CR1020 Restoration Guidance

Discussion in 'Yamaha' started by LFazio51, Nov 25, 2017.

  1. LFazio51

    LFazio51 AK Subscriber Subscriber

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    Power Supply C. Board -1: Proposed changes to TR712/715 for improved cooling (UPDATE 1)

    Update to previous post - When placing the Main Power Supply C.Board back into position the bracket closest to the front of the receiver encroaches too much and will not allow it to properly mount. Therefore, it appears I'll have to modify the rear bracket and use for both transistors. I will widen the vertical piece of the bracket so that it is wide enough to hold both transistors.
     

     

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  2. LFazio51

    LFazio51 AK Subscriber Subscriber

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    E.Cap Board - Old Component Measurements
    Having removed all components except the rectifier and diodes, I thought I would share some measurements taken of them.

    Electrolytic Capacitors:
    -(2x) 1000uf/50v - (1) 630uf, 2.9ohms esr, 2.5% v.loss / (1) 632uf, 3ohms esr / 2.5% v.loss
    -(1x) 220uf/63v - 194.2uf, 2.6ohms esr, 1.4% v.loss
    -(1x) 100uf/63v (orange) - 113uf, 3ohms esr, .8% v.loss

    Ceramic Capacitors - All measurements within original spec averaging .01uf, .2% v.loss

    Resistors/Fusistors - All measurements exactly as indicated on schematics.

    Diodes & Rectifiers - Please see photos below

    CIG_IMG005.jpg CIG_IMG006.jpg CIG_IMG003.jpg CIG_IMG004.jpg CIG_IMG001.jpg CIG_IMG002.jpg
     
  3. Oilmaster

    Oilmaster Drillers do it deeper Subscriber

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    Your diodes are fine
    Nice photos, as usual we may say by now :)

    Your caps are tired; the higher the capacitance, the lower the ESR should be.
    So, starting with the orange cap as a reference point (which is known to be the best quality amongst them), the rest doesn't proportionally match in ESR.
    To kill off in advance the potential response from ESR freaks, ESR is also cap type/model dependent, yes....
    Recap was about time.
     
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  4. LFazio51

    LFazio51 AK Subscriber Subscriber

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    That's what I was thinking Oilmaster!
     
  5. Oilmaster

    Oilmaster Drillers do it deeper Subscriber

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    Well, you know, first we help you as kind folks during inventory stage, then unload our guns on you during execution phase :beatnik:
    That's our reward.....

    Just joking ! :)

    In retrospective of my 6 months (or was it 9 ?) CR-2020 restore project (at least 3 evenings per week and 1 day per weekend), I would rate the PSU cap board as only 5% of the entire job. Pre-amp stage will be the biggest hurdle, notably due mandatory opening of all toggle and slide switches.

    With a bit of luck, you can enjoy your CR-2020 next xmas

    I should made the complete CR-2020 rebuild thread, yes, but I am already starting a massive rebuild project of 4 pieces of Victor JM-S7 amps.
    Can't wait to start with those....
    So perhaps I'll abuse your thread instead :)
     
    Last edited: Dec 20, 2017
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  6. LFazio51

    LFazio51 AK Subscriber Subscriber

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    Please do! I think your level of abuse is directly proportionate to my success! :) And rest assured, I've already considered my rate of progress (especially since I'm a Newb, asking many questions, and moving in a very slow and methodical manner) and concur with your time frame. Plenty of upside though; patience should prove very rewarding both in product results and skill growth. If research wasn't such a significant portion of this project, I might be able to improve the timeline but, given it's my first project, I've little confidence this project will conclude sooner than projected.
     
  7. LFazio51

    LFazio51 AK Subscriber Subscriber

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    Material & Wiring Questions

    After much consideration, I've concluded that it would be best for me to completely remove the Main Power Supply Control board and Main Amp boards in order to minimize the difficulty of component replacement, especially given the quantities of small components and my entry-level skill set. This will likely lead to the replacement/modification of some internal wires and definitely require the use of a wire wrap tool. While researching some of these materials, I'm left with a few questions I was hoping to get answered. I realize I could have posted these in the "DIY" Forums but given the empirical knowledge of the CR1020 contained in this thread, I thought it would be more efficient here.

    Questions:

    1. WIRE SIZE - MAIN AMP BOARD: I would like to better understand the different wires sizes and recommended types for the following. I may want to replace them even though I understand it's not necessary:
    a. Brown/Yellow (Amp Board to PSU speaker protect relay)
    b. Orange/White +B/-B (to filter cap board)
    c. Blue/Grey E/-b terminals (to PSU control board)

    2. WIRE WRAPPING TOOL: I've seen many of these tools available in many different sizes and was hoping someone could help or recommend the most appropriate?
     
  8. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    I've been reading your thread with great interest. I don't have one of these amps and most likely never will but have been enjoying your thread. I like the way you are approaching the project and most especially the way that you are documenting it. The thread should be a very useful reference for others in the future. :thumbsup:

    The few times that I've needed to remove and disconnect a complete board I found that it was much easier to just de-solder the entire wire-wrap lead block from the board rather than disturb the wire wraps themselves. It's clean, neat and easy. And then you can just replace/re-solder the block when re-assembling. This saves disturbing the wire wrap entirely.

    Cheers,
    James
     
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  9. LFazio51

    LFazio51 AK Subscriber Subscriber

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    PSU Control Board Removal - Unwrap Pins or De-solder?
    Bratwurst, I never considered this approach and really appreciate your providing this option. Something I will "tuck away" and remember for future projects. Unfortunately, for this CR1020, I'm not really certain it's an option due to the quality and condition of the boards in these Yamaha units. Oilmaster and Avionic have expressed that the board quality is poor, and once exposed to the abnormal heating conditions in this area, traces and pads are easily lifted; therefore, I believe the proper approach with these units must be careful and calculated, with minimal disturbance of good weld joints. Based on the photo below, everything looks great on these pin joints running along the left side of the PSU Control Board. But now you have me wondering if it's even a good idea to "unwrap" them as this may generate abnormal pressure on a joint that looks good to the naked eye, but could/might "twist the pad off" when doing so. I've been able to remove the board out of the frame farther than I anticipated and may choose to perform the work without a complete removal. I'll cross that bridge when I come to it. The decision will likely fall between the benefits of work access vs. the risk of board damage! :idea: Thanks again for providing this idea, I really appreciate it, as well as compliments on the photos - I think they make threads much more interesting as well ;)

    CR1020 PSU Control Board Pins.JPG
     
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  10. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    Heh, heh. Actually iirc it was a tip from Avionic that I read a while back. :) Just passing it on.

    Cheers,
    James

    ps: as I slowly rebuild my soldering skill I've rediscovered liquid solder flux. It really helps get solder removed as quick as possible to reduce how much heat the board etc soak(s) up.
     
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  11. Oilmaster

    Oilmaster Drillers do it deeper Subscriber

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    The photo in post #108 is hiding many stories ;)

    As this unit has had fair amount of interventions before it landed on my bench, several wrapped wires already snapped off, while some were already soldered; one big mess, and too little length left for stripping (which is an inch long for wrapping !)

    So... soldering them directly on the board like a through-hole components is a risky approach (despite some of them are actually installed like that off-factory), and one needs decent access to the solder side of the board until the last one is done. yeah...duh !!! good luck with that, I thought.....

    So... I decided to install PCB solder lugs (providing a post with an eyelet), which allows the wires to be soldered on after installing the board back into its final position. They come in various forms and shapes, but basically like these:

    pcb-solder-lugs.jpg

    Well.... hereby some feedback on trying this......not that easy, but with patience and 2 extra hands it can be done nicely. Why two extra hands? Well, to keep them in a straight position when soldering them into the PCB, otherwise the scene looks like a forest after a hurricane passed by.

    Second hurdle: they may unsolder themselves when soldering in the wire into the eyelet..... yeah ! really annoying! This is were my feedback comes in: take the highest model possible, with TWO holes, in which case the lower hole is there to avoid too much heat going to the PCB solder.

    Nevertheless, I had to limit the heat exposure when soldering the wires in place, and not all of the wire solder joints made were perfectly filled mops (but functionally perfectly fine). I don't like showing it, but here you go:

    AK-31.jpg

    PS, you may notice that one big white square power resistor is replaced by a jumper. That is due to the LED conversion for which the large resistor was no longer required. Those are now 5 LEDs in series. But later I had to add a resistor of 120~150 ohm to dim the LEDs a bit, which would have nicely fit were the jumper is now (now it is part of the wire going to the first LED). Therefore I recommend to install two of those PCB solder lug terminals instead of that jumper, in which case you can later either install a jumper or the current-controlling resistors for the LEDs.

    You may also notice that connection points LB and LC are no longer used; this is due to the same LED conversion; the "loop" does not return to the PCB halfway the loop anymore.
     
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  12. LFazio51

    LFazio51 AK Subscriber Subscriber

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    As always, sage advice and well appreciated Oilmaster! Once again, you've given me much to think about. Every time I feel as if I've made a decision on process and procedure, additional considerations are uncovered, improving the educational aspect and my fond appreciation for this journey.

    Consideration for Main PSU Control Board Removal
    Given what I've been able to research on wire wrapping, along with my concerns for complete board removal, and the additional considerations caused by both, my current level of access may prove to be sufficient (I've posted some photos below for comment), at least significant enough to afford an attempt at recapping without total removal. Again, would love to get comments from those that have tried and can see where I'm currently positioned with regards to access.

    CIG_IMG001.jpg

    CIG_IMG005.jpg

    Consideration for removing wire wrap pins vs. un-wrapping for complete board removal
    Installing the solder lug pins would appear to be the best approach if complete board removal is required unless the pins can be removed with the "wrap intact." Both strategies will require solder work and likely present equal risks. Un-wrapping no longer appears to be an option due to the ultimate need to replace the entire wire since an extra 1"-2" of extra striped wire length would be required. My gut opinion tells me that I should attempt re-capping without complete board removal based my access as illustrated in the photos. If board removal is ultimately required, I feel like it would be best to de-solder the pins, leaving my overall level of success to determine if the pins get solder back or replaced with solder lugs.

    Main PSU Control Board - Overall Condition (trace side)

    CIG_IMG002.jpg
     
  13. avionic

    avionic " Black Knights " Subscriber

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    Power transformer looks like it has a little skin cancer. Great photos.:thumbsup:
     
  14. LFazio51

    LFazio51 AK Subscriber Subscriber

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    You got that right sir. I unscrewed it last night and will be desoldering for complete removal - those end bells will get powder coated before reassembly! I knew someone was gonna catch that! :biggrin:
     
  15. avionic

    avionic " Black Knights " Subscriber

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  16. LFazio51

    LFazio51 AK Subscriber Subscriber

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    Good Morning to All and here's to a Happy New Year! I trust this past week has been somewhat relaxing as we close 2017.

    Transformer Removal - I finally found some time to remove the transformer and thought I would share a few photos in case someone wanted to share some relevant information regarding it's condition or re-install. It appears to be in overall good condition with the exception of the end bell covers - I'll need to get those painted or powder-coated as mentioned above. Regardless, wires and cabling look to be in very good condition. I also managed to remove the AC leads from the fuse block and outlet without damaging anything - YAY! Heck, I was able to get the lead removed from the AC terminal without removing the connecting wire to the others - for a newb, I thought I got kind of lucky!! As always, advice and information is very much appreciated!!

    IMG_0524.JPG
    IMG_0518.JPG
    IMG_0519.JPG
    IMG_0520.JPG
    IMG_0521.JPG
    IMG_0522.JPG
    IMG_0529.JPG
    IMG_0527.JPG
     
  17. CosmoK

    CosmoK New Member

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    Great thead! I've got a 1020 with all the usual power supply problems and will be studying your saga as I start on my restoration this winter. Keep up the good work!
     
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  18. LFazio51

    LFazio51 AK Subscriber Subscriber

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    Project Update - Removal, Repair, & Reinstall Strategy
    Understanding that repairing and reinstalling one board/section at a time is preferable, I'm hesitant to implement this approach due to the level of tear-down required to access each section (i.e. e.cap board, main PSU board, main amp board, etc) along with the need to reconnect and disconnect cabling multiple times. Removal of the E.Cap board required disconnecting main amplifier leads along with other leads from the main PSU board, and the removal of these boards has also provided much greater access to the removal of the main amplifier boards. Moving forward with the standard strategy of repairing and testing each section individually would require that I complete both the E.Cap and Main PSU board, reinstall, and reconnect all cabling, including those from the Main Amp Boards in order to properly test those repairs. Once testing has been completed, all Main Amp Board cabling would then need to be disconnected again in order to remove and repair them. While this may be an option, I believe any gains accrued in the ease of troubleshooting would be far outweighed by the negatives/risk associated with connecting and disconnecting wires multiple times, therefore, I decided to remove the Main Amplifier Boards wile the E.Cap and Main PSU Control Board have been disconnected. I believe the destruction of the right speaker terminal on the main PSU board validates these thoughts; while proceeding no differently than the removal of the left speaker lead, with great caution, and an iron set to 600*, the right terminal simply broke in half when heated! (see pic below).

    IMG_0572.JPG

    Current Disassembly & Board Status
    1. E-Cap Board - Removed / All electrolytic and ceramic capacitors have been removed waiting for the installation of new components
    2. Main PSU Control Board - Disconnected from E. Cap board but still connected and wire-wrapped to the receiver - waiting for testing of old components and new components installation. Will modify location of TR712/715 according to Post #119.
    3. Main Amplifier Boards - Disconnected and removed from the chassis. Boards are extremely dusty and dirty. Boards need to be removed from heat sinks and components tested to determine status of transistors. Would appreciate some experienced advice on testing along with information concerning any "known bad" transistors or other components that should be replaced. (see pics below)

    Main Amp Board 1 Condition (Main Amp board #2 is in the identical condition)
    IMG_0543.JPG
    IMG_0556.JPG
    Interstitial Space between heatsink & TR613/614 below
    IMG_0546.JPG
    TR606 Below
    IMG_0552.JPG
    TR611/612 Below
    IMG_0553.JPG IMG_0554.JPG
    TR608 Below
    IMG_0551.JPG

    Go Forward Strategy - Accepting All Advice

    Since the Main Amplifier boards and heat-sinks have been removed, access to the pre-amp and tone boards has been greatly improved (see pic below). Its unclear to me whether I should move forward with working on repairs to the pre-amp and tone boards next due to the improvement of access and would like to gain some advice here. It seems logical to work on the pre-amp/tone boards next since access has been improved but I'm unsure at the moment. The following sequence would appear to be the most logical:

    1. Repair Pre-Amp/Tone Boards
    2. Repair Main Amp boards and reinstall
    3. Reinstall Transformer
    4. Repair E.Cap Board and reinstall
    5. Repair Main PSU Control Board and reinstall
    6. Repair lights

    IMG_0573.JPG

    IMG_0560.JPG

    Please post all advice and comments freely. Do not hesitate to share any errors you see along with technical information for component testing or known bad components relative to any board.

    And finally, here's wishing everyone a happy and healthy New Year! And for all those traveling and partying this evening, PLEASE BE SAFE!
     
  19. LFazio51

    LFazio51 AK Subscriber Subscriber

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    HAPPY NEW YEAR!!!

    Transistors - Main Amplifier C. Board (TR613/TR614 Measurements/Recommendations) -
    It appears that based on the following measurements, these transistors appear to be "out of spec" and therefore should be replaced. After researching I've found recommendations for the "On-Semi MJ21193/94" I would like someone familiar with the CR1020 to validate this cross-reference or make an alternate recommendation. I've not yet checked the smaller transistors contained within this board but would like to get some advice on "known bad actors" that need replacing along with the appropriate replacement if possible.

    MAIN AMP C. BOARD 1
    -TR614 (Toshiba 2SB555) - PNP - [hFE=105 / Uf=576mV]
    -TR613 (Toshiba 2SD425) - NPN - [hFE=57 / Uf=588mV]

    MAIN AMP C. BOARD 2
    -TR614 (Toshiba 2SB555) - PNP - [hFE=96 / Uf=569mV]
    -TR613 (Toshiba 2SD425) - NPN - [hFE=66 / Uf=581mV]

    Transistors - Main PSU C. Board Recommendations
    -
    Given the focus of transistors in this Post, I thought it would be efficient to spend some time focused on those housed on the Main PSU Control board. There are many smaller transistors contained in this board and again, would be very nice to better understand any "known bad actors" along with their appropriate replacement.
     
  20. Oilmaster

    Oilmaster Drillers do it deeper Subscriber

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    TR613/614 seem to measure normal; first of all it was normal in the 70's that NPN and PNP differed in Hfe values in general (amongst a given complementary pair) due to the state of manufacturing process at that time. Much has changed since then .....

    Furthermore, there is hardly any voltage amplification by these power output devices (it's current here), so nearing "unity gain".
    In other words, actual Hfe does not matter and searching high Hfe and equal Hfe between pairs is meaningless.

    I would say that you could keep the original output transistors; they are also the vintage heart of the unit that we like to see in there.

    What does matter is changing out the driver transistors (TR11/12). VERY fortunately, Toshiba has just started the production of new TO-126 audio transistors, FINALLY having new subs in production (after 15 years wait) for the most famous 2SB649/2SD669 (A or non-A version). They are TTC004B and TTA004B, which will be perfect for that location ! Digikey started to sell them a month ago, while Mouser last week; of course I ordered 50 each of them to see this week to measure and test them out in an upcoming rebuild project. Well, what's to test there actually? they have the right specs....

    ********

    Well back to the PSU control board first as you indicate.....

    TR702 (relay driver) is a trannie that I would replace by default in older units (together with the relay, of course); decent available sub for that is KSA708C
    (note: the C-suffix is not the Hfe ranking for this case, but ECB pin order. Make sure to order the C-version)

    TR712 & 715 was already covered in previous posts.

    Besides all electrolytic caps, I normally replace all zener diodes as well.

    Sub for D715 (HZ78) is TZX6V8D
    Sub for D716/717 (HZ12C) is TZX14B

    While on zeners, sub for D602 (HZ6C) is TZX6V2C
     
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