fuse, you have problems beyond shorted output transistors.

Mark the transistors as to their position before removing.

Maximum positive and negative voltages should be equal and the junction between each pair of transistors should be approximately half the maximum. The base connections, which are now open, should measure very close to the emitter terminal of the same transistor. These base measurements can be done without the 100 ohm resistors.

These 100 ohm resistors will be dissipating just over 3 watts each, so they will get hot fast. You can get away with 1 or 2 watt resistors for the measurements, but do it quickly and maybe do one channel at a time.
 
Mike; The 3-4 section cap can be replaced with shorty radials. I don't have a list anymore of the caps I used for this, but i ended up mounting 3 of them at the origin point where the 390 ohm 3w resistors are, and grounded them at the terminal strips. Left the old can in (for aesthetics) unhooked. The 3000 uf 35V were replaced with 3300uf 50v and stuffed the cans. Be very careful with them as they are a voltage doubler circuit and the phenolic mounts are brittle. Best to drill out the rivets, and remove the cans with the phemolics, use a heat gun to loosen the adhesive holding the cardboard cover to the can, and then cut the can below or at the shoulder. Gut the can and install the new cap inside, glue the can cover back on, bolt the phenolic wafer to the chassis and wire it up. Here's a picture of my 59-A from 2011with the new caps in it. This was 1st attempt and looks a little rough. I haven't taken any subsequent pics, but you get the idea. The 20A main cap was moved from the center of the chassis to the terminal strip at the top with the 3 390ohm resistors in line with 20B and 20C. It will be on the extreme right of the terminal strip. This will reduce power supply wiring from around the driver section, as 3 of the 4 sections originate there. The 3300uf caps are on a terminal strip on the side ofthe chassis. Subsequent builds have them stuffed. This one was the 1st Hybrid amp i rebuilt and I wasn't really comfortable with Voltage doublers at the time, so I just moved the leads wire by wire from one cap to the other. vs. pulling the can, stuffing it and trying to remember where everything went.

Still working real good.
49A and 59A amp porn.JPG
 
Fred; I just added that to my 49-A and 59-A manuals errata sections. Thanks
Larry
 
Wow! Lot's of great information here without having to ask questions. Thanks.

Best to drill out the rivets, and remove the cans with the phemolics, use a heat gun to loosen the adhesive holding the cardboard cover to the can, and then cut the can below or at the shoulder. Gut the can and install the new cap inside, glue the can cover back on, bolt the phenolic wafer to the chassis and wire it up.
View attachment 634243

So what you're saying is that the 3000uF caps are cardboard covers over a metal can? If so, are you gluing the metal can and the cardboard cover back on? Are you using expoxy?
 
Yes to the cap although with a replacement cap inside you can leave off the metal can part and epoxy the cardboard directly to the base of the old cap and it'll hold.

Yes to the diodes. You could use a diode bridge in place of Cr 3-4-5-6. 4A will be plenty, although i use the 8A version that looks like a table. That way you can epoxy it flat to the bottom of the chassis with theleads sticking up and connect as original. It's a bit of overkill, but I'd rather have some headroom there. No adverse effects.
 
If you should go the parts donor route, you can get the 59A in the 1965 FUTURA and AMBASSADOR. The 690A in the 1964 FUTURA and AMBASSADOR is the SAME IDENTICAL AMP (just has a different model #). Same goes for the Tuner. 59-T for 1965, 690-T for 1964. The only two years for this amp, and tuner.

The 49-A used in the Custom Electra in 1965/66 is very similar to the 59-T with the exception of the number of output transistors, (4 in the 49-A vs. 8 in the 59-A), the extra bias circuitry. the connecting cable for the tuner, and the transformers Other than that they are pretty much the same, so 95% of the parts interchange.
 
historically ceramics last longer than anything else out there. In this case the ceramic has the advantage of size (or lack of it. Normally I use the film as it's cheaper and I have the room in most applications, but in this case I'd use the ceramic.
 
Digi-Key BC2379-ND, Vishay VY1472M63Y5UQ63V0, at 71 cents is X1Y1 rated (highest rating for XY capacitors) and is suitable for all X and Y applications.
 
Thanks Fred. That's one penny cheaper than the Kemet ceramic I found and has higher voltage ratings. Looks like a winner! However, I notice that it's 4700pF instead of .01uF.
 
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Here's an update:

I ordered replacement capacitors yesterday.

I tested all of the output transistors today. The left channel, which has the replaced ECG121 transistors back in 1977, appear to be good. The right channel, which has the original transistors, has an open Base-Emitter Reverse Bias. So all four appear to be bad. Here are the measurements I found. The values are in volts using the Diode setting on my multimeter.

1965_FisherAmbassador_TransistorTest.png


Anyway, I found some NOS ECG121's on eBay, so I purchased those.
 
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Couple of questions...

1. I have a co-worker who has also been serving as an electrical mentor. He's extremely talented. Definitely knows his stuff. In fact, he designed and built a mixing console from the ground up for a couple of ADR stages at my work. He's also thoroughly knowledgeable with regards to amplifiers. He went to school back in the day for it. Anyway, he suggested that I change out the power cord to a NEMA-5 and ground the chassis to Earth Ground. He says that this would bring it up to modern standards, and that he does it on all of his equipment. What are people's thoughts on this?

2. Can someone please explain the Auto Shutoff for me? I simply cannot wrap my brain around the schematic. I've been looking at it and following the circuit to the point where I'm utterly confused. To me, it seems that the Tuner will not turn on if the Auto Shutoff switch is in the "OFF" position. Without a working stereo, I cannot confirm one way or the other. I understand in principle what the feature is supposed to do. I just can't figure it out electrically. And what is the component near the tuner switch that is labeled as "M1"?

1965_FisherAmbassador_TunerSwitchSchematic.png
 
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As the switch works the same in all models, I've copied the pertinent sections fron the 1965 Custom Electra OWNERS Manual.

M1 is the phono motor. S1 is the Phono Motor Switch on the turntable. Basically the Auto-Shutoff will shut the whole machine down when the last record is done. Great for bedtime listening, so the machine isn't doing anything but wasting electricity.

For everything to work "NORMALLY" put the Auto-Shutoff switch in the OFF position. To shut down the whole unit at the end of the last record at bedtime or any other time where you're not real handy to shut it off, turn the Auto switch ON.


AUTO-SHUTOFF.jpg
 
Hi Larry,

Thanks for the reply. I understand what the switch does. However, when studying the schematic, it's not making sense electrically. If you follow the circuit path with the Auto Shutoff switch in the "OFF" position and with the Main power switch in the "ON" position, then the circuit is not closed unless the tuner switch is also in the "ON" position. I'm actually thinking that this is an error with the schematic. It appears that the "ON" and "OFF" positions of the Auto Shutoff switch are mislabeled and backwards. By reversing the labeling, the circuit makes logical sense and works as described.

The following picture is the power source circuit combined from both the 59A and 59T schematics. This is how it's currently indicated.

1965FisherAmbassador_PowerCircuit.jpg
 
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